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
correct option: e
Users' Answers & Comments2
The following oxides react with water except
A
Na2O
B
SO3
C
NO2
D
CO2
correct option: e
Users' Answers & Comments3
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
correct option: d
Users' Answers & Comments4
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)
correct option: b
Users' Answers & Comments5
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
correct option: b
Users' Answers & Comments6
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
correct option: c
Users' Answers & Comments7
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
correct option: a
Cu2+ + 2e- → Cu, From the equation 2 Faraday will liberate 63.5gm of copper The quantity of electricity passed (Q) Q = 1. 0 965 = 965 coulomb :. 2 x 96500 → 63.5, 965 → x. x = 965 / 2x96500 x 63.5 = 0.3175g \(\approx\) 0.328
Users' Answers & Comments8
How many electrons are removed from Cr2- when it is oxidized to CrO42-?
A
o
B
2
C
4
D
8
correct option: c
Users' Answers & Comments9
Substances which absorb water from the atmosphere without dissolving in it are sid to be
A
anhydrous
B
hygroscopic
C
insolube
D
hydrated
correct option: b
Users' Answers & Comments10
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
correct option: d
Users' Answers & Comments