$Mg^{2+}$ is isoelectronic with

The number of protons,neutrons and electrons in ${ }_{71}^{175} Lu$,respectively,are:

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

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

State whether the following statements are true or false:
$(i)$ Isobars have different atomic numbers.
$(ii)$ $_{14}^{30}\text{Si}$,$_{16}^{32}\text{S}$ are isotones.
$(iii)$ Niels Bohr was the first to suggest that the atom is spherical.
$(iv)$ Rutherford's model is accepted as the nuclear model of the atom.

Which property of an element is always a whole number?