2000 - WAEC Chemistry Past Questions and Answers - page 3
21
Chemical equilibrium is attained when
A
reactants in the system are used up
B
concentrations of the products are greater than those of the reactants
C
concentrations of the reactants and products remain constant
D
reactants stop forming the products
correct option: c
Users' Answers & Comments22
What is the effect of using vanadium (V) oxide as catalyst in the reaction represented by the following equation? 2SO2 + O2 ⇌ 2SO3; ∆H = - xKJmol-1
A
Decreases the value of ∆H
B
Increases the collision rate of reactant particles
C
Shifts equilibrium position to the right
D
Reduces the time for attainment of equilibrium
correct option: a
Users' Answers & Comments23
A finely divided from of a metal burns more readily in air than the rod from because the rod has
A
higher molar mass
B
smaller surface area
C
protective oxide coating
D
diferent chemical properties
correct option: b
Users' Answers & Comments24
Which of the following will displace copper from a solution of copper (ll) salt?
A
Aluminium ions
B
Magnesium
C
Silver
D
Zinc ions
correct option: b
Users' Answers & Comments25
What is the value of x in the following equation? Cr2O72- + 14H+ + xe- → 2Cr3+ + 7H2O
A
1
B
6
C
8
D
12
correct option: b
Users' Answers & Comments26
In which of the following is the oxidation number of sulphur equal to -2?
A
S8
B
H2S
C
SO 2
D
SO 3 2-
correct option: b
Users' Answers & Comments27
An iron nail placed in a solution copper (ll) tetraoxosulphate (VI) is soon covered with a deposit of copper which of the following equations represents the reactions ?
A
Fe 2+ (aq) + Cu(s) → Fe 3+ + Cu 2+ (aq)
B
Fe 2+ (aq) + Cu(s) → Fe(s) + Cu2+ (aq)
C
Fe (s) + Cu2+ (aq) → Fe2+(aq) + Cu2+ (aq)
D
Fe(s) + Cu2+ → Fe2+(aq) + Cu(s)
correct option: d
Users' Answers & Comments28
0.10 mol dm-3 NaCI conducts electricity better than 0.10 mol dm-3 CH3COOH because the solution of NaCI
A
contains more ions
B
is neutral to litmus
C
has a lower molar mass
D
has a higher pH
correct option: a
Users' Answers & Comments29
Which of the following occurs when a solution of CuSO4 is electrolysed using copper electrodes?
A
The cathode becomes coated with copper
B
Both electrodes gain electrons
C
The blue colour of the solution fades gradually
D
The anode increases in mass
correct option: a
Users' Answers & Comments30
Which of the following procedures is suitable for identifying the food colouring added to a pastry sample?
A
The cathode becomes coated with copper
B
Both electrodes gain electrons
C
The blue colour of the solution fades gradually
D
The anode increases in mass
correct option: a
Users' Answers & Comments