Question

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R:
Assertion A: 3.1500 g of hydrated oxalic acid dissolved in water to make 250.0 mL solution will result in 0.1 M oxalic acid solution.
Reason R: Molar mass of hydrated oxalic acid is 126 g mol^–1.
In the light of the above statements, choose the correct answer from the options given below.

• A. A is false but R is true
• B. Both A and R are true but R is NOT the correct explanation of A
• C. Both A and R are true and R is the correct explanation of A
• D. A is true but R is false

Answer 1

The Correct Option is C

Step 1: Verifying the Assertion A 
Given mass of hydrated oxalic acid = 3.1500 g 
Molar mass of hydrated oxalic acid = 126 g/mol 
Volume of solution = 250.0 mL = 0.250 L 
To calculate molarity (M), we use the formula: \[ M = \frac{\text{moles of solute}}{\text{volume of solution in liters}} \] Moles of solute: \[ \text{moles} = \frac{3.1500 \, \text{g}}{126 \, \text{g/mol}} = 0.0250 \, \text{mol} \] Thus, molarity: \[ M = \frac{0.0250 \, \text{mol}}{0.250 \, \text{L}} = 0.1 \, \text{M} \] So, Assertion A is correct. 
Step 2: Verifying the Reason R 
The molar mass of hydrated oxalic acid is indeed 126 g/mol, as given in the question. This confirms that Reason R is correct.
Thus, both Assertion A and Reason R are true, and Reason R explains Assertion A.