Question

An ionic atom equivalent to hydrogen atom has wavelength equal to 1/4 of the wavelengths of hydrogen lines. The ion will be.

• A. $He^{+}$
• B. $Li^{+ +}$
• C. $Ne^{9 +}$
• D. $Na^{10 +}$

Answer 1

Answer: (A)

$He^{+}$

Answer 2

$\bar{\nu} \propto \frac{1}{\lambda} \propto Z^{2} \Rightarrow \lambda Z^{2} =$constant

$\Rightarrow \lambda = \frac{\lambda}{4}Z^{2} \Rightarrow Z = 2$.