Left-hand panel: gas-phase metallicity (12 + log(O/H)) versus stellar mass (log M_⋆/M_⊙) for BPT-SF galaxies (upper-panel), BPT-non-SF galaxies (middle panel), and their combined sample (bottom panel). The coloured curves on each plot in the left-hand panel correspond to median metallicities estimated in the bins of log M_⋆/M_⊙ and log SFR, colour coded with respect to log SFR in a given bin. Right-hand panel: gas-phase metallicity (12 + log(O/H)) versus log SFR for BPT-SF (upper-panel), BPT-non-SF (middle panel), and their combined sample (bottom panel). The coloured curves on each plot in the right-hand panel correspond to the median metallicities estimated in bins of log SFR and log M_⋆/M_⊙. The [N II]-BPT classification along with the maximum star-burst line from Kauffmann et al. (2003a) is used to separate SF (upper-panel) and non-SF galaxies (middle panel). The gas-phase metallicities of BPT-SF (upper-panel) and BPT-non-SF (middle panel) galaxies are obtained using the empirical calibrations involving the O3N2 diagnostic provided in Curti et al. (2017) and Kumari et al. (2019), respectively. The bottom panel consists of both BPT-SF and BPT-non-SF galaxies and hence their metallicities are obtained from both SF (Curti et al. 2017) and non-SF (Kumari et al. 2019) calibrations, depending on the type of galaxy populations.