WAEC Chemistry Past Questions & Answers - Page 83

411.

The quality of electricity required to discharge 1 mole of univalent ion is

A.

9600C

B.

48250C

C.

96500C

D.

193000C

Correct answer is C

No explanation has been provided for this answer.

412.

A compound with molecular formula CH2O2 is

A.

A Carbohydrate

B.

A Carboxylic acid

C.

An alkanol

D.

An ester

Correct answer is B

No explanation has been provided for this answer.

413.

Which of the following bonds are broken when ethanol is boiled?

I. Covalent bonds
II. Ionic bonds
III. Hydrogen bonds

A.

I only

B.

II only

C.

III only

D.

I, II, III

Correct answer is C

No explanation has been provided for this answer.

414.

Which of the following salts when dissolved in water will form a solution that will change blue litmus to red?

A.

CH3COONa

B.

NH4Cl

C.

NaCl

D.

KCl

Correct answer is B

No explanation has been provided for this answer.

415.

On evaporation to dryness, 3503 of saturated solution of salt Z gave 55.5g of salt. What is the solubility of the salt? [Z = 101]

A.

1.57 moldm-3

B.

3.14 moldm-3

C.

6.28 moldm-3

D.

12.56 moldm-3

Correct answer is A

Saturated solution = 3503
mass of salt Z in saturated solution = 55.5g
Number of moles of salt = \(\frac{55.5}{101}\) = 0.55mole
3503 of solution contains 0.55mole

1000cm3 will contain \(\frac{1000 \times 0.55}{350}\) = 1.57mol/dm3