Describe at least two signs that indicate a severe storm, like a derecho, is on the way.

bank of heavy shelf clouds , extreme weather

Explanation:

Derecho is characterised by wind damages swath beyond 240 miles & wind gusts 58 mph

Signs of an approaching derecho are - bank of heavy clouds (arcus clouds) paired with extreme weather events

what are the choices?

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.