Chemistry Solutions PYQ series 2023

Question:

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason(R)

Assertion (A): Molar mass 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

In the light of the above statements . Choose the correct answer from the options given below:

(A) Both (A) and (R) are True but (R) is not the correct explanation of (A) (B) (A) is false but (R) is True.  (C) (A) is True but (R) is false (D) Both (A) and (R) are True and (R) is  the correct explanation of (A)

Answer:

Ans:-D The hydrated oxalic acid is represented as: \[ \text{H}_2\text{C}_2\text{O}_4 \cdot 2\text{H}_2\text{O} \] To calculate the molarity (M): \[ M = \frac{W \times 1000}{M \times V} \] where: - \(W = 12.6 \, \text{g}\) (mass of hydrated oxalic acid) - \(M = 126 \, \text{g/mol}\) (molar mass of hydrated oxalic acid) - \(V = 250 \, \text{mL}\) (volume of the solution) Substituting the values: \[ M = \frac{3.15 \times 1000}{126 \times 250} \] Simplifying further: \[ M = \frac{12.6}{126} = 0.1 \, \text{mol/L} \] The reason given is correct as it is used as a fact in the explanation of the assertion.

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