WAEC Chemistry Past Questions & Answers - Page 192

956.

What term is used to describe an oxide whose aqueous solution turns blue litmus red?

A.

Strong electrolyte

B.

Acid anhydride

C.

Amphoteric oxide

D.

Basic oxide

Correct answer is B

No explanation has been provided for this answer.

957.

Substance Q reacts with cold water to form a solution which turns red litmus blue. Substance Q could be

A.

zinc

B.

phosphorus

C.

lead

D.

sodium

Correct answer is D

No explanation has been provided for this answer.

958.

Which of the following solutions will give a precipitate with dilute tetraoxosulphate (V) acid? l. Lead (ll) trioxonitrate (V) solution ll. Barium chloride solution lll. Sodium chloride solution

A.

l only

B.

ll only

C.

l and ll only

D.

ll and lll only

Correct answer is C

Both i and ii will precipitate with H2SO4, SEE EQUATION BELOW

Pb(NO3)2+H2SO4→PbSO4+2HNO3.

H2SO4 +BaCl2 → BaSO4 + 2HCl

both PbSO4 and BaS04 are slightly solid so they precipitate out of solution as solid

959.

Which of the following salts can be prepared by reacting the metal with dilute H2SO4?

A.

CuSO4

B.

MgSO4

C.

BaSO4

D.

PbSO4

Correct answer is B

No explanation has been provided for this answer.

960.

Bees inject an acidic substance when they sting. Which of the following chemical could be used to treat bee stings?

A.

CH3COOH

B.

NaHCO3

C.

C2H5OH

D.

H2O2

Correct answer is B

Bees on the other hand have acidic toxins in their stings, and so an alkaline solution should be applied to neutralize them. Baking soda (\(NaHCO_{3}\)) mixed with cold water is usually the most effective way of making an alkaline solution.