WAEC Past Questions and Answers - Page 1643

8,211.

Striga spp. is a parasitic weed of

A.

Cotton

B.

Orange

C.

Groundnut

D.

Sorghum

Correct answer is D

No explanation has been provided for this answer.

8,212.

Which of the following insect-pests possesses biting and chewing mouthparts?

A.

Grasshopper

B.

Weevil

C.

Aphid

D.

Cotton stainer

Correct answer is A

No explanation has been provided for this answer.

8,213.
8,214.

0.10 mol dm-3 NaCI conducts electricity better than 0.10 mol dm-3 CH3COOH because the solution of NaCI

A.

contains more ions

B.

is neutral to litmus

C.

has a lower molar mass

D.

has a higher pH

Correct answer is A

0.10 mol \(dm^{-3}\) NaCI conducts electricity better than 0.10 mol \(dm^{-3}\) \(CH_3COOH\) because the solution of NaCI contains more ions. When an ionic compound like NaCI dissolves in water, it dissociates into its component ions, \(Na^+\) and \(Cl^{-}\)

8,215.

An iron nail placed in a solution copper (ll) tetraoxosulphate (VI) is soon covered with a deposit of copper which of the following equations represents the reactions ?

A.

Fe 2+ (aq) + Cu(s) → Fe 3+ + Cu 2+ (aq)

B.

Fe 2+ (aq) + Cu(s) → Fe(s) + Cu2+ (aq)

C.

Fe (s) + Cu2+ (aq) → Fe2+(aq) + Cu2+ (aq)

D.

Fe(s) + Cu2+ → Fe2+(aq) + Cu(s)

Correct answer is D

No explanation has been provided for this answer.