2002 - JAMB Chemistry Past Questions and Answers - page 2
11
When dissolved in water, NaOH flakes show
A
An endothermic change
B
An exothermic change
C
A slow reaction
D
A rapid reaction
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12
CU2S(s) + O2(g) → 2CU(s) + SO2(g)
What is the change in the oxidation number of copper in the reaction above?
What is the change in the oxidation number of copper in the reaction above?
A
+1 to 0
B
0 to +2
C
+2 to +1
D
0 to +1
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13
The product of the electrolysis of dilute sodium hydroxide using platinum electrodes are
A
Hydrogen and oxygen gases
B
Water and hydrogen gas
C
Water and sodium metal
D
Sodium metal and oxygen gas
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14
The solubility of a salt of molar mass 101g at 20oC is 0.34 mol dm-3. If 3.40g of the salt is dissolved completely in 250cm3 of water in a beaker, the resulting solution is
A
A suspension
B
Saturated
C
Unsaturated
D
Supersaturated
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15
Tetraoxosulphate (VI) acid burns the skin by
A
Hydrolysis
B
Hydration
C
Heating
D
Dehydration
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16
When a salt loses its water of crystallization to the atmosphere on exposure, the process is said to be
A
Efflorescence
B
Deliquescence
C
Effervescence
D
Fluorescence
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17
Three drops of a 1.0 mol dm-3 solution of NaOH are added to 20 cm3 of a solution of pH 8.4. The pH of the resulting solution will be
A
Close to that of pure water
B
Unaltered
C
Greater than 8.4
D
Less than 8.4
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18
25cm3 of a 0.2 mol dm3 solution of Na2CO3 requires 20 cm3 of a solution of HCl for neutralization. The concentration of the HCl solution is
A
0.5 mol dm3
B
0.6 mol dm3
C
0.2 mol dm3
D
0.4 mol dm3
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19
The substance least considered as a source of environmental pollution is
A
Lead compounds
B
Organophosphorous compounds
C
Silicate minerals
D
Uranium
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20
The fuming of kettles is caused by the presence in the water of
A
Calcium tetraoxosulphate (VI)
B
Calcium hydrogentrioxocarbonate (IV)
C
Calcium hydroxide
D
Calcium trioxocarbonate (IV)
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