JAMB Past Questions and Answers - Page 1173

5,861.

Which of the following reactions would be expected to have the highest entropy change?

A.

Liquid → Gas

B.

Solid → Liquid

C.

Gas → Liquid

D.

Gas → Solid

Correct answer is A

The phase change from a liquid to a gas involves an increase in entropy. In the gas phase, molecules have higher degrees of freedom and are more dispersed compared to the liquid phase, resulting in higher entropy change.

5,862.

Which noble gas is radioactive and is produced as a decay product of uranium and thorium?

A.

Argon

B.

Krypton

C.

Radon

D.

Neon

Correct answer is C

Radon is a radioactive noble gas and is produced as a decay product of uranium and thorium in the Earth's crust. It is colorless, odorless, and tasteless, making it potentially hazardous when it accumulates in enclosed spaces.

5,863.

What happens to the position of equilibrium, if a reversible exothermic reaction is subjected to a decrease in temperature?

A.

The position of equilibrium shifts to the left

B.

The position of equilibrium shifts to the right.

C.

The position of equilibrium remains unchanged

D.

The reaction stops

Correct answer is B

When the temperature is decreased in a reversible reaction, the equilibrium shifts in the direction that produces heat (exothermic direction). For an exothermic reaction, this means the equilibrium position shifts to the right, favoring the forward reaction.

5,864.

Hard water is water with high concentrations of dissolved ions, in particular calcium and

A.

magnesium ions

B.

nitrogen ions

C.

phosporus ions

D.

helium ions

Correct answer is A

Hard water is water with high concentrations of dissolved ions, in particular calcium and magnesium ions