* Carbon's Valence: Carbon has four valence electrons, meaning it can form four bonds with other atoms.

* Hydrogen's Valence: Hydrogen has one valence electron and can form only one bond.

In the formula CH5, carbon would need to form five bonds, which is impossible given its valence.

Possible Formulas with Carbon and Hydrogen:

* CH4 (Methane): This is a stable molecule with carbon forming four single bonds to four hydrogen atoms.

* C2H6 (Ethane): Carbon forms four bonds, but in this case, two carbons are bonded to each other and the remaining bonds are with hydrogen atoms.

Let me know if you have any other questions about molecular formulas!