${\mathrm{SF}}_6,{\mathrm{PCl}}_5,{\mathrm{IF}}_7$ and ${\mathrm{BrF}}_5$  have 12, 10, 14, 12 electrons respectively on the central atom of corresponding molecule.

Determine the number of molecules that expands its octet?

S, P, I and Br has empty d-orbitals, thereby successfully expand its octet and accommodate more than eight electrons in its valence shell.
${\mathrm{SF}}_6,{\mathrm{PCl}}_5,{\mathrm{IF}}_7$ and ${\mathrm{BrF}}_5$.

Hence, total 4 molecules that can expand its octet.