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.

3,646.

As the concentration of an electrolyte reduces, the conductivity

A.

reduces to zero

B.

decreases

C.

increase

D.

is unaffected

Correct answer is C

No explanation has been provided for this answer.

3,647.

When ΔH is negative, a reaction is said to be

A.

ionic

B.

reversible

C.

exothermic

D.

endothermic

Correct answer is C

No explanation has been provided for this answer.

3,648.

3Cu(s) + 8HNO3(aq) 3Cu(NO3)2(aq) + 4H2O(l) + 2NO(g)
In the equation above, copper is

A.

an electron acceptor

B.

a base

C.

an oxidizing agent

D.

a reducing agent

Correct answer is D

A reducing agent (also called a reductant or reducer) is an element or compound that loses (or "donates") an electron to another chemical species in a redox chemical reaction. Since the reducing agent is losing electrons, it is said to have been oxidized. In the reaction, Copper is oxidized.

3,649.

2SO2(g) + O2(g) ↔ 2SO3(g)
ΔH = -189 kJ mol-1
The equilibrium constant for the reaction above is increased by?

A.

decreasing the temperature of the system

B.

Increase the pressure of the system

C.

The addition of a catalyst to the system

D.

Increasing the surface area of the vessel

Correct answer is A

Decrease in temperature favors in Equilibrium Constant[k] for this exothermic reaction.

3,650.

C(s) + 2S(g) → CS2(g)
ΔH = +89 kJ mol-1
The chemical equation above implies that

A.

each of carbon and sulphur has 89 kJ of energy

B.

both carbon and sulphur contribute 89 kJ of energy

C.

89 kJ of energy is released

D.

89 kJ of energy is absorbed

Correct answer is D

No explanation has been provided for this answer.