Consider two covalent compounds `AL_(n_(1)) and BL_(n_(2))`, if central atom (A) of first compounds has total six electron pairs and central atom (B) of second compound contains total five electron pairs in its valence shell and both compounds are planar and non-polar then calculate value of experssion `(n_(1)-n_(2))^(2)`.
[Where `n_(1) and n_(2)` are number of monovalent surrounding atom (L)]

Explanation

To solve the problem, we need to determine the values of \( n_1 \) and \( n_2 \) for the two compounds \( AL_{n_1} \) and \( BL_{n_2} \) based on the given information about their central atoms and electron pairs.

### Step-by-Step Solution:

1. **Identify the Electron Pairs for Compound A**:
- The central atom \( A \) has a total of 6 electron pairs.
- This indicates that the hybridization of \( A \) is \( sp^3d^2 \) (which corresponds to an octahedral geometry).
- Since the compound is planar and non-polar, we can deduce that there are 4 surrounding monovalent atoms (L) in the equatorial plane and 2 lone pairs occupying the axial positions.

**Conclusion**:
\[ n_1 = 4 \]

2. **Identify the Electron Pairs for Compound B**:
- The central atom \( B \) has a total of 5 electron pairs.
- This indicates that the hybridization of \( B \) is \( sp^3d \) (which corresponds to a trigonal bipyramidal geometry).
- Since the compound is planar and non-polar, we can deduce that there are 3 surrounding monovalent atoms (L) in the equatorial plane and 2 lone pairs occupying the axial positions.

**Conclusion**:
\[ n_2 = 2 \]

3. **Calculate the Expression**:
- Now we need to calculate the expression \( (n_1 - n_2)^2 \).
- Substitute the values of \( n_1 \) and \( n_2 \):
\[ (n_1 - n_2)^2 = (4 - 2)^2 = 2^2 = 4 \]

### Final Answer:
\[ (n_1 - n_2)^2 = 4 \]