Explanation:
monochloroacetic acid also means: chloroacetic acid
pKa of monochloroacetic acid= 1.4 x 10^-3 (I believe this should have been given in the problem or perhaps in the textbook)
Formula: pH= pKa + log ( some number in M)
pH= -log (1.4 x 10^-3) + log (0.25M)= 2.85 + -0.602= 2.25
pH= 2.25