JAMB Chemistry Past Questions & Answers - Page 70

346.

What volume of oxygen will remain after reacting 8cm\(^3\) of hydrogen gas with 20cm\(^3\) of oxygen gas

A.

10cm\(^3\)

B.

12cm\(^3\)

C.

14cm\(^3\)

D.

16cm\(^3\)

Correct answer is D

No explanation has been provided for this answer.

347.

The number of electrons in the valence shell of an element of atomic number 14 is?

A.

1

B.

2

C.

3

D.

4

Correct answer is D

No explanation has been provided for this answer.

348.

Suitable reagents for the laboratory preparation of nitrogen are

A.

sodium dioxonitrate(III) and ammonium chloride

B.

sodium trioxonitrate(V) and ammonium chloride

C.

sodium chloride and ammonium trioxonitrate(V)

D.

sodium chloride and ammonium di-ozonitrate(III)

Correct answer is A

No explanation has been provided for this answer.

350.

Methanoic acid mixes with water in all proportions and has about the same boiling point as water. Which of the following methods would you adopt to obtain pure water from a mixture of Sand, water and methanoic acid?

A.

Extractive distillation

B.

Filtration followed by distillation

C.

Neutralization with sodium hydroxide followed by distillation

D.

Neutralization with sodium hydroxide followed by filtration

Correct answer is A

Due to the presence of maximum Azeotrope,we use extractive distilination (with extractive distilation agents like sulfone) used for mixtures with low relative volatility,nearing unity.

Azeotrope is a mixture of liquids that has a constant boiling point because the vapour has thesame composition as the mixture.