JCECE Engineering JCECE Engineering Solved Paper-2015

  • question_answer
    \[pH\]of \[{{10}^{-8}}N\]\[NaOH\] is

    A) \[8.0\]                                  

    B) \[6.0\]

    C) \[6.98\]                               

    D) \[7.04\]

    Correct Answer: D

    Solution :

    \[\because \]     \[[NaOH]={{10}^{-8}}M\] \[\therefore \]  \[[O{{H}^{-}}]=1\times {{10}^{-8}}M\] Here, \[[O{{H}^{-}}]\] of water in this dilute solution should be added \[\therefore \]  \[{{[O{{H}^{-}}]}_{Total}}=\underbrace{1\times {{10}^{-7}}M}_{{{H}_{2}}O}+\underbrace{1\times {{10}^{-8}}M}_{NaOH}\] \[\therefore \]\[pOH=-\log [O{{H}^{-}}]=8-\log 11=8-104=6.96\] \[pH=14-pOH=14-6.96=7.04\]


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