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

What do you understand by isoelectronic species? Name a species that will be isoelectronic with each of the following atoms or ions.
$(i)$ $F^{-}$
$(ii)$ $Ar$
$(iii)$ $Mg^{2+}$
$(iv)$ $Rb^{+}$

The pair of atoms having the same number of neutrons is

The charge of an electron is $-1.6 \times 10^{-19} \ C$. The value of the net charge on a $Li^{+}$ ion will be:

Which of the following is correct?

What are $_{17}^{35}Cl$ and $_{17}^{37}Cl$? Why?