Chemistry questions and answers

Chemistry Questions and Answers

Learn more about the properties, composition, and structure of substances (elements and compounds) with these Chemistry questions and answers. This Test can be used by students preparing for Chemistry in JAMB, WAEC, NECO or Post UTME.

256.

The formation of ethene from dehydration of ethanol can be described as-------

A.

an addition reaction

B.

an elimination reaction

C.

an oxidation reaction

D.

a substitution reaction

Correct answer is B

No explanation has been provided for this answer.

257.

Which of the following pairs of compounds would form a precipitate when their aqueous solutions are mixed?

A.

NaCl and KNO\(_{3}\)

B.

KCL and NaNO\(_{3}\)

C.

K\(_{2}\)SO\(_{4}\) and BaCl\(_{2}\)

D.

NH\(_{4}\)NO\(_{3}\) and CO\(_{3}\)

Correct answer is C

when potassium sulfate is mixed with barium chloride a white precipitate of barium sulfate will be form. barium sulfate is slightly soluble in water, so it will precipitate out as a solid

BaCl2 + K2SO4 → BaSO4 + 2KCl 

note; all substances are aqueous except BaSO4 which is solid

258.

The alkanol represented by the structure above is

A.

primary and dihydric

B.

secondary and monohydric

C.

tertiary and dihydric

D.

secondary and dihydric

Correct answer is A

It is primary alcohol because it has only one alkyl group and dihydric because it has two hydroxyl groups

259.

If humid air is polluted by chlorine discharged, the air can be restored by sprinkling

A.

solid MnO\(_{2}\)

B.

acidified KMnO\(_{4}\)

C.

acidified FeSO\(_{4}\)

D.

saturated NaCl(aq)

Correct answer is B

Chlorine is a toxic gas and when it pollutes the air, it can be neutralized by using acidified KMnO4. The reaction between chlorine and acidified KMnO4 results in the formation of chloride ions, manganese(II) ions, and water, which are harmless. This is why acidified KMnO4 is used to restore air polluted by chlorine discharge.

260.

Cathodic protection of metals is based on

A.

standard electrode potential of hydrogen

B.

its electrical conductivity

C.

nature of oxides formed

D.

relative tendencies of oxidation

Correct answer is D

No explanation has been provided for this answer.