a)
m Mn2O3 = 2*55u + 3*16u= 110u+48u=158u
% Mn = 110u/158u*100%= 69,6% ≈ 70%
% O = 48u/158u*100% = 30,4% ≈30%
b)
m Cu2O = 2*64u+16u=144u
% Cu = 128u/144u*100%= 88,9%≈89%
%O = 16u/144u*100%= 11,1%≈11%
c)
N2O5= 2*14u+ 5*16u= 28u+ 80u =108u
%N = 28u/108u*100%= 25,9%≈26%
%O = 80u/108u*100% = 74,1%≈74%
,,/ ,, - dzielenie
,, *,, - mnożenie
