In water, \(\mathrm{O}\) is, \(s p^3\)-hybridized. Due to stronger lone pairlone pair repulsions than bond pair-bond pair
repulsions, the \(\mathrm{HOH}\) bond angle decreases from \(109.5^{\circ}\) to \(104.5^{\circ}\). Thus, water is a bent molecule. \(\mathrm{H}_2 \mathrm{O}_2\) has a non-planar structure. The two oxygen atoms are linked to each other by a single covalent bond (i.e., peroxide bond) and each oxygen is further linked to a hydrogen atom by a single covalent bond. The two O-H bonds are, however, in different planes. The dihedral angle between the two planes being \(111.5^{\circ}\) in the gas phase. Thus, the structure of \(\mathrm{H}_2 \mathrm{O}_2\) is like that of an open book.