Uttarakhand PMT Uttarakhand PMT Solved Paper-2011

  • question_answer
    The pH of a solution obtained by mixing 50 mL of\[0.4\text{ }N\text{ }HCl\]and 50 mL of\[0.2\text{ }N\text{ }NaOH\]is

    A)  \[-log\text{ }2\]          

    B)  \[-log\text{ 0}.2\]

    C)  1.0             

    D)  2.0

    Correct Answer: C

    Solution :

     50 mL of \[0.4\text{ }NHCl=\frac{0.4}{1000}\times 50\,g\,eq.\]      \[=0.02\text{ }g\text{ }eq.\] 50 mL of \[0.2\text{ }N\text{ }NaOH=\frac{0.2}{1000}\times 50\,g\,eq.\]             \[=0.01\text{ }g\text{ }eq.\] After neutralisation,\[HCl\]left = 0.01 g eq. Total volume = 100 mL \[[HCl]=\frac{0.01}{100}\times 1000=0.1\,N\] \[=0.1\,M={{10}^{-1}}M\] \[pH=-\log [{{H}^{+}}]=-\log [{{10}^{-1}}]\] \[pH=1\]


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