Assertion : An orbital cannot have more than two electrons, moreover, if an orbital has two electrons they must have opposite spins.
Reason : No two electrons in an atom can have same set of all the four quantum numbers.

Options

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

Answer

To solve the assertion and reason question, we will break down the statements and analyze them step by step.

### Step 1: Analyze the Assertion
The assertion states: "An orbital cannot have more than two electrons; moreover, if an orbital has two electrons, they must have opposite spins."

- According to the **Pauli Exclusion Principle**, no two electrons can occupy the same quantum state within an atom. This means that an orbital, which can be defined by a set of quantum numbers, can hold a maximum of two electrons.
- Furthermore, if there are two electrons in the same orbital, they must have opposite spins. This is because the spin quantum number for electrons can either be +1/2 or -1/2. Therefore, to comply with the Pauli Exclusion Principle, if one electron has a spin of +1/2, the other must have a spin of -1/2.

### Step 2: Analyze the Reason
The reason states: "No two electrons in an atom can have the same set of all four quantum numbers."

- This statement is also a direct consequence of the **Pauli Exclusion Principle**. Each electron in an atom is described by four quantum numbers:
1. Principal quantum number (n)
2. Azimuthal quantum number (l)
3. Magnetic quantum number (m)
4. Spin quantum number (s)

- If two electrons were to have the same set of all four quantum numbers, they would be indistinguishable and would violate the Pauli Exclusion Principle. Therefore, at least one of the quantum numbers must differ between any two electrons in the same atom.

### Step 3: Conclusion
Both the assertion and the reason are true statements, and the reason correctly explains the assertion. Therefore, we can conclude that:

- **Assertion**: True
- **Reason**: True
- **Relationship**: The reason is the correct explanation of the assertion.

### Final Answer
Both the assertion and the reason are true, and the reason is the correct explanation of the assertion.

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