A : orbital angular momentum of(1s,2s,3s,etc) all s electrons is same
R : orbital angular momentum depends on orientation of orbitals .

Options

A. IF both assertion & reason are true and the reason is the correct explanation of the assertion then mark
B. IF both assertion & reason are true but the reason is not the correct explanation of the assertion , then mark
C. IF assertion is true statement but reason is false , then mark
D. If both assertion and reason are false statements then mark

Answer

To analyze the given statements regarding orbital angular momentum, let's break down the solution step by step.

### Step 1: Understand the Assertion (A)
The assertion states that the orbital angular momentum of all s electrons (1s, 2s, 3s, etc.) is the same.

- **Explanation**: The orbital angular momentum (L) is determined by the azimuthal quantum number (l). For s orbitals, the value of l is always 0 (i.e., l = 0 for 1s, 2s, 3s, etc.).

### Step 2: Calculate Orbital Angular Momentum
Using the formula for orbital angular momentum:
\[ L = \sqrt{l(l + 1)} \cdot \frac{h}{2\pi} \]
Substituting l = 0:
\[ L = \sqrt{0(0 + 1)} \cdot \frac{h}{2\pi} = \sqrt{0} \cdot \frac{h}{2\pi} = 0 \]

- **Conclusion**: The orbital angular momentum for all s electrons is indeed 0. Therefore, the assertion is **true**.

### Step 3: Understand the Reason (R)
The reason states that orbital angular momentum depends on the orientation of orbitals.

- **Explanation**: The orientation of orbitals is described by the magnetic quantum number (m). However, the formula for orbital angular momentum depends solely on the azimuthal quantum number (l), not on the orientation (which is related to m).

### Step 4: Determine the Truth of the Reason
Since the orbital angular momentum does not depend on the orientation of orbitals but rather on the azimuthal quantum number, the reason is **false**.

### Final Conclusion
- **Assertion (A)**: True
- **Reason (R)**: False

Thus, the correct option is that the assertion is true, but the reason is false.

---