Edge length of $\mathrm{NaCl}$ unit cell is 552 pm. Then which are correct statements

 $$\begin{gathered} \mathrm{For} \mathrm{NaCl} \\ \mathrm{a}(\mathrm{edge} \mathrm{length})=2{\mathrm{r}}_{{\mathrm{c}}^{+}}+2{\mathrm{r}}_{{\mathrm{a}}^{-}}=552\mathrm{pm}; \end{gathered}$$

${\mathrm{r}}_{{\mathrm{c}}^{+}}+{\mathrm{r}}_{{\mathrm{a}}^{-}}=276\mathrm{pm},{\mathrm{r}}_{{\mathrm{c}}^{+}}/{\mathrm{r}}_{{\mathrm{a}}^{-}}=0.52;{\mathrm{r}}_{{\mathrm{c}}^{+}}/{\mathrm{r}}_{{\mathrm{a}}^{-}}=95/181$

Nearest distance between two ${\mathrm{Na}}^{+}$ ions is the distance from body center to edge center is

i.e.$\sqrt{{\left(276\right)}^2+{\left(276\right)}^2}=276\sqrt{2}\mathrm{pm}$.