The molecular geometry and bond angle of the H2O molecule can be determined using quantum chemistry principles, specifically by applying the Valence Shell Electron Pair Repulsion VSEPR theory and molecular orbital theory.1. Determine the Lewis structure: The H2O molecule has a central oxygen atom bonded to two hydrogen atoms, with two lone pairs of electrons on the oxygen atom. The Lewis structure is: O / \ H H2. Determine the electron pair geometry: The oxygen atom has four electron domains two bonding pairs and two lone pairs . According to VSEPR theory, these electron domains will arrange themselves to minimize repulsion, resulting in a tetrahedral electron pair geometry.3. Determine the molecular geometry: Since there are two bonding pairs and two lone pairs, the molecular geometry is bent or angular.4. Determine the bond angle: In a tetrahedral electron pair geometry, the ideal bond angle between the bonding pairs is 109.5. However, the presence of lone pairs on the central oxygen atom causes a greater repulsion compared to bonding pairs. As a result, the bond angle between the two hydrogen atoms in H2O is slightly compressed to approximately 104.5.In summary, the molecular geometry of the H2O molecule is bent or angular, with a bond angle of approximately 104.5, as determined by quantum chemistry principles.