Question

why are large intercellular space present in the leaves

Answer 1

that spaces have to kept for storage and some functioning purpose

Answer 2

Leaves have large inter-cellular spaces to allow for gaseous exchange.

EXPLANATION:

Leaves exchange gases through their stomata.  The leaves need to give out oxygen and take in carbon dioxide to prepare their food. The inter-cellular spaces facilitate this exchange of gases.

It is through these inter-cellular spaces that the stomata carry out the process of transpiration through which leaves lose water. Transpiration is essential so that plants can give out excess water and keep the tissues and cells protected.