Chemistry - Thermodynamics - I Question with Solution | TestHub
If four identical samples of an ideal gas initially at same state (Po, Vo, To) are allowed to expand to double their volumes by the following processes:
Process I: Isothermal reversible process
Process II: Reversible process P2V = constant
Process III: Reversible adiabatic process
Process IV: Irreversible adiabatic expansion against constant external pressure.
If the final states of gases are shown by different points in the graph represented, then match each point with the correct process:
Options:
Answer:
Solution:
All four end at 2Vo, so a higher point means higher final pressure. I: P = Po/2. II: P = Po/√(2) = 0.71Po (highest). III: P = Po/2γ (lowest, as T falls most in the reversible adiabatic). IV: adiabatic but irreversible, so less work is done by the gas than in III, final T is higher than in III, and with the same V the pressure is higher than in III; it is still below isothermal since T < To. Order from top: II > I > IV > III, i.e. II-1, I-2, IV-3, III-4. Matches (b).
