Question

how does repulsive forces acts as a reason for solid are hard to get compressed than liquids and liquida are hard to get compressed than gases?

Answer 1

In solids the particles are very close to each other and on further compression their nuclei come very close to each other due to positive charge of the nucleus the repulsion takes place and this is called as repulsive force.
Now in case of liquids the molecules are not as close as in solids and hence can be somewhat compressed till the repulsive force becomes prominent.
In case of gases the particles are the farthest and hence more compression is possible.