Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
MHT CET202313 May 2023Evening ShiftChemistryThermodynamics (C)Actual

An ideal gas absorbs 210 ~J of heat and undergoes expansion from 3 ~L to 6 ~L against a constant external pressure of 10^5 ~Pa . What is the value of U ?

Options

  1. A310 ~J
  2. B-90 ~J
  3. C-210 ~J
  4. D190 ~J

Correct answer

B. -90 ~J

Step-by-step solution

1 ~Pa =1 10⁻⁵ bar 10^5 ~Pa =1 bar W =- P _ ext V =-1 (6-3)=-3 dm ^3 bar 1 dm ^3 bar =100 ~J W =-300 ~J Q =+210 ~J According to first law of thermodynamics, U = Q + W U=+210 ~J +(-300 ~J )=-90 ~J

Practice Thermodynamics (C) on Quantrex Academy →

More from Thermodynamics (C)

Identify the INCORRECT statement 2026The standard enthalpies of formation of CH₄ (g), CO₂ (g) and H₂ O(l) are -74.8 kJ mol ⁻¹ , -393.5 kJ mol ⁻¹ and -285.8 kJ mol ⁻¹ respectively. Then the enthalpy change for the give 2026For an ideal gas undergoing an isothermal change, there is 2026Ozone is formed by the reaction O _ 2(g) + O _ (g) O _ 3(g) , H = -107.2 kJ . Given O=O bond energy is 498.0 kJ mol ⁻¹ , the average bond energy of ozone is: 2026H and S for a reaction are 35.5 kJ mol ⁻¹ and 83.6 J K ⁻¹ respectively. Assuming that H and S do not vary with temperature, the reaction is spontaneous when: 2026The heat of combustion of carbon to CO ₂ is -393.5 kJ mol ⁻¹ . The heat released on the formation of 35.2 g of CO ₂ by combustion of C is: 20265 moles of a gas is allowed to pass through a series of changes as shown in the graph, in a cyclic process. The processes C A , B C and A B respectively are 20251 mole of an ideal gas is allowed to expand isothermally and reversibly from 1 L to 5 L at 300 K. The change in enthalpy (in kJ ) is ( R =8.3 ~J ~K ⁻¹ ~mol ⁻¹ ) 2025 Full Thermodynamics (C) list All MHT CET PYQs