A. Atomic heat capacities of the crystalline solid elements are nearly constant and equal to 6.2 kcal/kg-atom according to the law of Petit and Dulong
B. Atomic heat capacities of all solid elements decrease greatly with decrease in temperature, approaching a value of zero at absolute zero temperature, when in the crystalline state
C. Generally, the heat capacities of compounds are lower in the liquid than in the solid state
D. The heat capacity of a heterogeneous mixture is an additive property, but when solutions are formed, this additive property may no longer exist