Question

A sponge can be pressed easily; still it is called a solid. Why?

Answer 1

Hint: The solids have a definite shape and volume. They cannot be compressed easily. The sponge is an exceptional example of a solid. The sponge is a porous solid. The atoms are arranged such that the array has space that can be occupied by the air.

Complete step by step answer:
The matter is composed of atoms or molecules. The arrangement of building blocks which are atoms and molecules gives a matter of various states, Physical and chemical properties. The force of interaction between these particles of matter gives a matter of its physical properties.
Solid-state is a state of matter in which the particles are packed tightly. The constituent particles can be atoms or solid.
The ‘sponge’ is a matter. The sponge is a porous material. It has the minute holes or gap between the atoms. The atoms have spaces between them. The air molecules can be easily trapped in the minute holes.
When we press the sponge, the air in the spaces is expelled out from the sponge. Therefore, the sponge can be compressed. The state of the sponge changes from the filled with the air to the no air form.
We know that the solid generally does not have the property of compressibility. The compressibility is a property of an object when the object is compressed and remains its shape until we apply the pressure. As we remove the pressure on the sponge, the material retains its original shape.
The sponge is composed of the atoms which are arranged in a regular pattern. The sponge is not a crystalline solid. But it is an amorphous solid like rubber. The sponge is an ‘aerosol’. The air is dispersed in the solid.
This makes it lighter in volume. The solids are incompressible. The sponge is considered as the solid as it has all other properties possessed by the solid. A sponge has a definite volume, has a definite shape. When pressure is relieved it attains its original shape.

Therefore, the sponge can be pressed easily but it is treated as a solid.

Additional information:
Properties of solid:
i) Solid have definite mass, volume, and shape
ii) Intermolecular distances between the solid particles are short and hence the forces of attraction are strong. As the intermolecular forces are inversely related to the distance between the particles.
iii) The atoms or molecules of the solid have a fixed position. They can oscillate about their mean positions.
iv) Solids change their shape on applying the force on it.
v) Based on the properties solid are classified as crystalline and amorphous solids. In crystalline solids, atoms are arranged in regular order. For example, ice.
vi) The solids in which the atoms are not packed in regular order or randomly ordered are called the non-crystalline or amorphous solids.

Note: note that the sponge is a hollow or porous solid. The example of porous solid is a pumice stone. It is a naturally obtained stone which has voids or pores in it. It is used to remove the dead skin from the foot.