JAMB Past Questions and Answers - Page 1597

7,981.

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.

7,982.

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.

7,983.

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

7,984.

Pure sulfuric acid is a liquid of 1.84 density. What volume of it would be required to prepare 250 cm3 of 2.0 M solution?


(H = 1, S = 32, O = 16)

A.

2.00

B.

2.66

C.

3.00

D.

3.66

E.

4.00

Correct answer is B

1000 cm3 of 1 m H2SO4 contains 98 gm of H2SO4
250 of 1 m H2SO4 (98)/(4) x (2)/(10) = 4.9 gm
But density = (mass)/(volume)
Volume = (Mass)/(Density) (4.90)/(1.84) = 2.66

7,985.

In the extraction of iron, which of the following reactions does NOT take place in the blast furnace?

A.

CO2 + C → 2CO

B.

2Fe2O3 + 3C → 4Fe + 3CO2

C.

Fe2O3 + 3C → 2Fe + 3CO2

D.

CaCO3 → CaO + CO2

E.

CaO + SiO2 → CaSiO3

Correct answer is B

No explanation has been provided for this answer.