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JAMB Chemistry Past Questions & Answers - Page 326

1,626.

To a solution of an unknown compound, a little dilute tetraoxosulphate (VI) acid was added with some freshly prepared iron (II) tetraoxosulphate (VI) solution. The brown ring observed after the addition of a stream of concentrated tetraoxosulphate (VI) acid confirmed the presence of?

CO $^{2-}_{3}$

Cl^-

SO $_{3}^{2-}$

NO $^{2-}_{3}$

View answer & explanation

Correct answer is D

NO $_{3}^{-}$ is confirmed, then the brown ring is due to the formation of FESO $_4$ .NO

1,627.

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

it is unaffected

it becomes zero

it decrease

it increase

View answer & explanation

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

1,628.

The graph above demonstrate the effect of?

surface area on the rate of reaction

catalyst on the rate of reaction

pressure on the rate reaction

concentration on the rate of reaction

View answer & explanation

Correct answer is A

No explanation has been provided for this answer.

1,629.

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

lowering the pressure of the reaction

increasing the surface area of the reactant

increase the rate of the reaction

lowering the energy barrier of the reaction

View answer & explanation

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.

1,630.

If a reaction is exothermic and there is a great disorder, it means that?

the reaction is static

the reaction is in a state of equilibrium

there will be a large increase in free energy

there will be a large decrease in free energy

View answer & explanation

Correct answer is D

If a reaction is exothermic and there is a great disorder for a spontaneous reaction to occur, a large decrease in free energy is evident.