Isotopes differ in

Assertion : An atom is electrically neutral.
Reason : Atom contains equal number of protons and neutrons.

How many neutrons are present in the nucleus of $_{88}Ra^{226}$?

$A$ sodium cation $(Na^+)$ has a different number of electrons from which of the following species?

In the neutral state,the element $M$ consists of the isotopes $_{14}M^{28}$,$_{14}M^{29}$,and $_{14}M^{30}$ in the ratio $60 : 30 : 20$ respectively. Correct statements about $M$ in the natural state include that:

Which of the following is $NOT$ a hydrogen-like species?