  Multiple molecular lines are useful for studying the physical properties of
multiphase star-forming gas in different types of galaxies. We probe the
molecular gas throughout the disc of the spiral galaxy NGC~5033, hosting an
active galactic nucleus (AGN), using multiple low-$J$ CO lines [$^{12}$CO(1-0,
2-1, 3-2 and $^{13}$CO(1-0, 2-1)] and dense gas tracers [HCN(1-0) and
HCO$^{+}$(1-0)]. Firstly, we determine the ratios of the integrated intensity
maps and the ratio of intensities in position velocity diagrams. Secondly, we
obtain the ratios of CO lines and high-density tracers at the centre; and
thirdly, we model these line ratios using a radiative transfer code. Line ratio
diagnostics reveal that the south of the gaseous disc contains cooler gas than
the northern part, and the centre hosts warmer and less tenuous gas with a
similar dense gas fraction compared to most galaxies of similar type. Our model
results mostly agree with the empirical ones in the sense that the central
region of NGC~5033 harbours warmer gas than that in the centres of normal
spirals and lenticulars without showing AGN activity. Finally, the
beam-averaged total molecular gas mass and gas surface density along the
galaxy's major axis show a radial gradient, i.e. increasing from the outskirts
up to the central region of size $1$~kpc where there is a depression in both
gas mass and surface density.
