JAMB Chemistry Past Questions & Answers - Page 345

1,721.

Hydrogen sulphide gas can act as?

A.

an oxidizing agent

B.

a dehydrating agent

C.

a bleaching agent

D.

a precipitating agent

Correct answer is D

When Hydrogen sulphide gas is bubbled through solutions of such metals, the colored sulphides are precipitated.

Hydrogen sulphide is a also strong reducing agent.

1,722.

The oxidation of ammonia in excess air produces?

A.

NO

B.

N2O

C.

NO2

D.

N2O4

Correct answer is A

In the presence of heated platinum catalyst, ammonia reacts with excess air to produce nitrogen (II) oxide, NO, (instead of nitrogen) and water.

1,723.

The equilibrium of an endothermic reaction which proceeds with an increase in volume can be shifted in the reverse direction by

A.

increasing the temperature and decreasing the pressure

B.

increasing the pressure and increasing the temperature

C.

decreasing the temperature and increasing the pressure

D.

decreasing the pressure and decreasing the temperature

Correct answer is C

No explanation has been provided for this answer.

1,724.

CuO(s) + H\(_2\)(g) ↔ Cu(s) + H\(_2\)O(g)
What is the effect of increasing the pressure on the equilibrium reaction above?

A.

The equilibrium is shifted to the left

B.

The equilibrium is shifted to the right

C.

There is no effect

D.

More H2(g) is produced

Correct answer is C

When amount / volume of gaseous reactants equal amount / volume of gaseous products, the change in pressure has no effect on the equilibrium position.

1,725.

A catalyst increase the rate of a chemical reaction by providing a path that?

A.

raise the activiation energy

B.

increase the temperature

C.

lowers the activation energy

D.

increase the concentration

Correct answer is C

The rate of a reaction can be increased by adding a suitable catalyst.

A catalyst is a substance which increases the rate of a chemical reaction but it is not used up (remains chemically unchanged at the end).

It provides an alternative reaction pathway of lower activation energy.