If the total mass of the products in a reaction is 90 grams what was the total mass of the reactants

Who is better, messi or cristiano, i need this for a chemistry class. asap

What are transitions between a liquid and gas called? identify which way they are transitioning

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?