Question

How do you know that nucleus is very small as compared to the size of atom.

Answer 1

As radius of an atom is approximately 10^-10 but radius of nucleus is approximately 10^-15

It is as small ball lying in center of big circle ground

Answer 2

The nucleus of an atom is about 10-15 m in size; this means it is about 10-5 (or 1/100,000) of the size of the whole atom. A good comparison of the nucleus to the atom is like a pea in the middle of a racetrack. (10-15 m is typical for the smaller nuclei; larger ones go up to about 10 times that.)