JAMB Past Questions and Answers - Page 1717

8,581.

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

A.

the reaction is static

B.

the reaction is in a state of equilibrium

C.

there will be a large increase in free energy

D.

there will be a large decrease in free energy

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.

8,582.

In which of the following is the entropy change positive?

A.

Thermal dissociation of ammonium chloride

B.

Reaction between an acid and a base

C.

Addition of concentrated acid to water

D.

Dissolution of sodium metal in water

Correct answer is A

Thermal dissociation of ammonium chloride is an endothermic reaction as heat is absorbed for a positive entropy, with more products than reactants.

8,583.

What quantity of aluminum is deposited when a current of 10A is passed through a solution of an aluminum salt for 1930s?
[Al = 27, F = 96500 C mol -1]

A.

0.2 g

B.

1.8 g

C.

5.4 g

D.

14.2 g

Correct answer is B

Q = It = 10 x 1930 ( given)

27g → 3F( since aluminum is trivalent)

27g → 3 x 96500

x → 19300

x = \(\frac{27 \times 19300}{3 \times 96500}\)

x = 1.8g

8,584.

Iron can be protected from corrosion by coating the surface with?

A.

gold

B.

silver

C.

copper

D.

zinc

Correct answer is D

No explanation has been provided for this answer.

8,585.

The IUPAC nomenclature of the compound LiAlH4 is?

A.

lithiumtetrahydridoaluminate (III)

B.

aluminium tetrahydrido lithium

C.

tetrahydrido lithium aluminate (III)

D.

lithium aluminium hydride

Correct answer is A

No explanation has been provided for this answer.