Water

Question 1

Blue cobalt chloride paper is used to test for

Answer 1

Water

Blue when dry, pink when wet

Question 2

Freezing point

Answer 2

0°

Question 3

Boiling point

Answer 3

100°C

Question 4

Ice is less dense than water

Answer 4

Therefore it floats on water

Question 5

Water is an excellent solvent

Answer 5

Many substances dissolve in it

Question 6

Water cycle

Answer 6

How water is recycled on the planet

Question 7

Water treatment stages

Answer 7

Screening 
Settling
Filtration
Chlorination 
Fluoridation

Question 8

Hard water

Answer 8

Water that does not easily form a lather with soap

Question 9

Soft water

Answer 9

Water that easily forms a lather with soap

Question 10

Hardness in water is caused by

Answer 10

The presence of calcium ions dissolved in the water

Question 11

Hardness can be removed by

Answer 11

Passing the water through an ion exchange resin or distillation

Question 12

Electrolysis

Answer 12

Water is broken down into its elements, hydrogen and oxygen

Production of a chemical reaction using electricity

Question 13

Hoffman voltmeter

Answer 13

Used in the electrolysis of water to form H2 and O

Twice as much hydrogen as oxygen is formed because water is H2O

Question 14

Negative electrode

Answer 14

Hydrogen gas is formed

Question 15

Positive electrode

Answer 15

Oxygen is formed