Which compound is an exception to the octet rule? h2o hcl ccl4 clf3

is an exception to the octet rule.

Explanation: Octet rule is general rule for most of the atoms which says that the atoms must have 8 electrons in their valence shell in order to be stable. For this they can gain, loose of share the electrons from the other elements.

The valence electrons can be determined by the lewis dot structures. Lewis dot structures are the structures in which the valence electrons around the nucleus of an element are shown.

For the given compounds, only one compound do not follow octet rule which is

In the given compound, the octet of all the 3 fluorine atoms are complete but chlorine has 10 electrons around it which is not followed by octet rule.