  The First Ionization Potential (FIP) bias, whereby elemental abundances for
low FIP elements in different coronal structures vary from their photospheric
values and may also vary with time, has been widely studied. In order to study
the temporal variation, and to understand the physical mechanisms giving rise
to the FIP bias, we have investigated the hot cores of three ARs using
disk-integrated soft X-ray spectroscopic observation with the Solar X-ray
Monitor (XSM) onboard Chandrayaan-2. Observations for periods when only one AR
was present on the solar disk were used so as to ensure that the AR was the
principal contributor to the total X-ray intensity. The average values of
temperature and EM were ~3 MK and 3.0E46/cm3 respectively. Regardless of the
age and activity of the AR, the elemental abundances of the low FIP elements,
Al, Mg, and Si were consistently higher than their photospheric values. The
average FIP bias for Mg and Si was ~3, whereas the FIP bias for the mid-FIP
element, S, was ~1.5. However, the FIP bias for the lowest FIP element, Al, was
observed to be higher than 3, which, if real, suggests a dependence of the FIP
bias of low FIP elements on their FIP value. Another major result from our
analysis is that the FIP bias of these elements is established in within ~10
hours of emergence of the AR and then remains almost constant throughout its
lifetime.
