Air

Question 1

Consists of the elements

Answer 1

Nitrogen (78%)
Oxygen (21%)
Argon (<1%)
Compounds of carbon dioxide (0.03%) and water vapour (0-4%)

Question 2

Air is a mixture because

Answer 2

Composition varies from place to place

The different gases condense as liquids at different temperatures

Question 3

Cobalt chloride paper

Answer 3

Used to test the presence of water
Blue when dry
Pink when wet

Question 4

Limewater is used

Answer 4

To test for carbon dioxide

Turns milky if presence

Question 5

Oxygen is prepared

Answer 5

By the breakdown of hydrogen peroxide into oxygen and water in the presence of manganese dioxide (MnO2)

Question 6

Manganese dioxide is a catalyst

Answer 6

Speeds up the breakdown of the hydrogen peroxide

Question 7

Glowing splint is used to test for

Answer 7

Oxygen

Relights a glowing splint

Question 8

Carbon dioxide is prepared by the reaction between

Answer 8

Dilute hydrochloric acid (HCI) and marble chips (calcium carbonate, CaCO3)

Question 9

Oxygen is used for

Answer 9

Breathing
Welding
Burning

Question 10

Carbon dioxide is used in

Answer 10

Photosynthesis
Fire extinguishers
Fizzy drinks