A 3.9 mole sample of uranium decays until only 3 moles remain. How many grams of uranium decayed? (Not remained!)

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?

What is the mass of 0.46 mol of mgcl2

Using the periodic table, complete the following. element: hydrogen symbol: h₂ molecular weight: g mass of one mole: g/mol