Compounds . 1.have different properties from the elements they are made from

2.have the same properties as the elements they are made from

3.can only exist as solids or liquids

4.are the same as molecules

What did not occur in the proterozoic eon a)the oxygen levels increase greatly in the atmosphere,b)the emergence of the eukarya , c)muti cella’s eukaryotic organisms began to diversify,d)anaerobic bacteria kept thriving with more oxygen