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QJEEAdv21Ch6e6e: JEE Advanced 2021 Chemistry - Class 11 JEEAdv21Ch6e6e Solution: An ideal gas undergoes a reversible isothermal expansion from…

An ideal gas undergoes a reversible isothermal expansion from state I to state II followed by a reversible adiabatic expansion from state II to state III. The correct plot(s) representing the changes from state I to state III is (are)

(p : pressure, V : volume, T : temperature, H : enthalpy, S : entropy)

Multiple Choice Options

  • A https://ik.imagekit.io/novatra/photos/2b60aa00a492368ce51414fde321c1cc3d95ee52221940867a81a237a973cb7c.webp
  • B https://ik.imagekit.io/novatra/photos/32db2eb950799f98aadc7a1e5f8ae133521e80e70f42742435bda57717f64d3e.webp
  • C https://ik.imagekit.io/novatra/photos/26a9e0033fac76a1b4a065e698ee0115c4b88aadf7b88fad2eede174050cba5a.webp
  • D https://ik.imagekit.io/novatra/photos/e7c2aca84222533f8b204ff74a681d8d1637efef24a61f52c4e0aa4827a7ab8b.webp

Step-by-Step Verified Solution

From state I to II Reversible isothermal expansion takes place. So, following changes take place,

● pressure decreases.
● Volume increases.
● Temperature remains constant.
● Enthalpy, H remains constant.
● Entropy, S for expansion increases.

So, all options follows the above mentioned conditions, so all graphs are correct for state I and II.

From state II to III Reversible adiabatic expansion takes place. So, following changes take place.

● pressure decreases.
● Volume increases.
● Temperature decreases.
● Enthalpy, H decreases.
● Entropy, S remains constant.
● H increases instead of decreasing, so only option (c) is incorrect.

All other options, i.e., (a), (b) and (d) follows the above mentioned conditions.

Therefore, correct graphical representations are (a), (b) and (d).

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