JEE Main & Advanced Sample Paper JEE Main - Mock Test - 26

  • question_answer
    Consider the acidity of the carboxylic acids
    (i)\[PhCOOH\]
    (ii)\[o-N{{O}_{2}}{{C}_{6}}{{H}_{4}}COOH\]
    (iii)\[p-N{{O}_{2}}{{C}_{6}}{{H}_{4}}COOH\]
    (iv)\[m-N{{O}_{2}}{{C}_{6}}{{H}_{4}}COOH\]
    Which of the following order is correct?

    A)  \[i>ii>iii>iv\]   

    B)  \[ii>iv>iii>i\]

    C)  \[ii>iv>i>iii\]   

    D)  \[ii>iii>iv>i\]

    Correct Answer: D

    Solution :

    [d]: Order of acidity is: E.W.G. increases the acidity of benzoic acid, o-isomer will have higher acidity than corresponding m-and p-isomers due to ortho-effect. In p-nitrobenzoic acid, both -R effect and -I effect of the nitro group increase the acidity while in m-nitrobenzoic acid, only the weaker -I effect increases the acidity. Therefore the correct order of acidity is it ii>iii>iv>i.


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