Although significant progress has been made in predicting the physical properties of organic compounds, some fundamental problems still exist. First, it is hard to correlate the functional group contribution and the molecular symmetry number with thermodynamic properties such as pressure and temperature. For example, the Clausius-Clapeyron equation indicates pressure impacts on the phase transition temperatures. Second, determining the functional group contribution and symmetry number is arbitrary. For example, the symmetry number of CH4 is designated as 12 because it has 4 C3 rotational axes. However, nine symmetry operations should be degenerated in the energy level. Moreover, the symmetry number of monoatomic gas is designated to 200. In contrast, the symmetry number of entirely asymmetrical molecules CHXYZ (X, Y, and Z denote different atoms or groups except for H) is 1. It is beyond common sense that the spin of an atom can contribute so much entropy. Moreover, it seems inverse to the order of entropy, reflecting the diversity of molecular configurations. Third, the geometric symmetry of mass distribution is solely selected without any reasoning. However, in quantum theory, the symmetry of orbits is vital to the reactions , and spectroscopy , . Therefore, it is essential to assess the definition of molecular symmetry and the quantitating approach based on the principle of straightforward and reasonable.