WAEC Chemistry Past Questions & Answers - Page 100

496.

Which of the following salt solutions will have a pH greater than 7?

A.

NaCI(aq)

B.

Na2CO3(aq)

C.

Na2SO4(aq)

D.

NaHSO4(aq)

Correct answer is B

No explanation has been provided for this answer.

497.

Calculate the mass of sodium hydroxide in 5.00 dm3 of a 0.125 mol dm-3 solution. [NaOH = 40 g mol-1]

A.

0.0156 g

B.

0.625 g

C.

1.00 g

D.

25.0 g

Correct answer is D

1 mole of NaOH per dm3 has a mass of 40g.
mass of NaOH in 0.125mole
= 0.125 x 40 = 5g.
mass in 5.00 dm3 of the solution.
= 5 x 5 = 25.0g.

498.

Which of the following substances increases in mass when heated in air?

A.

Sodium chloride

B.

lodine crystals

C.

Magnesium ribbon

D.

Copper (ll) oxide

Correct answer is C

No explanation has been provided for this answer.

499.

A substance is said to be hygroscopic if it absorbs

A.

water from the atmosphere to form a solution

B.

heat from the surrounding

C.

carbon (IV) oxide from the atmosphere

D.

moisture from the atmosphere without dissolving

Correct answer is D

No explanation has been provided for this answer.

500.

Which of following acids forms normal salts only?

A.

Tetraoxosulphate (VI) acid

B.

Trioxosulphate (IV) acid

C.

Acetic acid

D.

Tetraoxophosphate (V) acid

Correct answer is C

So we can determine that the basicity of Acetic acid is 1 because it releases one hydrogen ion in an aqueous solution.

Due to this they act as very weak acids. When weak acid reacts with strong base, they tend to form normal salt.