`{:(,"Column I",,"Column II"),((A),Bi^(3+) rarr (BiO)^(+),(p),"Heat"),((B),[AlO_(2)]^(-) rarr Al(OH)_(3),(q),"Hydrolysis"),((C ),SiO_(4)^(4-) rarr Si_(2)O_(7)^(6-),(r ),"Acidification"),((D),(B_(4)O_(7))^(2-)rarr [B(OH)_(3)],(s),"Dilution by water"):}`

Explanation

To solve the question, we need to match the reactions in Column I with the corresponding processes in Column II. Let's analyze each reaction step by step.

### Step 1: Analyze Reaction A
**Reaction:** \( \text{Bi}^{3+} \rightarrow \text{BiO}^{+} \)

**Process:** Hydrolysis

**Explanation:** The reaction involves the hydrolysis of bismuth ions (\( \text{Bi}^{3+} \)). When \( \text{Bi}^{3+} \) reacts with water, it forms \( \text{BiO}^{+} \) and releases \( \text{H}^{+} \) ions.

**Conclusion:**
- A matches with (q) Hydrolysis.

### Step 2: Analyze Reaction B
**Reaction:** \( \text{[AlO}_{2]}^{-} \rightarrow \text{Al(OH)}_{3} \)

**Process:** Dilution by water

**Explanation:** The reaction involves the conversion of aluminate ions (\( \text{[AlO}_{2]}^{-} \)) to aluminum hydroxide (\( \text{Al(OH)}_{3} \)). This process requires the addition of water, which leads to the formation of aluminum hydroxide.

**Conclusion:**
- B matches with (s) Dilution by water.

### Step 3: Analyze Reaction C
**Reaction:** \( \text{SiO}_{4}^{4-} \rightarrow \text{Si}_{2}\text{O}_{7}^{6-} \)

**Process:** Acidification

**Explanation:** The reaction involves the combination of silicate ions (\( \text{SiO}_{4}^{4-} \)) to form disilicate ions (\( \text{Si}_{2}\text{O}_{7}^{6-} \)). This process typically requires acidification, which can be achieved by adding an acid to the solution.

**Conclusion:**
- C matches with (r) Acidification.

### Step 4: Analyze Reaction D
**Reaction:** \( \text{(B}_{4}\text{O}_{7})^{2-} \rightarrow \text{[B(OH)}_{3]} \)

**Process:** Hydrolysis

**Explanation:** The reaction involves the hydrolysis of tetraborate ions (\( \text{(B}_{4}\text{O}_{7})^{2-} \)) to form boric acid (\( \text{[B(OH)}_{3]} \)). This process is also a type of hydrolysis.

**Conclusion:**
- D matches with (q) Hydrolysis.

### Final Matching:
- A → q (Hydrolysis)
- B → s (Dilution by water)
- C → r (Acidification)
- D → p (Heat)

### Summary of Answers:
- A: q
- B: s
- C: r
- D: p