JAMB Chemistry Past Questions & Answers - Page 81

401.

A chemical reaction in which the hydration energy is greater than the lattice energy is referred to as

A.

A reversible reaction

B.

A spontenous reaction

C.

An endothermic reaction

D.

An exothermic reaction

Correct answer is D

In salts for which the hydration energy is higher than the lattice energy, solvation occurs with a release of energy in the form of heat. A reaction in which there is a release of energy as LIGHT OR HEAT is EXOTHERMIC.

402.

The gas that is used for the treatment of cancer is

A.

Neon

B.

Radon

C.

Xenon

D.

Argon

Correct answer is B

No explanation has been provided for this answer.

403.

Calculate the volume in cm3 of oxygen evolved at s.t.p when a current of 5A is passed through acidified water for 193s?
[F = 96500 C mol1. Molar volume of a gas at s.t.p = 22.4dm3]

A.

0.056dm3

B.

0.224dm3

C.

224.000dm3

D.

56.000dm3

Correct answer is A

Q = 193 x 5 = 965C
40H \(\mapsto\) 2H2O + O2 + 4e
4 x 96500C = 22.4dm3
965C = x

x = \(\frac{22.4 \times 965}{4 \times 96500}\)
= 0.056dm3

404.

An isotope has an atomic number of 15 and a mass number of 31. The number of proton it contains is

A.

16

B.

15

C.

31

D.

46

Correct answer is B

No explanation has been provided for this answer.

405.

An example of a solid emulsion is

A.

Butter

B.

Hair cream

C.

Milk

D.

Cod-liver oil

Correct answer is A

No explanation has been provided for this answer.