Practice question

**Internal energy** state function depends only on temperature for ideal gas, U = f/2 n R T, change ΔU = n C_v ΔT, first law connects heat, work, internal energy, for expansion work done by gas positive, compression work done on gas negative, heat added positive. In an isothermal process ( T = constant ), the internal energy of an ideal gas ( U , temperature-dependent) remains constant ( Δ U = 0 ), and heat supplied equals work done ( Δ Q = Δ W ), making option C correct. Using first law ΔU = Q - W, W = ∫ P dV, isobaric