7/30/2019 Form 3 Chap 6 Questions & Answers

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1. For each mineral given, write E for element and C for compound in the space provided.

a Platinum f Sulphur

b Carbon g Silicate

c Carbonate h Sulphide

d Mercury i Silver

e Oxide j Gold

2. Match the mineral content( types of ore ) to the natural mineral in the table below.

Natural minerals Types of ore

a Bauxite Tin oxideb Cassiterite Magnesium carbonatec Hematite Copper carbonated Magnetite Calcium carbonateE Malachite Lead sulphide

f Galena Iron oxideg Limestone/Marble Aluminium oxide

3. Complete the concept map below about silicon compounds.

Sand Flint Clay Silicon Oxygen QuartzAsbestos Feldspar Oxygen Metal Silicon Mica

Silicon compounds

a.b.....................

Silica Silicate

fg.......................

h

c.

d

e.

i. j.

k l.

composition composition

examples

examples

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4.

Figure above shows an experiment to study the reaction between magnesium ribbon and oxygen.

(a)i. What can you observe in this experiment?

_________________________________________________________________________( 1 mark )

ii. Give one reason for the observation in (ai).

__________________________________________________________________________( 1 mark )

b. What is the source of oxygen in this experiment?

__________________________________________________________________________( 1 mark )

c. Write the word equation for the reaction.

( 1 mark )(d)i. Predict what can be observed if magnesium ribbon is replaced by iron filings.

__________________________________________________________________________( 1 mark )

ii. Give one reason for your answer in (di).

___________________________________________________________________________( 1 mark )

Potassium manganate(VII)

Glass woolMagnesium ribbon

heat

+

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5.

Figure above shows a mixture of zinc filings and sulphur being heated.

a. What is the compound formed?________________________________________________________________________

( 1 mark )

b. Write the chemical equation for the reaction that takes place.

( 1 mark )

ci. Predict what will happen if aluminium is used instead of zinc.

_______________________________________________________________________( 1 mark )

ii. Explain your prediction.

_______________________________________________________________________( 1 mark )

Mixture of zinc filings and sulphur

heat

+

7/30/2019 Form 3 Chap 6 Questions & Answers

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6. Figure 6 shows the apparatus used in an activity

Figure 6

(a) What is this apparatus used for?

(1 mark)

(b) (i) At what temperature is the first fraction distilled out

(1 mark)

(ii) What is this product?

(1 mark)

(c) How do the fractions differ from the following aspects as the boiling point of the distillate increase?

(i) Viscosity

(1 mark)

(ii) Colour

(1 mark)

(iii) Amount of soot when burnt

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(1 mark)

(d) (i) At what temperature is the last fraction collected?

(1mark)

(ii) Give two uses for this fraction

...(1 mark)

7.

Figure above shows a limestone being heated over high heat.

a. Explain what you observed.

( 1 mark )

b. Write the chemical equation to represent the effect of heat on limestone.

( 1 mark )

c. What is produced when water droplets are added to the product formed in (a).

( 1 mark )

d. Write the chemical equation to represent the reaction in (c).

( 1 mark )

e. What is the use of slaked lime in agriculture?

( 1 mark )

Glass rod

Nichrome wire

Limestone

Strong flame

+

+

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8. Give the common name and the elements that make up the following calcium compounds.

Common name Calcium compound Elements

Calcium carbonateCalcium oxideSolid calcium hydroxideCalcium hydroxide solution

7/30/2019 Form 3 Chap 6 Questions & Answers

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Answer

1. a, b, d, f, i, j Ec, e, g, h, - C

2. a. Aluminium oxideb. Tin Oxide

c. Iron oxided. Magnesium carbonatee. Copper carbonatef. Lead sulphideg. Calcium carbonate

3. a Siliconb Oxygenc Sandd Quartze Flintf Clay

g Micah Felspari Asbestos

j Siliconk Oxygenl Metal

4. a i) Magnesium powder burns with brightwhite flame

ii) Magnesium reacts with oxygen

b. Potassium manganate (iv)

c. Magnesium +oxygen ----magnesiumoxide

d. i) Iron fillings glowii) Iron is less reactive than magnesium

5. a Zinc sulphideb Zinc + sulphur -------zinc sulphidec i) The reaction take place faster and more

vigorouslyii) Aluminium is more reactive than zinc

6. a. To carry out fraction distillation of

petroleumb i) at about 20o Cii) Cooking gas

c i) the viscousity increasesii) The fraction becomes darker in colouriii) More soot is produced

d. i) at about 350oC to 400oCii) To tar roads and as printing ink

7. a. it decomposes and forms calcium oxide/quicklime

b. calcium carbonate-----------calcium oxide +carbon dioxide

c. calcium hydroxide / slake limed. calcium oxide+ water------calcium

hydroxide

e. to reduce soil acidity

8. a quicklimeb limestone/marblec slake limed lime watere calcium, oxygenf . Calcium carbon, oxygeng. calcium , hydrogen, oxygenh. calcium, hydrogen, oxygen