Final answer:
A water molecule has four nonbonding electrons, which are the electrons on the oxygen atom that are not involved in bonding with the hydrogen atoms.
Step-by-step explanation:
The number of nonbonding electrons present in a molecule of water is as follows: Oxygen has six valence electrons, but in a water molecule, it forms two covalent bonds with hydrogen atoms, each bond consisting of a pair of electrons. This leaves four nonbonding electrons on the oxygen atom, which are organized into two lone pairs. Thus, the correct number of nonbonding (lone pair) electrons in a water molecule is four.