$Na^{+}$ ion is isoelectronic with

An atom has the electronic configuration of $1s^2, 2s^2 2p^6, 3s^2 3p^6 3d^{10}, 4s^2 4p^5$. Its atomic weight is $80$. Its atomic number and the number of neutrons in its nucleus shall be

Calculate the number of electrons, protons, and neutrons in $Cl_{2}$, $Cl$, and $Cl^{-}$. (Given for $Cl$: $Z = 17$ and $A = 35$)

An element has an electronic configuration of $2, 8, 18, 1$. If its atomic weight is $63$,then how many neutrons will be present in its nucleus?

Which of the following pairs represents an iso-electronic species?

Symbols $_{35}^{79} Br$ and $^{79} Br$ can be written,whereas symbols $_{79}^{35} Br$ and $^{35} Br$ are not acceptable. Answer briefly.