JAMB Chemistry Past Questions & Answers - Page 241

1,201.

If one mole of aluminium contains 6 x 1023 atoms of aluminium, how many atoms are contained in 0.9g of aluminium?
(Al = 27)

A.

1.0 x 1021

B.

6.6 x 1021

C.

2.0 x 1022

D.

1.0 x 1022

E.

5.4 x 1023

Correct answer is C

1 Mole or 27 gms of Al contains 6 x 1021 atoms
0.9 gms of Al will contain (6 x 1023 x 0 g)/(27 1) = 0.2 x 1023 or 1022

1,202.

Which one of the following metals is not normally extracted by chemical reduction because of its position in the electrochemical series?

A.

Copper

B.

Iron

C.

Lead

D.

Potassium

E.

Zinc

Correct answer is D

No explanation has been provided for this answer.

1,203.

When hydrogen sulphide and sulphur dioxide are each passed in turn into a solution of potassium dichromate?

A.

both gases change the colour of the solution from yellow to colourless

B.

both gases causes sulphur to be deposited

C.

only hydrogen sulphide decolourizes the solution

D.

only sulphur dioxide deposits sulphur

E.

only hydrogen sulphide deposits sulphur

Correct answer is E

No explanation has been provided for this answer.

1,204.

Which of the following compounds and elements would sublime on exposure to the atmosphere?

A.

Ice

B.

Sulphur

C.

Phosphurous

D.

Iodine

E.

Potassium iodie

Correct answer is D

No explanation has been provided for this answer.

1,205.

What mass of sodium carbonate solution is in 500 cm3 of 0.1 molar sodium carbonate solution?

(Na = 23, C = 12, O = 16)

A.

10.6 g

B.

5.3 g

C.

500 g

D.

10 g

E.

20 g

Correct answer is B

106 gm Na2CO3 in 1000 cc = 1m
53 gm Na2CO3 in 500 cc = 1m
For 0.1 molar we have (53)/(10) = 5.3