Principal quantum number of an atom represents :

Options

A. Size of the orbital
B. Spin angular momentum
C. Orbital angular momentum
D. Space orientation of the orbital

Answer

To answer the question "Principal quantum number of an atom represents:", we can break down the explanation into a step-by-step solution.

### Step-by-Step Solution:

1. **Definition of Principal Quantum Number**:
The principal quantum number is denoted by the symbol 'n'. It is a fundamental quantum number in quantum mechanics that describes the energy levels of electrons in an atom.

2. **Indication of Energy Levels**:
The principal quantum number indicates the energy levels of electrons. As 'n' increases, the energy level of the electron also increases. For example, n=1 corresponds to the first energy level, n=2 to the second, and so on.

3. **Relative Distance from the Nucleus**:
The principal quantum number also represents the relative distance of the electron from the nucleus. Higher values of 'n' mean that the electron is located further away from the nucleus.

4. **Size of the Orbital**:
The principal quantum number can be interpreted as denoting the size of the orbital. For instance, the 1s orbital (n=1) is smaller than the 2s orbital (n=2). Therefore, as 'n' increases, the size of the orbital increases.

5. **Conclusion**:
In summary, the principal quantum number represents the energy level, the relative distance from the nucleus, and the size of the orbital of an electron in an atom.

### Final Answer:
The principal quantum number of an atom represents the energy level, relative distance from the nucleus, and size of the orbital.

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