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JEE Main & Advanced Sample Paper JEE Main Sample Paper-22

  • question_answer
    Calculate the pH at \[{{25}^{o}}C\] after 50 M of 0.1 M ammonia solution .is treated with 25 ml of 0.1 M HCl solution. (The dissociation constant of ammonia; \[{{K}_{b}}=2\times {{10}^{-5}})\]

    A)  8.6                              

    B)  9.3

    C)  7.8                              

    D)  None of these

    Correct Answer: B

    Solution :

               
    \[N{{H}_{3}}\,\,\,+\] \[HCl\xrightarrow{\,}\] \[N{{H}_{4}}Cl\]
    \[20\times 0.1\] \[25\times 0.1\] 0
    =5 =2.5 0
    2.5 0 2.5
                \[pOH=p{{K}_{b}}+\log \,\frac{2.5}{2.5}=4.7\]             \[pH=14-4.7=9.3\]


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