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JEE Main & Advanced Sample Paper JEE Main Sample Paper-24

  • question_answer
    A buffer solution is prepared in which the concentration of \[N{{H}_{3}}\] is \[0.30\] M and the concentration of \[N{{H}_{4}}^{+}\] is \[0.20\] M. If the equilibrium constant, \[{{K}_{b}}\] for \[N{{H}_{3}}\] equals\[1.8\times {{10}^{-5}}\], what is the pH of this solution? \[(\log 2.7=0.433)\].

    A)  \[9.08\]                                    

    B)  \[9.43\]

    C)  \[11.72\]                                  

    D)  \[8.73\]

    Correct Answer: B

    Solution :

    \[[N{{H}_{3}}]=0.3\,M\,\,\,\,\,\,[NH_{4}^{+}]\,=0.2M\] \[{{K}_{b}}\,=1.8\times {{10}^{-5}}\] \[{{p}^{OH}}\,=p{{k}_{b}}\,+\log \,\frac{[salt]}{[base]}\,=4.74\,+\log \,\frac{0.2}{0.3}\]


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