2014 - JAMB Chemistry Past Questions and Answers - page 3
21
Zn (s) + CuSO 4(aq) → ZnSO 4(aq) + Cu (s)
In the reaction above, the oxidation number of the reducing agent changes from
In the reaction above, the oxidation number of the reducing agent changes from
A
0 to + 4
B
0 to + 2
C
+ 1 to + 2
D
+ 1 to + 3
correct option: b
Users' Answers & Comments22
H 2O (g) + C (s) → H2(g) + CO(g)
The oxidizing agent in the reaction above is
The oxidizing agent in the reaction above is
A
CO(g)
B
C(s)
C
H2O(g)
D
H(2)(g)
correct option: c
Users' Answers & Comments23
Calculate the quantity of electricity in coulombs required to liberate 10g of copper from a copper compound
[Cu=64, F = 96500 Cmol-1]
[Cu=64, F = 96500 Cmol-1]
A
32395.5
B
30156.3
C
60784.5
D
15196.5
correct option: b
Cu → Cu2++ 2e
64g Cu requires 2 x 96500 coloumbs 10g Cu requires x columbs
x = 10x2x96500/64 =30156.3
Users' Answers & Comments64g Cu requires 2 x 96500 coloumbs 10g Cu requires x columbs
x = 10x2x96500/64 =30156.3
24
How many faraday of electricity is required to produce 0.25 mole of copper?
A
1.00F
B
0.01F
C
0.05F
D
0.50F
correct option: d
Cu → Cu2+ + 2e
1mole Cu requires 2f
0.25 mole Cu requires x
x = 0.25x2/1 = 0.50f
Users' Answers & Comments1mole Cu requires 2f
0.25 mole Cu requires x
x = 0.25x2/1 = 0.50f
25
If the change in free energy of a system is -899 Jmol-1 and the entropy change is 10Jmol-1k-1 at 250C, calculate the enthalpy change.
A
+2081 Jmol-1
B
-2081 Jmol-1
C
-649 Jmol-1
D
+649 Jmol-1
correct option: a
∆G = ∆H - T∆S
-899 = ∆H - 2980
∆H = -899 + 2980 = + 2081 Jmol-1
Users' Answers & Comments-899 = ∆H - 2980
∆H = -899 + 2980 = + 2081 Jmol-1
26
In an equilibrium reaction, which of the following conditions indicates that maximum yield of the product will be obtained?
A
Equilibrium constant is very large
B
∆H - T∆S = O
C
∆ H > T ∆ S
D
Equilibrium constant is less than zero
correct option: a
Users' Answers & Comments27
In a chemical reaction, the change in concentration of a reactant with time is
A
entropy of reaction
B
enthalpy of reaction
C
rate of reaction
D
order of reaction
correct option: c
Users' Answers & Comments28
Cr 2O\(\frac{2 -}{7}\) (aq) + H 2O(1)⇌ 2CrO \(\frac{2 -}{4}\) (aq) + 2H + (aq)
What happens to the reaction above when the hydrogen ion concentration is increased?
What happens to the reaction above when the hydrogen ion concentration is increased?
A
more of the products will be formed
B
the reaction will not proceed
C
the equilibrium position will shift to the right
D
the equilibrium position will shift to the left.
correct option: d
Users' Answers & Comments29
Which of the following will shift to the left from dilute tetraoxosulphate (VI) acid?
A
Lead
B
Magnesium
C
Cpper
D
Gold
correct option: b
Users' Answers & Comments30
The gas that is removed by the water in the flask is
A
O 2
B
SO 2
C
HCI
D
H 2
correct option: c
Users' Answers & Comments