A student added anhydrous copper(II) sulfate to a test tube containing an aqueous solution.
Which row correctly describes the colour change the student observed?
| before addition | after addition |
A | white | pink |
B | white | blue |
C | blue | white |
D | pink | blue |
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During the treatment of ground water, large insoluble particles are allowed to settle to the bottom of a tank.
What is this process called?
Sedimentation
Anaerobic digestion
Screening
Chlorination
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There are many steps involved when treating water.
Which of the answers below is the incorrect reason for the treatment step being carried out?
| Treatment | Explanation |
A | filtration | to remove dissolved solids |
B | carbon filtration | to remove tastes and odours |
C | sedimentation | to remove mud and sand |
B | chlorination | to kill bacteria |
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Potable water is produced from a water source near a country spring as shown in the flow diagram.
Which processes occur at P and Q?
| P | Q |
A | chlorination | filtration |
B | chlorination | distillation |
C | filtration | distillation |
D | filtration | chlorination |
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Which is the correct reason for carrying out each step when treating water?
| Adding carbon | Chlorination | Sedimentation |
A | kill microbes | remove salts | remove solids |
B | remove salts | remove odours | kill microbes |
C | remove odours | kill microbes | remove solids |
D | remove odours | remove solids | remove salts |
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Which row correctly identifies the substance based on the experiment and observations carried out?
| Experiment | Observations | Identity of bold substance |
A | Pink crystals are heated | The crystals turn blue and steam is given off | anhydrous cobalt(II) chloride |
B | Water is added to a white solid | The white solid turns blue | anhydrous copper(II) sulfate |
C | Blue crystals are heated | The crystals turn white and steam is given off | anhydrous cobalt(II) chloride |
D | Water is added to a blue solid | The blue solid turns pink | hydrated copper(II) sulfate |
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