Mr(H2CO3) = Ar(H)*2 + Ar(C) + Ar(O)*3 = 2+12+48 = 62.
Mr(Al2(SO4)3)= Ar(Al)*2 + Ar(S)*3 + Ar(O)*12 = 54+96+192 = 342.
Mr(H2CO3) = Ar(H)*2 + Ar(C) + Ar(O)*3 = 2+12+48 = 62.
Mr(Al2(SO4)3)= Ar(Al)*2 + Ar(S)*3 + Ar(O)*12 = 54+96+192 = 342.