H2SO4
M(H2SO4)=2*1+32+4*16=98
w(H)=2*1*100%/98=2,04%
w(S)=1*32*100%/98=32,66%
w(O)=4*16*100%=65,30%
KMnO4
M(KMnO4)=39+55+4*16=158
w(K)=1*39*100%/158=24,68%
w(Mn)=1*55*100%/158=34,81%
w(O)=4*16*100%/158=40,51%
C6H10
M(C6H10)=6*12+1*10=82
w(C)=6*12*100%/82=87,80%
w(H)=10*1*100%/82=12,20%