Medium MCQ +4 / -1 PYQ · JEE Mains 2021

For an ideal gas the instantaneous change in pressure 'p' with volume 'v' is given by the equation ${{dp} \over {dv}} = - ap$. If p = p0 at v =0 is the given boundary condition, then the maximum temperature one mole of gas can attain is : (Here R is the gas constant)

  1. A ${{{p_0}} \over {aeR}}$ Correct answer
  2. B ${{a{p_0}} \over {eR}}$
  3. C infinity
  4. D 0$^\circ$C

Solution

$\int\limits_{{p_0}}^p {{{dp} \over P} = - a\int\limits_0^v {dv} }$<br><br>$\ln \left( {{p \over {{p_0}}}} \right) = - av$<br><br>$p = {p_0}{e^{ - av}}$<br><br>For temperature maximum p-v product should be maximum<br><br>$T = {{pv} \over {nR}} = {{{p_0}v{e^{ - av}}} \over R}$<br><br>$${{dT} \over {dv}} = 0 \Rightarrow {{{p_0}} \over R}\{ {e^{ - av}} + v{e^{ - av}}( - a)\} $$ = 0<br><br>${{{p_0}{e^{ - av}}} \over R}\{ 1 - av\} = 0$<br><br>$v = {1 \over a},\infty$<br><br>$T = {{{p_0}1} \over {Rae}} = {{{p_0}} \over {Rae}}$<br><br>at v = $\infty$<br><br>T = 0<br><br>Option (a)

About this question

Subject: Physics · Chapter: Thermodynamics · Topic: Zeroth and First Law

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