Assertion : Photochemical smog is produced by nitrogen oxides.

Reason : Vehicular pollution is a major source of nitrogen oxides.

• If both assertion and reason are true and the reason is the correct explanation of the assertion.

• If both assertion and reason are true and the reason is not the correct explanation of the assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

Among the following, the one which is not a "green house gas", is

• N₂O

• CO₂

• CH₄

• O₂

The ozone layer forms naturally by :

• the interaction of CFC with oxygen

• the interaction of UV radiation with oxygen

• the interaction of IR radiation with oxygen

• the interaction of oxygen and water vapour

Among the following, the one that is not a green house gas is:

• Methane

• Ozone

• Sulphur dioxide

• Nitrous oxide