WAEC Chemistry Past Questions & Answers - Page 92

456.

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

457.

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...

458.

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

459.

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.

460.

Cathode rays cause an object placed behind a perforated anode to cast a shadow on the screen. This observation shows that the rays

A.

are positively charged

B.

are negatively charged

C.

Have mass

D.

travel in straight lines

Correct answer is D

Rays travels in straight lines and finds its way through any opening available. It could be refracted, reflected or transmitted based on any obstacle. Option A,B,C are not the reason why the cathode are coasted shadows