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.

1,641.

When concentrated sodium chloride solution is electrolysed using inert electrodes the products are?

A.

oxygen and hydrogen

B.

hydrogen and oxygen

C.

sodium and oxygen

D.

soduim hydroxide, hydrogen and chlorine

Correct answer is D

When concentrated NaCl solution undergoes electrolysis, sodium hydroxide and hydrogen are produced at the cathode while chlorine is produced at the anode.

1,642.

If two metallic ions of the same concentration migrate to a graphite cathode, the one that would be preferentially discharged is the one that has the

A.

smaller mass

B.

lower electrical charge

C.

greater stability in solution

D.

stronger tendency to accept electrons

Correct answer is D

No explanation has been provided for this answer.

1,643.

Consider the following equation; Cr2O7(aq)2- + 14H+(aq) + 6e- → 2Cr3+(aq) + 7H2O(I). The oxidation number of chromium changes from

A.

-2 to + 3

B.

- 2 to + 6

C.

+ 6 to + 3

D.

+ 7 to + 6

Correct answer is C

No explanation has been provided for this answer.

1,644.

A visible change is observed when a strip of iron is placed in an aqueous solution of

A.

FeSO4

B.

ZnSO4

C.

CuSO4

D.

MgSO4

Correct answer is C

No explanation has been provided for this answer.

1,645.

Which of the compounds will leave a metal residue when heated?

A.

Cu(NO 3 )2

B.

AgNO3

C.

K2CO3

D.

CaCO3

Correct answer is B

No explanation has been provided for this answer.