If I start with 5 grams of C3H8, and was able to produce 7.11 grams of H2O, what was my percent yield

Aballoon inflated with three breaths of air has a volume of 1.7 l. at the same temperature and pressure, what is the volume of the balloon if five more same-sized breaths are added to the balloon?

In this chemical reaction, 325 grams of barium (ba) react completely. how many moles of lithium (li) are produced?

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?