Which of the following orbital does not make sense ?

Options

A. 3d
B. 3f
C. 5p
D. 7s

Explanation

To determine which of the given orbitals does not make sense, we need to analyze each orbital based on the principles of quantum mechanics, specifically the relationships between the principal quantum number (n) and the azimuthal quantum number (l).

### Step-by-Step Solution:

1. **Understanding Quantum Numbers**:
- The principal quantum number (n) can take positive integer values: 1, 2, 3, 4, etc.
- The azimuthal quantum number (l) can take values from 0 to (n-1).
- Each value of l corresponds to a specific type of orbital:
- l = 0 corresponds to s orbitals
- l = 1 corresponds to p orbitals
- l = 2 corresponds to d orbitals
- l = 3 corresponds to f orbitals
- l = 4 corresponds to g orbitals, and so on.

2. **Analyzing Each Orbital**:
- **3d**:
- Here, n = 3. The possible values for l are 0, 1, or 2.
- Since l = 2 corresponds to d orbitals, 3d is valid.

- **3f**:
- Here, n = 3. The possible values for l are still 0, 1, or 2.
- However, l = 3 corresponds to f orbitals, which is not possible when n = 3 (since l must be less than n).
- Therefore, 3f does not make sense.

- **5p**:
- Here, n = 5. The possible values for l are 0, 1, 2, 3, or 4.
- Since l = 1 corresponds to p orbitals, 5p is valid.

- **7s**:
- Here, n = 7. The possible values for l are 0, 1, 2, 3, 4, 5, or 6.
- Since l = 0 corresponds to s orbitals, 7s is valid.

3. **Conclusion**:
- The only orbital that does not make sense based on the quantum number rules is **3f**.

### Final Answer:
**3f does not make sense.**

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