  We continue our analysis of the Galactic oxygen-rich supernova remnant (SNR)
G292.0+1.8, which was observed with the {\it Chandra X-ray Observatory}. The
high angular resolution {\it Chandra} data resolve metal-rich ejecta knots as
well as the shocked circumstellar medium. X-ray emission from the ejecta
material in G292.0+1.8 is dominated by highly ionized O, Ne and Mg. Measured
abundance ratios suggest that this material was produced during the hydrostatic
evolution of the massive progenitor star. In contrast to Cassiopeia A, there is
little evidence for X-ray-emitting ejecta from explosive nucleosynthesis, i.e.,
material enriched in Si, S, and particularly, Fe. This limits the amount of
mixing or overturning of deep ejecta material in G292.0+1.8 and suggests that
the ejecta are strongly stratified by composition and that the reverse shock
has not propagated to the Si/S or Fe-rich zones. On the other hand, the bright
equatorial belt is dominated by X-ray emission with normal chemical
composition, which supports shocked dense circumstellar material for its
origin. We find that the thermal pressure in the SNR is much higher than the
pressure in the pulsar wind nebula (PWN), indicating that the reverse shock has
not yet begun to interact with the PWN.
