AL-HAMD EVENING ACADEMY (F.Sc,B.Sc)Munir Plaza,Block J Dera Ghazi Khan

MAJOR TESTING ROUND-1 PHYSICS PART I, TEST NO 13,Name____________________ Class __________ Roll No_________ Section________Date_____Paper Physics 1st Year Test 13 Chapter 11(start to Cp-Cv=R ) Total Marks:40 (OBJECTIVE PART) Time:20 min

Q.1 MCQs Marks:1x9=91. The sum of all forms molecular energies of a substance is called a. temp b. internal energy c. pressure d. K.E

2. The internal energy of an ideal gas system is generally a. transnational K.E

b. P.E c. vibrational K.E d. all

3. Average K.E of molecules is called a. internal energy

b. temp c. pressure d. none

4. For an ideal gas system, the internal energy is directly proportional to its a. mass b. absolute temp c. density d. all

5. In thermodynamics, the internal energy in a function of a. path b. state c. position d. both a & b

6. The area of the graph b/w P and V is equal to a. change in internal energy

b. change in heat energy

c. work done d. change of temp

7. eq W = – ∆μ represents a. isothermal compression

b. adiabatic expansion

c. isothermal compression

d. adiabaticcompression

8. When a gas expands adiabatically a. law of conservation of energy does not hold

b. internal energy of the gas is used in doing work

c .no energy is required for expansion.

d. Energy is required and comes from the walls of the container of the gas

9.The value of boltzman constant K is a.1.38x10-23 jk-1 b. 1.38x10-25jk-1 a.1.38x10-29 jk-1 d a.1.38x10-17jk-1

AL-HAMD EVENING ACADEMY (F.Sc,B.Sc)Munir Plaza,Block J Dera Ghazi Khan

MAJOR TESTING ROUND-1 PHYSICS PART I, TEST NO 13,Name____________________ Class __________ Roll No_________ Section________Date_____Paper Physics 1st Year Test 13 Chapter 11(start to Cp-Cv=R ) Total Marks:40 (SUNJECTIVE PART) Time:20 min

Q.2 NOTE Write short answers of any 5 questions marks 4x2=8

I. Define internal energy of an ideal gas.II. Is it possible that there is change in temp of a body without giving/taking

heat to /form it?III. What happens to the internal energy of a gas during (a). isothermal

expansion (b). adiabatic expansion IV. Why is the average velocity of the molecules in a gas zero but the average

of the square of velocities is not zero?V. Why does the pressure of a gas in a car tyre increase when it is driven

through some distance?VI. Specific heat of a gas at constant pressure is greater than specific heat at

constant volume. Why?VII. Why does the temperature drop in an adiabatic expansion process? Long Questions NOTE attempt any two questions marks 16Q.3 a. Explain how molecular movement causes the pressure exerted by a gas

and derive the equation P = 2/3 No < ½ mv2> where No is the number of molecules per unit volume of gas. (5)

b. Estimate the average speed of nitrogen molecules in air under standard conditions of pressure and temperature (3)

Q.4 a. Define CP and CV .Also prove that CP – CV =R (5) b. A sample of gas is compressed to one half of its initial volume at constant pressure of 1.25 x 105 Nm–2. During the compression, 100 J of work is done on the gas. Determine the final volume of the gas. (3) Q.5 Define and explain first law of thermodynamics. (5) b. What is the average translational kinetic energy of molecules in a gas at temperature 27c0 (5)

PRACTICAL Q.6 Write the short answers of any 2 questions. Marks 2x2=4

i. A screw gauge has 50 divisions on its circular scale. The pitch of the screw gauge in 0.5 mm. What is its least count?

ii. If zero of circular scale in above the reference line and 95th div in coinciding with reference line what will be zero error and zero correction of total No of division on circular scale are 100.

iii. Define positive and negative zero error of screw gauge.

Q.7 Write the short procedure of an experiment to find the area of cross section of a wire using screw gauge. (3)