CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2004

  • question_answer
    Oxygen is 16 times heavier than hydrogen. Equal volumes of hydrogen and oxygen are mixed. The ratio of speed of sound in the mixture to that in hydrogen is:

    A)  \[\sqrt{8}\]                                       

    B)  \[\sqrt{2/17}\]

    C)  \[\sqrt{1/8}\]                   

    D)  \[\sqrt{32/17}\]

    Correct Answer: B

    Solution :

    Let one mole of each gas has same volume as V. When they are mixed, then density of mixture is. \[{{\rho }_{mixture}}=\frac{mass\text{ }of\,C>2+mass\text{ }of\,{{H}_{2}}}{volume\text{ }of\,{{O}_{2}}+volume\text{ }of\text{ }{{H}_{2}}}\]                 \[=\frac{32+2}{V+V}\]                 \[=\frac{34}{2\,V}=\frac{17}{V}\] also,                       \[{{\rho }_{{{H}_{2}}}}=\frac{2}{V}\]        Now, velocity \[\upsilon ={{\left( \frac{\gamma P}{\rho } \right)}^{\frac{1}{2}}}\]or \[\upsilon \propto \frac{1}{\sqrt{\rho }}\]                 \[\frac{{{\upsilon }_{mixture}}}{{{\upsilon }_{{{H}_{2}}}}}=\sqrt{\left( \frac{{{\rho }_{{{H}_{2}}}}}{{{\rho }_{mixture}}} \right)}\]                                 \[=\sqrt{\left( \frac{2/V}{17/V} \right)}\]                                 \[=\sqrt{\left( \frac{2}{17} \right)}\]


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