The unit representing atomic radii and ionic radii is

In $Cl_2$, the van der Waals radius is $180 \ pm$. What is the distance between the two atoms (in $pm$)?

Arrange all elements of group $1$ in increasing order of their ionic radius.

Of the following,the ion with the smallest ionic radius is

Which of the following sets of ions represents a group of isoelectronic species?

From the given set of species,point out the species from each set having the least atomic/ionic radius:
$(A)$ $F^{-}, Na^{+}, Mg^{+2}$
$(B)$ $Ni, Cu, Zn$
$(C)$ $N^{-3}, Cs^{+}, H^{-}$
$(D)$ $Li, Li^{+}, Be^{+2}$