Question

Assertion :Both work and heat are manifested by an effect on the surroundings. Reason: Work done by/on the system and $\Delta H$ appear only at the boundary of system.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
• C. Assertion is correct but Reason is incorrect.
• D. Assertion is incorrect but Reason is correct.

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

Work

• In Thermodynamics:
defined as any quantity that flows across the boundary of a system during a change in its state and is completely convertible into lifting of a weight in the surroundings
• appears only at the boundary of a system
• appears only during a change in state
• manifested by an effect in the surroundings

Heat

• defined as the energy transferred as a result of a difference in the temperature between the system and the surroundings
• heat is the energy transferred from regions of high temperature (vigorous thermal motion) to regions of low temperature (lesser thermal motion)
• the process of heating is the transfer of energy that makes use of the differences in thermal motion (random, chaotic motion of molecules) between the system and its surroundings
• Heat appears only at the boundary of a system
• heat appears only during a change in state
• heat is manifested by an effect in the surroundings