The radial distribution curve of ` 2s` sub-level consists of `x` nodes. Value of `x` is :

Explanation

To determine the number of nodes in the radial distribution curve of the 2s sub-level, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definitions**:
- **Nodes** are points where the probability density of finding an electron is zero. There are two types of nodes: angular nodes and radial nodes.
- The total number of nodes in an atomic orbital is given by the formula:
\[ \text{Total Nodes} = n - 1 \]
- The number of angular nodes is given by \( L \).
- The number of radial nodes is given by:
\[ \text{Radial Nodes} = n - 1 - L \]

2. **Identify Quantum Numbers for 2s**:
- For the 2s sub-level:
- The principal quantum number \( n = 2 \).
- The azimuthal quantum number \( L = 0 \) (since 's' orbitals have \( L = 0 \)).

3. **Calculate Total Nodes**:
- Using the formula for total nodes:
\[ \text{Total Nodes} = n - 1 = 2 - 1 = 1 \]

4. **Calculate Angular Nodes**:
- Since \( L = 0 \):
\[ \text{Angular Nodes} = L = 0 \]

5. **Calculate Radial Nodes**:
- Using the formula for radial nodes:
\[ \text{Radial Nodes} = n - 1 - L = 2 - 1 - 0 = 1 \]

6. **Conclusion**:
- The number of radial nodes for the 2s sub-level is 1. Therefore, the value of \( x \) is:
\[ x = 1 \]

### Final Answer:
The value of \( x \) is 1.

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