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1999 - WAEC Chemistry Past Questions and Answers - page 3

21

30cm3 pf hydrogen at s.t.p combine with 20cm3 of oxygen to form steam according to the following equation 2H2(g) + O2(g) → 2H2O(g). Calculate the total volume of the gaseous mixture at the end of the reaction

A
50cm3
B
35cm3
C
30cm3
D
25cm3
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22

An exothermic reaction is one which involves

A
attainment of dynamic equilibrium
B
loss of heat to the surrounding
C
evolution of gas as it proceeds
D
positive change in value of enthalpy
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23

Which of the following is an acid salt?

A
NH4CI
B
MgSO4 7H2O
C
CH3COONa
D
NaHCO3
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24

Which of the following compounds dissolves in water to form a solution with pH below 7?

A
Sodium tetraoxosulphate (VI)
B
Potassium hydroxide
C
Ammonium chloride
D
Sodium trioxocarbonate (IV)
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25

If the solubility of KHCO3 is 0.40 mole dm-3

A
4.0g
B
10.0g
C
40.0g
D
100.0g
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26

The property of calcium chloride which makes it useful as a drying agent is that it is

A
ionic
B
deliquescent
C
a strong electrolyte
D
a normal salt
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27

Which of the following lowers the activation energy of a chemical reaction?

A
Freezing mixture
B
Reducing agent
C
Water
D
Catalyst
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28

Consider the reaction represented by the following equation: H2(g) + 12(g) → 2HI(g). The number of effective collisions of molecules of the reactants decreases as

A
the temperature is raised
B
the pressure increased
C
the volume of the system is increased
D
a catalysty is intoduced into the system
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29

What will be the effect of increase in pressure on the following system at equilibrium? 2NH2(g) N2(g) + 3H2(g)

A
Activation energy will decrease
B
the forward reaction will be favoured
C
the concentration of ammonia will increase
D
the reaction will go to completion
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30

Which of the following is not correct about oxidation number convention? The oxidation number of a/an

A
element in the free state is zero
B
monatomic ion is equal to its charge
C
alkali meta like sodium in its compounds is + 1
D
atom of a diatomic molecules is + 2
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