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.

2,761.

In the extraction of iron, which of the following reactions does NOT take place in the blast furnace?

A.

CO2 + C → 2CO

B.

2Fe2O3 + 3C → 4Fe + 3CO2

C.

Fe2O3 + 3C → 2Fe + 3CO2

D.

CaCO3 → CaO + CO2

E.

CaO + SiO2 → CaSiO3

Correct answer is B

No explanation has been provided for this answer.

2,762.

5cm3 of a saturated solution of sodium chloride at 30°C gave, on careful evaporation, 1.95g of solid salt. The solubility of sodium chloride at 30°C?

(Na = 23, Cl = 35.5)

A.

5.00 mole dm3

B.

5.67 mole dm3

C.

6.00 mole dm3

D.

6.67 mole dm3

E.

7.00 mole dm3

Correct answer is D

1.95 gms of NaCl dissolves in 5 cm solution at 30°C
Number of gm of solute required to dissolve in
100 gm = (1.950 x 100)/ (5 x 1) = 1.95 x 20 = 39.0
390 gms will dissolve in 1000 dm3
Solution
Solubility of NaCl at 30°C in
(dm3 is 390)/(Mol wt g NaCl) = 6.67 mol dm3

2,763.

The electronic configuration of elements X and Y are X = 2, 8, 6; Y = 2, 8, 7. The bond in the compound formed by X and Y is expected to be?

A.

ionic

B.

covalent

C.

dative covalent

D.

metallic

E.

none of the above

Correct answer is B

No explanation has been provided for this answer.

2,764.

Which of the following is NOT a true statement of the kinetic Theory of Gases?

A.

The molecules move at random

B.

The size of molecules is negligble as compared with the volume of gas

C.

The molecular collisions are perfectly elastic

D.

Every molecule has the same kinetic energy at a particular temperature

E.

The average kinetic energy is proportional to the absolute temperature of the gas

Correct answer is D

No explanation has been provided for this answer.

2,765.

The products of the reaction between dilute sulphuric acid and sodium thiosulphate crystals are?

A.

Na2SO4 + SO2 + O2 + H2O

B.

Na2SO3 + SO3 + O2 + H2O

C.

Na2SO4 + SO2 + S + H2O

D.

Na2SO4 + SO3 + S + H2O

E.

Na2SO4 + SO2 + H2O only

Correct answer is C

\(Na_2S_2O_3 + H_2SO_4 → Na_2SO_4 + SO_2 + S↓ + H_2O\). Sodium thiosulfate reacts with sulfuric acid to produce sodium sulfate, sulphur dioxide, sulfur, and water.