`{:(,"Column I",,"Column II"),((A),B_(2)H_(6),(p),"Borax"),((B),BF_(3),(q),"Lewis acid"),((C ),AlCl_(3),(r ),ppi-ppi " back bonding "),((D),H_(3)BO_(3),(s),NaBH_(4)):}`

Answer

To solve the matching question between Column I and Column II, we will analyze each compound in Column I and identify its corresponding property or classification in Column II.

### Step-by-Step Solution:

1. **Identify A: B₂H₆**
- B₂H₆, also known as diborane, is a compound of boron and hydrogen. It is often associated with the formation of borax (Na₂B₄O₇·10H₂O) in various chemical reactions.
- **Match:** A → S (Borax)

2. **Identify B: BF₃**
- BF₃ (Boron trifluoride) is a well-known Lewis acid. It can accept an electron pair due to the empty p-orbital of boron, which allows it to act as an electron pair acceptor.
- **Match:** B → Q (Lewis acid)

3. **Identify C: AlCl₃**
- AlCl₃ (Aluminum chloride) is also a Lewis acid. It has an empty d-orbital that allows it to accept electrons easily, making it a strong Lewis acid.
- **Match:** C → Q (Lewis acid)

4. **Identify D: H₃BO₃**
- H₃BO₃ (Boric acid) is often referred to as boric acid and is commonly associated with the term "borax" in certain contexts. However, in this case, it is more appropriate to classify it as a compound that exhibits pπ-pπ back bonding due to the presence of p-orbitals in boron and oxygen.
- **Match:** D → P (pπ-pπ back bonding)

### Final Matches:
- A → S (Borax)
- B → R (Lewis acid)
- C → Q (Lewis acid)
- D → P (pπ-pπ back bonding)