What is the mass in grams of 2.48x10^22 atoms of oxygen?

I think you take that then convert to moles then covert that to grams

1 mol = 6.02 x 10²³ atoms

*6.02 x 10²³ is Avogadro's number and you will have to use it to solve this.

# grams oxygen = 2.48 x 10²² atoms x 1 mol x 16.00 g O ÷ 6.02 x 10²³ atoms ÷ 1 mol O = 0.659 grams O

the reaction mixture contains some ammonia, plus a lot of unreacted nitrogen and hydrogen. the mixture is cooled and compressed, causing the ammonia gas to condense into a liquid. the liquefied ammonia is separated and removed. the unreacted nitrogen and hydrogen are then recycled back into the reactor .