Question

You react 25.0 g hydrogen gas with 30.2 g oxygen gas. Determine the mass of water that can be produced from these reactants.

Answer 1

This is a limiting reagent problem? How do I know that? Because BOTH reactants are given. Basically what you do is to work TWO simple stoichiometry problems to determine the amount of water produced, then take the SMALLER value. Here is a solved example of a simple stoichiometry problem. Just follow the steps.
http://www.jiskha.com/science/chemistry/stoichiometry.html