hope u guys can answer to my question
i didn find anything about fatty acids,i mean are they weak or strong acids?.
do they have a single carboxyl groub or two carboxyl grouP?
You must have looked long and hard. The structure is visible here: http://en.wikipedia.org/wiki/Fatty_acids
And the strength of the acid is determined by the electronegativity of the chain behind the "acid H". You can see her a little more: http://en.wikipedia.org/wiki/Organic_acid
With that you should be able to figure out your answers.