Benzene is treated with isobutyl alcohol in presence of conc. ${\mathrm{H}}_2{\mathrm{SO}}_4$.

Compare the relative stability of the following species and indicate their magnetic properties:

${\mathrm{O}}_2, {{\mathrm{O}}_2}^{+}, {{\mathrm{O}}_2}^{-}\left(\mathrm{superoxide}\right), {{\mathrm{O}}_2}^{2-}\left(\mathrm{peroxide}\right)$

If $\mathrm{NaCl}$ is doped with ${10}^{-3} \mathrm{mol} \% {\mathrm{SrCl}}_2$. What is the concentration of cation vacancies?

$$\begin{gathered} \left(\mathrm{A}\right) 6.023\times {10}^{20}. \\ \left(\mathrm{B}\right) 6.023\times {10}^{18}. \\ \left(\mathrm{C}\right) 6.023\times {10}^{23}. \end{gathered}$$

Enter your correct answer as A, B or C.