JEE Main 2023 — Some Basic Concepts Of Chemistry Question with Solution

Firstly, let's calculate the molarity of the oxalic acid solution given in the Assertion (A).

The molarity (M) is defined as the number of moles of solute per liter of solution. The number of moles of solute is given by the mass of the solute divided by its molar mass.

So, the number of moles of hydrated oxalic acid is $$\frac{3.1500\text{g}}{126\text{g/mol}}=0.025\text{mol}$$

And the volume of the solution is 250.0 mL, or 0.250 L.

Therefore, the molarity of the solution is $$\frac{0.025\text{mol}}{0.250\text{L}}=0.1\text{M}$$

This matches the molarity given in the Assertion (A), so the Assertion is true.

The Reason (R) gives the molar mass of hydrated oxalic acid as 126 g/mol, which was used in the calculation above. Therefore, the Reason is also true.

Moreover, the Reason (R) is the correct explanation of Assertion (A), as it provides the necessary information (the molar mass of hydrated oxalic acid) to calculate the molarity of the solution.

So, the correct option is C: Both A and R are true and R is the correct explanation of A.