  Using the results of our first paper on the Chandra HRC observation of the
Orion Nebula Cluster (ONC), here we explore the relation between the coronal
activity of its 1-Myr-old pre-main sequence population and stellar parameters.
We find that median X-ray luminosities of low mass stars (M/M_sun < 3) increase
with increasing mass and decreasing stellar age. Brown dwarfs (0.03 < M/M_sun <
0.08) follow the same trend with mass. From M~0.1 to M~0.5M_sun, median
L_X/L_bol values increase by about half an order of magnitude and then remain
constant at ~10^-3.5 for the mass range from 0.5 to 3.0 M/M_sun. In these same
two mass ranges, L_X/L_bol remains roughly constant with age, until it drops by
more than two orders of magnitudes at the epoch when ~2-4M_sun stars are
expected to become fully radiative.
  We find a dependence of L_X and L_X/L_bol on circumstellar accretion
indicators and suggest three possible hypotheses for its origin. In spite of
improved X-ray and rotational data, correlations between activity indicators
and rotation remain elusive for these stars, possibly indicating that stars for
which rotational periods have been measured have reached some saturation level.
  Our study of X-ray activity vs. stellar mass leads us to propose that the few
HRC X-ray sources not associated with any optical/infrared counterpart trace a
yet to be discovered stellar population of deeply embedded, relatively massive
ONC members.
