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.

2,611.

Which of the following statement is false?

A.

Acids react with some metals, liberating hydrogen

B.

Acids react with carbonates, liberating carbondioxide

C.

Acids conduct electricity and are decomposed by the current, liberating hydrogen at the anode

D.

Acids have a sour taste

E.

Acids change the colour of indicators

Correct answer is C

Thus, with a dilute solution of sulphuric acid and platinum electrodes, hydrogen gas is evolved at the cathode

2,612.

If one of the following oxides is heated with hydrogen or carbon using a bunsen burner, it is not reduced to the metal. Which one is it?

A.

Lead oxide

B.

Magnesium oxide

C.

Copper oxide

D.

Tin oxide

E.

Iron oxide

Correct answer is B

No explanation has been provided for this answer.

2,613.

Cellulose and starches can be classified as one of the following?

A.

sugars

B.

sucrose

C.

hydrocarbons

D.

carbohydrates

E.

isomers

Correct answer is D

No explanation has been provided for this answer.

2,614.

The best way of collecting chlorine is?

A.

by downward displacement of air

B.

by upward displacement of air

C.

over water

D.

under water

E.

over mercury

Correct answer is B

Chlorine gas is 2.5 times denser than air, hence it is best collected by the downward delivery or upward displacement of air.

2,615.

A cold aqueous solution of sodium chloride is electrolyzed using a graphite anode and an iron cathode. In the course of the electrolysis the electrolyte is continuously stirred. The liquid left after electrolysis will therefore consist of?

A.

sodium hydroxide solution

B.

chlorine water

C.

pure water

D.

sodium hypochlorite solution

E.

hydrochloric acid solution

Correct answer is A

we take cold aqueous to be concentrated solution of NaCl.

NaCl → \(Na^+    + Cl^-\)

 \(H_2O → H^+   + OH^-\)

H ion will be preferably discharged at the cathode while Cl ion will be discharged at the anode(due to high concentration)

Thus, NaOH is left in the solution.