Why is 2,4,6-trinitrophenol a very strong acid?

2 4 6 dinitrophenol 2 4 6 trinitrophenol is a very strong acid because it contains three nitro group which are electron withdrawing groups davido electrons by the resonance and the control of phones by the minus I effect to of Nitrogen atom also because it is more electronegative ..

so it is more strong acid..

-R effect is directly propotional to the acidic charecter.

NO2 shows -R effect so, the ring contains 3 NO2 group, so its acidity increases by 3times.

So it is very strong acid.