In ${\text{XeF}}_2$ , Xenon undergoes ${\text{sp}}^3\text{d}$  hybridization and the molecule to be linear due to presence of three lone pairs ,where 2 fluorine atoms bonded linearly to Xe on opposite sides. In ${\text{CO}}_2$ the two oxygen atoms double bonded to carbon atom in opposite sides and the resulting geometry of ${\text{CO}}_2$ molecule is linear. In ${\text{BeCl}}_2$ the two chlorine atoms are bounded to Be in opposite sides by $180°$ as bond angle. Hence the geometry of  ${\text{BeCl}}_2$ is linear. But in ${\text{H}}_2\text{O}$ the oxygen undergoes ${\text{sp}}^3$  hybridization and geometry is angular.