Which of the following ie//are posssible ?

Options

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

Explanation

To determine which of the given subshells are possible, we need to analyze the subshells associated with each principal quantum number (n). The subshells are designated as s, p, d, and f, and they are available in specific shells based on the value of n.

### Step-by-Step Solution:

1. **Identify the Shells and Their Subshells**:
- For n = 1 (K shell): Only has the subshell **1s**.
- For n = 2 (L shell): Has the subshells **2s** and **2p**.
- For n = 3 (M shell): Has the subshells **3s**, **3p**, and **3d**.
- For n = 4 (N shell): Has the subshells **4s**, **4p**, **4d**, and **4f**.

2. **Evaluate Each Given Subshell**:
- **3f**: The third shell (n=3) does not have an f subshell. Therefore, **3f is not possible**.
- **4d**: The fourth shell (n=4) does have a d subshell. Therefore, **4d is possible**.
- **2d**: The second shell (n=2) does not have a d subshell. Therefore, **2d is not possible**.
- **3p**: The third shell (n=3) does have a p subshell. Therefore, **3p is possible**.

3. **Conclusion**:
- The possible subshells from the given options are **4d** and **3p**.
- The subshells **3f** and **2d** are not possible.

### Final Answer:
The possible subshells are **4d** and **3p**.

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