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JEE Main & Advanced JEE Main Paper (Held on 12-4-2019 Morning)

  • question_answer
              5 moles of \[A{{B}_{2}}\]weigh \[125\times {{10}^{3}}kg\]and 10 moles of \[{{A}_{2}}{{B}_{2}}\]weigh \[300\times {{10}^{3}}kg\]. The molar mass of \[A({{M}_{A}})\]and molar mass of \[B({{M}_{B}})\]in \[kg\,mo{{l}^{-1}}\]are:                   [JEE Main Held on 12-4-2019 Morning]

    A) \[{{M}_{A}}=50\times {{10}^{-3}}\]and \[{{M}_{B}}=25\times {{10}^{-3}}\]

    B) \[{{M}_{A}}=25\times {{10}^{-3}}\] and \[{{M}_{B}}=50\times {{10}^{-3}}\]

    C) \[{{M}_{A}}=5\times {{10}^{-3}}\] and \[{{M}_{B}}=10\times {{10}^{-3}}\]

    D) \[{{M}_{A}}=10\times {{10}^{-3}}\]and \[{{M}_{B}}=5\times {{10}^{-3}}\]

    Correct Answer: C

    Solution :

    \[5[{{M}_{A}}+2{{M}_{B}}]=125\] \[{{M}_{A}}+2{{M}_{B}}=25\]                                        ....(1) \[2{{M}_{A}}+2{{M}_{B}}=30\]                          ....(2) from eq. & \[{{M}_{A}}=5\] \[{{M}_{B}}=10\]


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