Mr(SO3)=Ar(S) + Ar(O) * 3=32 + 48=80
w(S)=Ar(S) / Mr(SO3) * 100%=32 / 80 * 100%=40%
w(O)=Ar(O) * 3 / Mr(SO3) * 100%= 48 / 80 * 100%=60%
w(S)=40%
w(O)=60%
Mr(SO3)=Ar(S) + Ar(O) * 3=32 + 48=80
w(S)=Ar(S) / Mr(SO3) * 100%=32 / 80 * 100%=40%
w(O)=Ar(O) * 3 / Mr(SO3) * 100%= 48 / 80 * 100%=60%
w(S)=40%
w(O)=60%