Question

The wave number of first line of Balmer series of hydrogen atom is $15200c{m}^{-1}$. What is the wave number of first line of Balmer series of $L{i}^{2+}$ ion.

• A. $15200c{m}^{-1}$
• B. $136800m^{-1}$
• C. $76000c{m}^{-1}$
• D. $13680c{m}^{-1}$

Answer 1

The correct option is B $136800m^{-1}$

As we know the energy of constant state for hydrogen species like $L{i}^{+}2$ or $H{e}^{+}$ are multiple of integral type of $Z^2$ times the energy of hydrogen atom in stationary form$,$

Hence the wave number of first line of ion $=3^2\times 15200/cm$

$=9\times 15200/cm=136800/cm$

hence,

option $\left(B\right)$ is correct answer.