Six protons are found in the nucleus of

Which of the following properties are different for neutral atoms of isotopes of the same element?

The number of electrons,protons and neutrons in a species are equal to $18$,$16$ and $16$ respectively. Assign the proper symbol to the species.

How many neutrons and protons are there in the following nuclei?
$_{6}^{13}C, _{8}^{16}O, _{12}^{24}Mg, _{26}^{56}Fe, _{38}^{88}Sr$

Among the following,the isoelectronic species is/are:
$(I)$ $O^{2-}, F^{-}, Na^{+}, Mg^{2+}$
$(II)$ $Na^{+}, Mg^{+}, Al^{3+}, F^{-}$
$(III)$ $N^{3-}, O^{2-}, F^{-}, Ne$

The atoms $_6C^{13}$ and $_8O^{17}$ are related to each other as .......