NEETChemistrySolutions
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): A 0.1 M aqueous solution of BaCl ₂ is isotonic with a 0.3 M aqueous solution of glucose at the same temperature (assuming complete dissociation of BaCl ₂ ). Reason (R): For any two isotonic solutions, their molar concentrations must always be equal. In the light of the above statements, choose the
Options
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A)
- BBoth (A) and (R) are correct but (R) is not the correct explanation of (A)
- C(A) is correct but (R) is not correct
- D(A) is not correct but (R) is correct
Correct answer
C. (A) is correct but (R) is not correct
Step-by-step solution
Isotonic solutions are those which have the same osmotic pressure at a given temperature. Osmotic pressure ( ) is given by = iCRT . For 0.1 M BaCl ₂ (assuming complete dissociation), i = 3 . ₁ = 3 0.1 RT = 0.3 RT For 0.3 M glucose (a non-electrolyte), i = 1 . ₂ = 1 0.3 RT = 0.3 RT Since ₁ = ₂ , the two solutions are indeed isotonic. Thus, Assertion (A) is correct. For two solutions to be isotonic, their effective particle concentrations ( i C ) must be equal. Their molar concentrations ( C ) do not need to be equal