Correct order of extent of overlapping is :-

Options

A. `2s-2s gt 2p-2p gt 2s-2p`
B. `1s-1s gt 2p-2p gt 2s-2p`
C. `1s-1s lt 2s-2s lt 3s-3s`
D. `3s-3s gt 3s-3p gt 3p-3p`

Answer

To determine the correct order of the extent of overlapping of various orbitals, we need to analyze the shapes and sizes of the orbitals involved. The extent of overlap is influenced by the size of the orbitals, which is determined by the principal quantum number (n).

### Step-by-Step Solution:

1. **Identify the Orbitals**: The orbitals mentioned are 1s, 2s, 2p, and 3s. We will analyze their sizes and shapes.

2. **Understand Orbital Sizes**:
- The size of orbitals increases with the principal quantum number (n).
- 1s is the smallest, followed by 2s, then 2p, and finally 3s, which is the largest.

3. **Determine Overlapping Characteristics**:
- **1s-1s Overlap**: The 1s orbitals are spherical and can overlap effectively with another 1s orbital, leading to a high extent of overlap.
- **2p-2p Overlap**: The 2p orbitals have a dumbbell shape and can overlap head-on, which also allows for a significant extent of overlap.
- **2s-2p Overlap**: The 2s orbital is spherical, while the 2p is dumbbell-shaped. The overlap here is less effective compared to 1s-1s or 2p-2p overlaps.
- **3s Overlap**: The 3s orbital is larger and less effective in overlapping with other orbitals compared to the smaller orbitals.

4. **Rank the Extent of Overlap**:
- The maximum overlap occurs with 1s-1s.
- Next is 2p-2p due to effective head-on overlap.
- Following that is 2s-2p, which has less overlap than the previous two.
- The least overlap occurs with 3s, as it is larger and less effective in overlapping.

5. **Conclusion**: Based on the analysis, the correct order of extent of overlapping from maximum to minimum is:
- 1s-1s > 2p-2p > 2s-2p > 3s.

### Final Answer:
The correct order of extent of overlapping is: **1s-1s > 2p-2p > 2s-2p > 3s**.