The atomic number of an element is derived from

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

Find the number of neutrons,electrons,and protons in the following species:
$(i)$ $_{15}^{31}P$
$(ii)$ $_{11}^{23}Na^{+}$
$(iii)$ $_{16}^{32}S^{2-}$
$(iv)$ $_{101}^{235}X$
$(v)$ $_{20}^{40}Ca^{2+}$
$(vi)$ $_9^{19}F^{-}$

$O^{2-}$ is isoelectronic with

The isobars are atoms with the same number of

From the following pairs of ions,which one is not an iso-electronic pair?