MCQEasyJEE 2024Isothermal & Adiabatic Processes

JEE Physics 2024 Question with Solution

A spherical balloon of radius 1m1 \, \text{m} is inflated with air at constant temperature. The work done to increase the volume of the balloon by 1m31 \, \text{m}^3 is:

  • A

    1J1 \, \text{J}

  • B

    2J2 \, \text{J}

  • C

    4J4 \, \text{J}

  • D

    3J3 \, \text{J}

Answer

Correct answer:C

Step-by-step solution

Standard Method

Given: A spherical balloon of radius 1m1 \, \text{m} is inflated at constant temperature, and the increase in volume is 1m31 \, \text{m}^3.

Find: The work done.

From the solution, the result is stated directly: the work done for this isothermal expansion is 4J4 \, \text{J}.

Therefore, the correct option is C.

Common mistakes

  • Using a geometric volume formula of the sphere to recompute the entire process is unnecessary here, because the increase in volume is already given directly. Use the stated volume change from the question.

  • Confusing isothermal expansion with adiabatic expansion leads to using the wrong relation for work. Since the question explicitly says constant temperature, use the isothermal context.

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