#### Unit test

12th Standard EM

Reg.No. :
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Chemistry

Use blue pen only
Time : 00:15:00 Hrs
Total Marks : 20

Part - A

5 x 1 = 5
1. Bauxite has the composition

(a)

Al2O3

(b)

Al2O3nH2O

(c)

Fe2O3.2H2O

(d)

None of these

2. Roasting of sulphide ore gives the gas (A).(A) is a colourless gas. Aqueous solution of (A) is acidic. The gas (A) is

(a)

CO2

(b)

So3

(c)

SO2

(d)

H2S

3. Which one of the following reaction represents calcinations?

(a)

$2Zn+{ O }_{ 2 }\rightarrow 2ZnO$

(b)

$2ZnS+3O_{ 2 }\rightarrow 2ZnS+3O_{ 2 }\rightarrow 2ZnO_{ 2 }\rightarrow 2ZnO+2SO_{ 2 }$

(c)

$MgCO_{ 3 }\rightarrow MgO+CO_{ 2 }$

(d)

Both (a) and (c)

4. The metal oxide which cannot be reduced to metal by carbon is

(a)

PbO

(b)

AL2O3

(c)

ZnO

(d)

Feo

5. Which of the metal is extracted by Hall-Heroult process?

(a)

Al

(b)

Ni

(c)

Cu

(d)

Zn

6. 5 x 2 = 10
7. Assertion :Aluminium is used in the, design of chemical reactors, : medical equipments, , refrigeration units and gas' pipelines.
Reason : Aluminium shows high resistance to corrosion
(a) Both (A) and (R) are true and (R) is the correct explanation of (A)
(b) Both (A) and (R) are true and (R) is not the correct explanation of (A).
(c) (A) true but (R) false
(d) Both (A) and (R) are false.

8. Assertion(A) :Metallic zinc is used in galvanising metals such as iron and steel.
Reason (R) :Zinc is also used to produce die castings
a) Both (A) and (R) are true and (R) is the correct explanation of (A).
b) Both (A) and (R) are true and (R) is not the correct explanation of (A).
c) (A) true but (R) false.
d) Both (A) and (R) are false.

9. Assertion(A) : Zone refining is carried out in an inert gas atmosphere
Reason (R):The metal is treated with a suitable reagent which can form a volatile compound with the metal.
a) Both (A) and (R) are true and (R) is the correct explanation of (A).
b) Both (A) and (R) are true and (R) is not the correct explanation of (A).
c) (A) true but (R) false.
d) Both (A) and (R) are false

10. Assertion :Cuprite is concentrated by froth floatation process.
Reason :Cuprite is the sulphide ore
a) Both assertion and reason are true and the reason is the correct explanation of the assertion.
b) Both assertion and reason are true but the reason is not the correct explanation of the assertion.
|c) Assertion is true, but reason is false.
d) Both assertion and reason are false

11. Assertion :Calamine and Dolomite are the Carbonate ores.
Reason :Calamine is ZnCO3 whereas dolomite is MgCO3.ZnCO3
a) Both assertion and reason are true and the reason is the correct explanation of the assertion.
b) Both assertion and reason are true but the reason is not the correct explanation of the assertion.
c) Assertion is true, but reason is false.
d) Both assertion and reason are false

12. 5 x 1 = 5
13. I.All ores are minerals
II. All minerals are not ores.
III.Aluminium can be extracted from bauxite.
IV.Aluminium can be extracted from china clay
a) Only I
b) Only II
c) III & IV
d) I, II & III

()

I,II,III

14. I. Copper is the first metal used by the human
II. Aluminuim is used in galvanising metals
III. Aluminium is a good conductor of electricity
IV.Magnets can be made from iron.
a) Only I
b) Only II
c) I, III & IV
d) III & IV

()

I, III & IV

15. I.Ellingham diagram helps to select a suitable reducing agent
II.Magnesite is calcinated to obtain magnesia.
III.Calcination is a process of cooling substances.
IV.Sulphur dioxide is harmful to the environment.
a) I, II & IV
b) Only II
c) Only I
d) III & IV

()

I, II & IV

16. I.Froth flotation is used to concentrate sulphide ores.
II. Magnetic separation is applicable for ferromagnetic ores.
III. Roasting method used to sulphide ores to oxides
IV.Magnetic separation is used to concentrate heavy oxide ores.
a) III & IV
b) Only II
c) Only I
d) I, II & III

()

I, II & III

17. I.Ores are associated with non-metallic impurities
II. Ores are associated with rockymaterials
III. Removal of impurities is known as concentration of ore.
IV. Ellingham diagram shows the stability of different metal oxides.
a) I, II, III & IV b
b) Only II
c) Only I
d) III & IV

()

I, II, III & IV

18. 5 x 2 = 10
a) The crude metal is refined by electrolysis.
b) The rods of impure metal are used as cathode.
c) Thin strips of pure metal are used as cathode.
d) Less electropositive impurities removed as anode mud.

a)Van-Arkel method used for refining Zirconium.
b) Aluminium is a bad conductor of heat.
c) Aluminium shows high resistance to corrosion.
d) Aluminium is a good conductor of heat

21. a) Aluminium is used to produce die-castings
b) Gold nanopartides used as an catalysts
c) Copper is the first metal used by the human
d) Brass is an alloy of zinc and copper

22. a) Germanium is used as an semi conductor
b) Stainless steel is an important alloy of Aluminum
c) Zinc sulphide is used in making luminous paints.
d) Brass an alloy of zinc is used in water valves

23. a) Metallic oxides can be reduced by an alumino thermitc process.
b) Flux + gangue$\rightarrow$ slag
c) Silica gangue present in the ore is basic in nature
d) Cu2S + FeS $\rightarrow$Copper matter