Question

All matters in the universe exist in three states, namely solid, liquid and gas.
a) Why do solid substances have a definite shape?
b) Write any two properties of a solid substance.
c) Will a solid substance expand on heating? Why?

TNSCERT Class 9 General Science Ch3 Is Matter Around us Pure

Answer 1

a) Because the forces b/w them are quite strong to keep Tue substance intact.

b) They have definite shape and volume.

c) Yes, because heating provided energy for breaking down the force of attractions b/w the particles of the solid.

Answer 2

Explanation:

Molecules within gases are further apart and weakly attracted to each other. Heat causes the molecules to move faster, (heat energy is converted to kinetic energy ) which means that the volume of a gas increases more than the volume of a solid or liquid.