Formal charge can be calculated from the following formula
Formal charge = valency of central atom - (number of lone pair of electrons + number of covalent bonds)
a) for methylene:
Formal charge = 4 -( 2+ 2) = 0
b) For methyl free radical
Formal charge = 4- (3 +1) = 0
Chloroacetic acid <em>is stronger. </em>
<em>This is because it contains (more electronegative) chlorine atoms in place of (less electronegative) hydrogen atoms.</em>
I think the awnser to your question is C
