WAEC Chemistry Past Questions & Answers

1,036.

Which of the following on burning in air contributes to acid rain?

Sulphur

Magnesium

Aluminium

Zinc

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Correct answer is A

No explanation has been provided for this answer.

1,037.

When sodium hydroxide solution is added to a solution of zinc salt, the white precipitate fromed redissolves in excess sodium hydroxide because

sodium is more reactive than zinc

sodium hydroxide is a strong alkali

zinc hydroxide is amphoteric

zinc hydroxide is unstable

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Correct answer is C

No explanation has been provided for this answer.

1,038.

A colourless, odourless liquid T, gives effervesce with sodium trioxocarbonate (IV) and a white precipitate with silver trioxonitrate (V) solution T is most probably

sodium chloride soluttion

barium chloride solution

dilute trioxonitrate (V) acid

dilute hydrochloric acid

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Correct answer is D

Take an unknown substance and add a few drops of it to the silver nitrate solution. If the silver nitrate solution turns white due to the formation of silver chloride, the acid is hydrochloric acid. If the solution remains clear, the acid is nitric acid. T is Hydrochloric Acid(an odorless, colorless solution with a pungent smell)

1,039.

Two-organic substances are labelled K and L if K gave a blue-black colour with iodine solution and L gave a deep red precipitate with Million's reagent, it can be concluded that

K is a carbhydrate and L is a protein

K is alkaline and L is acidic

K is unsaturated and L is a reducing sugar

K is a reducing agent and L is an amino acid

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Correct answer is A

No explanation has been provided for this answer.

1,040.

Which of the following needs to be hydrolysed before it shows reducing property?

Glucose