261. For a given substance at a specified temperature, activity is __________ to fugacity.
A. Directly proportional
B. Inversely proportional
C. Equal
D. None of these
✅ The correct answer is option A.
Thermodynamics MCQs
262. Internal energy of an ideal gas
A. Increases with increase in pressure
B. Decreases with increase in temperature
C. Is independent of temperature
D. None of these
✅ The correct answer is option D.
263. The Joule-Thomson co-efficient is defined as (∂T/∂P)H. Its value at the inversion point is
A. ∞
B. 1
C. 0
D. -ve
✅ The correct answer is option C.
264. Air enters an adiabatic compressor at 300K. The exit temperature for a compression ratio of 3, assuming air to be an ideal gas (Y = Cp/Cv = 7/5) and the process to be reversible, is
A. 300(32/7)
B. 300(33/5)
C. 300(33/7)
D. 300(35/7)
✅ The correct answer is option A.
265. The expression for entropy change, ΔS = n Cp . ln (T₂/T₁), is valid for the __________ of a substance.
A. Simultaneous pressure & temperature change
B. Heating
C. Cooling
D. Both B and C
✅ The correct answer is option D.
266. All gases above its inversion temperature, in a throttling process will show
A. A heating effect
B. No change in temperature
C. A cooling effect
D. Either A or C
✅ The correct answer is option A.
267. Work done is a
A. Property of the system
B. Path function
C. Point function
D. State description of a system
✅ The correct answer is option B.
268. In a reversible process
A. Tds = dE + dW
B. DE – dW = Tds
C. DW – dE = Tds
D. Tds – dW + dE >0
✅ The correct answer is option A.
269. The change in __________ is equal to the reversible work for compression in steady state flow process under isothermal condition.
A. Internal energy
B. Enthalpy
C. Gibbs free energy
D. Helmholtz free energy
✅ The correct answer is option C.
270. In the reaction, H₂ +I₂ ⇋ 2HI, addition of an inert gas will
A. Increase the partial pressure of H₂
B. Increase the partial pressure of I₂
C. Increase the total pressure and hence shift the equilibrium towards the right
D. Not effect the equilibrium conditions
✅ The correct answer is option D.