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JEE Main & Advanced Sample Paper JEE Main Sample Paper-9

  • question_answer
    Steam at \[1atm\And 100{}^\circ C\] enters a radiator & leaves as water at \[1atm\And 80{}^\circ C,\] take \[{{L}_{y}}=540\text{ }cal/cm\And {{s}_{water}}\]\[=11\text{ }cal/gm/{}^\circ C.\] If the total energy given off as heat, the % age arises from the cooling of water is

    A)  100                       

    B)  54      

    C)  3.6                        

    D)  8.2

    Correct Answer: C

    Solution :

    Let m is the amount of steam that passes off the radiator. Heat released due to condensation of steam, \[{{H}_{1}}=m{{L}_{v}}=540mcal\] Heat released due to cooling of water, \[{{H}_{2}}=ms\Delta \theta =m\times 1\times 20=20m\,cal\] Required percentage \[=\frac{{{H}_{2}}}{{{H}_{1}}+{{H}_{2}}}\times 100=\frac{20m}{560m}\times 100=3.6%\]


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