  Spectroscopic observations in X-ray wavelengths provide excellent diagnostics
of the temperature distribution in solar flare plasma. The Solar X-ray Monitor
(XSM) onboard the Chandrayaan-2 mission provides broad-band disk integrated
soft X-ray solar spectral measurements in the energy range of 1-15 keV with
high spectral resolution and time cadence. In this study, we analyse X-ray
spectra of three representative GOES C-class flares obtained with the XSM to
investigate the evolution of various plasma parameters during the course of the
flares. Using the soft X-ray spectra consisting of the continuum and
well-resolved line complexes of major elements like Mg, Si, and Fe, we
investigate the validity of the isothermal and multi-thermal assumptions on the
high temperature components of the flaring plasma. We show that the soft X-ray
spectra during the impulsive phase of the high intensity flares are
inconsistent with isothermal models and are best fitted with double peaked
differential emission measure distributions where the temperature of the hotter
component rises faster than that of the cooler component. The two distinct
temperature components observed in DEM models during the impulsive phase of the
flares suggest the presence of the directly heated plasma in the corona and
evaporated plasma from the chromospheric footpoints. We also find that the
abundances of low FIP elements Mg, Si, and Fe reduces from near coronal to near
photospheric values during the rising phase of the flare and recovers back to
coronal values during decay phase, which is also consistent with the
chromospheric evaporation scenario.
