In which of the following ionic pairs,is the second ion smaller in size than the first ion?

The size of isoelectronic species $F^{-},$ $Ne$ and $Na^{+}$ is affected by
$(a)$ Nuclear charge $(Z)$
$(b)$ Valence principal quantum number $(n)$
$(c)$ Electron-electron interaction in the outer orbitals
$(d)$ None of the factors because their size is the same.

Among the isoelectronic ions $(O^{2-}, N^{3-}, Mg^{2+}, Na^{+})$,the ions with the least and the highest ionic radius are,respectively

The ionic radii of $Rb^+$ and $I^-$ are $1.46 \ \overset{o}{A}$ and $2.16 \ \overset{o}{A}$ respectively. Which type of crystal structure is possible?

The species $Ar$,$K^{+}$ and $Ca^{2+}$ contain the same number of electrons. In which order do their radii increase?

The correct sequence which shows the decreasing order of the ionic radii of the elements is: