Which of the following angular momentum is not possible for electron in Bohr’s orbit?

Options

A. `0barh`
B. `bar h `
C. `2barh`
D. `3barh`

Explanation

To determine which angular momentum is not possible for an electron in Bohr's orbit, we can follow these steps:

### Step 1: Understand the formula for angular momentum in Bohr's model
In Bohr's model of the atom, the angular momentum (L) of an electron in orbit is quantized and is given by the formula:

\[ L = n \frac{h}{2\pi} \]

where:
- \( L \) is the angular momentum,
- \( n \) is the principal quantum number (which can take values 1, 2, 3, ...),
- \( h \) is Planck's constant.

### Step 2: Identify the possible values of \( n \)
The principal quantum number \( n \) can only take positive integer values (natural numbers). Therefore, the possible values of angular momentum can be expressed as:

\[ L = \frac{h}{2\pi}, \frac{2h}{2\pi}, \frac{3h}{2\pi}, \ldots \]

This means that the angular momentum can be \( \frac{h}{2\pi}, \frac{2h}{2\pi}, \frac{3h}{2\pi}, \) etc.

### Step 3: Determine which angular momentum is not possible
Since \( n \) can only be 1, 2, 3, ... (natural numbers), it cannot be 0. Therefore, the angular momentum corresponding to \( n = 0 \):

\[ L = 0 \]

is not possible for an electron in Bohr's orbit.

### Conclusion
The angular momentum that is not possible for an electron in Bohr's orbit is **0**.

### Final Answer
Thus, the answer is option A: **0**.

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