How many kj or heat are needed to completely vaporize 23.4 g of h2o? the heat of vaporization for water at boiling point is 40.6 kj/mole. 31.2 52.8 23.4 2.26 none of the above?

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