Size of neucleus increases from protium to tritium so in `H_(2),D_(2)&T_(2)` area off overlapping also increases in the same order.
Q. Which overlapping is responsible for bond formation in `H_(2),D_(2),T_(2)` respectively?

Options

A. 1s-1s in each
B. 2s-2s in each
C. 1s-2s in each
D. 1s-2s I `T_(2)`, 1s-1s in rest

Answer

To solve the question regarding the overlapping responsible for bond formation in H₂ (protium), D₂ (deuterium), and T₂ (tritium), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Isotopes**:
- Protium (H) has 1 proton and 0 neutrons.
- Deuterium (D) has 1 proton and 1 neutron.
- Tritium (T) has 1 proton and 2 neutrons.

2. **Understand the Concept of Overlapping**:
- The bond formation in diatomic molecules like H₂, D₂, and T₂ involves the overlapping of atomic orbitals. In hydrogen isotopes, the relevant atomic orbital is the 1s orbital.

3. **Determine the Electronic Configuration**:
- All three isotopes (H, D, T) have the same electronic configuration: 1s¹. This means they each have one electron in the 1s orbital.

4. **Analyze the Overlapping**:
- Since the bond formation depends on the electrons in the outermost shell, and all isotopes have one electron in the 1s orbital, the overlapping responsible for bond formation in all three isotopes will be the same.
- The overlapping that occurs when two 1s orbitals come together is called 1s-1s overlapping.

5. **Conclusion**:
- Therefore, the overlapping responsible for bond formation in H₂, D₂, and T₂ is 1s-1s overlapping.

### Final Answer:
The overlapping responsible for bond formation in H₂, D₂, and T₂ is **1s-1s** overlapping.

---