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 |
Did this page help you?
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
Did this page help you?
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
Did this page help you?
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 |
Did this page help you?
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 |
Did this page help you?
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.
Did this page help you?
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 |
Did this page help you?
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 |
Did this page help you?
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
Did this page help you?
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 |
Did this page help you?