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.

156.

A hydrogen chloride gas reacted with oxygen gas to yield water and chlorine gas. The mole ratio of the hydrogen chloride gas to water is

A.

1:3

B.

2:1

C.

3:1

D.

4:1

Correct answer is B

4HCl + O\(_{2}\) -- 2Cl\(_{2}\) + 2H\(_{2}\)O
4:2 = 4/2
2:1

157.

Which of the following statements about liquids is/are true?


I. Liquids maintain their volume at constant temperature.
II. Liquids have fixed shape
III. Liquids do not diffuse
IV. Change in pressure affects volume of liquids

A.

I only

B.

IV only

C.

I and IV only

D.

II and III only

Correct answer is A

A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure

158.

When air in a syringe is compressed such that there is no change in temperature, the

A.

air liquefies

B.

pressure increases

C.

intermolecular space increases

D.

density decreases

Correct answer is B

Since the temperature of air remain constant.So, it is a isothermal process.
PV=K
This eq. shows that on increasing pressure, the volume gets reduced and vice-versa.
Since the syringe is slowly compressed, volume is decreasing.
Therefore, the pressure inside the syringe will increases because the molecules now hit the syringe walls more frequently.

159.

Consider the following reaction equation
N\(_{2}\)(g) + 3H\(_{2(g)}\)  ⇌ 2NH3(g) ∆H = -92kJ

Increasing the temperature of the reaction would

A.

shift the equilibrium to the right

B.

increase the yield of ammonia

C.

decrease the amount of hydrogen

D.

decrease the yield of ammonia

Correct answer is D

In this case, an increase in in temperature will cause the equilibrium position to shift to the left thereby decreasing the yield of ammonia.

160.

Which of the following statements about an equilibrium system is correct?

A.

Forward and backward reactions occur at the same rate

B.

The concentrations of reactants must equal that of the products

C.

The concentrations of, reactants and products can be changed by adding a catalyst,

D.

The concentrations of reactants and products are not affected by a change in temperature

Correct answer is A

Equilibrium is a state of a system where there is no observable change in the properties of the system with respect to time