Are the volumes and composition of molecules the same for different substances?

Different substances may differ from each other.

1) The composition of the molecules.

Example – carbon dioxide CO2 and ammonia NH3

2) The structure of molecules having the same composition.

An example is isomers of organic substances, for example n-butane (CH3-CH2-CH2-CH3) and isobutane (CH3-CH (CH3) -CH3).

3) The structure of the crystal lattice.

An example is carbon and diamond.

The volumes of molecules of different substances do not coincide and depend on the number and type of atoms included in the molecule – from monatomic molecules of inert gases to huge polymer molecules of organic substances.

The compositions of molecules of different substances in some cases may coincide (example 2), but in this case they will have a different structure.