Assertion (A) : An atom consists of electron, proton and neutron. Electron revolves around nucleus. However, most of space in an atom is empty.

Reason (R) : From Rutherford's experiment, size of the nucleus is 10^-10 m and from kinetic theory, size of atom is 10^-15 m.

Both A and R are true and R is the correct explanation of A.

Rutherford also concluded from his experiments that the size of the nucleus is between 10^-15 and 10^-14 m.

According to Kinetic theory, the size of an atom is around 10^-10 m or around 10,000 to 100,000 times the size of the nucleus proposed by Rutherford. Hence, the distance of the electrons from the nucleus should be around 10,000 to 100,000 times the size of the nucleus.

This eventually implies that most of the atom is empty space.