Dependence of the molecular gas mass in M_⊙ with excitation temperature for 4C12.50. The colour code clarifies the tempertature ranges considered as ‘cold’, ‘warm’ and ‘hot’ in this work. The small red circles indicate the cold H₂ masses infered from CO(2–1) ALMA data for different apertures with the radius varying from 0.5″ to 2″ (see text). The black solid line shows the best fit to the warm (G12) and hot data points, with the equation and coefficient of determination, R². G12: Guillard et al. (2012); D11: Dasyra & Combes (2011); D14: Dasyra et al. (2014); L22: Lamperti et al. (2022).