Question

Give reason for the following: 

(a) Nucleus of an atom is heavy and positively charged. 

(b) An atom is electrically neutral. 

Answer 1

(a) Nucleus consists of proton and neutron. Proton has positive charge whereas neutron has no charge hence net charge on nucleus is positive. Nucleus is heavy because of the presence of proton and neutron. 

(b) An atom is electrically neutral because it possess same number of proton (positive charge) and electron (negative charge).