KVPY Sample Paper KVPY Stream-SX Model Paper-29

  • question_answer
    The ammonia evolved from the treatment of 0.30 g of an organic compound for the estimation of nitrogen was passed in 100 mL of 0.1 M sulphuric acid. The excess of acid required 20 mL of 0.5 M sodium hydroxide solution for complete neutralization. The organic compound is 

    A) Urea     

    B) benzamide

    C) Acetamide

    D) thiourea

    Correct Answer: A

    Solution :

    \[{{H}_{2}}S{{O}_{4}}\]is dibasic.
    \[{{M}_{eq}}\,of\,{{H}_{2}}S{{O}_{4}}taken\,=100\times 0.2=20\]
    \[{{M}_{eq}}\,of\,{{H}_{2}}S{{O}_{4}}\]neutralized by\[NaOH\]
    \[=20\times 0.5=10\]
    \[{{M}_{eq}}\] of \[{{H}_{2}}S{{O}_{4}}\] neutralized by\[N{{H}_{3}}\]
    \[%of N\],
    \[\frac{1.4 \times {{M}_{eq}}of acid neutrialised by N{{H}_{3}}}{Wt. of organic compound}\]
    \[=\frac{1.4\times 10}{0.3}46.6\]
    % of nitrogen in urea \[=\frac{14\times 2\times 100}{60}=46.6\]

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