Which of the following does not has a linear arrangement of atom?

The oxygen has 6 valence electrons and thus needs 2 more electrons from 2 hydrogen atoms to complete its octet. Then, this leaves two lone electron pairs that are not bonded to any other atom. The two hydrogen atoms and the two lone electron pairs are as far apart as possible at nearly 109^o bond angle. This is tetrahedral electron pair geometry. The two lone electron pairs exert a little extra repulsion on the two bonding hydrogen atoms to create a slight compression to a 104^o bond angle. The water molecule is in bent molecular geometry because of the lone pairs of electrons.