WAEC Past Questions and Answers - Page 1402

7,006.

When concentrated sodium chloride solution is electrolysed using inert electrodes, the products are

A.

oxygen and hydrogen

B.

hydrogen and chlorine

C.

sodium and oxygen

D.

sodium and chlorine

Correct answer is B

No explanation has been provided for this answer.

7,007.

Consider the following equation: Cr2O2-7(aq) + 14H+(aq) + 6e- → 2Cr3+(ag) + 7H2O(1). The oxidation number of chromium changes from

A.

-2 to + 3

B.

-2 to + 6

C.

+6 to +3

D.

+7 to + 6

Correct answer is C

No explanation has been provided for this answer.

7,008.

The reduction of three seedlings of maize to two plants per stand is referred to as

A.

Rogueing

B.

Thinning

C.

Weeding

D.

Pruning

Correct answer is B

Thinning refers to the process of reducing the number of seedlings in a plant stand to achieve proper spacing and optimum plant density. In the context of the question, thinning involves removing one out of three seedlings of maize, resulting in two plants remaining per stand.

 

7,009.

Which of the following tools are used in soil analysis?
I. pH meter
II. Sieve
III. Hygrometer

A.

I and II

B.

I and III

C.

I, II and III

D.

II and III

Correct answer is C

All the tools listed are used in soil analysis. A pH meter is used to measure the acidity or alkalinity of the soil. A sieve is used to separate and grade soil and rock particles according to their size. A hygrometer is used to measure the moisture content in the atmosphere, which can affect soil moisture levels.

 

7,010.

Examples of cover crops are

A.

Centrosema pubescens and Mucuna utilis

B.

Moringa oleifera and Imperata cylindrica

C.

Panicum maximum and Pennisetum purpureum

D.

Calopogonium mucunoides and Gliricidia sepium

Correct answer is A

Cover crops are plants that are primarily grown for the benefit of the soil rather than the crop yield. They are typically grown to suppress weeds, manage soil erosion, help build and improve soil fertility and quality, and control diseases and pests. Centrosema pubescens and Mucuna utilis are examples of cover crops. They are used to improve soil fertility and control weeds.