JAMB Chemistry Past Questions & Answers - Page 170

846.

Lime - water, which is used in the laboratory for the detection of carbon(iv)oxide is an aqueous solution of

A.

Ca(OH)2

B.

CaCO3

C.

CaHCO3

D.

CaSO4

E.

N2CO3

Correct answer is A

No explanation has been provided for this answer.

847.

Which of the following methods may be used to prepare trioxonitrate (V) acid (nitric acid) in the laboratory?

A.

Heating ammonia gas with tetraoxosulphate (VI) acid

B.

Heating ammonium trioxonitrate (V) with tetraoxosulphate (VI) acid

C.

Heating sodium trioxonitrate (V) with tetraoxosulphate (VI) acid

D.

Heating potassium trioxonitrate (V) with calcium hydroxide

E.

Heating a mixture of ammonia gas and oxygen.

Correct answer is C

No explanation has been provided for this answer.

848.

In dilute solution the heat of the reaction NaOH + HCl = NaCl + H2O is - 57.3kJ. Therefore the heat of the reaction 2NaOH + H2SO4 \(\to\) Na2SO4 + 2H2O is

A.

+ 28.65 kJ

B.

- 28.65KJ

C.

+ 57.3KJ

D.

- 114.6 KJ

E.

- 229.2 KJ

Correct answer is D

NaOH + HCl = NaCl + H2O \(\Delta\)H = -57.3kJ

Heat of reaction of 2NaOH + H2O4

NaSO4 + H2O is

= 57.3 x 2 = -114.6 kJ

849.

For the reaction 2Fe3+ 2I- \(\to\) 2Fe2+ + I2, which of the following statements is TRUE?

A.

Fe is oxidized to Fe3+

B.

Fe3+ is oxidized to Fe2+

C.

I- is oxidized to I2

D.

I- is reduced to I2

E.

I- is displacing an electron from Fe3+

Correct answer is C

No explanation has been provided for this answer.

850.

In which of the following reactions does hydrogen peroxide act as a reducing agent?

A.

H2S + H2O2 \(\to\) S + 2H2O

B.

PbSO3 + H2O2 \(\to\) PbSO4 + H2O

C.

2I+ 2H+ + H2O2 \(\to\) I2 + 2H2O

D.

PbO2 + 2HNO3 + H2O2 \(\to\) Pb(NO3)2 + 2H2O + O2

E.

SO2 + H2O2 \(\to\) H2SO4

Correct answer is D

No explanation has been provided for this answer.