In an isochoric process, the volume of the gas remains constant. Since work done is given by: \[ W = P \Delta V \] where \( \Delta V \) is the change in volume, if there is no change in volume (\( \Delta V = 0 \)), the work done by the gas is zero.
Thus, the correct answer is (C).
The standard heat of formation, in kcal/mol, of $Ba^{2+}$ is:
Given: Standard heat of formation of SO₄²⁻(aq) = -216 kcal/mol, standard heat of crystallization of BaSO₄(s) = -4.5 kcal/mol, standard heat of formation of BaSO₄(s) = -349 kcal/mol.