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
correct option: b
Users' Answers & Comments12
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
correct option: a
Users' Answers & Comments13
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
correct option: a
Users' Answers & Comments14
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
correct option: c
At 20oC
0.34 mol/dm of the salt dissolve
= 0.34 * 101 = 34.34gm
Of the salt dissolved.
∴ 34.34gm dissolve is 1,000cm3
If only 250 cm3 is the required mass
X = (250/1000) * 34.34
= 8.555gm
If only 3.40gm of the salt dissolved ,the solution is unsaturated
Users' Answers & Comments0.34 mol/dm of the salt dissolve
= 0.34 * 101 = 34.34gm
Of the salt dissolved.
∴ 34.34gm dissolve is 1,000cm3
If only 250 cm3 is the required mass
X = (250/1000) * 34.34
= 8.555gm
If only 3.40gm of the salt dissolved ,the solution is unsaturated
15
Tetraoxosulphate (VI) acid burns the skin by
A
Hydrolysis
B
Hydration
C
Heating
D
Dehydration
correct option: d
Users' Answers & Comments16
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
correct option: a
Users' Answers & Comments17
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
correct option: a
Users' Answers & Comments18
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
correct option: a
Users' Answers & Comments19
The substance least considered as a source of environmental pollution is
A
Lead compounds
B
Organophosphorous compounds
C
Silicate minerals
D
Uranium
correct option: c
Users' Answers & Comments20
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)
correct option: b
Users' Answers & Comments