Question

Why airs are compessible but no liquid?

Answer 1

You're wrong in saying liquids are not compressible; liquids are compressible, but this property is very limited due to the strong intermolecular forces of attraction.

Answer 2

if you see both air and water,there are particles of matter present in both of them.but in air,the particles have less intermolecular attraction.i.e they have less connections between them.they having little intermolecular attraction can be compressed easyly because they have more spaces too.but in case of water or liquids the attraction is a bit more than air but less tha solid substances.so it has comparitively less spaces than air.so it is not compressable as air will do.