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.

3,556.

CO(g) + H2O(g) → CO2(g) + H2(g)
From the reaction above, calculate the standard enthalpies of formation of CO2(g), H2O(g) and CO(g) in kJ mol-1 are -394, -242, and -110 respectively.

A.

-262 kJ mol-1

B.

-42 kJ mol-1

C.

+42 kJ mol-1

D.

+262 kJ mol-1

Correct answer is B

CO + H2O → CO2 + H2 DH = 394 kJ mol-1
-242 + 110 = -352 kJ mol-1
35 = -394 -(352)
= -394 + 352
= -42 kJ mol-1

3,557.

In the electrolysis of a concentrated solution of sodium chloride using electrodes, which of the following ions are discharged at the cathode and anode respectively?

A.

Na+ and Cl-

B.

Na+ and OH-

C.

H+ and OH-

D.

H+ and Cl-

Correct answer is D

In the electrolysis of conc. NaCl,

anions = \(Cl^- and  OH^-\)

cations = \(H^+ and   Na^+\)

So, hydrogen ion will migrate to the cathode, and Cl ion will migrate to the anode at the expense of hydroxide ion because of higher concentration in the solution

3,558.

When at equilibrium, which of the reactions below will shift to the right if the pressure is increased and the temperature is kept constant?

A.

2SO3(g) ↔ 2SO2(g) + O2(g)

B.

2CO2(g) ↔ 2CO(g) + O2(g)

C.

2H2(g) + O2(g) ↔ 2H2O(g)

D.

2NO(g) ↔ N2(g) + O2(g)

Correct answer is C

No explanation has been provided for this answer.

3,559.

If y is an oxidizing agent that reacts with a reducing agent, Z, which of the following is correct?

A.

Y increases in oxidation number

B.

Y becomes reduced

C.

Z loses protons

D.

Z gains protons

Correct answer is B

No explanation has been provided for this answer.

3,560.

Which of the following will change when a catalyst is added to a chemical reaction?

A.

The activation energy

B.

The potential energy of the reactants

C.

The heat of the reaction

D.

the potential energy of the product

Correct answer is A

No explanation has been provided for this answer.