The bond formed between a proton (H+) and an ammonia molecule (NH3) is a coordinate covalent bond, also known as a dative covalent bond.

Here's why:

* Ammonia (NH3) has a lone pair of electrons: The nitrogen atom in ammonia has a lone pair of electrons that are not involved in bonding.

* Proton (H+) is electron deficient: A proton is simply a hydrogen atom that has lost its electron, making it positively charged and electron deficient.

* Sharing of electrons: The lone pair of electrons on the nitrogen atom in ammonia is donated to the proton (H+), forming a covalent bond. Since the electron pair is donated entirely by one atom (nitrogen), it's considered a coordinate covalent bond.

This bond formation results in the formation of the ammonium ion (NH4+), which is positively charged.