Ihave been waiting for 20 min! a sample of pure iron has a mass of 5 g calculate its volume

Which best describes the present-day universe? opaque, expanding very slowly, stars produce heavy elements transparent, expanding at an accelerated rate, stars produce heavy elements opaque, expanding at an accelerated rate, stars produce only hydrogen and helium transparent, expanding very slowly, stars produce only hydrogen and helium

If a molecule is polar, what kind of bonds will it have

How can a ringing telephone can be heard through a closed door