Question

The frequency of 1^st line of Balmer series in $H_{2}$ atom is $\nu_{0}$. The frequency of line emitted by singly ionised He atom is.

• A. $2\nu_{0}$
• B. $4\nu_{0}$
• C. $\nu_{0} ⥂ / ⥂ 2$
• D. $\nu_{0} ⥂ /4 ⥂$

Answer 1

Answer: (B)

$4\nu_{0}$

Answer 2

$\nu \propto Z^{2} \Rightarrow \frac{\nu_{H_{2}}}{\nu_{He}} = \left( \frac{1}{2} \right)^{2} = \frac{1}{4} \Rightarrow \nu_{He} = 4\nu_{H_{2}}$= 4ν₀