CET Karnataka Medical CET - Karnataka Medical Solved Paper-2011

  • question_answer
    \[0.023g\]of sodium metal is reacted with \[100c{{m}^{3}}\]of water. The pH of the resulting solution is

    A)  \[10\]              

    B)  \[8\]

    C)  \[9\]              

    D)  \[12\]

    Correct Answer: D

    Solution :

    \[\underset{0.023}{\mathop{\underset{(2\times 23=46)}{\mathop{2Na+2{{H}_{2}}O}}\,}}\,\xrightarrow{{}}2\underset{0.04}{\mathop{\underset{(2\times 40=80)}{\mathop{NaOH+{{H}_{2}}}}\,}}\,\] \[\therefore \] \[[O{{H}^{-}}]=\frac{0.04}{40}\times 10={{10}^{-2}}\] \[\because \] \[pOH=-\log [O{{H}^{-}}]\] \[pOH=2\] \[\because \] \[pH+pOH=14\] \[pH=14-pOH\] \[pH=14-2\] \[pH=12\]


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