Sample Question Papers Clas XI

SET – ONE [ DELHI REGION] HALF-YEARLY EXAMINATION(2014-15)

CLASS:XI SUB: CHEMISTRY TIME: 3 Hours M.MARKS:70

BLUE PRINT

S.No. UNIT VSA SA I SA II VALUE

BASED LA TOTAL

1 Mark

2 Marks

3 Marks

4 Marks

5 Marks

1 Some Basic concepts of

chemistry 1(1) 1(2) 1(3) - 3(6)

2 Structure of Atom 1(1) - 3(3) - 4(10)

3 Classification of Elements

and Periodicity in Properties 1(1) - - 1(5) 2(6)

4 Chemical Bonding and

molecular Structure - - 3(3) - 3(9)

5 States of Matter: Gases and

Liquids - 1(2) 2(3) - 3(8)

6 Thermodynamics 1(1) 1(2) 2(3) - 4(9)

7 Equilibrium 1(1) - 1(4) 1(5) 3(10)

8 Redox Reactions - 1(2) - 1(5) 1(7)

9 Hydrogen - 1(2) 1(3) - 1(5)

Total 5(5) 5(10) 12(36) 1(4) 3(15) 26(70)

“Value Education with Training”



GENERAL INSTRUCTIONS :All questions are compulsory.

Q. No. 1 – 5 are very short answer question, carrying 1 marks each. Answer these question in one

word or about one sentence each.

Q. No. 6- 10 are short answers questions, carrying 2 marks each. Answer in about 30 words each.

Q. No.11 - 22 are also short answers questions, carrying 3 marks each. Answer in about 40 words

each..

Q. No. 23 is Value Based question carrying 4 marks.

Q No. 24 – 26 are also long answer questions, carrying 5 marks each. Answer these in about 70

words each.

*Use log tables if necessary.

Q.1 If 10 volumes of dihydrogen react with 05 volumes of dioxygen gas, how many volumes of

water will be produced?

Q.2 What is the relationship between De-Broglie wavelength of a matter wave with the velocity of

a microscopic particles .

Q.3 Mention IUPAC name and symbol of element having Aomic Number 127.

Q.4 For an isolated system Δ U = 0 ; what will be ΔS ?

Q.5 Write expression to determine Solubility Product of BaSO4.

Q.6 How much Copper oxide can be obtained from 12.35 g of Copper carbonate ?At. Mass Cu = 63.5

Q.7 How will you justify that Hydrogen Peroxide can be used as

(i) Oxiding Agent (ii) Bleaching Agent.

Q.8 State Hess’s law of Constant Heat Summation by giving an example.

OR

Define the terms Enthalpy of Neutralisation and Bond Enthalpy ?

Q.9 For the Galvanic cell reaction ;

Zn (s) + 2Ag+ (aq) Zn2+ (aq) + 2Ag (s).

i) which electrode is negatively charged ?

ii) what is the direction of the current ?

Q.10 What will be minimum pressure required to compress 500 dm3 of air at 1 bar to 200 dm3 at

300C ?


Q. 11 (i) Draw resonating structures of CO32- .

(ii) Draw the geometry of BrF3 and Pcl5 molecule.

Q.12 Calculate the wave length & Frequency of light wave whose period is 2.0 x 10 -10 s.

Q.13. Give one example of the following

(i) Ionic Hydride (ii) Covalent Hydride (iii) Interstitial Hydride

OR

( i) What causes temporary and permanent hardness of water ?

( ii) Why H2O2 is stored in wax-lined plastic bottles?

Q.14. What is the wavelength of light emitted when the electron in a Hydrogen atom undergoes

transition from the energy level n=4 to n=2.

Q.15 Define Hybridisation . Draw the shapes of BeCl2 and Ethyne.

Q.16 (a) Give an example of Surface Tension.

(b) Calculate temperature of 4.0 mole of a gas occupying 5 dm3 at 3.32 bar if R=0.083 bar dm3

K-1 mol-1 ?

Q.17 For a reaction at 298 K 2A + BC ΔH = 400 kJ mol-1 and Δ S = 0.2 kJ mol-1

At what temperature will be the reaction become spontaneous considering ΔH and ΔS to be

constant over the temperature range ?

Q.18 Derive the relationship between Cp&C v.

Q.19 Write molecular orbital configuration & Campare Bond-Order & magnetic behaviour of N2&O2 .

Q.20 (i) Write Dalton’s Law of Partial Pressure

(ii) Which gas will liquefy first and why? CO2 gas or NH3 gas.

(ii) What is the importance of a and b in Vander waal gas Equation

Q21 a) Draw the Shapes of dyz& dx2-y2 orbitals.

b) State Heisenberg’s Uncertainty Principle. Give its mathematical expression.

Q.22 CaCO3 + 2HCl CaCl2 +H2O +CO2. What mass of CaCO3 is required to react with 25ml of

0.75M HCl completely.( molar mass of CaCO3 =100g & HCl =36.5g)

Q.23 Acids find wide Application in different industries like fertilizer, textile ,Leather etc. At home

,their use for cleaning toilets is very common. However in recent times, bad elements are

using these acids. For example, incidents of Acid throwing on faces ,thereby causing burns

on the face, are being often reported. Balloons filled with acids are thrown on the passers

by on Holi festival.A mixture of Acids is used by the miscreants to cheat women in the name

of cleaning their Gold Jewellery.

After reading the above paragraph, answer the following questions.


(i)What values are expressed in the above paragraph

(ii)Which two acids are mixed to dissolve Gold and in what ratio. Name this mixture also.

Q.24. ( a) Find the conjugate acid / base for the following species : F- , HCN, NH3, CO3 2-

(b) Calculate the pH of the following solution:0.3 g of NaOH dissolved in water to give 200 ml

of solution.

OR

a) Predict if the solutions of the following salts as neutral ,acidic or basic :

NaCl , NH4NO3 , KCN , Na NO2 ,

(b) Explain the terms Buffer Solution & Common ion Effect.

Q.25 (a) Balance the following equations-

(i) HNO 3 + H2S NO +S (by oxidation No. method)

(ii) MnO4-+ Fe +2 Mn+2 +Fe +3 +H2O ( by ion-electron method)

(b) Give example of redox reaction which is also a combination reaction.

OR

(a) Balance the following equations-

( i)MnO4- + I - MnO2 + I2 ( in basic medium by ion-electron method)

(ii) Cr 2O 7- + SO2 Cr +3 + SO 4-2( in acidic medium by oxidation-No. method)

(b) Give 2 differences in oxidation No. & valency.

Q.26 a)Which one will have lower first ionisation energy- Kr or Xe

b) Which one will have lower electron-gain enthalpy. N or O

c) Predict the formula of binary compound that would be formed by ( i)element 114 & F

d) write the general configuration of d block element

e) Arrange the following in increasing order of metallic character :B,Al,Mg,K

OR

a)Which one will have lower first ionisation energy- K or Ar

b) Which one will have lower electron-gain enthalpy. Be or B

c) Predict the formula of binary compound that would be formed by ( i)Calcium & Iodine

d) write the general configuration of f block element.

e) Arrange the following in increasing order of non- metallic character :B,C,Si,N,F




MARKING SCHEME

Ans.No VALUE POINTS / SOLUTIONS

V.P Wise Marks

1. 10 Volumes of water will be produced. 1

2. λ= h/mv or λ = h/p . 1

3. Unbiseptium(Ubs) 1

4. ∆ S > 0 , Positive 1

5. BaSO4=Ba++ + SO4-- ,Ksp=S2 1

6. Molar mass Calculations Answer = 39.8 g

2

7. (i)Reaction of H2O2 with Cl2 water (ii)H2O2=H2O+[O], Coloured Subs+[O]=Colourless Subs

1+1

8. Correct definitions. 1+1

9. (i) Zn anode carries negative charge. ii) Current flows from silver to zinc in outer circuit.

1 1

10. At constant temperature, From Boyle’Law P1V1=P2V2 1 barX500dm3=P2X200dm3 Answer P2=2.5 bar

1 1/2+1/2

11. Draw correct Structure 1+1+1

12. Frequency = 5.0 x 10 9 s -1 Wave Length = 6.0 x 10 -2 m

½ +½+½ ½ +½+½

13. Correct Answer or Correct Causes 3

14. Rydberg Formula, Substitute values and Calculate Answer=486 nm

1+1+1

15. Correct Definition of Hybridisation Structure of Compounds with explanation

1 2

16 (i) Correct Example of Surface Tension (ii) PV=nRT,Substutute the Value and find T=50 kelvin

1 ½+ ½ +1

17. Formula : ∆G = ∆H - T∆S At equilibrium ∆G =0 : ∆H =T∆S T = 2000K

1 1 1

18. Correct Derivation of Cp-Cv=R 3

19. (i) Correct MOC of N2 and O2 (ii) Calculation of Bond Order of N2 and O2

½ + ½ ½ + ½


(iii) N2=Diamagnetic O2=Paramagnetic ½ + ½ 20 (i)Correct Definition

(ii) NH3 gas due to its low Critical temperature (iii)a=Measure of Inter molecula force in a gas molecule b=Effective Size of gas molecule

1 1 ½+ ½

21 (a) Correct Shapes (b ) Impossible to measure simultaneously the position and the momentum of microscopic particles with absolute accuracy. [or any other correct definition] ∆x . ∆p ≥ h / 4 π

½ + ½

1

1

22. HCl in 25 ml of 0.75M=24.375X25/1000=0.6844g 0.6844g HCl will react with CaCO3=100X0.6844g/73=0.938 g

1 2

23. a-(i)The acid should be sold in the market permitting its Licence (ii)Don’t expose your Gold Jewellery to unknown person. (iii)Being Good Citizen, We should not use Acid or any other harmful chemicals while palying with colours or water or Balloon b-Conc.HCl+Conc.HNO3 Ratio=(3:1) Name-Aqua Regia

1+1 (any Two values) ½+ ½ +1

24 a) HF , CN- , NH3, HCO3-,

[or any other correct option] b) Molarity Formula Calculations Answer= 0.0375 OR a) NaCl - Neutral , NH4NO3 - Acidic KCN - Basic , Na NO2 - Basic b) i) Correct explanation with example ii) Correct explanation with example

1+1 1 1 1

25. a)Balance equations stepwise b) Correct explanation

1+1+1 2

26. a (i) Xenon ii) Nitrogen iii) UuqF4 (b) (n-1)d1-10 ns1-2 (c) B<K<Mg<Al Or a (i) Potassium ii)Beryllium iii) CaI2 (b) (n-2)f1-14 (n-1)d00-1 ns2 B<Si<C<N<F

1 1 1 1 1 1 1 1 1 1

***********************************************************


SET – TWO [ DEHRADUN REGION] HALF-YEARLY EXAMINATION(2014-15)


BLUE PRINT

S.No. UNIT VSA SA I SA II VALUE

BASED LA TOTAL

1 Mark

2 Marks

3 Marks

4 Marks

5 Marks

1 Some Basic concepts of chemistry - - 2(3) - - 2(6)

2 Structure of Atom 1(1) 1(4) 1(5) 3(10)

3 Classification of Elements and Periodicity in Properties

1(1) 1(2) 1(3) - - 3(6)

4 Chemical Bonding and molecular Structure

1(1) - 1(3) - 1(5) 3(9)

5 States of Matter: Gases and Liquids

- 1(2) 2(3) - - 3(8)

6 Thermodynamics 1(1) 1(2) 2(3) - 4(9)

7 Equilibrium - 1(2) 1(3) - 1(5) 3(10)

8 Redox Reactions - - 2(3) - - 2(6)

9 Hydrogen 1(1) 1(2) 1(3) - - 3(6)

Total 5(5) 5(10) 12(36) 1(4) 3(15) 26(70)




GENERAL INSTRUCTIONS :All questions are compulsory. Q. No. 1 – 5 are very short answer question, carrying 1 marks each. Answer these question in one word or about one sentence each. Q. No. 6- 10 are short answers questions, carrying 2 marks each. Answer in about 30 words each. Q. No.11 - 22 are also short answers questions, carrying 3 marks each. Answer in about 40 words each.. Q. No. 23 is Value Based question carrying 4 marks. Q No. 24 – 26 are also long answer questions, carrying 5 marks each. Answer these in about 70 words each. *Use log tables if necessary. 1) Considering X-axis as the internuclear axis which out of the following will not form a sigma (σ)

bond and why? (a) 1s and 1s (b) 1s and 2px (c) 2py and 2py & (d) 1s and 2s.

2) What is the basic difference in approach between the Mendeleev’s Periodic Law and Modern

Periodic Law?

3) Use molecular orbital theory (MOT) to explain why the Be2 molecule does not exist.

4) Give condition for a reaction to be spontaneous.

5) What do you understand by the term: Hydrogen economy?

6) Explain why: (i)

Chlorine has higher negative electron gain enthalpy than Fluorine.

(ii) Nitrogen has higher first ionization enthalpy than oxygen.

7) At 25⁰C and 760 mm of Hg pressure, a gas occupies 600 mL volume. What will be its pressure at

a height where temperature is 10⁰C and volume of the gas is 640 mL?

8) Calculate the standard enthalpy of formation of CH3OH(l) from the following data :

i)CH3OH(l) + 3/2 O2(g) → CO2(g) + 2H2O(l) ∆rH⁰ = -726 kJ mol-1

ii) C (s) + O2 (g) → CO2 (g) ∆cH⁰ = -393 kJ mol-1

iii)H2 (g) + 1/2 O2 (g) → H2O (l) ∆fH⁰= -286 kJ mol-1

OR

Define the following:

(i) standard enthalpy of combustion (ii) standard enthalpy of atomization

9) (I)The following concentrations were obtained for the formation of NH3 from N2 and H2 at

equilibrium at 500 K. [N2] = 1.5 x 10—2 M, [H2] = 3.0 x 10—2 M, and [NH3] = 1.2 x 10—2 M.

Calculate equilibrium constant.

(II) Give the relationship between Kp and Kc for a general reaction.

10) Define Coal gasification. How can the production of dihydrogen be increased in this process?


11) Calculate the concentration of HNO3 in moles per litre in a sample, which has a density, 1.41 g

mL-1, and the mass percent of nitric acid in it being 69%.

12) Use the periodic table to answer the following questions:

(i) Identify an element with 5 electrons in the outer sub shell.

(ii) Identify an element that would tend to lose 2 electrons.

(iii) Identify an element that would tend to gain 2 electrons.

(iv) ) Identify the group having elements in solid, liquid and gaseous state at room

temperature.

13) CaCO3 reacts with aqueous HCl to give CaCl2 and CO2 according to the reaction,

CaCO3(s) +2 HCl → CaCl2 (aq) + CO2 (g) + H2O (l),

what mass of CaCO3 is required to react completely with 25 ml of 0.75 M HCl?

14) Explain why:

(i) BeH2 molecule has a zero dipole moment although the Be—H bonds are polar.

(ii) H2O is liquid while H2S is gas.

(iii) NH3 molecule is more polar than NF3.

15) A neon—dioxygen mixture contains 70.6 g O2 and 167.5 g neon. If pressure of the mixture of

gases in the cylinder is 25 bar. What is the partial pressure of O2 and Ne in the mixture?

16) (I) Express the change in internal energy of a system when:-

(a) No heat is absorbed by the system from the surroundings, but work (w) is done on the

system. What type of wall does the system have?

(b) No work is done on the system, but ‘q’ amount of heat is taken out from the system and

given to the surroundings. What type of wall does the system have?

(c) ‘w’ amount of work is done by the system and ‘q’ amount of heat is supplied to the

system. What type of system would it be?

17) (i) At 473K, equilibrium constant, Kc for decomposition of PCl5, is 8.3 x 10-3,if decomposition is

depicted as:

PCl5(g) → PCl3(g) + Cl2(g) ∆rH⁰ = 124.0 kJ mol—1

(a) Write an expression for Kc for the reaction

(b) What is the value of Kc for the reverse reaction at the same temperature.

(ii) The value of Kc for the reaction 2A → B + C is 2 x 10 –3. At a given time, the composition of

reaction mixture is [A] = [B] = [C] = 3 X 10 –4 M. in which direction the reaction will proceed?

18) (I)Critical temperature of CO2 and CH4 are 31.1⁰C and -81.9⁰C respectively. Which of these has

stronger intermolecular forces and why?

(II)In terms of Charles’ law explain why -273⁰C is the lowest possible temperature.


(iii) why vegetables are cooked with difficulty at a hill station ?

19) (A) Enthalpies of formation of carbon to CO (g), CO2 (g), N2O (g), and N2O4 (g) are -110, -393, 81,

and 9.7 kj mol-1 respectively. Find the value of ∆rH for the reaction:

N2O4 (g) + 3CO (g) → N2O (g) + 3CO2 (g)

(B) Predict in which of the following, entropy increases/decreases:

(i) A liquid crystallizes into a solid.

(ii) Temperature of a crystalline solid is raised from 0 K to 115 K.

20) Balance the following redox reactions by ion-electron method:

MnO4—

(aq) + I—(aq) → MnO2(s) + I2(s) (basic medium)

21) What are the causes of temporary & permanent hardness of water? Give Clark’s method for

removing temporary hardness of water .

22) (a) Given the standard electrode potentials, K+/K = -2.93 V, Hg2+/Hg = 0.79 V, Ag+/Ag = 0.80 V,

Mg2+/Mg = -2.37 V, Cr3+/Cr = -0.74 V.Arrange these metals in increasing order of their

reducing power.

(b) Find oxidation no. of the underlined elements in each of the following species:

(i) K2MnO4 (ii) NaBH4.

(c) Can we use KCl as electrolyte in the salt bridge of the cell:

Cu(s) l Cu2+ (aq) ‖ Ag+(aq) l Ag (s).

OR

Depict the galvanic cell in which the reaction:

Zn(s) + 2 Ag+ (aq) → Zn2+ (aq) + 2Ag(s), takes place, further show-

(i) Which of the electrode is negatively charged?

(ii) The carriers of the current in the cell.

(iii) Individual reactions at each electrode.

23) Different types of electromagnetic waves are playing very important role in our day to day life.

Use of X-rays and ultrasound waves is well known in medical field. Our cellphone works by

emitting and catching radiation. No doubt all these have proved very helpful but there are

strong views that these radiations are harmful if we are exposed to them for a long time.

After reading the above paragraph,answer the following questions:

i. what values are expressed in the above para.

ii. why is it advised not to keep your cellphone in the breast pocket of your shirt.

iii. why a person should go for minimum X-ray.

iv. give one important application of ultrasound waves in medical fields.


24.(a) (I) The electron energy in hydrogen atom is given by En=( - 2.18 x 10—18 )/n2 J. Calculate the

energy required to remove an electron completely from the n=2 orbit. What is the longest

wavelength of light in cm that can be used to cause this transition?

(II) What is the lowest value of n that allows g orbitals to exist?

(III) a. How many sub-shells are associated with n=4?

b. How many electrons will be present in the sub-shells having ms value of –1/2 for n=4?

OR

(a)The threshold frequency,ν0 for a metal is 7.0 x 1014s-1.Calculate the kinetic energy of an electron emitted when radiation of frequency ν= 1.0 x 1015 s-1 hits the metal. h= 6.6 x 10-34Js (b) The unpaired electrons in Al and Si are present in 3p orbital. Which electrons will experience more effective nuclear charge? (c) In Rutherford’s experiment, generally the thin foil of heavy atoms, like gold, platinum etc. have been used to be bombarded by the α-particles. If the thin foil of light atoms like aluminium etc. is used, what difference would be observed from the above results?

25) (a) What is meant by the term bond order? Calculate the bond order of: O2, O2+, O2

—

(superoxide), O22—(peroxide).

(b) Compare the relative stability of these species and indicate their magnetic properties also. OR

(i)Arrange the following in increasing order of their size : (a) Na+ (b) Mg2+ (c) O2- (d) F-

(ii) What are the atomic numbers of elements whose outermost electros are represented by

(a) 2p4 (b) 3p5 (c) 4s1

(iii) Which atoms are indicated by the following configurations? (a) [Ne] 3s2 3p3

(b) [Ar] 4s2 3d1 (c) [He] 2s1

26 (a) what do you mean by pH? The concentration of hydrogen ion in a sample of soft drink is

3.8×103 M. What is its pH ?

(b) Describe the effect of:

(i) addition of H2

(ii) addition of CH3OH

(iii) removal of CO

(iv) removal of CH3OH, on the equilibrium of the reaction,

2 H2 (g) + CO(g) → CH3OH(g)

OR

(a)Define Buffer solution. Give example

(b) What is the effect of change in temperature on ‘Kw’ (ionic product of water)?

Calculate the molar solubility of Ni(OH)2 in 0.10 M NaOH. The ionic product of Ni(OH)2

is 2.0 × 10-15.




MARKING SCHEME Q No

Value Points Point wise mark

Total mark

1 ONLY (C), x-axis as internuclear axis,lateral overlapping between the two 2py

forming a π-bond.

½+1/2 1

2 the basic difference in approach between the Mendeleev’s Periodic Law and

Modern Periodic Law is the change in basis of classification of elements

from atomic weight to atomic number.

1 1

3 E.C.of 4Be= 1s2 2s2,m.O.E.C. of Be2 = σ1s2 σ*1s2 σ2s2 σ*2s2

Bond order =1/2 (4-4) = 0, Hence Be2 does not exist.

½+1/2 1

4 ΔG < 0 1 1

5 the production, storage and transportation of energy in the form of liquid or

gaseous H2.

1 1

6 (i)Due to small size of F, the e- -e- repulsions in the 2p-subshell are

comparatively large and hence the incoming e- is not accepted with the

same ease as is the case with larger Cl-atom.

(ii)E.C. of 7N = 1s2 2s2 2p3 in which 2p-orbitals are exactly half-filled is more

stable than the E.C. of 8O = 1s2 2s2 2p4 in which 2p-orbitals are neither half-

filled or completely filled.

1+1 2

7 P1 = 760 mm Hg, V1 = 600mL, T1 = 25 + 273 =298 K, V2 = 640 mL and T2 = 10 +

273 = 283 K

According to combined gas law,

P1 V1/ T1 = P2 V2/ T2

P2= P1 V1T2/T1 V2

P2= 676.6 mm Hg

½

½

1

1

8 Aim : C(s) + 2 H2 (g) + ½ O2 (g) → CH3OH(l), ΔfH⁰ = ?

Eqn. (ii) + 2 X Eqn. (iii) - Eqn. (i) gives the required Eqn. with

ΔH = - 393 + 2 X (-286) – (-726) kJ mol-1 = - 239 kJ mol-1

OR

(i) Standard enthalpy of combustion is defined as the enthalpy

change per mole (or per unit amount)of a substance, when it

½ +

½ + 1

1+1

2

2


undergoes combustion and all the reactants and products being

in their standard states at the specified temperature.

(ii) It is the enthalpy change on breaking one mole of bonds

completely to obtain atoms in the gas phase.

9 (I) the equilibrium reaction is : N2 (g) + 3 H2 (g) = 2 NH3(g)

Kc = [NH3]2/[ N2][ H2]3

Kc = [1.2 X 10-2]2/[ 1.5 X 10-2][ 3.0 X 10-2]3

= 3.55 X 102

(II) Kp =Kc (RT) Δn

½+1/2

+1/2

1/2

2

10 The process of producing syngas or synthesis gas from coal is called ‘coal

gasification’ .

C(s) + H2O (g) 1270 K,Ni CO(g) + H2 (g)

the production of dihydrogen, obtained from coal gasification, can be

increased by reacting CO(g) of syngas with steam in presence of iron

chromate as catalyst at 673 K.

CO(g) + H2O (g) FeCrO4,673 K CO2(g) + H2 (g)

1 + 1 2

11 Mass percent of 69% means that 100 g of HNO3 solution contain 69 g HNO3

by mass.

Molar mass of HNO3 = 63 g mol-1

Moles in 69 g HNO3 = 69 g / 63 g mol-1 = 1.095 mole

Volume of 100 g HNO3 solution = 100 g / 1.41 g mL-1 = 70.92 mL = 0.07092 L

the concentration of HNO3 in moles per litre = 1.095 mole / 0.07092L

= 15.44 M

½

½

1

1

3

12 (i) halogens, eg. F, Cl, Br, I etc. (ii) alkaline earth metals, eg. Mg, Ca, Sr, Ba.

(iii) O or S (iv) 17th Gr. (Halogen)

1 X 3 3

13 Step 1.To calculate mass of HCl in 25 mL of 0.75 M HCl

1000 mL of 0.75 M HCl = 0.75 mole = 0.75 X 36.5 g = 24.375 g

So, 25 mL of 0.75 M HCl = 24.375 g X 25 g / 1000 = 0.6844 g.

Step 2. To calculate mass of CaCO3 reacting completely with 0.6844 g of HCl

CaCO3(s) +2 HCl → CaCl2 (aq) + CO2 (g) + H2O (l)

2 mol of HCl, i.e.2X 36.5 b = 73 g HCl react completely with CaCO3 = 1mol

=100 g

0.6844 g of HCl will react completely with CaCO3 = 100 X 0.6844 g / 73 =

0.938 g

½

1

½

1

3


14 (i) BeH2 molecule is linear (H-Be-H ) so that the two Be-H bond moments are

equal and opposite and hence cancel out.

(ii) Due to H – bonding in H2O

(iii) In NH3 all the bond dipoles are in same direction as that of lone pair

while in NF3 bond dipoles are opposite to that of lone pair.

1 X 3 3

15 nO2 = 70.6 g/ 32 g mol-1 = 2.21 mol, nNe = 167.5 g /20 g mol-1 = 8.375 mol

xO2 = 2.21 /2.21 + 8.375 = 0.21, xNe = 1-0.21 = 0.79,

Pgas = Ptotal X xgas,

PO2 = 25 bar X 0.21 = 5.25 bar, PNe = 25 bar – 5.75 bar = 19.75 bar

½+1/2

½+1/2

½+1/2

3

16 (i) Δ U = w ad, wall is adiabatic

(ii) Δ U = - q, thermally conducting walls

(iii) Δ U = q – w, closed system

1 X 3 3

17 (i) (a) Kc = [PCl3(g)] [Cl2(g)]/ [PCl5 (g) ]

(b) = K’ = 1/ Kc = 1/ 8.3 X 10-3 = 120.48

(ii) Qc = [B] [C] / [A]2 ,as [A] = [B] = [C] = 3 X 10-4 M,

Qc = 1, as Qc ˃ Kc, reverse direction.

½

1

½

½+1/2

3

18 (i) CO2 due to its higher Tc

(ii) At this temp. volume of gas becomes zero

(iii) B.P. decreases because of lower atm .pressure

1 X 3 3

19 (A) ΔfH = Ʃ ΔfH (products ) - ΔfH (reactants )

= [ΔfH (N2O) + 3 ΔfH (CO2)] – [ΔfH(N2O4) + 3 ΔfH(CO)]

= [81 + 3 (-393)] – [9.7 + 3 (-110)]kJ = 777.7 kJ

(B) (i) entropy decreases (ii) entropy increases

½

½

1

½+1/2

20 2 MnO4—

(aq) + 6I—(aq)+ 4 H2O(l) → 2MnO2(s) + 3I2(s) + 8OH- 1+1+1

for

steps

3

21 Temporary hardness is due to bicarbonates of calcium & magnesium

whereas permanent hardness is due to chlorides and sulphates of the same

Clark’s method: In this method calculated amount of lime is added to hard

water. It precipitates out calcium carbonate and magnesium hydroxide

which can be filtered off.

Ca( HCO3)2 Ca (OH)2 2CaCO32H2O

1+1+1

3

22 (a) Ag+/Ag < Hg2+/Hg < Cr3+/Cr < Mg2+/Mg < K+/K

(b)(i) oxidation number of Mn = +6 (ii) oxidation number of B = +3

1

½+1/2

3


(c) KCl cannot be used as electrolyte in the salt bridge because Cl- ions will

combine with Ag+ ions to form white precipitate of AgCl.

OR

Zn(s) l Zn2+ (aq) ‖ Ag+(aq) l Ag (s)

(i) zinc electrode (ii) the ions

(iii) Zn(s) →Zn2+ (aq) + 2e-, Ag+(aq) + e- → Ag (s)

1

1

½+1/2

+1

3

23 (i) the appliances involving electromagnetic radiation of any kind should be

used as little as possible as these radiations are generally harmful in the

living system.

(ii) It is believed that radio waves of cell phone could interact with our heart

this problem is more serious for people using cardiac pacemaker hence it is

advised not to keep cell phone in the breast pocket of shirt.

(iii) X-ray is a type of hjgh energy radiation this can be destructive to all living

cells and can cause DNA damage and mutations.

(iv) Ultra sound waves are high frequency sound waves they are used to

treat pain conditions and to promote tissue healing in physiotherapy.

1X4

4

24 i)Energy change = 5.45X10-19J, E = hc/λ ,

λ =3.65 X 10-5 cm

(ii) n = 5, (iii) (a) 4 (b) 16

OR

(a) K.E. = h(ν – ν⁰)= 1.988X 10-19 J

(b) Electrons present in 3 p- subshell of Si atom will experience more

effective nuclear charge due to its smaller size.

(c) α-particles will deflected more in heavy atoms like gold, platinum

etc. and less deflected in light atoms like Al etc.

1+1

1+1+1

2

1

2

5

25 a)The no. of bonds present in a molecule.

Bond order of O2=2, O2 +=2.5,O2-=1.5, O2

2-=1

B)Stability order, O2 +, O2 ,O2 -,O2

2-

Magnetic properties –Paramgnetic- O2 +, O2 ,O2 - ,

Diamagnetic O22-

OR

i) Mg2+< Na+ < F - < O2-

ii)a) 8 b) 15 c)19

iii)a)Phosphrous b) Scandium c) Lithium

½

1/2X4

½

1/2X4

1/2X4

1/2X3

1/2X3

5


26 a)It is the negative logarithm of hydronium ion concentration

Solution

pH = – log[3.8 × 10–3]

= – {log[3.8] + log[10–3]}

= – {(0.58) + (– 3.0)} = – { – 2.42} = 2.42

Therefore, the pH of the soft drink is 2.42

and it can be inferred that it is acidic.

b) towards i)RHS ii) LHS iii) LHS iv) RHS

OR

a)The solution which resists a change in its pH on addition of small amount

of acid or base. Eg. NH4Cl +NH4OH

b)Increases with increase in temperature

c) Solution Let the solubility of Ni(OH)2 be equal to S.S mol/L of Ni2+ and 2S

mol/L of OH–, but the total concentration of OH– = (0.10 + 2S) mol/L

because the solution already contains 0.10 mol/L of OH - from NaOH.

Ksp = 2.0 × 10-15 = [Ni 2+] [OH- ]2

= (S) (0.10 + 2S)2

As Ksp is small, 2S << 0.10,

thus, (0.10 + 2S) ≈0.10

Hence,

2.0 × 10 = S (0.10) 2 S = 2.0 × 10 -13M = [Ni 2+]

1+2

1/2X4

5

***************************************************************


SET – THREE [ CHANDIGARH REGION] HALF-YEARLY EXAMINATION(2014-15)


BLUE PRINT









each..



words each.


1. State the modern periodic law.

2. Identify the species oxidised and reduced in the following redox reaction.

H2S (g) + Cl2 (g) → 2 HCl (g) + S (s)

3. What is the pH of our blood? Why does it remain constant inspite the variety of food and spices

we eat?

4. Assign oxidation number to P in (i) NaH2PO4 (ii) H4P2O7

5. What is common ion effect?

6. Calculate the mass of an atom of carbon -12 in grams. Express the result up to three significant

figures.

7. Explain why BeH2 molecule has a zero dipole moment although the Be–H bonds are polar.

8. a) For a reaction both ∆H and ∆S are positive. Under what conditions will

the reaction occur spontaneously?

b) For the reaction, 2Cl (g) Cl2(g);

what are the signs of ∆H and ∆S ?

9. What do you understand by isoelectronic species? Name a species that will be isoelectronic

with each of the following:

(i) F– (ii) Ar

10. a) Draw the structure of hydrogen peroxide.

b) Hydrogen peroxide is used as a bleaching agent. Why?


OR

Among NH3, H2O and HF, which would you expect to have highest magnitude of hydrogen

bonding and why?

11. Define :

(i) Molarity (ii) Empirical formula (iii) Atomic mass

12. 3.0 g of H2 react with 29.0 g of O2 to form H2O.

(i) Which is the limiting reagent?

(ii) Calculate the maximum amount of H2O that can be formed?

(iii) Calculate the amount of the reactant left unreacted.

13. An electron has a speed of 500 m/s with uncertainty of 0.02%. What is the uncertainty in

locating its position?

14. Account for the following:

(i) Electron gain enthalpy of fluorine is less than that of chlorine.

(ii) First ionization enthalpy of boron is less than that of beryllium.

(iii) Lithium shows anomalous behaviour as compared to other group members.

15. (a) Draw the Lewis structure of CO32- ion.

(b) Predict the shape of the following molecules using VSEPR model:

(i) NH3 (ii) H2O

16. What will be the pressure exerted by a mixture of 3.2 g of methane and 4.4 g of carbon dioxide

contained in a 9 dm3 flask at 270C ?

17. Explain the following terms:

a) Enthalpy of formation

b) State function

c) Free energy

18. (i) Write the general outer electronic configuration of d-block elements. (ii) Among the

elements of the third period- Na, Mg, Al, Si, P, S, Cl, Ar;

Pick out the element:

a) With the highest ionization enthalpy

b) With the largest atomic radius

c) That is the most reactive non-metal

d) That is the most reactive metal.

19. a) For the reaction: 2A(g) + 2B2(g) 2AB2(g), the equilibrium

constantKp at 270C is 4.0 What is the value of Kp for

(i) 2AB2 ( g) 2 A (g) + 2B2 (g)


(ii) A (g) + B2(g) AB2(g)

b) The value of Kc for the reaction: 2A B + C is 2 x 10-3 . At a

given time, the concentration of reaction mixture is [A] = [B] = [C] =

3 x 10-4 M. In which direction will the reaction proceed?

20. What is meant by hybridisation of atomic orbital? Give the shapes of sp, sp2, sp3 and sp3d

hybrid orbital.

21. What causes the temporary and permanent hardness of water? Discuss the method of

softening of hard water by synthetic ion exchange resins.

22. Balance the following chemical equations by oxidation number method or ion-exchange

method:

(i) MnO4–(aq) + Br–(aq) → MnO2(s) + BrO3

– (aq) (in basic medium)

(ii) Fe2+(aq) + Cr2O72– (aq) → Fe3+ (aq) + Cr3+(aq) (in acidic medium)

OR

a) What you mean by the term 'oxidation number'?

b) Depict the galvanic cell in which reaction

Zn(s) + 2Ag+ (aq) → Zn2+ (aq) +2Ag(s) takes place. Further show:

(i) Which of the electrode is negatively charged,

(ii) The carriers of the current in the cell, and

(iii) Individual reaction at each electrode.

23. Rohit takes an open pan to cook vegetables and pulses at hill station, while Sohan cooks pulses

and vegetables in pressure cooker at the same place. The gas cylinder of Rohit lasts for only

fifteen days whereas Sohan uses one gas cylinder per month.

(i) Who will cook vegetables and pulses faster and why?

(ii) What is reason for delay in cooking by Rohit?

(iii) What value is possessed by Sohan?

(iv) Why does Sohan need only one gas cylinder per month and not two like Rohit?

24. a) Differentiate between an orbit and an orbital.

b) The 4f subshell of an atom contains 10 electrons. What is the

maximum number of electrons having same spin in it?

c) What is the number of orbitals for n=3?

d) How many radial nodes are present in 3p orbitals?

e) What is the physical significance of square of ψ ?


OR

a) Write the electronic configuration of Cr+3ion.

b) What is Pauli's exclusion principle? Why is it called exclusion principle?

c) Explain why exactly half-filled and completely filled orbitals are extra stable?

25. a) Derive the relationship between Cp and Cv.

b) Calculate the standard enthalpy of formation of CH3OH(l)

from the following data:

(i) CH3OH(l) + 3/2 O2 (g) CO2(g) + 2H2O(l); ΔrH0 = -726 kJ/mol

(ii) C(graphite) + O2 (g) CO2 (g); ΔcH0 = -393 kJ/mol

(iii) H2 (g) + ½ O2 (g) H2O (l) ; ΔfH0 = -286 kJ/mol

OR

a) Explain why the entropy of a pure crystalline solid is zero at 0 K? State the law on which it is

based.

b) For the reaction 2 A (g) + B (g) → 2D (g), ΔU0 = –10.5 kJ and ΔS0 = –44.1 J/K. Calculate ΔG0

for the reaction, and predict whether the reaction may occur spontaneously.

26. a) What is solubility product of a salt? Find out the relationship between

the solubility and solubility product of CaF2.

b) Predict if the solutions of the following salts are neutral, acidic or basic:

NaCl, KBr, NaCN, NH4NO3, NaNO2 and KF

OR

(i) Describe the effect of the following on the equilibrium of the reaction:

2H2 (g) + CO (g) CH3OH (g)

a) addition of H2 b) addition of CH3OH

c) removal of CO d) removal of CH3OH

(ii) What is meant by the conjugate acid-base pair? Find the conjugate acid/base for the

following species:

HNO2, CN–, HClO4 and S2–




MARKING SCHEME Q. NO.

ANSWERS MARKS

1 The properties of the elements are the periodic function of their atomic number 1 2 H2S is oxidised and Chlorine is reduced. 1

3 pH of our blood is 7.4. It remains constant because it is a buffer. 1

4 a) +5 b) +5 1

5 It is defined as the suppression of the degree of dissociation of a weak electrolyte by the addition of a strong electrolyte containing a common ion.

1

6 mass of an atom of C-12 = 12/ N0 = 1.99 X 10-23 g 1+1

7 BeH2 is a linear molecule, the resultant dipole moment of two Be-H bonds get cancelled giving zero dipole moment.

2

8 (a) The reaction will be spontaneous only when T∆S >∆ H (b) ∆H = -ve ; ∆S = -ve

1 ½ + ½

9 Species having same no. of electrons. (i) Ne (ii) Cl- 1+ ½ + ½

10 (a) Correct structure (b) Hydrogen peroxide decomposes to form water and nascent oxygen. Thus bleaching action of H2O2 is due to oxidation of colouring matter by nascent oxygen. OR since electronegativity of F is the highest, so, magnitude of the +ve charge on hydrogen and -ve charge on F is the highest and hence H-bonding is strongest in H-F.

1 +1

11 (i) no. of moles present per litre of the solution (ii) which gives the simplest whole no. ratio present between the different atoms in a compound (iii) mass of an atom as compared with 1/12 of the mass of C-12 atom

1 + 1+ 1

12 (i) 3 g of H2 require O2 = (32 /4 ) x 3 = 24 g Hydrogen is the limiting reagent. (ii) Water formed = 27 g (iii) O2 left unreacted = 5 g

1 1 1

13 Uncertainty in velocity, ∆v = 500 X 0.02% = 0.1 m/s ∆x Xm∆v = h/4∏, uncertainty in position = 5.77 X 10-4 m

1 1 1

14 (a) Due to smaller size of F electron –electron repulsions are very strong (b) ) in Be electron is to be removed from fully filled 2s orbital (c ) small size,absence of vacant d-orbitals

1 1 1

15 (a) Correct structure (b) ) NH3- pyramidal,H2O-bent or angular

1 1 +1


16 moles of CH4 = 3.2/16 = 0.2, p(CH4) = nRT/V = 5.54 X 104 Pa ; (R= 8.314) moles of CO2 = 4.4/44 = 0.1 p(CO2) = nRT/V = 2.77 X 104 Pa ; (V = 9 x 10-3 m3) Total pressure = 8.31 X 104 Pa

1 1 1

17 (a) No. of moles present per litre of the solute (b) which tells about the simplest whole no. ratio of different atoms present in a compound (c ) mass of an atom as compared with 1/12of the mass of C-12 atom

1 1 1

18 (i) ns0-2(n-1)d1-10

(ii) (a) Argon (b) Sodium (c) Chlorine (d) Sodium 1 ½ X 4 = 2

19 a) (i) 0.25 (ii) 2 b) in reverse direction

1+1 1

20 The process of mixing of orbitals of slightly different energies to form equal no. of new set of orbitals of same energy and shape is called hybridization. sp is linear, sp2 trigonal planar, sp3 tetrahedral and sp3d trigonal bipyramidal.

1 ½ x 4

21 Temporary hardness is due to the presence of magnesium and calcium hydrogen carbonates. Permanent hardness is due to the presence of soluble salts of magnesium and calcium in the form of chlorides and sulphates in water. The hard water is first passed through cation exchange resin and then through anion exchange resin. The resulting water is freed from both cations and anions and is called demineralised water.

2 + 1

22 a) 2MnO4–(aq) + Br–(aq) + H2O(l) → 2MnO2(s)+ BrO3

– (aq) + 2OH–(aq) b) 6Fe2+(aq) + Cr2O7

2–(aq) + 14H+(aq) → 6 Fe3+(aq) + 2Cr 3+(aq) + 7H2O(l) OR a) Oxidation number is the charge which an atom appears to have when present in the combined state. b) Zn (s) l Zn+2 (aq) ll Ag+(aq) l Ag(s) (i) Zinc electrode is negatively charged. (ii) The ions carry current. The electrons flow from Zn to Ag electrode. (iii) Zn(s) Zn+2 (aq) + 2 e and Ag+(aq) + e Ag(s)

1½ 1½ or 1 ½ ½ 1

23 a) Sohan because in pressure cooker temperature is more than 100◦C and latent heat of steam is also used in cooking. b) The atmospheric pressure is less at hill station due to which water boils below 100◦C and vegetables and pulses take long time in cooking. c) Sohan is using scientific method to save time, money and energy. d) Sohan needs less fuel as pressure cooker helps in cooking at faster rate.

1 1 1 1

24 a) An orbit is a well defined circular path around the nucleus in which the electron revolves whereas an orbital is a three-dimensional region around the nucleus where there is maximum probability of finding the electron. b) 7 electrons c) 9 orbitals (1 in 3s, 3 in 3p and 5 in 3d) d) no. of radial nodes = n - l - 1 = 3 - 1 - 1 = 1 node. e) ψ2 denotes the probabilityof finding electron at a point.

1 1 1 1 1


a) 1s2 2s2 2p6 3s2 3p6 4s03d3 or [Ar]4s03d3 b) No two electrons in an atom can have the same set of four quantum numbers. Or There can be a maximum of two electrons in an orbital. It is called exclusion principle because if one electron has a particular set of four quantum numbers then others are excluded from having that set. c) (i) symmetry (ii) exchange energy

1 2 2

25 a) correct derivation b) Do eq(ii) + 2 x eq(iii) – eq(i) ΔH = -393 + 3 x (-286) – (-726) = -239 kJ/mol. OR a) At 0 K, there is a perfectly ordered arrangement of the constituent particles of a pure crystaliine solid, so entropy is taken zero.It is based on third law of thermodynamics. b) Δng = 2-3 = -1 ΔH0 = ΔU0 + ΔngRT = -12.98 KJ ΔG0 = ΔH0 -TΔS0 = 0.16 KJ

2 3

26 a) Solubility product of a salt is defined as the product of the molar concentrations of its ions in a saturated solution, each concentration raised to the power equal to the number of ions produced on dissociation of one mole of the electrolyte. Ksp = [Ca+2][F-]2 = s x (2s)2 = 4s3 b) NaCN, NaNO2 , KF solutions are basic NaCl, KBr solutions are neutral NH4NO3 solutions is acidic. OR i) a) Equilibrium will shift in the forward direction b) Equilibrium will shift in the backward direction c) Equilibrium will shift in the backward direction d) Equilibrium will shift in the forward direction ii) An acid-base pair which differ by a proton. NO2

-, HCN, ClO4- and H2S

2 + 3

****************************************************


SET – FOUR [ GURGAON REGION] HALF-YEARLY EXAMINATION(2014-15)


BLUE PRINT

S. No. Unit VSA

1 Marks

SA I

2 Marks

SA II

3 Marks VBQ

LA

5 Marks Total

1 Some basic concept of chemistry 2(1) 3( 2) 8(3)

2 Structure of atom 1 (1) 4(1) 5 (1) 10(3)

3 Classification of elements 1 ( 1 ) 3(2) 7(3)

4 Chemical bonding 2(1) 3 (2) 8(3)

5 States of matter 1 (1) 3 (2) 7(3)

6 Thermodynamics 2(1) 3(1) 5 (1) 10(3)

7 Equilibrium 1 (2) 3 (1) 5 (1) 10 (4)

8 Redox reaction 2(1) 3(1) 5(2)

9 Hydogen 2(1) 3(1) 5(2)

TOTAL 4(5) 10(5) 36(12) 4(1) 5 (3) 70(26)









each..



words each.


Q.1. Write de-Broglie expression for wavelength of matter wave.

Q 2 Give the IUPAC name and symbol of an element having atomic number 118.

Q.3.Under what conditions of temperature and pressure do real gases tend to show ideal gas

behaviour ?

Q.4.Write the expression for kpfor:-

NO(g) + O3(g) NO2(g) +O2 (g)

Q 5 Write the conjugate acid and base of NH3.

Q6 Calculate the molarity of NaOH in the solution prepared by dissolving its 4g in enough water to

form 250ml of the solution.

Q 7 Out of NH3 and NF3 which has higher dipole moment and why?

OR

Ionization energy of Sodium is lower than that of Magnesium but its 2nd ionization energy is

higher. Why?

Q 8 For a reaction at 298 K 2 A + B → C ΔH = 400 kJ mol-1 and Δ S = 0.2 kJ mol-1

At what temperature will be the reaction become spontaneous considering ΔH and ΔS to

be constant over the temperature range ?


Q 9 Write chemical reactions to show amphoteric nature of water.

Q 10 Calculate oxidation number of central atoms in the following compounds;

H2SO4, H2SO5, KMnO4 and K2Cr2O7.

Q 11 Calculate the no of atoms in each of the following;

I. 52g of He

II. 52u of He.

Q 12 CaCO3 reacts with aqueous HCl according to the reaction; CaCO3 (s) + 2HCl (aq) → CaCl2 (aq) + CO2 (g) + H2O (l). What mass of CaCO3 is required to react completely with 25 ml of 0.75M HCl?

Q 13. Calculate the enthalpy of formation of benzene using following data:-

C6 H6 (I) + 15/2 O2 (g) 6CO2 (g) + 3 H2 O (l) ∆H 0= -3266.0 kJ

C(s) + O2 (g) CO2 (g) ∆H 0 = -393.1 KJ

H2 (g) +1/2 O2 (g) H2O (l) ∆H 0= -286.0 KJ Q 14. Balance the following ionic equation by ion electron method or oxidation number method in acidic medium - Mg + NO3

-1 Mg2+ + N2O + H2O Q 15 What is the structure of H2O2 . Explain two methods to remove permanent hardness of water.

Q 16 . (a) Why chlorine has higher electron gain enthalpy than fluorine ?

(b) Why Nitrogen has higher first ionization potential than oxygen atom?

Q 17 (a) Calculate the molar solubility of Ni (OH)2 in 0.10 M NaOH The ionic product of Ni (OH)2 is

2.0 X 10 -15

(b)Predict if the solutions of following salts are neutral, acidic or basic. NaCl & KF.

Q 18 Discuss the shapes of the following molecules using VSEPR theory.

(i) BCl3 (ii) BeCl2 (iii) SF6

Q 19 Calculate the total pressure in a mixture of 8g O2 and 4 g H2 confined in a vessel of volume 1

dm3 at 270C. (R = -0.083 bar dm-3 K-1 mol-1).

Q 20 (a) Why are the axial bonds longer as compared to equatorial bonds in PCl5?

(b) Write difference between σ and π bond?

Q 21 (a) Write Van der waal’ s equation for n moles of real gas

(b) Discuss in brief the significance of van der waal’s constants ‘a’and ‘b’.

Q 22 Compare the relative stability of the following species and indicate their magnetic properties.

O2+, O2

- (Superoxide), O22- (Peroxide)

Q 23 By studying the spectrum of light coming from some distant star, it becomes possible to

identify the elements present on the star. Answer the following questions:

(i)How does a scientist identify the elements present on the star by studying the spectrum

of light from the star?


(ii) What are the wavelengths of the two characteristic lines in the visible region in the

atomic spectrum of sodium?

(iii) What is the value associated with this ?

Q 24 (a)State the following;

(i) Hund’s Rule,

(ii) Pauli’s Exclusion Principle and

(iii) Aufbau’s Principle.

(b) Give ground state electronic configuration of the following; Cu, Cr2+, Fe and Cl-1.

( c ) Given Cr Z=24, Cu Z= 29, Fe Z= 26 Cl Z=17

OR

(a) Give two limitation of Bohr`s Atomic Model.

(b) State Heisenberg`s uncertainty principle.

(c) A microscope using suitable photons is employed to locate an electron in an atom With in

distance of 0.1 A. what is the uncertainty involved in the measurement of its velocity.

Q 25 a) State and explain Le- chatelier ‘s principle

b) What will be the effect of increase in pressure on the following equilibria:-

(1) H2 (g) + I2(g) = 2HI(g)

(2) N2 (g) + 3H2 (g) = 2NH3 (g).

(3) N2 O4 (g) =2NO2(g)

OR

a) Give an example of acidic buffer.

b) Select Lewis acid and Lewis base from the following: Cu2+ , H2O, BF3 , OH—1

c) What will be the pH of 0.002M HCl ? (log 2 =0.3010)

Q26 (a)What will happen to entropy when

I)Sugar dissolves in water II) Water freezes to form ice

b) The equilibrium constant for the reaction is 10. Calculate the value of ∆G0, Given

R= 8 J K—1 mol— T= 300K

OR

(a) What is Hess’s Law of constant heat summation. Explain with example.

(b) For the reaction

2A(g) + B(g) 2D (g)

∆ UØ = -10.5 KJ and ∆ SØ = -44.1 JK-1

Calculate ∆ GØ for the reaction and predict whether the reactions may occur spontaneously.




MARKING SCHEME

A 1 λ = h/mv 1 mark

A 2. Ununoctium uuo 1 Marks

A 3 Low pressure , High temperature

A 4 Correct Expression

A 5 Acid = NH4+ , Base = NH2-

A 6 No. of moles of NaOH=4/10=0.1

Molarity =0.1X1000/250=0.4M A 7 Correct Difference

OR Explanation on the basis of e.c of Na and stable e.c of Na+ ion 2 Mark

A 8 ΔG = ΔH -TΔS 1/2

ΔG=0, ΔH =TΔS , or T = ΔH/ ΔS ------------------------------1/2

T = (400 K J mol-1)/(0.2KJ K-1 mol-1) -----------------------------(1)

T= 2000K---------------------------------------------------- --------1/2

Reaction will be spontaneous above this temperature ---------------------1/2

A 9 Give any two reactions with an acid and a base i.e. HCl and NH3.

A 10 +6,+6,+7 and +6 resp.

A 11 13 x 6.022x1023 and 13 atoms.

A 12 Using stoichiometry calculations limiting reagent. W = 0.9375g

A13. C6H6 (l) + 15/2 O2(g) 6 CO2(g) + 3 H2O (l)

H C6H6 = - 2356.6 – 858 + 3266 = + 49.4 Kj / Mole 3 Marks

A 14 . Correct Balancing by any one of the method 3 Marks

A 15 Correct structure 1 Mark

Removal of hardness 2 Mark

A 16 a) Very small size of 2p subshell in flourine and explanation 1.5 Mark

b) Stable electronic configuration in Nitrogen and explanation 1.5Mark


A 17 (a)Ksp = 2.0x10-15 =[Ni2+][OH-]2

Solubility = 2.0x10-13M 2+1

(b) NaCl- Neutral, KF- Basic

A 18 (i) Trigonal Planar (ii) Linear (iii) Octahedral 1 mark each

A 19 nO2 = 8/32 = 0.25

224

2 ==Hn

22 HOH nnT

n +=

= 0.25 + 2 = 2.25

V = 1 dm3 = 1L, T = 300 K

V

nRTP = = 2.25 x 0.082 x 300= 55.35 atm. 3

A 20. (a) less bond angle so more repulsion at axial position

(b) any correct two difference 2+1

A 21 (a) Correct equation 1

(b) a’ related to the magnitude of the attractive force among the molecule of a particular

gas 1

‘b’ determine the volume occupied by the gas molecules which depend upon size of

molecule 1

A 22. Stability Order O22- ˂O2

- ˂O2+

O2- -------------Diamagnetic

O22- , O2

- -----------Paramagnetic

A 23 (i) Each element has characteristic line spectrum. By comparing the lines present in the

spectrum of light from the star with those of the atomic spectra of elements a scientist

identifies the elements present on the star. The presence of element helium on the sun, was

detected by studying the spectrum of light from the sun.

(ii) 589.2 nm and 589.6 nm. These wavelengths are responsible for the golden yellow light

emitted by sodium vapour lamps

(iii) use of chemistry in research

A 24 Proper definition and proper electronic configuration (1+1+1+1/2x4=5)

OR


a) One mark for each correct limitation 2

b) Correct Definition 1

c) ½ mark for correct formula, 1 mark for calculation and ½ marks for answer.

A 25 a) Exact definition + exact explanation --------------------------- 1+1

b) i) No effect

ii) gets shifted to the right

iii) Gets shifted to the left (1+1+1)

OR

a) CH3COOH + CH3COONa --------------------------------------- -(1)

b) lewis acid Cu2+, BF3 ½ × 4 =2

lewis basis H2O, OH-

c) pH = - log[H+]/ mol L-1

= - log (2 x 10-3)

= - (-3 +0.3010) 1+1=2

A 26 a) i) Entropy increases (1+1)

ii) Entropy decreases

b) ΔG0 = -RT ln K

= -2.303 RT log k ------------------------------------------------ 1/2

R= 8.0 J K-1 mol-1, T= 300k, K=10 -------------------------------------- 1

ΔG = -2.303 X (8J K-1mol-1) x (300k)X (log 10) ---------------------- 1/2

= -5527 J mol-1 = -5.527KJ mol-1 ------------------------------------ (1)

a) Enthalpy change in a reaction is same weather the reaction takes place in one step or in

several steps. With any example (2)

b) ∆G = ∆H - T∆S

=12.978 – 298 (-44.1x103)

= +0.164KJ (3)


SET – ONE [ DELHI REGION] SESSION ENDING EXAMINATION(2014-15)


BLUE PRINT S.NO CHAPTER 1 MARKS 2 MARKS 3 MARKS 5 MARKS TOTAL

1 Some basic concepts of

chemistry 3×1 3

2 Structure of atom 1×1 2×1 3×1 6

3 Classification of Elements

and Periodicity in

properties

1×1 3×1 4

4 Chemical Bonding and

Molecular Structure

2×1 3×1 5

5 States of Matter: gas and

Liquids

1×1 3×1 4

6 Thermodynamics 1×1 5×1 6

7 Equilibrium 2×1 5×1 7

8 Redox Reaction 3×1 3

9 Hydrogen 3×1 3

10 S-Block Elements 3×1 4* 3+4*

11 P-Block Elements 2×1 3×1 5

12 Organic Chemistry-Basic

principles and tech.

1×1 2×1 3×1 6

13 Hydro-carbon 3×1 5×1 8

14 Environmental Chemistry 3×1 3

Total 5 5 12 3+1* 70




GENERAL INSTRUCTIONS:

(i) All questions are compulsory.

(ii) Marks for each question are indicated against it.

(iii) Questions no.1to 5 is very short answer questions and carries 1 marks each.

(iv) Questions no.6to 10 is short answer questions and carries 2 marks each.

(v) Questions no. 11to22 are also short answer question and carry 3 marks each.

(vi) Questions no.23 carry 4 marks and Q.No.25 to 26 are long answer questions of 5

marks each.

(vii) Use long Tables, if necessary. Use of calculators is not allowed.

Q1. . Which gas law is shown by the following graph?

PV

P

Q2. . what is inductive effect ?.

Q3. Write the electronic configuration of Cr+ ion. [Atomic number of Cr = 24]

Q4. Predict the sign of ∆S for the reaction:

2NaHCO3 (s) → Na2CO3 (s) + CO2 (g) + H2O (g)

Q5. . Write the IUPAC name and symbol for the element with atomic number 118.

Q6. . Account for the following:

a) NH3 molecules has more dipole moment that NF3 although N – F bond is more polar than

N – H bond.

b) H2O is a liquid while H2S is a gas.

Q7. what are electrophiles and nucleophiles ? explain with examples.


Q8. which of the following are lewis acids ?

AlCl3, H2O, BF3, H+ ,NH3,and NH4+.

Q9. . What is the state of hybridization of carbon in

(a) CO32- (b) diamond

Q10. . The mass of an electron is 9.1 × 10-31 kg. if its kinetic energy (K.E.) is 3.0× 10-25 J, calculate its

wavelength. (h = 6.626 × 10-34 J s)

Q11. a) State Pauli’s exclusion principle.

b) Account for the following:

i) Bohr’s orbits are called stationary states.

ii) A moving cricket ball cannot have wave character.

Q12. Calcium carbonate reacts with aqueous HCl to give CaCl2 and CO2 according to the reaction:

CaCO3 (s) + 2HCl (aq) → CaCl2 (aq) + CO2 (g) + H2O (l)

What mass of CaCO3 is required to react completely with 25 ml of 0.75 M HCl?

[Molar mass/g mol-1 : Ca = 40 u, C = 12 u, O = 16 u, H = 1 u, Cl = 35.5 u]

Q13. Account for the following:

a) Ionization enthalpy of nitrogen (Z = 7) is more than that of oxygen (Z = 8).

b) Noble gases have large positive electron gain enthalpies.

c) An anion is always bigger than its parent atom.

Q14. . a) Write the molecular orbital configuration of 𝑂𝑂2+. Calculate its bond order and predict its

magnetic behaviour.

b) Using VSEPR model, predict the geometry of SF6 molecule.

Q15. (a) Write van de Waals equation for ‘n’ moles of a real gas.

b) An open beaker at 27 0C is heated to 477 0C. what fraction of air would have been

expelled out?

Q16. . Explain the following terms:

a) Acid rain

b) Green chemistry

c) Ozone layer depletion

Q17. What happens when?

(A). sodium metal is dropped in water?

(b). sodium metal dissolves in liquid ammonia?

(c). Sodium metal is heated in free supply of air?


OR

Comment on the following observations:

a) The mobility’s of the alkali metal ions in aqueous solution are:

Li+ < Na+ < K+ < Rb+ < Cs+

b) Beryllium and magnesium do not give colour to flame whereas other alkaline earth metals

do so.

c) Alkaline earth metals cannot be obtained by chemical reduction methods.

Q18. Explain the following with suitable reasons:

a) Diamond is covalent, yet it has high melting point.

b) CO2 is a gas but SiO2 is a solid.

c) B to TI, +1 oxidation state becomes more stable.

Q19. ( a) Arrange the following in order of property mentioned against each:

i) (CH3)3C+, CH3CH2CH+, CH3CH2CH2CH2 +

[Increasing stability]

CH3

ii) HCOOH, CH3COOH, CH3CH2COOH [Increasing acidic strength]

b) Write the name of isomerism among the following compounds:

CH3 – O – CH2CH2CH3 and C2H5 – O – C2H5

Q20. How is hydrogen peroxide prepared industrially? How does it concentrated? Explain why it is stored in coloured wax-lined glass or plastic bottles? Q21. Balance the following ionic reaction with the help of oxidation number method: (Acidic

medium) N2H4 (l) + Cl𝑂𝑂3− (aq) → NO (g) + 𝐶𝐶𝐶𝐶− (aq)

Q20. Write IUPAC names of the products obtained by the ozonolysis of the following compounds:

(i) 2-ethylbut-1-ene

(ii) 1-phenylbut-1-ene ; Explain the reactions.

Q23. Amitabh was getting his house white-washed. His friend Suresh came to see his house. He found that quick lime was being soaked in water and decanted solution was being taken for white-washing by the worker. Suresh found that the lime solution that was used in the process was not as white as the walls after the white-wash. He asked Amitabh, “How is it that the walls look so sparkingly white while lime water that is used, does not.”

(a) How can you explain the difference in the whiteness of the lime water and the walls?

(b) How does lime water react with chlorine gas? Name the product that is formed.

Q24. (a) Define solubility product. Write solubility product expression for Zr3(PO4)4.

(b) Calculate the pH of 0.01 M CH3COOH solution. [Ka(CH3COOH) = 1.74 × 10-5]

(c) Explain why NaCl is precipitated when HCl (g) is passed through the saturated solution of

NaCl.


OR

(a) equal volumes of 0.002 MN solutions of Na(IO3) and Cu(CLO3)2 are mixed together. Will it

lead to the precipitation of Cu(LO3)3 = 7.4 × 10−8]

(b). define Le-Chatelier’s principle. What is the effect of:

(i). addition of H2

(ii). Removal of CO

On the equilibrium : 2H2 (g) + CO (g) CH3OH?

Q25. (a) State first law of thermodynamics. Heat (q) and work done (W) individually are not state functions but their sum is always a

state function. Explain why? (b) Calculate the standard enthalpy change (∆rH0) and standard internal energy change (∆ru0)

for the following reaction at 300 K: OF2 (g) + H2O (g) → O2 (g) + 2HF (g)

Standard enthalpy of formation (∆rH0 ) of various species are given as below : (∆rH0)/Kj mol-1 :

OF2 (g) =23.0 H2O (g)=-241.8 , HF (g) =268.6 J K -1, R=8.314 JK -1 mol. -1

OR

(a) Predict the sign of the entropy change for each of the following changes;

(i) Hg (l)→ Hg (g)

(ii) Steam → water

(b) For a reaction at 25 0C , 2A (g) + B (g) 2D (g)

∆U 0 = - 10.5kJ and ∆S 0 = -44.1 JK -1. Calculate ∆G 0 for the reaction and predict whether the

Reaction is spontaneous or not at 25 0C.

Q26. (a) Explain the following reactions with suitable examples:

(i) Wurtz reaction.

(ii) Friedel-craft, alkylation reaction.

(b) An alkene ‘A’ on ozonolysis gives a mixture of ethanol and pentane-3-one. Write structure and IUPAC name of ‘A’. ( c) give one chemical test to distinguish between ethane and ethyne.

OR

(a) Write suitable reason for the following:

(i) C – C bond length in benzene ring is 139 pm which is in between C – C single bond 154 pm and C = C double bond 133 pm.

(ii) Trans-2-butene has higher melting point than cis-isomer.

(b) Give a chemical test to distinguish between but-1-yne and but-2-yne.

(c ) How will you carry out following conversions:

(i) Ethene to benzene

(ii) 1-bromopropane to 2-bromopropane.




MARKING SCHEME

Ans.No. Brief Answers Marks

1 The graph represents Boyle’s law. 1

2. polarization of a σ-bond caused by the polarization of adjacent . σ-bond is

called inductive effect.

1

3. 1s,22s22p6 3s23p63d5. 1

4. Reactant NaHCO3 is a solid and it has low entropy. Among the products, there

are one solid and two gases. Therefore the entropy increases.

1

5. Ununoctium(Uuo) 1

6. a) This is because in the case of NH3, the orbital dipole due to lone pair is in the

same direction as the resultant dipole moment of the N – H bonds, whereas in

NF3, the orbital dipole is in the direction opposite to the resultant dipole

moment of the three N – F bonds. The orbital dipole because of the lone pair

decreases the effect of the resultant N – F bond moments which result in low

dipole moment o b) There is hydrogen bonding in H2O while there is no such

bonding in H2S. Due to associated H2O molecules, the boiling point of H2O is

raised.

1

1

7. 1. Electrophiles are electron loving reagents. They are electron deficient and

so, act as lewis acid and seek electrons.

Examples : H+, H3O+,NO2+(from HNO3), SO2OH+,NO+,Br+,AlCl3,BF3 are neutral

species which act as electrophiles.

2. Nucleophiles are nucleus loving reagents. They are electron rich and so, act

as a lewis base and donate electrons.

Example: Cl-,Br-.

1

1

8. (I) AlCl3: lone pair deficient.

(I) BF3: lone pair deficient.

(II) H+ : electron deficient.

(III) NH4+: electron deficient.

1/2x4

9. (a) carbon atom in CO32- is sp2 hybridized.

(b) carbon in diamond is sp3

1

1


10. K.E = 1

2𝑚𝑚𝑣𝑣2 or v = �2×𝐾𝐾.𝐸𝐸.

𝑚𝑚

Substituting the values, we have 𝑣𝑣 = �2×3.0×10−25𝑘𝑘𝑘𝑘𝑚𝑚2𝑠𝑠−2

9.1×10−31𝑘𝑘𝑘𝑘

= 812 m s-1

λ = ℎ𝑚𝑚𝑣𝑣

= 6.626×10−34

9.1×10−31 ×812

= 8967× 10-10 m

= 896.7 nm

½

½

½

½

11. a) Pauli’s exclusion principle state: No two electrons in an atom can have the

same set of four quantum numbers.

It can also be stated as: only two electrons may exist in the same orbital and

these electrons must have opposite spin.

b) i) According to Bohr, electrons in an atom move around the nucleus in

orbits of fixed radius and energy. Therefore Bohr’s orbits are called stationary

states.

ii) Objects like cricket ball have a large mass (compared to an electron or a

photon). The wavelength associated with such moving objects is so short that

their wave properties cannot be detected .

1

1

1

12. 1000 ml of 1.0 M HCl = 1 mol of HCl

25 ml of 0.75 M HCl = 11000

× 25 × 0.75 mole of HCl

= 0.01875 mole of HCl

CaCO3 (s) + 2HCl (aq) → CaCl2 (aq) + CO2 (g) + H2O (l)

2 moles of HCl react with = 100 g of CaCO3

0.01875 Mole of HCl react with = 1002

× 0.01875 = 0.9375 g.

½

½

½

½

1

13. a) Nitrogen has the electronic configuration 1s22s22𝑝𝑝𝑥𝑥12𝑝𝑝𝑦𝑦12𝑝𝑝𝑧𝑧1 , which is stable

half-filled configuration in contrast with the configuration of O

1s22s22𝑝𝑝𝑥𝑥22𝑝𝑝𝑦𝑦12𝑝𝑝𝑧𝑧1 , which is not as stable. Therefore ionization enthalpy of N is

more than that of O.

b) Noble gases have a stable electronic configuration. These elements do not

accept the electron easily. Therefore they have large positive electron gain

1

1

1


enthalpies.

c) An anion is formed when a neutral atom gains one or more electrons.

Atom + electron/s → Anion

The electrons that are added to the atom suffer repulsion from the electrons

already present. Moreover, the added electrons generally occupy the next

orbital, which is further away from the nucleus. Therefore the anion is always

bigger than its parent atom.

14. a) The M.O. configuration of 𝑂𝑂2+:

(𝜎𝜎1s)2(𝜎𝜎*1s)2(𝜎𝜎2s)2(𝜎𝜎*2s)2(𝜎𝜎2pz)2(𝜋𝜋2pz)2(𝜋𝜋2𝑝𝑝𝑥𝑥2 ≡ 𝜋𝜋2𝑝𝑝𝑦𝑦2)(𝜋𝜋 ∗ 2𝑝𝑝𝑥𝑥1 =

𝜋𝜋 ∗ 2𝑝𝑝𝑦𝑦1)

Bond order = 𝑁𝑁𝑏𝑏−𝑁𝑁𝑎𝑎2

= 10−62

= 2

Magnetic behavior : paramagnetic because of the presence of two unpaired

electrons.

b) SF6 has octahedral geometry according to VSEPR theory.

1

½

½

1

15. a) Van de Waals equation for n moles of real gas is:

�𝑝𝑝 + 𝑎𝑎𝑛𝑛2

𝑉𝑉2 � (V – nb) = nRT

b) Let the initial and final volumes be V1 and V2.

Applying Charles law: 𝑉𝑉2𝑉𝑉1

= 𝑇𝑇2𝑇𝑇1

Substituting the values, we have 𝑉𝑉2𝑉𝑉1

= 477+27327+273

= 750300

Or 𝑉𝑉2𝑉𝑉1

= 2.5

Subtracting 1 from both sides, we get

𝑉𝑉2

𝑉𝑉1− 1 = 2.5 − 1 𝑜𝑜𝑜𝑜

𝑉𝑉2 − 𝑉𝑉1

𝑉𝑉1= 1.5

Or fraction of air expelled out = 1.5.

½

½

½

1

½

16. a) Acid rain: it refers to the ways in which acid from the atmosphere is

deposited on the earth’s surface. Oxides of nitrogen and sulphur which are

acidic in nature can be blown by wind along with solid particles in the

atmosphere and finally settle down either on the ground as dry deposition, or

1


in water, fog and snow as wet deposition.

b) Green chemistry: Green Chemistry is a way of thinking and is about utilizing

the existing knowledge and principles of Chemistry and other sciences to

reduce the adverse impact on environment. Utilization of existing knowledge

base for reducing the chemical hazards along with the developmental

activities is the foundation of green chemistry.

c) Ozone layer depletion: the upper stratosphere consists of ozone which

protects us from the harmful effects of harmful UV radiations coming from the

sun. it is important to maintain the ozone shield. In recent years there have

been reports of the depletion of this protective ozone layer because of the

presence of certain chemicals in the stratosphere. The main reason for the

depletion of ozone layer is the release of chlorofluorocarbons compounds

(CFCs), also known as freons. These chemicals are used in refrigerators and air-

conditioners. Once these are released into the atmosphere. Chlorine radicals

produced from CFCs cause the breakdown of ozone.

1

1

17. (a). Sodium metal is dropped in water

2Na + 2H2O→ 2NaOH + H2

Hydrogen gas is released.

(b). sodium metal dissolves in liquid ammonia

Na + (x + y) NH3 → [Na(NH3)x]+ + [e(NH3)y]-

A deep blue solution is formed which is conducting in nature.

(c). sodium metal is heated in free supply of air

2Na + O2 → Na2 O2

Or

a) Hydration enthalpies of alkali metal ions decrease with increase in ionic

sizes. The higher the hydration energy, the lower will be the ionic mobility. Cs+

with the lowest hydration enthalpy has the maximum mobility and Li+ the

lowest ionic mobility.

b) in flame, the electrons are excited to higher energy levels. When they drop

back to the ground state, the difference of energy is emitted in the form of

visible light. Electrons in Be and Mg are too strongly found to get excited by

the flame. Hence, these elements do not impart colour to the flame.

c) alkaline earth metals have negative value of reduction potential in solution.

Hence they cannot be obtained by chemical reduction method.

1

1

1

1

1

1


18. a) Diamond has a rigid three dimensional network of carbon atoms, each

carbon is tetrahedrally attached to four carbons around it. Because of this,

diamond has high melting point.

b) In CO2 molecule, carbon atom undergoes sp hybridization. Two sp

hybridized orbitals overlap with the two p-orbital’s of oxygen to form two

sigma bonds. Other two electrons of carbon form 𝑝𝑝𝜋𝜋 − 𝑝𝑝𝜋𝜋 bonding with

oxygen atoms. SiO2 is a covalent three dimensional network solid in which

each silicon atom is tetrahedrally bonded to four oxygen atoms. Network

compounds have generally high melting and boiling points. Therefore, CO2 is a

gas but SiO2 is a solid.

c) as we move from B to TI, due to poor shielding effect of d and f-orbitals, the

ns2 electrons of the metals are held more and more tightly by the increasing

positive charge of the nucleus. Therefore only p1 electron can take part in

bonding. Thus +1 oxidation state becomes more stable. This is called inert pair

effect

1

1

1

19. a.

i. CH3CH2CH2CH2 + < CH3CH2CH+ < (CH3)3C+

CH3

ii. CH3CH2COOH < CH3COOH < HCOOH

b. Metamerism

1

1

1

20. In industry, H2O2 is prepared by the auto oxidation of 2-alkylanthraquinols

2-ethylanthraquinol ⇌ H2O + oxidized product

1% H2O2 is formed. It is extracted with water and concentrated to ~ 30% (by

mass) by distilled under reduced pressure. It is further concentrated to ~ 85%

by careful distillation under reduced pressure. The remaining water can be

frozen out to obtain pure H2O2.

H2O2 decomposes slowly on exposure to light

2H2O2 (l) → 2H2O (l) + O2 (g)

To avoid this, it is stored in coloured wax-lined glass or plastic bottles.

1

1

1

21. 𝑁𝑁2−2 H4 (l) + Cl+5 𝑂𝑂3

− → N+2 O (g) + Cl- (aq)

In this, N2H4 acts as a reducing agent, whereas Cl𝑂𝑂3− acts as an oxidizing agent.

Total increase in oxidation number of N = 2× 4 = 8

½

½


And total decrease in oxidation number of Cl = 1 × 6 = 6

∴ To balance increase/decrease in oxidation number, multiplying N2H4 by 3

and Cl𝑂𝑂3− by 4, we get

3N2H4 (l) + 4Cl𝑂𝑂3− (aq) → NO (g) + 𝐶𝐶𝐶𝐶− (aq)

To balance N and Cl atoms, multiplying NO by 6 and Cl—by 4, we get

3N2H4 (l) + 4Cl𝑂𝑂3− (aq) → 6NO (g) + 4𝐶𝐶𝐶𝐶− (aq)

Balancing O atoms by adding 6H2O to R.H.S., we get

3N2H4 (l) + 4Cl𝑂𝑂3− (aq) → 6NO (g) + 4𝐶𝐶𝐶𝐶− (aq) + 6H2O (l)

In this, H atoms get automatically balanced.

½

½

½

½

22. (i) (CH3CH2)2 – C = CH2 (CH3CH2)2 –C=O +HCHO

(ii)Zn/H2O Pentan-3-one & methanal

(i) O3

(ii) CH3CH2-CH=C6H5 CH3CH2CHO +C6H5CHO

(ii) Zn/H2O Propanal & Benjaldihyde

11\2

11\2

23. (a) Coating of lime water on the walls reacts with CO2 present in the

atmosphere to give calcium carbonate which has a bright white colour. The

reaction is explained as under:

Ca(OH)2 + CO2 → CaCO3 + water

(b) On passing Cl2 gas through lime water, we obtain bleaching powder.

Ca(OH)2 + 2Cl2 → CaCl2 + Ca(OCl)2 + 2H2O

2

2

24. (a). solubility product of a substance may be defined as the product of the

concentration of the ions raised to the number of respective ions in a

saturated solution.

For Zr3(PO4)4 , the solubility product expression may be given by

Ksp = [Zr4+]3 [PO3-]4

(b). pH of 0.01 M CH3COOH solution

Use the relation ά= �𝑘𝑘𝑎𝑎𝑐𝑐

(assuming ά as small compared to 1 )

Substracting the values in the above equation, we have

=𝛼𝛼 = �1.74×10−5

0.01= √1.74 × 10−3 = √17.4 × 10−4

= 4.17 × 10−2 = 0.0417

2

2


[H+] = [H3O+] = C 𝛼𝛼 = 0.01 × 0.0417

= 0.000417

pH = - log (0.000417)

= 3.38

(c). on passing HCL (g) through a saturated solution of NaCL, the ionic product

[Na+] [Cl-] becomes more than the solubility product. Therefore, precipitation

of NaCl takes place.

Or

NaIO3 → Na+ + I𝑂𝑂3−

Cu(ClO3)2 Cu2+ + 2Cl𝑂𝑂3−

Concentration of Cu2+ ions in the solution will be 0.002 M and that of I𝑂𝑂3− ions

will be 0.002 in the solution before mixing. After mixing, the volume will

become double; therefore, the concentration will be reduced to half. Thus the

concentration will be

[Cu2+] = 0.0022

= 0.001

[I𝑂𝑂3−] = 0.002

2 = 0.001

Ionic product,

[Cu+][IO3]2 = (0.001)(0.001)2

= 1× 10-3 × 1 × 10-6

= 1 × 10-9

As the ionic product is less than solubility product, precipitation of Cu(IO3)2 will

not take place.

(b) le- chatelier’s principle states that change in any factor such as

temperature, pressure, concentration etc., will cause the equilibrium to shift in

such a direction so as to reduce or counteract the effect of the change.

(i) Addition of H2 will shift the equilibrium in the forward direction.

(ii) Removal of CO will shift the equilibrium in the backward direction.

1

½

½

1

1

1

1

25. (a) First law of thermodynamics: The energy of an isolated system is constant.

q And w can depending on how the change is carry out. But the sum of q and

1


W i.e., ∆U will depend only upon the initial and final state .That is why the sum

i.e. ∆U is is a state function .

(b) ∆rH0 = ∑ ∆fH (products ) - ∑ ∆fH (reactants)

= [0 +2× (-268.6)] - [23.0 + (-241.8)]

= (-573.2)-(23.0-241.8)

=-573.2 + 218.8

= -354.4 kJ = -354400 J

∆𝑜𝑜U = ∆rH -∆ nRT ≡ -354400-[1×8.314×300]

= -354400-2494

=-351906 J or 351.9 kJ

OR

a) (i) Hg (l) Hg (g)

Disorder increase in going from liquid state to gaseous state.

Therefore ∆S = -ve

(ii) Steam Water

Disorder decrease in moving from gaseous state to liquid state.

Therefore ∆S = +ve

b) for the reaction 2A (g) + B (g) → 2D (g)

∆ng = 2 – 3 = -1

∆Ho = ∆Uo + ∆ngRT

= -10.5 kJ + (-1)(8.314 × 10-3 × 298 kJ)

= (-10.5 – 2.48) kJ

= -12.98 kJ

According to gibbs Helmholtz equation

∆Go = ∆Ho - T∆𝑆𝑆o

= -12.98 kJ – 298 (-44.1 × 10-3 kJ)

= -12.98 kJ + 13.14 kJ

= 0.16 kJ

As ∆Go is +ve, the reaction would not occur spontaneously.

½

½

1

1

1

½

1

½

½

1

½

½

½

26. (i) Wurtz reaction

CH3I + 2Na + ICH3 CH3 – CH3 + 2NaI

When an alkyl halide is treated with sodium metal in dry ether, bigger alkane is

formed.

1


ii) Friedal-crafts alkylation reaction

Cl + CH3 Cl + Cl CH3

CH3

(b) Alkene CH3CHO + CH3CH2COCH2CH3

Alkene reacts with ozone and gives ozonide products. This ozonide on

hydrolysis will give the products as under. Thus A has the structure

CH3 – CH2 – C = CH – CH3

CH2

CH3

3-Ethylpent-2-ene

( c) Distinction between ethane the ethyne:

Ethyne gives a white precipitate with ammoniacal silver nitrate (Tollen’s

reagent).

CH ≡ CH AgC ≡ CAg

Silver diacetylide

Ethane does not give this test.

Or

(a) (i) this is because of the resonance structure of benzene.

Thus, all the C – H bonds in benzene are equivalent and they have the same

bond length (139 pm) which is in between the C – C single bond length and C –

C double bond length.

(ii) trans-2-butene has a higher melting point than cis-isomer.

H CH3 CH3 CH3

C = C C = C

CH3 H H H

1

1

1

1

1

1


Molecules of trans isomer can fit more tightly into one another giving a

compact lattice as compared to cis-isomer. Thus, the force of attraction

between molecules in trans-isomer will be more and hence, trans-isomer will

melt at a higher temperature.

(b) Distinction between but-1-yne and but-2-yne

CH3CH2C ≡ CH CH3C ≡ C – CH3

But-1-yne but-2-yne

But-1-yne has an acidic hydrogen (terminal hydrogen). It will give Tollen’s

reagent test and Fehling solution test. But-2-yne has no acidic hydrogen and

hence it will not give these tests.

CH3CH2C ≡ CH CH3CH2C ≡ CAg CH3CH2C ≡ CCu

White ppt. Red ppt.

( C ) (i) Ethene to benzene

CH2 = CH2 CH2ClCH2Cl CH2 = CHCl CH ≡ CH C6H6

(ii) 1-Bromopropane to 2-Bromopropane

CH3CH2CH2Br CH3CH = CH2 CH3 – CH – CH3

Br

1-Bromopropane propane 2-Bromopropane

1

1

1

**********************************************************


SET – TWO [ GURGAON REGION] SESSION ENDING EXAMINATION(2014-15)


BLUE PRINT

S.No Chapters V.S.A S.A S.A

Long

Answers

Total

Marks

1 Some basic concepts of chemistry 1 1 0 3

2 Structure of Atom - 1 1 - 5

3

Classification of Elements and Periodicity in

property 1 1 4

4 Chemical Bonding and Molecular Structure 1 - - 1 6

5 States of Matter 1 - 1 - 4

6 Thermodynamics 1 2*2 - - 5

7 Equilibrium - - 2*3 - 6

8 Redox Reactions - - 1 - 3

9 Hydrogen - - 1 - 3

10 S-block Elements - 1 1 - 5

11 P-Block Elements - - 1 1 8

12

Organic Chemistry: Some basic Principles And

Techniques - 2 6

13 Hydrocarbons - - 1 1 8

14 Environmental Chemistry - - 1(VBQ) - 4

TOTAL 5 5 12+1 3 70


SET – TWO [ GURGAON REGION] SESSION ENDING EXAMINATION(2014-15)








(vi) Questions no.23 carry 4 marks and Q.No.25 to 26 are long answer questions of 5 marks

each.


1. What does a mole represent?

2. Which electrons take part in bond formation?

3. Locate the position of element with atomic number 33.

4. Define Charles law?

5. What is the entropy change when a liquid vaporizes?

6. Mention the conditions under which the reaction is spontaneous?

7. How many grams of NaOH should be dissolved to make 100 ml of 0.15 M NaOH solution?

8. (a.) Why Rutherford’s model was discarded?

(b.) Write the electronic configuration of S2-

9. The reaction of NH2 CN(s) with oxygen was affected in a bomb calorimeter and ∆U was found to

be -742.7 Kj/mol of cyanamide at 298 K. calculate enthalpy change for the reaction

NH2CN(s)+3/2 O2 (g) N2 (g) + CO2 (g) + H2O(l)

OR

Calculate the enthalpy change for the reaction:-

H2 (g) +Cl2 (g) 2HCl (g)

Given that bond energies H-H, Cl-Cl and H-Cl bonds are 433,244 and 431Kj/mol respectively

10 . Why is Li2CO3 decomposed at a lower temperature whereas Na2CO3 is decomposed at a higher temperature?


11. Write the equilibrium constant for the reaction :

(a) Fe3+

(aq) + 30H- (aq) Fe(OH)3 s

(b) Cu(NO3)2 (s) 2CuO (s) + 4NO2(g) + 02 (g)

ii) What is the conjugate acid of NH3?

12. Account for the following.-

(i) Na and K impart colour to the flame but Mg does not?

(ii) Lithium is the best reducing agent in aqueous solution?

(iii) Which out of the two- lithium or sodium forms nitrides?

13. (a) What is inert pair effect? Give one example.

(b) Why is CO2 gas whereas SiO2 is solid?

14. (a) Which of the following carboanion is more stable?

(i) (CH3)3CCH2 θ

CH3CƟHCH2CH3

(ii) CH3CH2CH2Ɵ

(b) Draw the resonating structures for CO32-.

c) Among carbocations which is the most stable?

15. Explain the following

a) CCl4 does not give white precipitate with silver nitrate solution on heating. Why?

b) Why is O2NCH2O- is expected to be more stable than CH3CH2O-

16.Complete the following

(a)CH3Br + Mg dry ether

(b) 2CH3CH2I + Na dry ether

c) CH3COONa + NaOH +CaO Δ___►

17. The kinetic energy of an electron is 4.55x10-25 J. the mass of electron 9.1x10-31 Kg. Calculate

velocity, momentum and the wavelength of the electron?

18. Give reasons:


a) Size of cation is always smaller than the parent atom.

b) Ionization enthalpy of nitrogen is greater than that of oxygen.

c) Electron gain enthalpies of beryllium and magnesium are positive.

19. What will be the pressure exerted by mixture of 3.2 g of methane and 4.4 g of carbon dioxide

contained in a 9 dm3 flask of 27o C.

20.The pH of 0.1 M solution of HCNOƟ is 2.34. Calculate the ionization constant for the acid and its

degree of ionization in the solution.

21. (a) Identify the substance oxidized and reduced:

N2H4 + 2H202 N2 + 4H2O

(b) Calculate the oxidization No. of Carbon in CH3CH2OH

(c) Balance the following:

MnO4–+Fe2+ Mn2++Fe3 (Acidic medium)

OR

(a) Balance the following equation Fe2++Cr2O72- → Fe3++ Cr3+

(b) What is salt bridge? Write its application also.

22.(a) Give two properties of Water which are due to Hydrogen bonding.

(b) Explain the Structure of H2O2.

23.Ramu had reared fishes ia local pond in the fields of his father.He was very fond of them.His

father had sprayed insecticides in the field to protect the paddy crop. However after a month

Ramu found that the percentage of fish in the pond had sharply declined.There was a thick green

covering of filamentous material and the water was putrifying.Ramu persuaded his father to turn

the direction of the irrigated water away from the pond?

(a) What may be the possible reasons for Ramu’s observation?

b) What do you mean by BOD

(c)What are the values depicted from this text about Ramu and his father?.

24. Give reason:

(a) Concentrated HNO3 can be transported in aluminum containers.

(b) Graphite is used as lubricant.

(c) A mixture if a dil. NaOH and aluminum piece is used to open holes.

(d) Carbon shows catenation but silicon does not.

(e) Tin (II) is a reducing agent but Pb(II) is not.


OR

A certain salt(X) gives the following results

(a) Its aqueous solution is alkaline to litmus.

(b) It swells up to glassy material (Y) on strong heating.

(c) When concentrated H2SO4 is added to hot solution of X, white crystals of an acid Z

separates out.

(d) Write equations for ii and iii. Also identify X, Y, Z.

25.(a) i) How many sigma and Pi bonds are present in CH2=CH—C≡CH

ii) Why H2+ is more stable than H2Ɵ?

iii) Why is B2 molecule paramagnetic?

(b) Discuss orbital structures of following molecules on the basis of hybridization

i) BH3

ii) BeCl2

OR

a) on the basis of VSEPR theory explain shapes of following i) NH3 ii) H2O

b) Which of the two NH3 or NF3 has higher dipole moment?

c) Why N2 is more stable than O2?

d) Why is ethyl alcohol miscible with water?

26. a) Why terminal alkynes are acidic in nature?

b) Write IUPAC name of following

CH3—C—CH2—COOH

║

O

c) Write the following conversions i) Propene to 2,3 -Dimethyl butane

ii) Ethene to Ethyne

iii) Benzene to Benzene sulphonic acid

OR

I. What effect does branching of an alkane chain has on its boiling point?

II. Define Ozonolysis Reaction?

III. Define cracking?

IV. Why benzene is extra ordinary stable though it contains three double bonds?

V. Why Nitro-benzene doesn’t undergo Friedel-Craft alkylation?


VI. SET – TWO [ GURGAON REGION] VII. SESSION ENDING EXAMINATION(2014-15)

VIII. CLASS:XI SUB: CHEMISTRY IX. TIME: 3 Hours M.MARKS:70

MARKING SCHEME

Q No 1. 2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

Value Points 6.022 x 1023

Valance electrons present in the outermost shell take part in the bond formation Period – 4 and group -13 At constant pressure, volume of a given mass of a gas increases or decreases by 1/273 of it’s volume at 00 C for every 10 rise or fall in temperature. Positive or increases. ∆G=∆H-T∆S, On the whole if ∆G is –ve the reaction is spontaneous Molarity = WB/MB x 1000/vol. of sol. in ml.

MB = 23+16+1 = 40 WB = 0.15 x 40 x 100/1000 = .6g

(a) Because it couldn’t explain the stability of atom. (b) 1s2 2s2 2p6 3s2 3p6

∆ng = 2-3/2 = ½

∆H = ∆v+∆ng RT Correct substitution of values,Correct answer -741.5 kJ/ mol

OR ∆rH=£B.E of H-H - £B.E of product =[B.E of H-H – B.E of cl-cl] =[2 x B.E of H-Cl bond] Correct substitution Correct Answer= -185KJ.

Lithium is less electropositive than sodium Lithium is smaller in size , thus lattice enthalpy of Li2CO3 is less Kc = 1 .

[Fe][OH]

Kc = [NO2(g)]4[O2(g)] Conjugate acid is NH4

+ Due to small size if Na and K, less energy required for the excitation of e-, whereas in Mg atom, due to small size, large amount of energy is required which is not possible in Bunsen flame. Due to most negative reduction potential. The reluctance of valence s-electrons to participate in bond formalin.

Marks

1 1

1/2,1/2

1

1

1 1

1+1

1+1

1 1

1 1

1+1

1+1+1


13. (i)

(ii)

14. (a) (b)

c)

15(a) (b)

16(i) (ii) (iii) 17

E.g.:- In gp 13 stability of +1 oxidation state increases down the group. As carbon can form π bond thus forms molecules of type O=C=O and exist as gas Whereas Si cannot form π bond so forms 3-dimensional network structure. CH3CH2CH2

0 Correct resonating structures Tertiary carbocation due to inductive effect and hyperconjugation Because CCl4 is covalent and cannot give chlorine ion in solution. Because of electron withdrawing nature of NO2 CH3MgBr CH3CH2CH2CH3 + 2NaI CH4 K.E= ½ mv2 V=√(2K.E/m) = √(2 x 4.55 x 10-25)/(9. 1 x 10-31) 103 m/s Momentum, =mv =9.1 x 10-31 x 103

= 9.1 x 10-28 kg m/s Wavelength, λ= h/mv = 6.629 x 10-34 . 9.1 x 10-31 x 103 =7.28 x 10-7 m Because of less number of protons in cation than in parent atom, the effective nuclear charge is more in cation than in parent atom. Because nitrogen has exactly half filled electronic configuration i.e 1s22s22p3 Because they have stable configuration P = nRT V PCH4 = (WCH4.RT)/CH4 ..V) PCH4 = 3.2 x 0.0821 x 300 = 0.55 atm

16 9 PCO2 = 4.4 x 0.0821 x 300 = 0.27 atm

44 9 Total pressure = PCH4+PCO2

=0.55+0.27=0.82 atm

1+1+1

1+1

1

1

1

1

11/2+11/2

1 1 1

1/2

1/2

½ ½

½ ½


18 (1)

(2)

(3)

19.

(a)

(b)

20. (a) (b)

21. (a)

(b)

(c)

21.

HCNO↔H+ + CNO- pH=2.34=-log[H+] [H+]=Antilog3.86= 4.57 x 10-3 M [CNO-]=[H+]=4.57 x 10-3 M Ka= (4.57 x 10-3 )( 4.57 x 10-3 ) 0.1 =2.09 x 10-4 α=√( Ka/c) = √{2.09 x 10-4)0.1)} = 0.0457 Substance oxidized N2H4 Substance reduced H2O2 C2

xH6+1O-2

2x+6-2=0 x=-2 Balancing can be done by any method 8H++MnO4

-+5Fe2+ → Mn2++4H2O+5Fe3+ OR Fe2++Cr2O7

2-+H+→Fe3++Cr3++H2O Oxidation no. inc by |¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯↓ Fe2++Cr2

6+O72-+H+→Fe3++Cr3++H20

| ↑ Oxidation no. dec. by €˳ for 2 atoms 6Fe2++Cr2O7

2-+14H+→6Fe3++2Cr3++7H2O Correct answer, maintains the internal circuit. (i) It exist as liquid at room temperature (ii) Its boiling point is high H2O2 has a non planar structure The O-H bond are on different planes thus the structure of H2O2 is like open book.

1

1

1

1

1/2

1

11/2

1

1

1

½ ½

1/2

11/2

½ ½


22. (1)

(2)

23.a) b)

c)

24. (a)

(b)

(c)

(d)

(e)

Algal bloom and eutrophication The amount of oxygen consumed by micro organism in decomposing organic waste of sewage water. Ramu has knowledge of environmental chemistry and is ecofriendly.The father is ignorant and self obsessed. Because HNO3 reacts with aluminum to form a thin film of aluminum oxide on its surface which protects it from further reaction 2Al(s) + 6HNO3(conc.)→Al2O3(s) + 6NO2(g) + 3H2O(l) Graphite has layered structure which are held by weak Vander Waals forces thus graphite cleanes easily between the layers. Therefore, it is very soft and slippery that’s why it is used as lubricant. NaOH reacts with Al to evolve H2 gas Thus the pressure of the gas produced can be used for clogged drains. 2Al(s) + 2NaOH(aq.) + 2H2O(l)→2NaAlO2(aq.) + 3H2(g) Because carbon is small in size and form C-C strong bond it can also form Pπ-Pπ multiple bond also. Due to inert pair effect Pb2+ is more stable than Pb4+ whereas Sn4+ is more stable than Sn2+ thus Sn2+ is a good reducing agent and Pb2+ is not. OR X→Na2B4O7 Y→NaBO2 + B2O3 Z→H3BO3 Na2B4O7.10H2O→ Na2B4O7→2NaBO2 +B2O3

Glassy bead Na2B4O7.10H2O + H2SO4→4H3BO3 + Na2SO4 + 5H2O (i) No. of σ bonds= 7 No. of π bonds=3 (ii) Both the ions have the same bond order (O.S) but they differ in their configuration H2

+ ion =[ σ1s]1 H2

- ion = [σ1s]2[σ*1s]1

Since H2- ion has an electron in the * bonding molecular orbit it is therefore,

less stable. (iii) B2:[ σ1s]2[σ*1s]2[σ2s]2[π2px]1[π*2py]1 Since B2 has two unpaired electron thus it is paramagnetic

(i) correct structure, Hybridization (ii) correct structure, Hybridization OR

1

1

1,1

1

1+1+2

1

1

1

1

1


(b)

25. (a)

(b)

26.a)

b)

(a) correct shapes (b) NH3 due to more +ve dipole moment (c) N2 has bond order 3 whereas has O2 Thus due to more BO of N2,it is

more stable (d) Because of hydrogen bonding

Hybridization of C in, C≡C is sp Due to more s-character of the C-H bond of 1-alkyne 3- Oxobutanoic acid HBr (i) CH3-CH=CH2→CH3-CH-CH3__Dry ether CH3-CH-CH-CH3 | Na | | Br CH3 CH3 Br2/Ccl4

(ii)CH2=CH2- →Br-CH2-CH2-Br___ KOH(alc)→ CH2=CHBr→HC≡CH

OR i) As branching increases, the surface area of alkene approaches that of a sphere. Since a sphere has minimum surface area, therefore, Vander walls forces of attraction are minimum and hence the boiling point of the alkene decreases with branching. ii) When an alkene is treated with ozone at low temperature ozonoid is obtained which when heated with Zn dust and water gives aldehydes and ketones depending upon the nature of alkene. Reaction is called ozonolysis. iii) The thermal decomposition of higher hydrocarbons into lower hydrocarbons in presence or absence of a catalyst is called cracking. iv) Due to resonance. v)The NO2 groups strongly deactivates the benzene ring for the attack of an electrophile.

1*3=3

2

1

1

1

1+1

1+1 1 1

1

1

1

1

1


SET – THREE [CHANDIGARH REGION] SESSION ENDING EXAMINATION(2014-15)


BLUE PRINT S.No. Unit VSA

(1Mark) SAI (2Mark)

SAII (3Mark)

VB (4Mark)

LA (5Mark)

Total

Unit I

Some Basic concept of chemistry

2(1) 3(1) 5(2)

Unit II Structure of atom 1(1) 2(1) 3(1) 6(3) Unit III Classification of elements

& periodicity in properties 1(1) 3(1) 4(2)

Unit IV Chemical Bonding & Molecular Structure

1(1) 5(1) 6(2)

Unit V States Of Matter 1(1) 3(1) 4(2) Unit VI Thermodynamics 2(1) 3(1) 5(2) Unit VII Equlibrium 1(1) 2(1) 3(1) 6(3) Unit VIII Redox Reaction 3(1) 3(1) Unit IX Hydrogen 3(1) 3(1) Unit X s-Block elements 5(1) 5(1) Unit XI p-Block elements 2(1) 3(1) 5(2) Unit XII Organic chemistry-Some

Basic Principles & Techniques

6(2) 6(2)

Unit XIII Hydrocarbon 3(1) 5(1) 8(2) Unit XIV Environmental Chemistry 4(1) 4(1) Total 5(5) 10(5) 36(12) 4(1) 15(1) 70(26)










(vi) Questions no.23 carry 4 marks and Q.No.25 to 26 are long answer questions of 5 marks

each.


Q.1 Calculate the total no. of angular nodes and radial nodes in 3p orbital (1)

Q.2 Which of the following have high lattice energy CsF, CsCl, CsBr, CsI.and Why?(1)

Q.3 Which has high electron affinity-F or Cl. (1)

Q.4 Write the conjugate base for HF & H2SO4. (1)

Q.5 Writes Vander Waal’s equation. (1)

Q.6 An element with massno.81 contains 31.7% more neutrons as compared to protons. Assign the atomic symbol.(2)

Q.7 Write the expression for the equilibrium constant Kc for each of the following reaction:

(i) Fe+3(aq)+3OH- (aq) ---- Fe(OH)3 (s)

(ii) I2 (s)+5F2(g) ----2IF5(g) (2)

Q.8How many significant figures are present in the following calculations:

(i) 5 X 5.364 (ii)0.0125+0.7676+0.0215 (2)

Q.9 Give reasons:

(i) Atomic radius of Ga is less than that of Al.

(ii)BF3 is not easily hydrolysed by water.


Q.10 iCalculate ∆fH0 of HClif bond energy of H-H bond is 437kJmol-1Cl-Cl bond is 244kJmol-1 and H-Cl is 433 kJmol-1. Q.11 An organic compound containing carbon, Hydrogen, Oxygen gave the percentage composition as C=40.687% H=5.085% The vapour density of the compound is 59. Calculate the molecular formula of the compound.

Q.12 (i) Define these: Aufbau Principle Hund’s Rule of maximum multiplicity

(ii) Write the electronic configuration of Cu+

Q.13 A student forgot to add the reaction mixture to the round bottomed flask at 270c but instead he placed the flask on the flame.After a lapse of time he realised his mistake and using the pyrometer he found that temperature of flask was 4770c. What fraction of air would have been expelled out? (3)

Q.14 Account for these:

(i) size of Na+ is lesser than Na.

(ii) Nitrogen has high ionisation energy than Oxygen.

(iii)Sixth period of the periodic table should have 32 elements.(3)

Q.15 (i) Balance the following equation by ion electron method:

Cr2O7-2(aq)+ SO2(g)--- Cr+3(aq)+SO4

-2(aq)( IN ACIDIC MEDIUM)

(II) Assign oxidation no. of Mn& N in KMnO4 And NO3- (3)

Q.16

(i) For the reaction 2Cl (g)--- Cl2(g) . What are the sign of ΔH &ΔS.

(ii) Which quantity out ofΔGr& ΔG0r will be zero at equilibrium?

(ii) why the entopy of perfectly crystalline substance is taken as zero? (3)

Q.17 Write the following naming reactions

(i) Wurtz Reaction (ii) Friedal-Craft Alkylation (iii) Peroxide effect (3)

Q.18

(i) Calculate the solubility of A2X3 in pure water, assuming that neither reacts with water.Ksp=1.1X10-23

(II) What will be the pH of 1M Na2SO4 sol? (3)

Q.19 (i) Write one method to remove the permanent hardness of water.

(ii) Is demineralised water fit for drinking purposes ?How can it be made useful?


(iii)Write one laboratory method of preparation of hydrogen gas(3)

Q.20 0.3780g of organic chloro compound gave 0.5740g of silver chloride in carius estimation .Calculate the percentage of chlorine present in the compound. (3)

Q.21 Write balanced equation :

(i) BF3+LiH --

(ii) NaH +B2H6--

(iii) B(OH)3 + H2O-- (3)

Q.22

(i) Write IUPAC Name of following compound: OHC-CH2-CH2-CHO

(ii) Explain InTolune CH3 group is O &P directing in nature.

(iii) Why HCOOH is more acidic than CH3COOH? (3)

Q.23 In slum areas in winter season people often burn coke angithis to heat up their rooms & then sleep their whole night.Sometimes cases of unconsciousness &death are reported from these houses,not because of their houses catches fire but because of the poisonous gases accumulated in their room.Even in urban areas, in winter where people keep their electric heaters on the whole night,incidents occur due to overheating of the electric heater or short circuiting.

After reading the paragraph answer the following questions:

(i) What values are expressed in above paragraph? (ii) How is poisoning caused by coke angithi ? (iii) what steps should be taken immediately as a part of treatment? (4)

Q.24

(i) Draw energy level diagram of O2. Calculate its bond order& write its magnetic property.

(ii) On the basis of VSEPR Theory Explain the Geometory Of; ClF3& CH4

Q.25 Give reasons for each:

(i) BeO is insoluble but BeSO4 Is soluble in water.

(ii)Be & Mg Do not impart colour to the flame .

(iii)Gypsum is added in the final stages of prepration of cement.

(iv)Alkali metals give deep blue color when dissolved in liquid ammonia.

(v)Li Forms oxide Na forms peroxide & K forms superoxide (5)

OR


(i) Write the balanced equation for the reaction of: Na2O2 and water Na2O and CO2

(ii) Write the various steps involved in the Solvay process for the prepration of Na2CO3

Q.26 (i) Arrange Benzene, n-Hexane &ethyne in decreasing order of acidic behaviour. Give reason.

(ii)Propanal& pentane-3-one are the ozonolysis products of an alkene .What is the structural formula of the alkene?

(iii) What happened on heating of phenol with Zn dust. Write reaction. (iv) Convert propyneino acetone.

OR

(i)Explain Markovnikov,sRule.write its mechanism.

(ii) Convert These:

Benzene into acetophenone.

Ethene into Benzene.




MARKING SCHEME S.No Answer Value Point 1 angular nodel=1

Radial node=n-l-1=3-1-1=1 1/2 1/2

2 CsF. Small size of anion ½+1/2 3 Cl 1 4 F- HSO4

- ½+1/2 5 (p+an2/V2) (v-nb)=nRT 1 6 A=p+n=81

P=x n= X+31.7% of x=1.317x X=35 symbol Br35

81

1/2 1/2 1

7 Kc=1/[Fe+3].[OH-]3 Kc=[IF5]2/[F2]5

1 1

8 (i)=4 (ii)=4 1+1=2 9 i) poor shielding of d orbital in Ga

(ii)Strong B-F bond due to back bonding 1 1

10 (i) Bond energy is the amount of energy released when bond is formed between t wo isolated atoms in ground state.

(ii) 1/2 H2 (g) + 1/2Cl2(g) → HCl(g) ∆fH0 = ? ∆fH0 =∑𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃 𝒆𝒆𝒃𝒃𝒆𝒆𝒆𝒆𝒆𝒆𝒆𝒆𝒆𝒆𝒆𝒆𝒆𝒆𝒆𝒆 𝒃𝒃𝒐𝒐 𝒓𝒓𝒆𝒆𝒆𝒆𝒓𝒓𝒆𝒆𝒆𝒆𝒃𝒃𝒆𝒆𝒆𝒆 -

∑𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃 𝒆𝒆𝒃𝒃𝒆𝒆𝒆𝒆𝒆𝒆𝒆𝒆𝒆𝒆𝒆𝒆𝒆𝒆𝒆𝒆 𝒃𝒃𝒐𝒐 𝒆𝒆𝒓𝒓𝒃𝒃𝒃𝒃𝒑𝒑𝒓𝒓𝒆𝒆𝒆𝒆 ∆fH0 = {1/2 x 437 + 1/2 x 244} -{433} = - 92.5kJmol-1

1 1

11 writing correct sep. calculating empirical formula (C2H3O2) correct molecular formula (C4H6O4)

1 1 1

12 .(i) Aufbau Principle: the orbitals are filled in increasing order of energy. Hund’s Rule: electron pairing did not take place until each orbital is first singly filled with parallel spin (ii) 3d10

1+1=2 1

13 consider Volume =V At 270c V1=V V2=? T1=300K T2=750K V1/T1=V2/T2 (1) V2=2.5V Volume Expelled=2.5V-V=1.5 V Fraction of air expelled=1.5v/2.5V=0.6

1 1 1

14 (i) High nuclear charge in Na+ after removal of electron, No of shell reduces.

(ii) Completely half filled configuration in N , symmetrical distribution leading to stability.

(iii) n=6 involve filling of4f,5d,6s&6p orbital hence 32elements only

1+1+1=3


15 Correct balanced equation Cr2O7

-2(aq)+3 SO2(g) +2H+--- 2Cr+3(aq)+3SO4-2(aq) +H2O

O.S. Of Mn=+7 N= +5

2 ½+1/2

16 (i) ΔH=-ve Δ S=-ve (ii) ΔGr=0 at equilibrium (iii) due to orderly arrangement of atoms.

1 1 1

17 (i) Wurtz synthesis: Higher alkanes are prepared by heating an alkylhalide (RX) with sodium metal in dry ether solution.

R-X +2Na + XR dry ether R-R + 2NaX CH3Br + 2Na + BrCH3dry ether CH3CH3 + 2NaBr (ii)

(iii)CH3-CH=CH2 +HBr--Peroxide------CH3CH2CH2Br

1 1 1

18 (i) KSP=(2S)3. (3s)3=1.1 x10-23 S=1.0X 10-5mol/l (ii) pH =7 (neutral soi. Of strong acid & strong base)

1 1 1

19 (i)Treatment with washing soda (sodium carbonate): MCl2 + Na2CO3--- MCO3+2NaCl Or any Method

(ii) No, By adding ions (iii) Generally prepared by the reaction of granulated zinc

with dilute hydrochloric acid as under Zn(s)+2HCl ---ZnCl2 +H2 (g)

1+1+1=3

20 Write formula Value substitution Write Ans % of chlorine = 35.5*mass of AgCl formed * 100/143.5 * mass of the substance = 35.5*0.5740*100/143.5*0.3780 = 19.6 %

1 1 1

21 B2H6+ LiF Na+[BH4]- [B(OH)4]-+ H3O+

1 1 1

22 .(i) butane1,4dial (ii) due to Hyperconjugation. (III) HCOOH is more acidic +I effect in CH3COOH

1 1 1

23 (i)Awareness regarding the harmful effect of coke , Careless attitude ,ignorance regarding harmful effect of coke (ii)coke burns to produce CO , which combine with Hb to form Carboxyhaemoglobin& function of hb to carry Oxygen to different parts get inhibited. (iii)Any Two steps Carry the patient into fresh air immediately. Artificial respiration, if not possible to breathe properly.

1 1 2

24 Energy level diagram 2


Bond order =2 Paramagnetic (ii) ClF3- T shape CH4- Tetrahedral

½ ½ 2

25 Correct Reason (i) BeO is covalent & BaSO4 is ionic (ii) Small size &high ionization energy (iii) To slow down the process of setting of cement&

impart greater strength. (iv) Due to the formation of ammoniated electron (v) Smaller cation can stablise smaller anion & larger

cation can stablise larger anion. OR NaOH +H2O2 Na2CO3 Correct steps in Solvay Process In Solvay process ,CO2 is passed through brine saturated with ammonia .when NaHCO3 being sparingly soluble gets precipitated. NaCl+ NH3 + CO2 -NaHCO3 + NH4Cl (i) Sodium bicarbonate thus formed is filtered, dried and then heated when sodium carbonate is Obtained. 2 NaHCO3 ------> Na2CO3 + CO2 + H2O

CO2 needed for the reaction shown in eq.(i) is prepared by heating calcium carbonate and the quick lime,CaO thus formed is dissolved in water to form slaked lime, Ca(OH)2. NH3 needed for the purpose is prepared by heating NH4Cl

1+1+1+1+1=5 1 1 3


26 (i) ethyne> benzene> Hexane Due to greater S-Character. (ii)3-Ethylhex-3-ene

(iii) (iv)

OR During addition across unsymmetrical compound the negative part go toward that side which contain less no. of Hydrogen atom. CH3-CH=CH2 +HBr--CH3 CH(Br) CH3

Conversion:

(1+1=2) 1 1 1

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SET – FOUR [ CHANDIGARH REGION] SESSION ENDING EXAMINATION(2014-15)


BLUE PRINT S.no

Name of the chapter

Weightage of the chapter

VSA-1

SA-2

SA-3

SA-4 Value based

SA-5

Total =70

1 Some basic concepts in Chemistry

5 1(1) 2(2) 3(5)

2 Structure of atom 6 1(2) 2(3) 3(8)

3 Classification of elements and periodicity in properties

4 1(1) 1(3) 2(4)

4 Chemical bonding and molecular structure

7 1(1) 2(3) 3(7)

5 State of matter 4 1(1) 1(3) 2(4)

6 Thermodynamics 4 1(1) 1(3) 2(4)

7 Equilibrium 7 1(2) 1(5) 2(7)

8 Redox reaction 3 1(3) 1(3)

9 Hydrogen 3 1(3) 1(3)

10 s-Block elements 5 1(2) 1(3) 2(5)

11 p-Block element 5 1(5) 1(5)

12 Organic-Some basic principles and techniques

6 2(3) 2(6)

13 Hydrocarbons 7 1(2) 1(5) 2(7)

14 Environmental Chemistry 4 1(4)

15 Total 70 5(1)= 5

5(2)= 10

12(3)=36

1(4)= 4

3(5)=15

30(70)





(viii) All questions are compulsory.

(ix) Marks for each question are indicated against it.

(x) Questions no.1to 5 is very short answer questions and carries 1 marks each.

(xi) Questions no.6to 10 is short answer questions and carries 2 marks each.

(xii) Questions no. 11to22 are also short answer question and carry 3 marks each.

(xiii) Questions no.23 carry 4 marks and Q.No.25 to 26 are long answer questions of 5 marks

each.

(xiv) Use long Tables, if necessary. Use of calculators is not allowed.

Q1. Define limiting reagent. Q2. Write IUPAC name and the symbol for the element with atomic number 120. Q3. Write the Vander Waals equation for ‘n’ mole of a gas. Q4. Predict the sign of entropy change for the reaction:

2O3(g) → 3O2(g) Q5. What is the state of hybridization of ‘S’ in SF4 molecule? Q6. Calculate the number of molecule and number of atoms of each type in 5.3g of Na2CO3.

(Atomic mass of sodium =23g ,carbon =12g and Oxygen = 16g) Q7.Calculate the molarity of a solution of ethanol in water in which the mole fraction of ethanol is 0.040(Assume the density of water as one). Q8. Calculate the Ph of solution obtain when 4g of sodium hydroxide has been dissolved in to 500 ml of the solution.

OR Derive the relationship between Kp and Kc. Q9. Account for the following

K2CO3 cannot be prepared by Solvey ammonium process Alkali metals are not found in nature

Q10 An alkene ‘A’ upon ozonolysis gives methnal and propan 2-one .What should be the structure of the alkene. Q11. Calculate the wavenumber for the longest wavelength transition in the Balmer series of atomic hydrogen.


Q12. (a) How many electrons in an atom may have the following quantum numbers? n = 4, ms = – ½ (ii) n = 3, l = 0 (b) What is the maximum number of emission lines when the excited electron of a H atom in n = 6 drops to the ground state? Q13 Consider the following species : Al3+, F- , Mg2+ , Ne ,Na1+ O2- and N3-

(i) What is common in them? (ii) Arrange them in the order of increasing ionic radii. (iii) What are these called as.

Q14 What is meant by the term bond order ? Calculate the bond order of : O2, O2

+ O2- and O2

2- species and arrange these species according to their decreasing order of stability. Q15. What is meant by hybridization .Explain sp and sp2 hybridization with an example? Q16. For a reaction . 2A (g) + B (g) → 2D (g), ∆U0 =-10.5 kJmol-1and ∆S0 = - 44.10 Jmol-1 .Calculate ∆G0 for the reaction and predict whether the reaction may occur spontaneously. Q17. 2.9 g of a gas at 950 C occupied the same volume as 0.184 g of hydrogen at 17 0 C at the same pressure. What is the molar mass of the gas? Q18. (a) What is the oxidation number of ‘S’ in HSO4

- ion? (b)Balance the following ionic equation by ion electronic method. P4(S) + OH-(aq) →PH3 + H2PO2

-

Q19. (a) Write a chemical equation to justify that hydrogen peroxide function as oxidizing. (b) Explain why hydrogen peroxide is stored in wax lined glass or plastic bottles (c ) Ice float on the surfaced of the water. Q20 Explain the following terms

(i) Beryllium and magnesium do not give colour to the flame whereas other alkaline earth metals do so , Why?

(ii) When alkali metals dissolved in dilute liquid ammonia, the solution acquire blue colour, why?

(iii) Alkali and alkaline earth metals cannot be obtained by chemical reduction method, why?

Q21. Write the IUPAC name of following organic compound.

(i) CH3CH2COCH2OCH3 (ii) CH2=CHCH (CH3) CH=CH2

Write the structure of the compound whose IUPAC name is 4-Hydroxy phenol. Q22. (a) Find the total number of sigma and pi bonds in the given molecule.

CH3CH (CH3) COCH2NO2 (b) What are carbocations . Arrange the primary secondary and tertiary carbocations according to their decreasing order of satiability.


Q23. A trainee pilot was flying his plane in stratosphere . His senior advised him not to fly the aero plane in the stratosphere. Answer the following the following questions: In your opinion , why the senior pilot advised his trainee not to fly the aeroplane in the stratosphere ? Write the possible chemical reaction affecting the stratosphere Mention the possible value associated with your reply. Q24. (a) What will be the Conjugate acids for the following Bronsted bases, (i) NH2

- ,NH3,HCOO- and H2O (b) What is Le chatlier principle? Under what conditions would we get maximum yield of ammonia in the Haber’s process? OR Q. (a) What are buffer solution .Explain with an example. (b) A sample of HI(g) is placed in a flask at a pressure of 0.2 atm . At equilibrium, the partial pressure of HI (g) is 0.04 atm. What is Kp for the given equilibrium? Q25.(i) Is boric acid a protic acid? Explain. (ii) Suggest a reason why the B-F bond in BF3 is shorter than B-F bond in BF4

-. (Iii) Diamond is used as abrasive Draw the structure of diborane . OR Q (a) When a metal (X) is treated with sodium hydroxide , a white precipitate (A) is obtained , which is soluble in excess of sodium hydroxide to give soluble complex (B) . Compound (A) is soluble in dil HCl to form compound (C) . The compound (A ) when heated strongly gives (D) which is used to extract metal . Identify X ,(A) ,(B) ,(C) and (D) . Write suitable equation to support your identity. (b) Explain Why Conc. HNO3 cannot be transported in aluminium container. ( c) Explain Why Conc. Aluminium utensils are not kept in water overnight . Q26. (a)The addition of HBr to propene yields 2-Bromo-propane, while in the presence of benzoyl peroxide the same reaction yields 1-Bromopropane. Explain and give the mechanism. (b) Explain Wurtzs reaction with an example .Why this method is not suitable for preparing odd number of carbons alkanes. 3+2 OR (a) Draw cis and trans isomers of But-2ene. Which isomer have higher boiling point and why? (b) Explain the following terms with an example. (i) Friedel craft reaction (ii) Kolbe’s electrolysis (iii) Kharash effect




Ans1. The reactant which get completely consumed 1 mark Ans2. Ubn unbinilium ½ +1/2 Ans3. Correction equation 1 marks Ans4. Entropy increases 1 marks Ans5. SP3 1 Marks Ans 6. 3.01 x1022 , 6.01 x1022 ,9.03 x1022 2 marks Ans7. Correct formula ½ mark Correct Calculation- 1 M Correct Calculation - 1/2 M Ans8. Correct calculation , answer 13 – 2 marks Ans9. (i) Because KHCO3 is soluble in water . (ii) These are reactive metals 1+1 Ans10. 2-Methyl But-1-ene 2 Ans11. Correct formula ,,correct calculation and correct answer 1+ 1 +1 Ans12. (i) 16 electrons, 2 electrons 2 (ii) 15 lines 2+1 Ans13. (i) All have 10 electrons (ii) Correct order Iii Iso -electronic species ½+1+1/2 Ans14. Definition Bond order O2 = 2 O2

+= 2.5 O2 -1 = 1.5 O22- =1.0

Correct order 1+1+1 Ans15. Correct definition , Correct explanation with example 1+2marks Ans16. ∆H = ∆U + ∆ngRT = 12.978Kj Mol-1 ∆G=0.164Kj Mol-1 Ans17. Apply formula PV=w/MRT M= 40 g mol-1 3marks Ans 18. O.N = +6 Correct balancing 1+2 Ans19. Write one equation in support of your answer 1+1 Due to its oxidation in air in presence of sunlight 1


Ans20. (i) Due to high ionization enthalpy of the Be and Mg (ii) Due to ammoniated electron Iii Very reactive matal 1+1+1 marks Ans21. Correct IUPAC name 1+1+1 Ans22. Correct number of sigma and Pi bonds Correct explanation and correct order 1+1+1 Ans23. Chloro fuloro carbon Freon gas released by aero plane reacts with stratosphere Correct equation Concern for environmental pollution. 1+1+1+1 Ans24. (i) NH3 NH4

+ , HCOOH and H3O+ High pressure , low temperature ,use of excess N2 And H2 2+3 Ans25 (i) It is a Lewis acid (ii) SP2 hybridisation in BF3

Iii it is hard Iv Correct shape 1+1+1+2 OR X= Al metal A=Al(OH)3 B=NaAlO2 C=AlCl3 D= Al2O3 Ans26. (i) Peroxide effect 1+1+1 (ii) Correct wurtz reaction 2 OR Correct drawing of Cis and trans isomers 2 Marks Correct explanation of each effect 1+1+1

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