Question

The depression in freezing point of water observed for the same amount of acetic acid (I), trichloroacetic acid (II) and trichloroacetic acid (III) decreases in the order

• A. I > II > III
• B. II > I > III
• C. III > I > II
• D. III > II > I

Answer 1

Answer: (D)

Depression in freezing point is a colligative property i. e., depends upon the number of ions present in the solution
Further, more the number the electron, withdrawing groups (-$I$ showing groups like $-F>-Cl>$ etc.) more is the tendency of acid to get ionise, thus, more is the number of ions and hence, depression in freezing point
Thus, the order of depression in freezing point in case of given carboxylic acids is
$\underset{(III)}{\text{trifluoroacetic acid }}>\underset{(II)}{\text{ trichloroacetic acid}}>$ acetic acid