According to Bohr's theory, the angular momentum of an electron revolving in the second orbit of the hydrogen atom will be

$\frac{h}{\pi}$

The correct answer is Option (4) → $\frac{h}{\pi}$

Given:

For Bohr’s model, angular momentum is quantized as

$L = n \frac{h}{2\pi}$

For second orbit (n = 2):

$L = 2 \frac{h}{2\pi} = \frac{h}{\pi}$

∴ The angular momentum of the electron in the second orbit is $\frac{h}{\pi}$.