Question

equation: 4NH3(g) + 5O2(g) -> 4NO(g) + 6H2O(g)
What mass of O2 is needed to produce 0.563g of NO? I think the answer is 750g but how do I get that answer?

Answer 1

A stoichiometry problem. Here is a solve example. Just follow the steps.
http://www.jiskha.com/science/chemistry/stoichiometry.html

Answer 2

It certainly won't take more than 1000 times as much O2 to make that much NO. Did you omit a decimal point somewhere?

Five moles of O2, with a mass of 160 g, are all that is required to make 4 moles of NO, with a mass of 112 g.

Try applying the 160/112 ratio to the amount of NO you want to produce.