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NEET Chemistry Some Basic Concepts of Chemistry / रसायन की कुछ मूलभूत अवधारणाएँ NEET PYQ-Some Basic Concepts Chemistry

  • question_answer
      \[6.02\times {{10}^{20}}\] molecules of urea are present in 100 mL of its solution. The concentration of solution is                                                                                                                                                      [NEET 2013]

    A)  0.02 M

    B)       0.01 M

    C)  0.001 M          

    D)       0.1 M

    Correct Answer: B

    Solution :

    Given, number of molecules of urea
    \[=6.02\times {{10}^{20}}\]
    \[\therefore \]      Number of moles \[=\frac{6.02\times {{10}^{20}}}{{{N}_{A}}}\]
    \[=\frac{6.02\times {{10}^{20}}}{6.02\times {{10}^{23}}}=1\times {{10}^{-3}}mol\]
    Volume of the solution
    \[=100\,mL=\frac{100}{1000}L=0.1L\]
    Concentration of urea solution
    (in mol \[{{L}^{-1}}\]) \[=\frac{1\times {{10}^{-3}}}{0.1}=mol\,{{L}^{-1}}\]
    \[=1\times {{10}^{-2}}mol\,{{L}^{-1}}=0.01\,mol\,{{L}^{-1}}\]       


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