Question

in which of the following species does the central atom violate the octet rule?
○ ch₄
○ pcl₄⁺
○ sf₄
○ co₂
○ nh₃

Explanation:

1. In $CH_4$, carbon has 4 valence - electrons and forms 4 single bonds with hydrogen, giving it an octet.
2. In $PCl_4^+$, phosphorus has 5 valence - electrons, loses 1 in forming the cation, and forms 4 single bonds with chlorine, giving it an octet.
3. In $SF_4$, sulfur has 6 valence - electrons and forms 4 single bonds with fluorine and has 1 lone pair. Sulfur has 10 electrons around it, violating the octet rule.
4. In $CO_2$, carbon has 4 valence - electrons and forms 2 double bonds with oxygen, giving it an octet.
5. In $NH_3$, nitrogen has 5 valence - electrons and forms 3 single bonds with hydrogen and has 1 lone pair, giving it an octet.

Answer:

C. $SF_4$