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 FeCl ₃ has a higher boiling point than a 0.1 M aqueous solution of CaCl ₂ . Reason (R): The boiling point of an aqueous solution is inversely proportional to the van 't Hoff factor of the solute. In the light of the above statements, choose the most appropriate answer fr
Options
- ABoth Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- BBoth Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- CAssertion (A) is false but Reason (R) is true.
- DAssertion (A) is true but Reason (R) is false.
Correct answer
D. Assertion (A) is true but Reason (R) is false.
Step-by-step solution
Assertion (A) is true: For dilute solutions, T _ b = i K _ b m . Assuming m M , the effective concentration is i M . For FeCl ₃ , i = 4 , so the effective concentration is 4 0.1 = 0.4 M . For CaCl ₂ , i = 3 , so the effective concentration is 3 0.1 = 0.3 M . Since FeCl ₃ produces a higher effective concentration of particles, it has a greater boiling point elevation and thus a higher boiling point. Reason (R) is false: The elevation in boiling point ( T _ b ) is directly proportional to the van 't Hoff factor ( i )