pH values of a few solutions are given :
Solution I : `2.2 - 2.4`
Solution II : `6.8`
Solution III : `7.4`
Solution IV : `10`
Solutions I, II, III and IV could be respectively

Options

A. Vinegar, hydrochloric acid, window cleaner and milk
B. Curd, Sodium hydroxide, milk of magnesia and coffee
C. Lemon juice, milk, human blood and milk of magnesia
D. None of these

Answer

To determine the nature of the solutions based on their pH values, we can categorize them as acidic, neutral, or basic. Let's analyze each solution step by step.

### Step 1: Identify the pH ranges
- **Solution I:** pH = 2.2 - 2.4
- **Solution II:** pH = 6.8
- **Solution III:** pH = 7.4
- **Solution IV:** pH = 10

### Step 2: Classify each solution based on pH
1. **Solution I (pH 2.2 - 2.4):**
- Since the pH is less than 7, this solution is acidic.
- Common acidic solutions include lemon juice or vinegar.
- We can identify this as **lemon juice**.

2. **Solution II (pH 6.8):**
- This pH is slightly below 7, indicating it is close to neutral but still acidic.
- The pH of milk is typically around 6.7 to 6.8.
- Therefore, we can identify this as **milk**.

3. **Solution III (pH 7.4):**
- A pH of 7.4 is slightly above neutral, indicating it is basic.
- The pH of blood is known to be around 7.4.
- Thus, this solution can be identified as **blood**.

4. **Solution IV (pH 10):**
- A pH of 10 indicates a basic solution.
- Common basic solutions include sodium hydroxide or milk of magnesia (magnesium hydroxide).
- Given the context, we can identify this as **milk of magnesia**.

### Summary of Identifications:
- **Solution I (2.2 - 2.4):** Lemon juice
- **Solution II (6.8):** Milk
- **Solution III (7.4):** Blood
- **Solution IV (10):** Milk of magnesia

### Final Answer:
- Solutions I, II, III, and IV could be respectively: **Lemon juice, Milk, Blood, Milk of magnesia.**

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