Which of the following gases supports burning?

1. oxygen
2. nitrogen
3. carbon dioxide
4. water vapour

Air is a mixture because:

1. the components of air retain their individual properties.
2. energy change takes place when the components of air are mixed together.
3. the composition of air remains the same everywhere.
4. the components of air cannot be separated by simple physical methods.

Write the chemical name of:

(a) Lime water

(b) The white insoluble solid formed on reaction of carbon dioxide with lime water.

What is atmosphere ?