NTA Abhyas JEE Main2020ChemistrySolutionsPractice
1 g of a monobasic acid (HA) in 100 g water lowers the freezing point by 0.1 K. If 0.75 g of same acid requires 15 ml of 1 5 N NaOH solution for complete neutralization, then % degree of ionization of acid in water is K f of H 2 O = 1 .86 K kg mol - 1
Options
- A0.22
- B0.25
- C0.34
- D0.50
Correct answer
C. 0.34
Step-by-step solution
Normal molecular weight of acid can be found as Meq of acid = Meq of NaOH N 1 V 1 = N 2 V 2 ; N 1 V 1 = M 2 V 2 0 .75 M acid × 1000 = 15 × 1 5 ; M acid = 250 Observed molecular weight of acid can be formed as ∆ T f = K f W acid M acid × 1000 W solvent × i ; 0 .1 = 1 .86 × 1 250 × 1000 100 × 1 + α 1 .34 = 1 + α α = 0 .34