Name two eleemts and two compounds present in air .

Give two uses of the following components present in air : (a) oxygen (b) nitrogen (c ) carbon dioxide (d) water vapour

Name the most abundant compound of hydrogen present on earth.

Name two osmolytes.

Name Two chemicals used to destroy germs present in water.

What is a photosystem? Name two important photosystems present in a cell.

Explain Gives two compounds.

Name two voids.

Name two terms given to the meristems present on the base of internodes.