Mr (H₂O)= A(H) * 2 + A(O)= 2+16=18
Mr (HCl)= A(H) + A(Cl)= 1+35,5=36,5
Mr (H₂SO₄)= A(H) *2 + A(S) + A(O) *4=2 + 32 + 64= 98
Mr (Ba(OH)₂)=A(Ba) + 2 * (O) + (H) * 2= 137+32+2=171
Mr (Ca(OH)₂)= A(Ca) +A(O) * 2 + A(H) * 2= 40+32+2=74
Mr (Al₂(SO₄)₃)= A(Al) * 2 + A(S) * 3 + A(O) * 12= 26*2+32*3+16*12=340