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NEET Sample Paper NEET Sample Test Paper-72

  • question_answer
    Boiling point of chloroform was raised by 0.323 K, when 0.5143 g of anthracene was dissolved in 35 g of chloroform. Molecular mass of anthracene is \[({{K}_{b}}\,\,for\,\,CHC{{l}_{3}}\,\,=\,\,3.9\,\,kg\,\,mo{{l}^{-1}})\]

    A) 79.42 g/mol                  

    B) 132.32 g/mol   

    C) 177.42 g/mol                 

    D) 242.32 g/mol   

    Correct Answer: C

    Solution :

    Here: \[\Delta {{T}_{b}}=0.323\,\,K\] \[\operatorname{w} = 0.5143 g weight of anthracene.\] \[\operatorname{W}=35 g weight of chloroform\] \[{{\operatorname{K}}_{b}}\,\,= Molal elevation constant \left( 3.9 kg/mol \right)\] \[m=\frac{{{K}_{b}}\times w\times 1000}{W\times \Delta {{T}_{b}}}=\frac{3.9\times 0.5143\times 1000}{0.323\times 35}\] \[= 177.42 g/mol\]


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