Calculate Ka for each of the following acids, given its pKa. Rank the compounds in order of

Question:

Calculate Ka for each of the following acids, given its pKa. Rank the compounds in order of decreasing acidity.
(a) Aspirin: pKa = 3.48
(b) Vitamin C (ascorbic acid): pKa = 4.17
(c) Formic acid (present in sting of ants): pKa = 3.75
(d) Oxalic acid (poisonous substance found in certain berries): pKa = 1.19