Year : 
2004
Title : 
Chemistry
Exam : 
JAMB Exam

Paper 1 | Objectives

21 - 30 of 50 Questions

# Question Ans
21.

The oxidation state of chlorine in HClO4 is

A. -5

B. -1

C. +1

D. +7

D
22.

ZnO(s) + CO(g) → Zn(s) + CO2(g)
In the reaction above, Zinc has been

A. decomposed

B. displaced

C. oxidized

D. reduced

D
23.

Which of the following acts as both reducing and oxidized agent?

A. H2

B. SO2

C. H2S

D. CO2

B
24.

In the electrolysis of brine, the anode is

A. platinum

B. copper

C. zinc

D. carbon

D
25.

The mass of silver deposited when a current of 10a is passed through a solution of silver salt for 4830s is
[Ag = 108, F = 96500 c mol-1]

A. 108.0g

B. 54.0g

C. 27.0g

D. 13.5gq

Detailed Solution

Ag + ie → Ag+
If w 96500 C deposit 108g of silver
∴ 10 * 4830 will deposit (10 * 4830 * 108)/96500
= 5216400/96500 = 54.06g
26.

2CO(g) + O2(g) → 2CO2(g)
Given that ΔH[CO]is -110.4 kJmol-1 and ΔH[CO2] is -393.0 kJmol-1, the energy change for the reaction above is

A. -503.7 kJ

B. -282.6 kJ

C. +282.6 kJ

D. +503.7 kJ

Detailed Solution

Energy change (ΔH) = 2ΔHCO2 - (2ΔHCO + ΔHO)
= 7x - 393 - (7 * 110.4 + 0)
= -393 + 110.4 = -282.6 kJ
27.

Which of the following hydrogen halides the highest entropy value?

A. HF

B. HCl

C. HBr

D. HI

A
28.

N2O4(g) ↔ 2NO2(g)
In the endothermic reaction above, more product formation will be favoured by

A. a constant volume

B. an increase in pressure

C. a decrease in pressure

D. a decrease in volume

C
29.

Which of the following shows little or no net reaction when the volume of the system is decreased?

A. H2(g) + I2(g) ↔ 2HI(g)

B. 2NO2(g) ↔ N2O4(g)

C. PCl5(g) ↔ PCl3(g) + Cl2(g)

D. 2O3(g) ↔ 3O2(g)

A
30.

The allotropy of carbon used in the decolourization of sugar is

A. Graphite

B. Soot

C. Charcoal

D. Lampblack

C
21.

The oxidation state of chlorine in HClO4 is

A. -5

B. -1

C. +1

D. +7

D
22.

ZnO(s) + CO(g) → Zn(s) + CO2(g)
In the reaction above, Zinc has been

A. decomposed

B. displaced

C. oxidized

D. reduced

D
23.

Which of the following acts as both reducing and oxidized agent?

A. H2

B. SO2

C. H2S

D. CO2

B
24.

In the electrolysis of brine, the anode is

A. platinum

B. copper

C. zinc

D. carbon

D
25.

The mass of silver deposited when a current of 10a is passed through a solution of silver salt for 4830s is
[Ag = 108, F = 96500 c mol-1]

A. 108.0g

B. 54.0g

C. 27.0g

D. 13.5gq

Detailed Solution

Ag + ie → Ag+
If w 96500 C deposit 108g of silver
∴ 10 * 4830 will deposit (10 * 4830 * 108)/96500
= 5216400/96500 = 54.06g
26.

2CO(g) + O2(g) → 2CO2(g)
Given that ΔH[CO]is -110.4 kJmol-1 and ΔH[CO2] is -393.0 kJmol-1, the energy change for the reaction above is

A. -503.7 kJ

B. -282.6 kJ

C. +282.6 kJ

D. +503.7 kJ

Detailed Solution

Energy change (ΔH) = 2ΔHCO2 - (2ΔHCO + ΔHO)
= 7x - 393 - (7 * 110.4 + 0)
= -393 + 110.4 = -282.6 kJ
27.

Which of the following hydrogen halides the highest entropy value?

A. HF

B. HCl

C. HBr

D. HI

A
28.

N2O4(g) ↔ 2NO2(g)
In the endothermic reaction above, more product formation will be favoured by

A. a constant volume

B. an increase in pressure

C. a decrease in pressure

D. a decrease in volume

C
29.

Which of the following shows little or no net reaction when the volume of the system is decreased?

A. H2(g) + I2(g) ↔ 2HI(g)

B. 2NO2(g) ↔ N2O4(g)

C. PCl5(g) ↔ PCl3(g) + Cl2(g)

D. 2O3(g) ↔ 3O2(g)

A
30.

The allotropy of carbon used in the decolourization of sugar is

A. Graphite

B. Soot

C. Charcoal

D. Lampblack

C