To investigate the solubility of sodium chloride, a technician dissolved different amount of sodium chloride in a specific volume of water while altering the temperature of water. What does temperature represent in this experiment?
A.dependent variable
B.intermediate variable
C.independent variable
D.controlled variable
E.fixed variable
2.1 mark
Which property is used to confirm the presence of pure water?
A.It turns white anhydrous copper (II) sulphate blue
B.It dissolves all other substances
C.It freezes at 0 °C
D.It is neutral to litmus paper
E.It turns blue cobalt (II) chloride paper pink
3.1 mark
In which type of oxides does Aluminum oxide belong?
A.Metal oxides
B.Insoluble oxides
C.Soluble oxides
D.Amphoteric oxides
E.Basic oxides
4.1 mark
What is the amount of charge when a current of 2 amperes flows through a certain point in an electrolyte for 0.5 second?
A.2 coulombs
B.1 coulomb
C.2.5 coulombs
D.1.5 coulombs
E.0.5 coulombs
5.1 mark
How can you prevent a hoe from getting rust?
A.By painting and oiling them.
B.By exposing them to air.
C.By keeping them in moisture.
D.By cleaning them with water after use.
E.By leaving them in the garden after use.
6.4 marks
Identify two products which can be formed in each of the following processes:
(i) Reaction of sodium with ethanol.
(ii) Partial fermentation of sucrose in presence of yeast cells.
(a)
What are the sources of organic acids? Give five points.
5 mk
(a)
What are the sources of organic acids? Give five points.
1 mk
(b)
Identify two products which can be formed in each of the following processes:
(i) Reaction of sodium with ethanol.
(ii) Partial fermentation of sucrose in presence of yeast cells.
3 mk
(b(i))
Reaction of sodium with ethanol.
1 mk
(b(ii))
Partial fermentation of sucrose in presence of yeast cells.
1 mk
((b)(i)
Partial fermentation of sucrose in presence of yeast cells.
0 mk
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7.4 marks
Briefly explain four alternative sources of energy that can be developed to replace the fossil fuels.
(a)
Why is it important to replace fossil fuels as an energy source?
4 mk
(a)
Why is it important to replace fossil fuels as an energy source?
1 mk
(i)
Ozone layer depletion
1 mk
(ii)
Green House effect
1 mk
(b)
Briefly explain four alternative sources of energy that can be developed to replace the fossil fuels.
6 mk
(b)
Briefly explain four alternative sources of energy that can be developed to replace the fossil fuels.
1 mk
(iii)
Eutrophication
1 mk
(iv)
Terrestrial pollution
1 mk
(v)
Acidic rain
1 mk
(vi)
Water pollution
1 mk
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8.8 marks
What mass of impure ammonium chloride (90%) would be needed to react completely with 14.8g of calcium hydroxide?
(a)
How is the concept of mole useful in Chemistry? Give four points.
4 mk
(a)
How is the concept of mole useful in Chemistry? Give four points.
1 mk
(b)
What mass of impure ammonium chloride (90%) would be needed to react completely with 14.8g of calcium hydroxide?
6 mk
(b)
What mass of impure ammonium chloride (90%) would be needed to react completely with 14.8g of calcium hydroxide?
1 mk
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Section C
9.15 marks
The following diagram was used to study the reaction of calcium and water.
Gas X produced was passed through black copper(ll) oxide which changed colour to brown. With the aid of a chemical equation, interpret this observation.
Hydrogen atom can react by either gaining or loosing electron. In both cases, energy is involved. With the aid of the chemical equation(s) and energy level diagram, interpret this observation.
(a)
Gas X produced was passed through black copper(II) oxide which changed colour to brown. With the aid of a chemical equation, interpret this observation.
7 mk
(b(i))
Give three properties of oxygen gas.
3 mk
(a)
Gas X produced was passed through black copper(ll) oxide which changed colour to brown. With the aid of a chemical equation, interpret this observation.
1 mk
(b)
Hydrogen atom can react by either gaining or losing electron. In both cases, energy is involved. With the aid of the chemical equation(s) and energy level diagram, interpret this observation.
8 mk
(b)
Hydrogen atom can react by either gaining or loosing electron. In both cases, energy is involved. With the aid of the chemical equation(s) and energy level diagram, interpret this observation.
1 mk
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10.15 marks
Give the explanation on the hydrogen chloride gas based on the following:
(a) the raw material for production of the gas.
(b) two chemical tests for hydrogen gas.
(c) four physical propertics of hydrogen chloride.
(d) five uses of hydrogen chloride gas.
(a)
the raw material for production of the gas.
1 mk
(b(ii))
Give three uses of oxygen gas based on the properties mentioned in (b) (i).
3 mk
(b)
two chemical tests for hydrogen gas.
1 mk
(c)
four physical propertics of hydrogen chloride.
1 mk
