Answer : If we consider the molecule of oxygen gas which in diatomic state, is bonded to other atom which is of same element this is called as homonuclear.
While in HCl there is a heteronuclear bonding observed because there are two different elements getting involved in the bond formation, also it creates a electrovalent species in itself and makes it more polar. They are creating a dipole moment by separating different charges in the molecule which cause it to get tightly bonded with each other.
The formula for water is H2O so there would have to be two Hyrdogens and one oxygen. Therefore it would be 4g of Hydrogen and 16g of Oxygen leaving you with 20g. The answer is D.
