2. Solved Papers
  3. AIIMS

AIIMS AIIMS Solved Paper-1999

  • question_answer
    The vapour pressure of benzene at a certain temperature is 640 mm of Hg. A non-volatile and non-electrolyte solid weighing 2.175 g is added to 39.08 g of benzene. The vapour pressure of the solution is 600 mm of Hg. What is the molecular weight of solid substance?

    A)  69.60                   

    B)         49.59   

    C)                         59.60                   

    D)         108.30.

    Correct Answer: A

    Solution :

    Relative lowering of vapour pressure is given by: \[\frac{{{P}^{0}}-{{P}_{s}}}{{{P}^{0}}}={{X}_{A}};{{X}_{A}}=\] mole fraction of solute \[{{P}^{0}}\]= vapour pressure of pure solvent \[{{P}_{s}}\] = vapour pressure of solution \[\Rightarrow \]  \[\frac{39.08/78}{39.08/78+2.175/{{M}_{A}}}\]\[\Rightarrow \]\[{{M}_{A}}=69.60\]


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