BCECE Engineering BCECE Engineering Solved Paper-2003

  • question_answer
    Which of the following will have maximum pH?

    A) \[\frac{M}{10}HCl\]        

    B)        \[\frac{M}{100}HCl\]

    C) \[\frac{M}{10}NaOH\]  

    D)        \[\frac{M}{100}NaOH\]

    Correct Answer: C

    Solution :

    Key Idea: \[pH=-\log [{{H}^{+}}]\] \[pH=14-pOH\] Calculate pH of all the solution to find which will have maximum\[~pH.\] (a)\[M/10\,HCl\] \[\therefore \]               \[[{{H}^{+}}]={{10}^{-1}}\] \[pH=-\log [{{H}^{+}}]\] \[=-\log [{{10}^{-1}}]\] \[=1\] (b) \[M/100\,HCl\] \[\therefore \]  \[[{{H}^{+}}]={{10}^{-2}}\]                 \[pH=-\log [{{H}^{+}}]\] \[=-\log [{{10}^{-2}}]\] \[=2\] (c) \[M/10\,NaOH\]  \[\therefore \]        \[[O{{H}^{-}}]={{10}^{-1}}\]                                 \[pH=14-pOH\] \[=14[-log{{10}^{-1}}]\] \[=14-1\] \[=13\]                 (d) \[M/100\,NaOH\]                 \[\therefore \]  \[[O{{H}^{-}}]={{10}^{-2}}\]                                 \[pH=14-pOH\]                                 \[=14-[log{{10}^{-2}}]\] \[=14-2=12\] \[\therefore \]\[M/10\,NaOH\]solution has highest pH.


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