JEE Main & Advanced Sample Paper JEE Main Sample Paper-47

  • question_answer
    A solution containing two non-interacting solid solutes A and B in the mass ratio 1:1 is isotonic with another solution 1 and 2 (in the same volume of the solution) having mass ratio 3 : 5. Calculate the molar mass ratio of A and B.

    A)  \[\frac{1}{2}\]                                   

    B)  \[\frac{1}{3}\]

    C)  \[\frac{3}{5}\]                                   

    D)  \[\frac{2}{3}\]

    Correct Answer: B

    Solution :

     Assume that the total masses of solutes in the two solutions 1 and 2 are 3 m and 5 m respectively. Then, if \[{{M}_{1}}\] and \[{{M}_{2}}\] are the molar masses, the total number of moles in a given volume of solution 1 at T K is \[\frac{1.5m}{{{M}_{1}}}+\frac{1.5m}{{{M}_{2}}}\] In solutions 2, this number is \[\frac{0.5m}{{{M}_{1}}}+\frac{4.5m}{{{M}_{2}}}\] The solutions are isotonic \[\therefore \] \[\frac{1.5m}{{{M}_{1}}}+\frac{1.5m}{{{M}_{2}}}=\frac{0.5m}{{{M}_{1}}}+\frac{4.5m}{{{M}_{2}}}\] By calculation, \[\frac{1}{{{M}_{1}}}=\frac{3}{{{M}_{2}}}\] \[\therefore \]    \[\left( \frac{{{M}_{1}}}{{{M}_{2}}} \right)=\frac{1}{3}\]

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