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  5. Organic Chemistry: Some Basic Principles & Techniques / कार्बनिक रसायन : कुछ मूलभूत सिद्धांत एवं तकन

JEE Main & Advanced Chemistry Organic Chemistry: Some Basic Principles & Techniques / कार्बनिक रसायन : कुछ मूलभूत सिद्धांत एवं तकन Question Bank Critical Thinking

  • question_answer
    An organic compound contains 49.3% carbon 6.84% hydrogen and its vapour density is 73. Molecular formula of the compound is [MP PET 2000; Kerala PMT 2004; Pb. CET 2004]

    A) \[{{C}_{3}}{{H}_{5}}{{O}_{2}}\]

    B) \[{{C}_{6}}{{H}_{10}}{{O}_{4}}\]

    C) \[{{C}_{3}}{{H}_{10}}{{O}_{2}}\]

    D) \[{{C}_{4}}{{H}_{10}}{{O}_{2}}\]

    Correct Answer: B

    Solution :

    Element.    No. of moles         Simple ratio  
    C 12 49.3/12 = 4.1 4.1/2.7 = 1.3 ´ 2 = 2.6 = 3
    H 1 6.84/1= 6.84 6.84/2.7=2.5´2=5
    O 16 43.86/16 = 2.7 2.7/2.7=1´2=2
    Empirical formula = \[{{C}_{3}}{{H}_{5}}{{O}_{2}}\] E.F. wt. = 12 ´ 3 + 1 ´ 5 + 16 ´2 = 73 Molecular wt = V.D. ´ 2 = 73 ´ 2 = 146 \[n=\frac{M.wt}{E.F.wt}=\frac{146}{73}=2\] Molecular formula = (E.F)n \[={{({{C}_{3}}{{H}_{5}}{{O}_{2}})}_{2}}={{C}_{6}}{{H}_{10}}{{O}_{4}}\].


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