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JEE Main & Advanced Sample Paper JEE Main Sample Paper-29

  • question_answer
    The emf of the cell \[\underset{(0.1M)}{\mathop{Fe\left| F{{e}^{2+}} \right|}}\,\]\[\underset{(2\,atm)}{\mathop{\left| {{H}^{+}} \right|{{H}_{2}}}}\,\], Pt is \[0.22\,V\] at \[{{25}^{o}}C\], pH of the solution at hydrogen electrode is

    A) 5                                             

    B) 4

    C) 6                                             

    D) 2.8

    Correct Answer: B

    Solution :

    \[\frac{6!}{2!}\,=360\,\,\,\,\,\,\,\,\,\,\,\times \times \times \times \times \times 2\] \[g'(x)\,=2f\,(2f(x)\,+2)\times f'(2f(x)\,+2)\,\times 2f'(x)\]                 \[x=0,\] \[g'(0)\,=2(-1)\,\times 1\times 2\times 1=-4\] \[f(x)\,=\sin ({{\sin }^{-1}}[x])\,=\left\{ \begin{matrix}    0, & 0\le x<1  \\    1, & 1\le x<\frac{\pi }{2}  \\ \end{matrix} \right.\] \[\therefore \,I=\int\limits_{0}^{1}{0\,dx+\int\limits_{1}^{\frac{\pi }{2}}{1dx=0\,+\left( \frac{\pi }{2}+1 \right)=\frac{\pi -2}{2}}}\]


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