Question

If the wave number of $1^{st}$ line of Balmer series of hydrogen atom is ‘x’ then the wave number of $1^{st}$ line of Lyman series of $H{e}^{+}$ ion will be

• A.
• B.
• C.
• D.

Answer 1

The correct option is C

$\overline{v}=R{z}^2[\frac{1}{n_1^2}-\frac{1}{n_2^2}]\Rightarrow X=R[\frac{1}{2^2}-\frac{1}{3^2}]\Rightarrow \frac{5R}{36}$
$\therefore R=\frac{36x}{5}$
$\overline{v_1}=R{2}^2[1-\frac{1}{2^2}]=3R$
Substituting R, we get $=3\times \frac{36x}{5}=\frac{108x}{5}$