JAMB Past Questions and Answers - Page 1716

8,576.

Which of the following is used in rocket fuels?

A.

HNO3

B.

CH3COOH

C.

H2SO4

D.

HCl

Correct answer is A

- Due to its unique powerful oxidizing nature, Nitric acid is often used in rocket fuels as a propeller

NB: Ethanol (not Ethanoic acid) is used alone or mixed with petrol as fuel for racing cars and in rockets.

8,578.

2H2(g) + O2(g) ⇌ 2H2O(g) ΔH = -ve
what happens to the equilibrium constant of the reaction above if the temperature is increased?

A.

it is unaffected

B.

it becomes zero

C.

it decrease

D.

it increase

Correct answer is C

This given equation shows the forward reaction is exothermic, which means an increase in temperature will cause the equilibrium position to shift to left to favor reactant formation, i.e K decreases 

8,579.

The graph above demonstrate the effect of?

A.

surface area on the rate of reaction

B.

catalyst on the rate of reaction

C.

pressure on the rate reaction

D.

concentration on the rate of reaction

Correct answer is A

No explanation has been provided for this answer.

8,580.

In the preparation of oxygen by heating KClO3 in the presence of MnO2, only moderate heat is needed because the catalyst acts by?

A.

lowering the pressure of the reaction

B.

increasing the surface area of the reactant

C.

increase the rate of the reaction

D.

lowering the energy barrier of the reaction

Correct answer is C

- The presence of MnO2 increase the rate of the reaction by providing a new reaction path / making more particles possess kinetic energy greater then the activation energy.