Question

The wavelength of radiation required to excite the electron from the first orbit to the third orbit in a doubly ionized lithium atom will be

• A. $134.25\mathring{A}$
• B. $125.5\mathring{A}$
• C. $113.7\mathring{A}$
• D. $110\mathring{A}$

Answer 1

The correct option is C $113.7\mathring{A}$

Given: $Z=3$, from $n=1$ to $n=3$
$\frac{1}{\lambda }=(1.097\times {10}^7){\left(3\right)}^2(1-\frac{1}{9})=8.776\times {10}^7{m}^{-1}$
Therefore, Wavelength required is $113.7\mathring{A}$