If 1 mole of an ideal gas is heated at constant volume, then:

Explanation

In thermodynamics, when an ideal gas is heated at constant volume, the work done on the system is zero because the volume does not change. According to the first law of thermodynamics, the change in internal energy (∆U) is equal to the heat added to the system (∆Q) minus the work done (∆W), or ∆U = ∆Q - ∆W. At constant volume, ∆W = 0, so ∆U = ∆Q. Furthermore, ∆U is directly proportional to the change in temperature (∆T) through the heat capacity at constant volume (Cv), hence ∆U = Cv∆T. This is why option B is correct. Options A, C, and D incorrectly associate or apply the relationships between ∆U, ∆T, and Cv/Cp.