JAMB Chemistry Past Questions & Answers - Page 184

916.

Weighed salts Y and Z were left exposed in the laboratory overnight. In the morning Y had gained weight, and Z had become liquid. What conclusion could be drawn about the nature of the two salts?

A.

Z is efflorescent

B.

Y and Z are efflorescent

C.

Y and Z are deliquescent

D.

Y and Z are hygroscopic

E.

Y is deliquescent

Correct answer is C

A deliquescent compound is a compound that, on exposure to the atmosphere, tends to absorb moisture from the atmosphere in large quantities. Hence, Y and Z are DELIQUESCENT.

917.

The reaction between hydrogen and iodine may be represented by the equation H2(g)+ I2(g) → 2HI(g), and is exothermic. Therefore

A.

an increase in temperature favours the forword reaction

B.

an increase in pressure favours the backward reaction

C.

both pressure and temperature muct be increased to favour the forward reaction

D.

a decrease in temperature will favour the forward reaction

E.

a decrease in pressure and an increase in temperature will favour the forward reaction

Correct answer is D

No explanation has been provided for this answer.

918.

Starch can be converted to ethyl alcohol by

A.

distillation

B.

fermentation

C.

isomerization

D.

cracking

E.

cooking

Correct answer is B

No explanation has been provided for this answer.

919.

Calcium hydroxide and ammonium chloride when heated together will give an important product. This compound may be obtained dry by

A.

dissolving it in water, recrystallizing it and then drying in the oven

B.

passing it through a concentrated aqueous solution of sodium hydroxide

C.

passing it through calcium oxide

D.

passing it through concentrated sulphuric acid

E.

passing it through anhydrous calcium choride

Correct answer is C

No explanation has been provided for this answer.

920.

In which of the following reactions is sulphur dioxide acting as an oxidizing agent?

A.

SO 2 + 2HNO3 →H2SO4 + NO2 + Heat

B.

2SO2 + 2H2O + O2→ 2H2SO4

C.

SO2 + 2H2O + CI2→ H2SO4 + 2HCI

D.

SO2 + 2H2S → 3S + 2H2O

E.

SO2 + H2O → H2SO3

Correct answer is D

No explanation has been provided for this answer.