Few statements are given regarding nodes in the orbitals. Mark the statement which is not correct.

Options

A. In case of `p_(z)`-orbital, xy plane is a nodal plane.
B. ns - orbital has (n + 1) nodes.
C. The number of angular nodes is given by l.
D. The total number of nodes is given by (n - 1) i.e. sum of l angular nodes and (n - l - 1) radial nodes.

Explanation

To determine which statement regarding nodes in orbitals is incorrect, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Understanding Nodes in Orbitals:**
- Nodes are regions in an orbital where the probability of finding an electron is zero. There are two types of nodes: radial nodes and angular nodes.

2. **Analyzing the First Statement:**
- **Statement:** "In case of Pz orbital, the xy plane is a nodal plane."
- **Analysis:** The Pz orbital has nodal planes that are perpendicular to the z-axis, which includes the xy plane. Therefore, this statement is **correct**.

3. **Analyzing the Second Statement:**
- **Statement:** "ns orbital has n + 1 nodes."
- **Analysis:** The number of nodes in an ns orbital is calculated using the formula:
\[ \text{Total Nodes} = n - 1 \]
For an ns orbital, the number of nodes is \(n - 1\), not \(n + 1\). Thus, this statement is **incorrect**.

4. **Analyzing the Third Statement:**
- **Statement:** "The number of angular nodes is given by L."
- **Analysis:** The azimuthal quantum number \(L\) indeed represents the number of angular nodes. Therefore, this statement is **correct**.

5. **Analyzing the Fourth Statement:**
- **Statement:** "The total number of nodes is given by n - 1, which is the sum of angular nodes and radial nodes."
- **Analysis:** The total number of nodes is indeed \(n - 1\), which is the sum of angular nodes (L) and radial nodes (n - l - 1). Therefore, this statement is **correct**.

### Conclusion:
After analyzing all statements, we find that the incorrect statement is:
- **"ns orbital has n + 1 nodes."**

### Final Answer:
The incorrect statement is: **"ns orbital has n + 1 nodes."**

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