1) M(MgO) = 40
W(Mg) = 24/40 = 0,6%
W(O) = 16/40 = 0,4%
2) M(N2O) = 44
W(N) = 14/44 = 0,31%
W(O) = 16/44 = 0,36%
3) M(NO) = 30
W(N) = 14/30 = 0,46%
W(O) = 16/30 = 0,53%
4) M(N2O5) = 108
W(N0 = 14/108 = 0,12%
W(O) = 16/108 = 0.14%
5) M(NaOH) = 40
W(Na) = 23/40 = 0.5%
W(O) = 16/40 = 0.4%
W(H) = 1/40 = 0.025%
6) M(C6H12O6) = 180
W(C) = 12/180 = 0.06%
W(H) = 1/180 = 0.005%
W(O) = 16/180 = 0.08%
7) M(Cu(NO3)2) = 188
W(Cu) = 64/188 = 0.34%
W(N) = 14/188 = 0.07%
W(O) = 16/188 = 0.08%