WAEC Past Questions and Answers - Page 1805

9,021.

Which of the following processes is a physical reaction?

A.

Electrolysis

B.

Hydrolysis

C.

Allotropic change

D.

Neutralization

E.

Corrosion

Correct answer is C

No explanation has been provided for this answer.

9,022.

Study carefully the reaction represented by the equation below. 2H2O 2(l) → O 2(g) + 2H2O(l). Which of the following will not reaction increase the reaction rate?

A.

Heating the hydrogen peroxide

B.

Adding a pinch of MnO2 to the reactant

C.

increasing the concentration of the H2O2

D.

Adding water to the reactant

E.

Exposing the reactant to sunlight

Correct answer is D

Reaction of decomposition of hydrogen peroxide is very slow in moderate temperatures without the presence of a catalyst.

It can be sped up by increasing the temperature, which triggers the reaction of thermal decomposition.

9,023.

Methanol is obtained from wood by

A.

esterification

B.

bacterial decomposition

C.

combustion

D.

fractional distillation

E.

destructive distillation

Correct answer is E

No explanation has been provided for this answer.

9,024.

The maximum number of electrons that can accommodated in the shell having the principal quantum number 3 is

A.

3

B.

9

C.

10

D.

18

E.

32

Correct answer is D

No explanation has been provided for this answer.

9,025.

When steam is passed over white-hot coke, the products are

A.

carbon (IV) oxide and nitrogen

B.

carbon (II) oxide and hydrogen

C.

carbon (ll) oxide and nitrogen

D.

carbon (lV) oxide and steam

Correct answer is B

Reaction:

C (white hot coke) + H\(_2\)O (steam) → CO + H\(_2\).