How many spherical nodal surfaces are there in 4s – sub-shell?

Answer

To determine the number of spherical nodal surfaces in the 4s subshell, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Principal Quantum Number (n)**:
The principal quantum number (n) indicates the shell level of the electron. For the 4s subshell, n = 4.

2. **Use the Formula for Nodal Surfaces**:
The number of spherical nodal surfaces in an ns orbital is given by the formula:
\[ \text{Number of nodal surfaces} = n - 1 \]

3. **Substitute the Value of n**:
Plugging in the value of n for the 4s subshell:
\[ \text{Number of nodal surfaces} = 4 - 1 \]

4. **Calculate the Result**:
Performing the calculation:
\[ 4 - 1 = 3 \]

5. **Conclusion**:
Therefore, the number of spherical nodal surfaces in the 4s subshell is 3.

### Final Answer:
The number of spherical nodal surfaces in the 4s subshell is **3**.