Classify each of the following as an atom, a compound, or a molecule:
the smallest possible “piece” of gold (au)
the smallest possible “piece” of quartz (sio2)
water (h2o)
what a molecule of co2 is made of
hydrogen gas (h2)

the cladogram shown here shows similarities and differences among several classes of vertebrates. anatomically, the four have limb structure as their common ancestor. we might separate the mammals from the other three classes because they a) divergent; do not lay eggs b) identical; are warm-blooded c) varied; a four chambered heart d) homologous; have mammary glands

oxygen +1 most likely