Can you look up the Ka for each acid? If so won't that tell you which is stronger? or are you supposed to do it some other way?
i cant find a Ka chart that includes all those, and also, i wasn't even any numbers whatsoever to work with!
Here is a site that explains acid strengths. It's a good bit of material to wade through BUT all of the possibilities are there. In this case, scroll down about 2/3 of the way to strenghts of oxy acid and a little further they talk about carboxylic acids. All of the acids you list are carboxylic acids. Then a paragraph or two later they talk about the effect of adding highly electronegative atoms (in this case Cl) and the effect on acidity. If you need more help just say the word. But I would go with CH3COOH, HCOOH, Cl......, and Cl2...... from weakest to strongest. I presume you are to use this kind of reasoning and not use Ka. However, if you wish I can look up the Ka for the acids. I know HCOOH is 1.7 x 10^-4 and acetic acid is 1.75 x 10^-5
Here is a table of Ka values.
(Broken Link Removed)
Do you know the names. formic, acetic, chloroacetic, dichloroacetic