Chemistry questions and answers

Chemistry Questions and Answers

Learn more about the properties, composition, and structure of substances (elements and compounds) with these Chemistry questions and answers. This Test can be used by students preparing for Chemistry in JAMB, WAEC, NECO or Post UTME.

3,101.

In two separate experiments, 0.36g and 0.71g of chlorine combined with a metal X to give Y and Z respectively. An analysis showed that Y and Z contain 0.20g and 0.40g of X respectively. The data above represents the law of ?

A.

multiple proportion

B.

conservation of mass

C.

constant composition

D.

reciprocal proportion

Correct answer is C

0.36g of Cl combines with 0.2g of x

1g of Cl will combine with \(\frac{1 \times 0.2}{0.32}\) = 0.56

0.71g of U combines with 0.49g of x

1g of U will combine with \(\frac{1 \times 0.4}{71}\) = 0.56

Ratio 0.56 : 0.56 = 1:1

3,102.

An iron ore is known to contain 70.0% Fe2O3. The obtain from 80kg of the ore is?

(Fe = 56, O = 16)

A.

35.0 kg

B.

39.2 kg

C.

70.0 kg

D.

78.4 kg

Correct answer is B

2Fe2O3 → 4Fe + 3O2
320g 224g 96g
(70) / (100) x (80) / (1) 56g
if 0.32kg of Fe293 contains 0.224 kg
Then 56kg will contain (56 x 0.224) / (0.32) =39.2 kg

3,103.

Which of the following are mixtures?
i, Petroleum
ii, Rubber latex
iii. Vulcanizer's solution
iv, Carbon (II)sulphide

A.

i, ii and iii

B.

i, ii and iv

C.

i and ii only

D.

i and iv

Correct answer is A

No explanation has been provided for this answer.

3,104.

Which of the following can be obtained by fractional distillation?

A.

Nitrogen from liquid air

B.

Sodium chloride from sea water

C.

Iodine from a solution of Iondine in carbon tetrachloride

D.

Sulphur from a solution of sulphur incarbon disulphide

Correct answer is A

No explanation has been provided for this answer.