Which is the coldest layer of the atmosphere of earth

Which gas is the most in the atmosphere

Which gas among these is essential for breathing

Burning requires

Choose the options which are correct according to air pollution

Algae and plants use carbon dioxide and water to produce oxygen. What is the name of this process?

lime water turns milky

___________ dissolves in water

when clear lime water is exoposed to air for some time it turns _____________