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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Which of the following statements regarding the uses of water are correct?
| 1 | Water in industry is used as a solvent and as a coolant. |
| 2 | All water used in industry is safe for human consumption. |
| 3 | Water in the household may contain dissolved salts. |
| 4 | Water in the household is used for sanitation and cooking. |
1, 3 & 4
1, 2 & 4
2, 3 & 4
1 & 4 only
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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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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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Which substances lead to the deoxygenation of water?
1 NH4NO3
2 Pb
3 Mg
4 Ca3(PO4)2
2 and 4
1 and 2
3 and 4
1 and 4
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Four water samples, W, X, Y and Z, were analysed in the laboratory to measure pH, boiling point, and the amount of dissolved solids.
The sources of water were:
The results are shown in the table below.
| Water sample | pH | Boiling point / °C | Mass of dissolved solids in 20 cm3 of water / g |
| W | 8.2 | 101.3 - 101.5 | 0.72 |
| X | 4.2 | 100.2 - 100.3 | 0.03 |
| Y | 7.0 | 100.0 | 0.00 |
| Z | 6.3 | 100.5 - 100.6 | 0.02 |
Which are the correct identities of water samples W, X, Y and Z?
| W | X | Y | Z | |
| A | acidic rain | pure water | tap water | sea water |
| B | pure water | tap water | sea water | acidic rain |
| C | tap water | sea water | acidic rain | pure water |
| D | sea water | acidic rain | pure water | tap water |
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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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Mineral water contains dissolved salts such as magnesium chloride. Which one of the following statements about mineral water is correct?
Mineral water boils at slightly above 100 °C.
Mineral water is pure water.
Mineral water boils at exactly 100 °C.
Another name for mineral water is fizzy water.
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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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