JAMB Past Questions and Answers - Page 1719

8,591.

Carbon (II) oxide is considered dangerous if inhaled mainly because it?

A.

can cause injury to the nervous system

B.

competes with oxygen in the blood

C.

competes with carbon (IV) oxide in the blood

D.

can cause lung cancer

Correct answer is B

Carbon monoxide is harmful when breathed because it displaces oxygen in the blood and deprives the heart, brain and other vital organs of oxygen.

8,592.

Coffee stains can best be removed by?

A.

Kerosine

B.

turpentine

C.

a solution of borax in water

D.

ammonia solution

Correct answer is C

Borax solution refers to sodium borax in water. it is used for cleaning purposes. borax is mildly alkaline and can help break down acidic stains, such as those from coffee

8,593.

Which of the following is incorrect?

A.

Nigeria was removed at first from Common Wealth during Abacha's regime

B.

Nigeria was at first bombarded in 1951

C.

Sierra Leone was never colonized

D.

Ethiopia was never colonized

Correct answer is C

Sierria used to be a colonial terriotry of the Great Britain, She gained her independence in 1956.

8,594.

Calculate the solubility in mol dm-3 of 40g of CuSO4 dissolved in 100g of water at 120°C?
[Cu = 64, S = 32, O = 16]

A.

4.00

B.

2.50

C.

0.40

D.

0.25

Correct answer is B

Solubility = \(\frac{\text{number of moles of solution}}{\text{vol of solution}}\)

100g of water = 100 cm\(^3\) = 0.1 dm\(^3\).

CuSO\(_4\) = 160 g/mol

No of moles of CuSO\(_4\) in 40g = \(\frac{40}{160}\)

= 0.25 mol.

Solubility = \(\frac{0.25}{0.1}\)

= 2.5 moldm\(^{-3}\).

8,595.

Substance employed as drying agents are usually?

A.

amphoteric

B.

hygroscopic

C.

efflorescent

D.

acidic

Correct answer is B

No explanation has been provided for this answer.