Which of the following orbitals does not make sense ?

Options

A. 6s
B. 3p
C. 2d
D. 4f

Answer

To determine which of the given orbitals does not make sense, we need to analyze the quantum numbers associated with each orbital. The principal quantum number (n) and the azimuthal quantum number (l) will help us identify the validity of each orbital.

### Step-by-Step Solution:

1. **Understanding Quantum Numbers**:
- The principal quantum number (n) indicates the energy level of the electron and can take positive integer values (1, 2, 3, ...).
- The azimuthal quantum number (l) defines the shape of the orbital and can take values from 0 to (n-1).

2. **Evaluating the Orbitals**:
- **6s**:
- Here, n = 6.
- The possible values for l are 0 to (6-1), which means l can be 0, 1, 2, 3, 4, or 5.
- Since l = 0 corresponds to the s orbital, **6s is valid**.

- **3p**:
- Here, n = 3.
- The possible values for l are 0 to (3-1), which means l can be 0, 1, or 2.
- Since l = 1 corresponds to the p orbital, **3p is valid**.

- **2d**:
- Here, n = 2.
- The possible values for l are 0 to (2-1), which means l can be 0 or 1.
- The d orbital corresponds to l = 2, which is not possible for n = 2. Therefore, **2d is not valid**.

- **4f**:
- Here, n = 4.
- The possible values for l are 0 to (4-1), which means l can be 0, 1, 2, or 3.
- The f orbital corresponds to l = 3, which is valid for n = 4. Thus, **4f is valid**.

3. **Conclusion**:
- The only orbital that does not make sense is **2d** since it violates the rule that l must be less than n.

### Final Answer:
The orbital that does not make sense is **2d**.

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