question_answer

Which of the following is weakest acid?

A)  

B)

C)  

D)  

Correct Answer: A

Solution :

 Presence of electron withdrawing group increases the acidic strength. It withdraws electrons from the carbon to which it is attached and this effect is transmitted throughout the chain. As a result the electrons are withdrawn more strongly from oxygen of\[O-H\]bond and promotes the release of proton. The o-nitrobenzoic acid is most acidic due to ortho effect while among the p and m-isomers, p-is more acidic because as the distance between\[-N{{O}_{2}}\]group and the\[-COOH\]group increases, the electron withdrawing influence decreases. Therefore, the order of acidic strength is as Hence,is the weakest acid.