Edwin Hubble found out that what appeared to be large clouds in space were not gas, but _

A: galaxies
B: the Oort cloud
C: comets
D: large stars

Iron reacts with oxygen to produce iron oxide (rust). this reaction is represented in an equation as 4fe + xo2 → 2fe2o3. identify the value of x that will balance the equation.

Where substance is produced during cellular respiration

Which of the following is an eon in the time scale? phanerozoic proterozoic archean all of the above