Match the following

Column-1 Acid		Column-2 $\mathrm{pKa}$ value
A)	${\mathrm{CH}}_3\mathrm{COOH}$	I)	$0.23$
B)	${\mathrm{F}}_3\mathrm{CCOOH}$	II)	$3.41$
C)		III)	$4.19$
D)		IV)	$4.76$

The correct match is

The acidity of carboxylic acid is directly proportional to the acid dissociation constant. But it is inversely proportional to the ${\mathrm{pK}}_{\mathrm{a}}$ value because the ${\mathrm{pK}}_{\mathrm{a}}$ is equal to the $-{\mathrm{logK}}_{\mathrm{a}}$. So, the order of acidity of given acids depends upon the $-\mathrm{M},-\mathrm{I}$ effect. It is directly proportional to the $-\mathrm{M},-\mathrm{I}$ effect. 

The acetic acid is least acidic. So, it has the ${\mathrm{pK}}_{\mathrm{a}}$ value of $4.76$. After that acidity of benzoic acid. So, it has the ${\mathrm{pK}}_{\mathrm{a}}$ value of $4.19$. After that acidity of $\mathrm{p}-$nitrobenzoic acid. So, it has the ${\mathrm{pK}}_{\mathrm{a}}$ value of $3.41$. The compound ${\mathrm{F}}_3\mathrm{CCOOH}$ is most acidic. So, it has the ${\mathrm{pK}}_{\mathrm{a}}$ value of $0.23$.