`{:("Column I","Column II"),((A)"Yellow ppt of "PbCrO_4,(p)"Blue or green colour to flame"),((B)"Sodium nitroprusside",(q)"Brown ring test"),(( C)"Nitrate ion",(r)"Chromyl chloride test"),((D)Cu"salt and "BO_3^(-3) "ion",(s)"Voilet colour with"Na_2S):}`

Explanation

To solve the question, we need to match the items in Column I with their corresponding properties in Column II. Let's analyze each option step by step.

### Step 1: Analyze Option A - Yellow ppt of PbCrO₄
- **Lead Chromate (PbCrO₄)** is known for forming a yellow precipitate.
- This yellow precipitate is formed during the **Chromyl Chloride Test**.
- Therefore, we can match:
- **A → r** (Chromyl chloride test)

### Step 2: Analyze Option B - Sodium Nitroprusside
- **Sodium Nitroprusside** is used to detect the presence of **sulphur** ions.
- When it reacts with sulphide ions (S²⁻), it produces a **violet color**.
- Therefore, we can match:
- **B → s** (Violet colour with Na₂S)

### Step 3: Analyze Option C - Nitrate Ion
- The **Brown Ring Test** is specifically used for the detection of **nitrate ions**.
- In this test, a brown ring is formed when nitrate reacts with iron(II) sulfate and concentrated sulfuric acid.
- Therefore, we can match:
- **C → q** (Brown ring test)

### Step 4: Analyze Option D - Cu salt and BO₃³⁻ ion
- **Copper salts** and **borate ions (BO₃³⁻)** both impart a **blue or green color to the flame** when heated.
- Therefore, we can match:
- **D → p** (Blue or green colour to flame)

### Final Matches:
- A → r (Chromyl chloride test)
- B → s (Violet colour with Na₂S)
- C → q (Brown ring test)
- D → p (Blue or green colour to flame)

### Summary of Matches:
- (A, r)
- (B, s)
- (C, q)
- (D, p)