Histograms of the distributions of the derived physical properties for the MCs of the FQS ¹³CO catalogue. Top left: masses derived from cold dust emission. Top centre: area. Top right: average mass surface density. Middle left: aspect ratio (σ_maj/σ_min). Middle centre: equivalent spherical radius. Middle right: velocity dispersion. Bottom left: virial parameter. Bottom centre: galactocentric radius. The vertical dashed lines indicate the reference position of the Local Arm (Xu et al. 2013), Perseus Arm (Choi et al. 2014), and Outer Arm (Hou & Han 2014) at the central Galactic longitude of the surveyed region l = 230°.