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.

3,481.

A concentrated solution containing H+, Cu2+, OH- and Cl- was electrolyzed using platinum electrodes.
The ion that will be discharged at the cathode is?

A.

Cu2+

B.

Cl-

C.

H+

D.

OH-

Correct answer is A

Metallic ions are discharged at the cathode

Ions lower in the electrochemical series are most easily discharged

Cu\(^+\) will be preferentially discharged

3,482.

2H2 + O22 → H2+O ΔH = -571kJ
In the equation above, how much heat will be liberated if 12.0g of hydrogen is burnt in excess oxygen?

A.

-1142 kJ

B.

-571 kJ

C.

+1142 kJ

D.

-1713 kJ

Correct answer is D

2H2 + O22 → H2+O ΔH = -571kJ
4.0g of Hydrogen burn in air to produce -571 kJ
∴ 12.0s of Hydrogen will burn in air to produce
(12 * -571)/4 = -1713kJ

3,483.

In which of the following reactions can the oxidation number of the nitrogen be said to have increased?

A.

2NO(g) + O2(g) → 2NO2(g)

B.

NO(g) + Cl2(g) → NOCl2(l)

C.

FeSO4(aq) + NO(g) → Fe(NO)SO4(s)

D.

NO(g) + Br2(l) → NOBr2(l)

Correct answer is B

The oxidation number of the nitrogen of N in NO = 2

The oxidation number of the nitrogen of N in NOCl\(_2\) = 4

OPTION B is the correct option

3,484.

When iron is exposed to moisture and it rusts, the value of ΔG for the reaction is

A.

neutral

B.

zero

C.

positive

D.

negative

Correct answer is D

No explanation has been provided for this answer.

3,485.

Phenolphthalein in acidic solution is

A.

red

B.

orange

C.

colourless

D.

yellow

Correct answer is C

No explanation has been provided for this answer.