The depression in freezing point of water observed for the same amount of acetic acid, dichloroacetic acid and trichloro acetic acid increases in the order given above. Explain briefly.

As we move from CH₃COOH to CCl₃COOH, the degree of dissociation ($\mathrm{\alpha }$ ) increases. So no. of particles increases. As no.of the particles increases depression in freezing point also increases.
Order of acidic strength :
${\mathrm{CH}}_3\mathrm{COOH}<{\mathrm{CH}}_2\mathrm{ClCOOH}<{\mathrm{CHCl}}_2\mathrm{COOH}<{\mathrm{CCl}}_3\mathrm{COOH}$