What will be the normality of a solution obtained by mixing 200ml of pure water to 100ml of 0.2N HCl solution?(A) 0.4N(B) 0.5N(C) 1.05N(D) 0.0667N

To find the normality (N) of the resulting solution after mixing pure water with an HCl solution, we need to consider the change in the number of equivalents of the acid in the solution. Normality is a measure of the concentration of reactive species in a solution, based on equivalents, which takes into account the chemical reaction occurring.

In this case, when you mix 100ml of 0.2N HCl solution with 200ml of pure water, there is no chemical reaction occurring. HCl dissociates into H⁺ and Cl⁻ ions in water, and there is no change in the number of equivalents for the HCl present in the solution.

The normality (N) is calculated using the formula:
N = (number of equivalents of solute) / (volume of solution in liters)

Since the number of equivalents of HCl remains the same before and after mixing, and the volume of the solution increases after mixing, the normality will decrease.

Initially, the number of equivalents of HCl is:
0.2N * 0.1L = 0.02 equivalents

After mixing, the total volume of the solution becomes 100ml + 200ml = 300ml = 0.3L.

So, the normality of the resulting solution will be:
N = (0.02 equivalents) / (0.3L) ≈ 0.0667N

The correct answer is (D) 0.0667N.