Question

If an electron in a hydrogen atom is in its $2^{nd}$ excited state, orbiting the nucleus in a stationary orbit of radius $4.65 \, \overset{^\circ }{A}$ , then its de-Broglie wavelength is

• A. $12.9\overset{^\circ }{A}$
• B. $3.5 \, \overset{^\circ }{A}$
• C. $9.7 \, \overset{^\circ }{A}$
• D. $6.6\overset{^\circ }{A}$

Answer 1

Answer: (C)

$2\pi r=n\lambda $
$\Rightarrow 2\pi =3\lambda $
$\lambda =9.7A$