Răspuns:
Explicație:
mH2=400g
n=?
MH2=2*1=2
n=m/M=400g/2 g/mol=200 moli
mN2=140 mg=0,140 g
MN2=2*14=28 g/mol
n=m/M=0,140g/28 g/mol=0,005 moli