1997 - WAEC Chemistry Past Questions and Answers - page 2
11
An acid is a substance which in the presence of water produces
A
salts
B
oxygen
C
effervescence
D
hydroxonium ions
correct option: d
Users' Answers & Comments12
Which of the following is a general method of preparing acids?
A
Direct combination of constituent elements
B
Double decomposition involving a salt solution
C
Reaction between an anhydride and water
D
Reaction between a base and an amphoteric oxide
correct option: c
There are several methods of preparation of acids. These include the following:
1. By the reaction between an acidic oxide of a non-metal (acid anhydride) and water.
SO2(g) + H2O(l) → H2SO3(aq) Trioxosulphate(IV)
P4010(s) + 2H2O(l) → 4HPO3(aq) Trioxophosphate(V)
Users' Answers & Comments1. By the reaction between an acidic oxide of a non-metal (acid anhydride) and water.
SO2(g) + H2O(l) → H2SO3(aq) Trioxosulphate(IV)
P4010(s) + 2H2O(l) → 4HPO3(aq) Trioxophosphate(V)
13
Which of the following is a general method of preparing acids?
A
Direct combination of constituent elements
B
Reaction between a base and an amphoteric oxide
C
Double decomposition involving a salt solution
D
Reaction between an anhydride and water
correct option: a
Users' Answers & Comments14
The loss of molecules of water of crystallization to the atmosphere by some crystalline salts is known as
A
efflorescence
B
effervescence
C
phosphorescence
D
fluorescence
correct option: a
Users' Answers & Comments15
Which of the following ions will migrate to the cathode during electrolysis?
A
Zinc ions
B
Chloride ions
C
Sulphide ions
D
Tetraoxosulphate (Vl) ions
correct option: a
Users' Answers & Comments16
What quantity of electrons (in mole) is lost when one mole of iron (ll) ions is oxidized to iron (lll) ions?
A
5 mole
B
4 mole
C
3 mole
D
2 mole
correct option: e
Users' Answers & Comments17
The common feature of reactions at the anode is that
A
electrons are consumed
B
oxidation is involved
C
ions are reduced
D
the electrode dissolves
correct option: b
Users' Answers & Comments18
From the following equations, what is the order of decreasing reactivity of X, Y and Z? Y (s) + X2+(aq) → Y2+
A
X>Y>Z
B
Y > X > Z
C
Z > Y > X
D
Y > Z > X
correct option: b
Users' Answers & Comments19
What is the value of x in the following equation? MnO- 4 + 4H+ + xe- → MnO 2 + 2H2O
A
2
B
3
C
4
D
7
correct option: b
Users' Answers & Comments20
If the value of ∆H for a reaction is negative, it means that the reaction is
A
slow
B
exothermic
C
spontaneous
D
irreversible
correct option: b
Users' Answers & Comments