When two your substances are combined so that each of the pure substances retains its own properties the result is a(n)?
a.
mixtureb.
isotopec.
elementd.
compound

How did the research presented in the article affect scientists' understanding of the evolution of eukaryotes

Which statements correspond to cellular respiration? co2 diffuses passively into the cell. co2 diffuses passively out of the cell. co2 must be pumped out of the cell. o2 diffuses passively when produced inside the cell. o2 diffuses passively when converted to co2. o2 is pumped in and forces co2 out.

The earth formed roughly 4.5 billion years ago, yet evidence of life dates back to about 3.5 billion years ago. which one is not a possible hypothesis of how life on earth arose?