What are the coefficients that would correctly balance this reaction? Ni + C4H8N2O2 → Ni(C4H8N2O2)2

a.1,2,1
b.2,2,1
c.2,1,1
d.2,2,2

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 .

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)