JEE Main & Advanced JEE Main Paper (Held On 09-Jan-2019 Morning)

  • question_answer
    The following results were obtained during kinetic studies of the reaction: \[2A\,\,+\,\,B\,\,\to \] Products
    Experi-ment  in \[\mathbf{mol}\text{ }{{\mathbf{L}}^{-\mathbf{1}}}\]  (in \[\mathbf{mol}\text{ }{{\mathbf{L}}^{-\mathbf{1}}}\] Initial Rate of reaction (in \[\mathbf{mol}\text{ }{{\mathbf{L}}^{-\mathbf{1}}}\] \[\mathbf{mi}{{\mathbf{n}}^{\mathbf{-1}}}\])
    I 0.10 0.20 \[6.93\,\,\times \,\,{{10}^{-3}}\]
    II 0.10 0.25 \[6.93\,\,\times \,\,{{10}^{-3}}\]
    III 0.20 0.30 \[1.386\,\,\times \,\,{{10}^{-2}}\]
    The time (in minutes) required to consume half of A is - [JEE Main Online Paper (Held On 09-Jan-2019 Morning]

    A) 5                 

    B) 1

    C) 100             

    D) 10

    Correct Answer: A

    Solution :

      \[6.93\,\,\times \,\,{{10}^{-\,3}}\,\,=\,\text{ }k\text{ }\times \text{ }{{\left( 0.1 \right)}^{x}}\text{ }{{\left( 0.2 \right)}^{y}}\] \[6.93\text{ }\times \text{ }{{10}^{-\,3}}=k\,\,\times \,\,{{(0.1)}^{x}}{{\left( 0.25 \right)}^{y}}\] So \[y=0\] and \[1.386\text{ }\times \text{ }{{10}^{-\,2}}=\text{ }k\text{ }{{\left( 0.2 \right)}^{x}}\,\,{{\left( 0.30 \right)}^{y}}\] Hit - So, \[r\,\,=\,\,k\,\,\times (0.1)\,\times \,{{(0.2)}^{0}}\] \[6.93\,\times \,{{10}^{-3}}\,=\,k\,\times \,0.1\,\,\times \,\,{{(0.2)}^{0}}\] \[k\,\,=\,6.93\,\,\times \,\,{{10}^{-2}}\,\] \[{{t}_{1/2}}\,=\,\frac{0.693}{2\,k}\,\,=\,\,\frac{0.693}{0.693\,\times \,{{10}^{-\,1}}\,\times \,2}\,\,=\,\,\frac{10}{2}\,\,=\,\,5\]


You need to login to perform this action.
You will be redirected in 3 sec spinner