2002 - JAMB Chemistry Past Questions and Answers - page 1
1
A compound contains 31.91% potassium, 28.93% chlorine and the rest oxygen. What is the chemical formula of the compound?
[K = 39, Cl = 35.5, O = 16]
[K = 39, Cl = 35.5, O = 16]
A
KClO4
B
KClO
C
KClO2
D
KClO3
correct option: d
K- (31.91%), Mole = 31.91/39 =0.8182
Cl-(28.93%), Mole = 28.93/35.5 = 0.815
O-(39.16%), Mole = 39.6/16 = 2.448
K = 0.8182/0.815 = 1
Cl = 0.815/0.815 = 1
O = 2.448/0.815 = 3
Users' Answers & CommentsCl-(28.93%), Mole = 28.93/35.5 = 0.815
O-(39.16%), Mole = 39.6/16 = 2.448
K = 0.8182/0.815 = 1
Cl = 0.815/0.815 = 1
O = 2.448/0.815 = 3
2
The formula CH2 for ethanoic acid is regarded as its
A
Molecular formula
B
General formula
C
Empirical formula
D
Structural formula
correct option: c
Users' Answers & Comments3
A little quantity of trichloromethane (b.pt 60,oC) was added to a large quantity of ethanol (b.pt 78,oC). The most probable boiling point of the resultant mixture is from
A
69 oC - 70 oC
B
70 oC – 74 oC
C
82 oC – 84 oC
D
60 oC – 78 oC
correct option: c
Users' Answers & Comments4
The chromatography separation of ink is based on the ability of the components to
A
React with solvent
B
React with each other
C
Dissolve in each other in the column
D
Move at different speeds in the column
correct option: d
Users' Answers & Comments5
In the reaction E+F ↔ G+H, the backward reaction is favoured if the concentration of
A
F is increased
B
E is increased
C
E is reduced
D
G is reduced
correct option: c
Users' Answers & Comments6
What amount of mercury would be liberated if the same quantity of electricity that liberates 0.65g of zinc is applied?
A
2.01g
B
1.00g
C
4.02g
D
8.04g
correct option: c
Zn2+ + 2e- → Zn
2F will be liberated 65g of Zn, if 0.65gm of Zn is liberated, the quantity of electricity used
X = (0.65/65) * 2
= 0.02F
∴ Hg+ + e- → Hg1
i.e 1F → 201gm of Hg
∴ 0.02 will liberated
Y = (0.02/1) * 201
= 4.02g
Users' Answers & Comments2F will be liberated 65g of Zn, if 0.65gm of Zn is liberated, the quantity of electricity used
X = (0.65/65) * 2
= 0.02F
∴ Hg+ + e- → Hg1
i.e 1F → 201gm of Hg
∴ 0.02 will liberated
Y = (0.02/1) * 201
= 4.02g
7
Which of the following equations show that a reaction is in equilibrium?
A
ΔG < O
B
ΔG = ΔH – TΔS
C
ΔG > O
D
ΔG = O
correct option: d
Users' Answers & Comments8
PCl5(g) ↔ PCl3(g) + Cl2(g)
In the reaction above, a decrease in pressure will
In the reaction above, a decrease in pressure will
A
Decelerate the reaction
B
Increase the yield of PCl3
C
Increase the yield of PCl5
D
Accelerate the reaction
correct option: b
Users' Answers & Comments9
When H2S is passed into a solution of iron (III) chloride, the solution turns
A
Pale green
B
Pale red
C
Brown
D
Colourless
correct option: c
Users' Answers & Comments10
The Arrhenius equation expresses the relationship between the speed of a reaction and its
A
Molecular collision
B
Heat of reaction
C
Catalyst
D
Activation energy
correct option: a
Users' Answers & Comments