JAMB Chemistry Past Questions & Answers - Page 406

2,026.

A little quantity of trichloromethane (b.pt 60,^oC) was added to a large quantity of ethanol (b.pt 78,^oC). The most probable boiling point of the resultant mixture is from

69 ^oC - 70 ^oC

70 ^oC – 74 ^oC

82 ^oC – 84 ^oC

60 ^oC – 78 ^oC

View answer & explanation

Correct answer is C

No explanation has been provided for this answer.

2,027.

The formula CH₂ for ethanoic acid is regarded as its

Molecular formula

General formula

Empirical formula

Structural formula

View answer & explanation

Correct answer is C

No explanation has been provided for this answer.

2,028.

A compound contains 31.91% potassium, 28.93% chlorine and the rest oxygen. What is the chemical formula of the compound?
[K = 39, Cl = 35.5, O = 16]

KClO₄

KClO

KClO₂

KClO₃

View answer & explanation

Correct answer is D

K- (31.91%), Mole = 31.91/39 =0.8182
Cl-(28.93%), Mole = 28.93/35.5 = 0.815
O-(39.16%), Mole = 39.6/16 = 2.448
K = 0.8182/0.815 = 1
Cl = 0.815/0.815 = 1
O = 2.448/0.815 = 3

2,029.

When sodium reacts with water, the resulting solution is

Weakly acidic

Neutral

Acidic

Alkaline

View answer & explanation

Correct answer is D

No explanation has been provided for this answer.

2,030.

\(C_{12}H_{22}O_{11(s)} + H_2SO_{4(aq)} → 12C(s) + 11H_2O(l) + H_2SO_{4(aq)}\)
In the reaction above, tetraoxosulphate (VI) acid function as

A dehydrate agent

An oxidizing agent

A reducing agent

A catalyst

View answer & explanation

Correct answer is A

A dehydrating agent is a substance that dries or removes water from a substance.

so when sulphuric acid with sugar, the sugar is charred by the removal of water, \(C_{12}H_{22}O_{11(s)} + H_2SO_{4(aq)} → 12C(s) + 11H_2O_{(l}) + H_2SO_{4(aq)}\)

the sulphuric acid is serving as a dehydrating agent.