A solution of known normality is diluted to two times. Which of the following changes during dilution ?

Options

A. Equivalent of solute
B. Moles of solute
C. Milli equivalent or milli moles of solute
D. Normality of solute

Answer

To solve the question regarding the changes that occur when a solution of known normality is diluted to two times its original volume, we can follow these steps:

### Step 1: Understand the Concept of Normality
Normality (N) is defined as the number of equivalents of solute per liter of solution. It can be expressed mathematically as:
\[ \text{Normality (N)} = \frac{\text{Number of equivalents}}{\text{Volume of solution in liters}} \]

### Step 2: Analyze the Dilution Process
When a solution is diluted, the amount of solute (in equivalents) remains constant, but the volume of the solution increases. For example, if we have a solution with a certain normality and we dilute it to twice its original volume, the volume in the formula for normality will increase.

### Step 3: Apply the Dilution Concept
Let’s denote:
- \( N_1 \) = initial normality
- \( V_1 \) = initial volume
- \( N_2 \) = final normality after dilution
- \( V_2 = 2V_1 \) = final volume after dilution

Since the number of equivalents remains constant during dilution, we can set up the equation:
\[ N_1 \times V_1 = N_2 \times V_2 \]
Substituting \( V_2 \):
\[ N_1 \times V_1 = N_2 \times (2V_1) \]

### Step 4: Solve for Final Normality
From the equation, we can simplify:
\[ N_2 = \frac{N_1 \times V_1}{2V_1} \]
This simplifies to:
\[ N_2 = \frac{N_1}{2} \]
This shows that the final normality \( N_2 \) is half of the initial normality \( N_1 \).

### Step 5: Conclusion
Thus, the only quantity that changes during the dilution of the solution is the normality. The normality decreases as the solution is diluted.

### Final Answer
The correct answer to the question is that the **normality of the solution changes during dilution**.

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