Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
MHT CET202613 April 2026Evening ShiftChemistryThermodynamics (C)Actual

A gas expands from a volume of 1 dm ^3 to 1.25 dm ^3 under a pressure of 1 bar. Find the change in internal energy if 150 J of heat is supplied to the system.

Options

  1. A125 J
  2. B175 J
  3. C-125 J
  4. D-175 J

Correct answer

A. 125 J

Step-by-step solution

Given V₁ = 1 dm ^3 and V₂ = 1.25 dm ^3 . Change in volume, V = 1.25 - 1 = 0.25 dm ^3 = 0.25 L. External pressure, P = 1 bar. Work done during expansion is given by W = -P V . W = -1 0.25 = -0.25 L bar. Since 1 L bar = 100 J, we have W = -0.25 100 = -25 J. Heat supplied to the system, q = 150 J. According to the first law of thermodynamics, U = q + W . U = 150 - 25 = 125 J. Answer: 125 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