Physics - Modern Physics Question with Solution | TestHub

${\text{r}}_{\text{n}}\propto {\text{n}}^2$

$\therefore {\text{r}}_{25}\propto {\left(25\right)}^2$

$\therefore \frac{{\text{r}}_1}{{\text{r}}_{25}}=\frac{{\left(1\right)}^2}{{\left(25\right)}^2}=\frac{1}{625}$

$\therefore {\text{r}}_{25}=625\times \text{0.53}=\text{331.25 }\stackrel{\circ }{\mathrm{A}}$