Assertion : Angular momentum of 1s, 2s, 3s, etc., is same.
Reason : 1s, 2s, 3s etc. , all have spherical shape.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Explanation

To solve the question, we need to analyze both the assertion and the reason provided.

### Step 1: Understand the Assertion
The assertion states that the angular momentum of the 1s, 2s, and 3s orbitals is the same. To evaluate this, we need to recall the formula for angular momentum in quantum mechanics:

\[ L = \sqrt{L(L + 1)} \cdot \frac{h}{2\pi} \]

### Step 2: Determine the Value of L for s Orbitals
For s orbitals (1s, 2s, 3s), the azimuthal quantum number \(L\) is always 0. This is because:
- For the 1s orbital, \(L = 0\)
- For the 2s orbital, \(L = 0\)
- For the 3s orbital, \(L = 0\)

### Step 3: Calculate Angular Momentum
Substituting \(L = 0\) into the angular momentum formula:

\[ L = \sqrt{0(0 + 1)} \cdot \frac{h}{2\pi} = \sqrt{0} \cdot \frac{h}{2\pi} = 0 \]

Thus, the angular momentum for 1s, 2s, and 3s orbitals is 0.

### Step 4: Conclusion on the Assertion
Since the angular momentum is 0 for all three orbitals, we conclude that the assertion is correct.

### Step 5: Analyze the Reason
The reason states that 1s, 2s, and 3s orbitals all have a spherical shape. This is true, as the s orbitals are indeed spherical in shape.

### Step 6: Evaluate the Relationship Between Assertion and Reason
While both the assertion and reason are correct, the reason does not explain why the angular momentum is the same. The angular momentum being zero is due to the value of \(L\) being zero, not solely because of the spherical shape of the orbitals.

### Final Conclusion
Both the assertion and reason are correct, but the reason does not adequately explain the assertion. Therefore, the correct option is B.

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