Thank you for reporting, we will resolve it shortly
Q.
The wave number of the first line of Balmer series of hydrogen is $15200 \,cm ^{-1}$. The wave number of the first Balmer line of $Li ^{2+}$ ion is
Structure of Atom
Solution:
$\bar{v}_{ H _2}^{\oplus}=R\left(\frac{1}{n_1^2}-\frac{1}{n_2^2}\right)=15200\, cm ^{-1}$
$\bar{v}_{ Li ^{2+}}=R Z^2\left(\frac{1}{n_1^2}-\frac{1}{n_2^2}\right)=3^2 \times 15200$
$=136800\, cm ^{-1}$