Why does hydrogen react with oxygen but helium does not ?

Which term best describes a community in which people work mostly in factories? a.agricultural. b.hunting and gathering. c.domesticated. industrial.

Which of these is most likely to happen if parallax measurements of star distances are taken after a gap of six months? the results would be accurate the results would be inconsistent the results would not be valid the results would not be repeated

Which of the following describes how binary fission and mitosis are similar? a)they are both used for growth or repair b)they both break down membrane-bound nuclei c)both invoke the replication of a single stand of dna d)both replicate genetic material