Here's why:

* Chemical formula: A chemical formula is a symbolic representation of a molecule or compound. It shows the types of atoms present in the molecule and their relative numbers.

Let's break down each example:

* H2O: This is the chemical formula for water, indicating it contains two hydrogen (H) atoms and one oxygen (O) atom.

* CO2: This is the chemical formula for carbon dioxide, indicating it contains one carbon (C) atom and two oxygen (O) atoms.

* C12HO: This is a chemical formula for a molecule containing 12 carbon (C) atoms, one hydrogen (H) atom, and one oxygen (O) atom. This could represent various molecules depending on the arrangement of the atoms.

Therefore, all these examples represent chemical formulas that provide information about the composition of specific molecules.