How many of the following compounds not having complete octet${\mathrm{CIO}}_2,\mathrm{NO},{\mathrm{NO}}_2,{\mathrm{SF}}_6,{\mathrm{H}}_2{\mathrm{SO}}_4,{\mathrm{BF}}_3,{\mathrm{BeCI}}_2$

SF₆ gives 12 electrons (6 pair of electrons) around S. Thus SF₆ does not obey octet rule.

In BF₃, 'F' completes its octet by sharing one electron from 'Boron' While 'Boron' shares three electron from three 'F' atom and has only 6 electrons in outermost shell. Thus, it has an incomplete octet.

BeCl₂ is a electron deficient molecule and it breaks the octete rule.
Beryllium only has two valence atoms and can only form electron pair bonds in two locations.

All compounds have deviation from octet principle.