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

Options

A. `2pih`
B. `5.25 xx 10^(6) m//s`
C. `(h)/(pi)`
D. `(2h)/(pi)`

Explanation

To find the moment of momentum (angular momentum) of an electron revolving in the second orbit of a hydrogen atom according to Bohr's theory, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Bohr's Postulates**: According to Bohr's theory, the angular momentum (L) of an electron in a circular orbit is quantized and given by the formula:
\[ L = n \frac{h}{2\pi} \]
where \( n \) is the principal quantum number (orbit number), and \( h \) is Planck's constant.

2. **Identify the Orbit**: We are interested in the second orbit of the hydrogen atom. For the second orbit, the principal quantum number \( n \) is equal to 2.

3. **Substitute the Value of n**: Plugging \( n = 2 \) into the formula for angular momentum:
\[ L = 2 \frac{h}{2\pi} \]

4. **Simplify the Expression**: Simplifying the expression gives:
\[ L = \frac{2h}{2\pi} = \frac{h}{\pi} \]

5. **Final Answer**: Therefore, the moment of momentum of an electron revolving in the second orbit of a hydrogen atom is:
\[ L = \frac{h}{\pi} \]