Principal quantum number is related to

Options

A. Size of the orbit
B. Spin angular momentum
C. Orbital angular momentum
D. Orientation of orbital in space

Answer

To solve the question regarding what the principal quantum number is related to, we can analyze the options provided step by step.

### Step 1: Understanding Principal Quantum Number
The principal quantum number, denoted as \( n \), is a key quantum number in atomic structure. It primarily indicates the energy level and size of the electron orbitals in an atom.

### Step 2: Analyzing the Options
1. **Size of the Orbit**: The principal quantum number \( n \) is directly related to the size of the electron orbitals. As \( n \) increases, the size of the orbitals increases, meaning electrons are found further from the nucleus.

2. **Spin Angular Momentum**: This is not related to the principal quantum number. Spin angular momentum is described by the spin quantum number \( s \).

3. **Orbital Angular Momentum**: This is determined by the azimuthal quantum number \( l \), not the principal quantum number \( n \).

4. **Orientation of Orbital in Space**: The orientation of orbitals is described by the magnetic quantum number \( m \), which is also not related to the principal quantum number.

### Conclusion
From the analysis, the only correct option is that the principal quantum number is related to the **size of the orbit**.

### Final Answer
The principal quantum number is related to the size of the orbit.

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