Using the equation 2h2+o2--> 2h2o if 19 g of oxygen reacts completely, how many grams of hydrogen must react with it? question options: 4.8 3.6 1.2 2.4

Sally is making a model of a magnesium atom with an atomic mass number of 24 for her chemistry class. she has foam balls for the protons, neutrons, and electrons. she has added 6 neutrons to her model so far. how many more neutrons does she need to add to complete her neutral atom of magnesium?