Plants use carbon dioxide for photosynthesis. Animals use it to make their:

Burning of petrol containing which of the following releases this toxic metal into the environment and can cause serious health hazards?

When animals and plants die and rot away or buried,they slowly form:

Which of the following oxides are released from industry and which dissolve in rain water to produce 'acidrain'.

Photochemical smog is formed due to the release of which toxic gas?

Plants get their nitrogen from nitrates in the:

Which of the following is used to remove pesticides and some other dissolves substances in modern water treatment process?

Where do animals get their  nitrogen from?

How much percentage of nitrogen  present in the atmosphere  is unreactive?

Which of the following is caused by gases in the air, chiefly carbon dioxide and methane?