1998 - WAEC Chemistry Past Questions and Answers - page 1
1
AN AQUEOUS SOLUTION IS ACIDIC IF
A
its pH value is high
B
it s corrosive
C
it changes the colour of litmus
D
it has a bitter taste
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2
The following oxides react with water except
A
Na2O
B
SO3
C
NO2
D
CO2
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3
Which of the following is not a property of trioxonitrate (V) salts?
A
Positive reaction to the brown ring test
B
Ability to dissolve in cold water
C
Decomposition on being strongly heated
D
Production of effervescence with saturated Na2CO3 solution
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4
Which of the following methods is suitable for the preparation of an insoluble salt?
A
Action of an acid on a metal
B
Double decomposition
C
Neutralisation
D
Action of an acid on a trioxocarbonate (IV)
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5
What is the function of sulphur (IV) oxide in the reaction represented by the following equation? SO 2(aq) + 2H2S(g) → 3S (s) + 2H 2O (l)
A
Dehydrating agent
B
Oxidising agent
C
Bleaching agent
D
Acid
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6
Which of the following will produce oxygen and hydrogen during its electrolysis using platinum electrode?
A
Glucose solution
B
Aqueous copper (ll) tetraoxosulphate (IV)
C
Dilute sodium chloride solution
D
Concentrated hydrochloric acid
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7
What mass of copper would be deposited by a current of 1. 0 ampere passing for 965 seconds through copper (ll) tetraoxosulphate (IV) solution? [Cu = 63.5; 1F = 96500C]
A
0.318g
B
0.635g
C
18g
D
6.35g
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8
How many electrons are removed from Cr2- when it is oxidized to CrO42-?
A
o
B
2
C
4
D
8
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9
Substances which absorb water from the atmosphere without dissolving in it are sid to be
A
anhydrous
B
hygroscopic
C
insolube
D
hydrated
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10
Pipe-borne water is usually chlorinated in order to
A
improve the teste of the water
B
remove the hardness in the water clear
C
coagulate sediments in the water
D
kill harmful bacteria in the water
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