JAMB Chemistry Past Questions & Answers - Page 111

551.

What quantity of copper will be deposited by the same quantity of electricity that deposited 9.0g of aluminum? (A = 27, Cu = 64)

A.

64g

B.

32g

C.

7.1g

D.

6.4g

E.

3.2g

Correct answer is B

Al has valency of 3+:

3F will deposit 27g

xF will deposit 9g

cross multiply → \(\frac{9g * 3F}{27g}\)

: 1F = 9g

Cu has valency of 2+:

2F will deposit 64g

1F will deposit xg

cross multiply → \(\frac{64g * 1F}{2F}\)

: 1F = 32g

552.

The following are s-block elements except

A.

lithium

B.

magnesium

C.

potassium

D.

calcium

E.

aluminium

Correct answer is E

No explanation has been provided for this answer.

553.

If sulphur is dissolved in carbon (IV) sulphide and  the solution allowed to evaporate the allotrope of sulphur formed is

A.

plastic sulphur

B.

amorphous sulphur

C.

rhombic sulphur

D.

monoclinc sulphur

E.

colloidal sulphur

Correct answer is C

rhombic Sulphur is prepared by allowing a saturated solution of Sulphur in carbon (iv) sulphide to evaporate slowly and crystals will gradually be deposited.

554.

Given that 1 mole of carbon -12 weighs 12.0g, how many atoms are there in 24.0g magnesium? (C = 12, Mg = 24, NA = 6.02 x 10 23mol-1)

A.

1/2 x 6.02 x 10 23

B.

1 x 6.02 x10 23

C.

2 x 6.02 x 10 23

D.

3x 6.02 x 10 23

E.

4x 6.02 x 10 23

Correct answer is B

No explanation has been provided for this answer.

555.

Which of the following is used extensively in manufacturing photographic chemicals?

A.

Aluminium chloride

B.

Zinc chloride

C.

Silver chloride

D.

Mercury (ll) chloride

E.

lron (ll) chloride

Correct answer is C

No explanation has been provided for this answer.