Using the equation 2h2+o2--> 2h2o if 19g of oxygen reacts completely, how many grams of hydrogen must react with it

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation:

Compare and contrast refraction of light and sound will give brainliest

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