WAEC Past Questions and Answers - Page 1397

6,981.

Cotton stainer is an insect pest of

A.

Cotton

B.

Pepper

C.

Okra

D.

Onions

Correct answer is A

The cotton stainer is an insect pest of cotton plants. The cotton stainer is an insect pest that primarily affects cotton plants, causing damage to the seeds and leading to staining of the cotton fibers, impacting cotton yield and fiber quality.

 

6,982.

Which of the following ions  requires the largest quantity of electricity for discharge at an electrode?

A.

2.0 mole of Q3+

B.

2.5 mole of R2+

C.

3.0 mole of T-

D.

4.0 mole of Y-

Correct answer is A

2.0 mole of Q3+ ions require the largest quantity of electricity for discharge at an electric. option B,C,D are all carrying a smaller quantity of electricity which not be proven for ant discharge

6,983.

P1V1 = P2V2 supports ?

A.

Charles’s law

B.

Boyles’s law

C.

Graham’s law

D.

Avogadro’s law

Correct answer is B

V = 1/P

cross multiply

K = VP

V1P1 = V2V2

For a fixed amount of an ideal gas kept at a fixed temperature, pressure and volume are inversely proportional. Or Boyle's law is a gas law, stating that the pressure and volume of a gas have an inverse relationship, when temperature is held constant.
The equations supports only Boyle’s law. Option A,C,D are not in support of the equation...

6,984.

A suitable reagent for distinguish between ethanoic and ethanol is

A.

bromine water

B.

Fehling’s solution

C.

sodium hydrogen trioxocarbonate (iv)

D.

Ammoniacal silver trioxonitrate(V)

Correct answer is C

Sodium hydrogen trionocarbonate iv is the only distinguishing reagent between ethanoic and ethanol. Option A, B, D are not conspicuous in distinguishing between ethanoic and ethanol

6,985.

Flow of current in electrolytes is due to the movement of

A.

electrons

B.

Holes and electron

C.

Ions

D.

Charges

Correct answer is C

No explanation has been provided for this answer.