Which of the following statements is not true ?

Options

A. Ionic bonds are non- directional while covalent bonds are directional.
B. Formation of `pi` - bond shortens the distance between the two concerned atoms.
C. Ionic bond is possible between similar and dissimilar atoms.
D. Linear overlapping of atomic p- orbitals leads to a sigma bond.

Explanation

To determine which statement is not true among the given options, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement Analysis:**
- **Statement 1:** "Ionic bonds are non-directional while covalent bonds are directional."
- **Analysis:** This statement is true. Ionic bonds, such as in NaCl, do not have a specific direction due to the electrostatic attraction between ions. In contrast, covalent bonds involve the sharing of electrons between specific atoms, making them directional.

2. **Statement 2:** "Formation of pi bond shortens the distance between the two concerned atoms."
- **Analysis:** This statement is also true. When a pi bond is formed between two atoms, it contributes to the overall bond strength, which results in a decrease in the distance between the bonded atoms.

3. **Statement 3:** "Ionic bond is possible between similar and dissimilar atoms."
- **Analysis:** This statement is not true. Ionic bonds typically form between dissimilar atoms, specifically between metals (which lose electrons and become positively charged) and nonmetals (which gain electrons and become negatively charged). Similar atoms would not form ionic bonds as they would not have the necessary charge difference.

4. **Statement 4:** "Linear overlapping of atomic p-orbitals leads to sigma bond."
- **Analysis:** This statement is true. Sigma bonds are formed by the head-on overlap of atomic orbitals, including p-orbitals. Linear overlapping of p-orbitals can indeed lead to the formation of a sigma bond.

### Conclusion:
Based on the analysis, the statement that is not true is **Statement 3:** "Ionic bond is possible between similar and dissimilar atoms."