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JEE Main & Advanced Chemistry Some Basic Concepts of Chemistry / रसायन की कुछ मूलभूत अवधारणाएँ Question Bank Self Evaluation Test - Some Basic Concepts of Chemistry

  • question_answer
    An organic compound whose empirical and molecular formula are same, contains 20% carbon, 6.7% hydrogen, 46.7% nitrogen and the rest oxygen. On heating it yields ammonia, leaving a solid residue. The solid residue gives a violet colour with dilute solution of alkaline copper sulphate. The organic compound is

    A) \[N{{H}_{2}}COON{{H}_{4}}\]          

    B) \[HCOON{{H}_{4}}\]

    C) \[N{{H}_{2}}NHCHO\]   

    D)   \[N{{H}_{2}}CON{{H}_{2}}\]

    Correct Answer: D

    Solution :

    [d]
    Element Percentage Atomic mass Relative no. of atoms Simplest ratio
    C 20% 12 1.66 1
    H 6.7% 1 6.7 4
    N 46.7% 14 3.33 2
    O 26.6% 16 1.66 1
    Empirical formula = Molecular formula\[=C{{H}_{4}}{{N}_{2}}O\,\,\,\text{or}\,\,\,N{{H}_{2}}CON{{H}_{2}}\] \[{{H}_{2}}NCON{{H}_{2}}+{{H}_{2}}NCON{{H}_{2}}\xrightarrow{\Delta }\]\[\underset{\text{biuret,}}{\mathop{{{H}_{2}}NCONHCON{{H}_{2}}}}\,+N{{H}_{3}}\] When an aqueous solution of biuret is treated with dilute sodium hydroxide and a drop of copper sulphate, a violet colour is produced. This test is known as biuret test, and is characteristic of compounds having the group \[-CONH-\]


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