NEET Physics Question - Thermal Physics

Assertion (A): If heat is supplied to an ideal gas in an isothermal process, the internal energy of the gas increases.

Reason (R): When an ideal gas expands adiabatically, it does positive work and its internal energy increases.

(1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)

(2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)

(3) (A) is true but (R) is false

(4) Both (A) and (R) are false

Solution:

For an ideal gas in an isothermal process, temperature is constant, so internal energy \(Delta U = 0\). Thus (A) is false. In adiabatic expansion, work \(W > 0\) is done by the gas and heat \(Q = 0\), so \(Delta U = -W < 0\), meaning internal energy decreases. Thus (R) is false. Both (A) and (R) are false.

Rankers Physics

Isothermal Process and Adiabatic Expansion

Solution:

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