Please help, once again. Can't seem to get this...

Consider the reaction of hydrogen and oxygen to form water as follows:

2 H2 (g) + O2 (g) --> 2 H2O (l)

if 10.5 g of hydrogen are placed in a reaction vessel, how many grams of oxygen are required to fully react with the hydrogen to make water? Numerical answers only; do not include units in your answer!

Which statement correctly describes the phosphate ion, ? it is composed of one phosphorus atom and four oxygen atoms covalently bonded together, and there is a –3 charge distributed over the entire ion. it is composed of one phosphorus atom and four oxygen atoms covalently bonded together, and there is a –3 charge on the phosphorus atom. it is composed of one phosphorus atom and four oxygen atoms ionically bonded together, and there is a –3 charge distributed over the entire ion. it is composed of one phosphorus atom and four oxygen atoms ionically bonded together, and there is a –3 charge on the phosphorus atom.