Air

Question 1

Air consists of the elements

Answer 1

Nitrogen (78%), oxygen (21%), argon (<1%), and the compounds carbon dioxide (0.03%) and water vapor (0-4%).

Question 2

Air is a mixture because

Answer 2

It’s composition varies from place to place and the different gases condense as liquids at different temperatures.

Question 3

Cobalt chloride papers

Answer 3

Used to test for the presence of water. It is blue when dry, pink when wet.

Question 4

Limewater is used to

Answer 4

test for carbon dioxide. Carbon dioxide turns limewater milky.

Question 5

Oxygen is prepared

Answer 5

By the breakdown of hydrogen peroxide (H2O2) into oxygen and water in the presence of manganese dioxide (MnO2).

Question 6

Manganese dioxide is a catalyst

Answer 6

It speeds up the breakdown of the hydrogen peroxide.

Question 7

A glowing splint

Answer 7

Used to test for oxygen. Oxygen relight a glowing splint.

Question 8

Carbon dioxide is prepared by

Answer 8

The reaction between dilute hydrochloric acid (HC1) and marble chips (calcium carbonate (CaCO3).

Question 9

Oxygen is used for

Answer 9

Breathing, welding and burning

Question 10

Carbon dioxide is used in

Answer 10

Photosynthesis, fire extinguishers and fizzy drinks