Results for the DGS sample and trends with observable parameters. The vertical axis of panels a, c, d, and e is M(H₂)_total/M(H₂)_CO (total M_H2 determined from the model over the M_H2 determined from CO observations and the Galactic conversion factor). The horizontal axes of these same panels are as follows: a: L_[C II]/L_CO(1−0) with colour code for Z. The correlation shown in the dashed line is described in the panel in the equation for M(H₂)_total/M(H₂)_CO as a function of the observed L_[C II]/L_CO(1−0); standard deviation is 0.25 dex. b: total M_H2 determined from the models vs. the observed L_[C II]. Our resulting relationship of M_H2 as a function of L_[C II] is given within the panel; standard deviation is 0.14 dex. c: M(H₂)_total/M(H₂)_CO vs. Z; d: M(H₂)_total/M(H₂)_CO vs. observed L_[C II]/L_TIR. e: M(H₂)_total/M(H₂)_CO vs. Σ_SFR, where SFR is determined from total IR luminosity from Rémy-Ruyer et al. (2015). Spearman correlation coefficients (ρ) and p-values in parenthesis are indicated within each panel. Red points are DGS galaxies with CO detections. Open symbols in all panels are upper limits due to CO non-detections.