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.

687.

Methanoic acid mixes with water in all proportions and has about the same boiling point as water. Which of the following methods would you adopt to obtain pure water from a mixture of Sand, water and methanoic acid?

A.

Extractive distillation

B.

Filtration followed by distillation

C.

Neutralization with sodium hydroxide followed by distillation

D.

Neutralization with sodium hydroxide followed by filtration

Correct answer is A

Due to the presence of maximum Azeotrope,we use extractive distilination (with extractive distilation agents like sulfone) used for mixtures with low relative volatility,nearing unity.

Azeotrope is a mixture of liquids that has a constant boiling point because the vapour has thesame composition as the mixture.

688.

In the preparation of oxygen by heating KCIO\(_3\) , in the presence of MnO\(_2\) only moderate heat is needed because the catalyst acts by \(_2\)

A.

lowering the pressure of the reaction

B.

increasing the surface area of the reaction

C.

increasing the rate of the reaction

D.

increasing the energy barrier of the reaction

Correct answer is C

No explanation has been provided for this answer.

689.

Which of the following pairs of substances will react further with oxygen to form a higher oxide?

A.

CO\(_2\) and H\(_2\)O

B.

NO and H\(_2\)O

C.

CO and CO\(_2\)

D.

SO\(_2\) and NO

Correct answer is D

No explanation has been provided for this answer.

690.

The boiling of fat and aqueous caustic soda is referred to as

A.

hydrolysis

B.

esterification

C.

acidification

D.

saponification

Correct answer is D

No explanation has been provided for this answer.