WAEC Chemistry Past Questions & Answers - Page 108

536.

A spot of oil paint on a shirt can best be removed using?

A.

brine

B.

detergent

C.

kerosine

D.

warm water

Correct answer is C

To remove oil paints, the use of chemicals is usually required, including turpentine, acetone, kerosene, and various paint thinners. 

537.

The hydrolysis of NH\(_4\)CI gives

A.

an acidic solution

B.

an alkaline solution

C.

a buffer solution

D.

a neutral solution

Correct answer is A

When you dissolve ammonium chloride crystals in water (H\(_2\)O), the ammonium chloride compound decomposes into its component ions: NH\(_4 ^+\) and Cl\(^-\). The reaction of these ions with water gives an acidic solution.

538.

Which of the following pH values indicates that a solution is a strong base?

A.

1

B.

5

C.

9

D.

13

Correct answer is D

No explanation has been provided for this answer.

539.

On heating, the following trioxocarbonate (IV) salts decompose to give solid residue except

A.

ammonium trioxocarbonate (IV)

B.

calcium trioxocarbonate (IV)

C.

lead (ll) trioxocarbonate(IV)

D.

zinc trioxocarbonate (IV)

Correct answer is A

Ammonium trioxocarbonate (IV) is an unstable compound. It decomposes on heating to yield ammonia, carbon (IV) oxide and water. All of these are gases.

540.

A substance L reacts with NH\(_4\)NO\(_{3(aq)}\) to generate ammonia gas. L is likely to be

A.

HCl

B.

NaOH

C.

CH3COOH

D.

CaSO4

Correct answer is B

The reaction between NH\(_4\)NO\(_{3(aq)}\) and any metal hydroxide produces ammonia, water and an alkali metal nitrate.