On freezing dilute aq. NaCl which crystallise out first

Options

A. Both together
B. Water
C. NaCl
D. (NaOH+HCl)

Answer

To solve the question of which component crystallizes first when freezing a dilute aqueous NaCl solution, we can follow these steps:

### Step 1: Understand the Components
In a dilute aqueous NaCl solution, we have two main components: water (H₂O) and sodium chloride (NaCl).

### Step 2: Identify Freezing Points
Next, we need to know the freezing points of both components:
- The freezing point of pure water is 0°C.
- The freezing point of NaCl is approximately -5.58°C.

### Step 3: Analyze the Freezing Process
When we lower the temperature of the solution, the component with the higher freezing point will freeze first. Since the freezing point of water (0°C) is higher than that of NaCl (-5.58°C), water will freeze before NaCl.

### Step 4: Conclusion
Therefore, when we freeze the dilute aqueous NaCl solution, water will crystallize out first.

### Final Answer
The answer is: **Water (Option B)** will crystallize out first.

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