Question

Based on the equation, $E=-2.0\times {10}^{-18}\frac{Z^2}{n^2}J$, the wavelength of the light that must be absorbed to excite hydrogen electron from level $n=1$ to level $n=2$ will be: $(h=6.625\times {10}^{-34}Js,C=3\times {10}^{4}m{s}^{-1})$

• A. $1.2\times {10}^{-7}m$
• B. $1.325\times {10}^{-7}m$
• C. $5.300\times {10}^{-10}m$
• D. $1.325\times {10}^{-10}m$

Answer 1

The correct option is A $1.2\times {10}^{-7}m$

Applying the formula-

$\frac{1}{\lambda }=R{Z}^2\frac{1}{n_1^2}-\frac{1}{n_2^2}$

$\frac{1}{\lambda }=R{Z}^2\frac{1}{1}-\frac{1}{4}$

$\lambda =\frac{4\times 912}{3}{A}^o\approx 1.2\times {10}^{-7}m$