Air, oxygen, carbon dioxide

Gap-fill exercise

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!

Air is a mixture of .
78% is .
21% is .
The rest is made up of , and other gases.
Oxygen is prepared by decomposing hydrogen using manganese as a .
Oxygen supports but carbon dioxide does not.
Carbon dioxide turns moist litmus paper .
Carbon dioxide is prepared using hydrochloric and calcium .
Carbon dioxide turns a milky colour.
Carbon dioxide is dense than air.
Fire extinguishers and fizzy drinks are two uses of gas.
Photosynthesis is a use of gas.