The number of different possible oxidation states of fluorine in the molecules $\left[{\mathrm{F}}_2,{\mathrm{OF}}_2,{\mathrm{O}}_2{\mathrm{F}}_2,\mathrm{HF}\right]=t$ Find the value of $t$.

Two fluorine atoms make up the diatomic molecule of fluorine. This depicts the element's default state. As a result, the oxidation state of each fluorine atom within must be zero.
 

O in OF2 has +2 oxidation state.

F in HF has an oxidation state of 1. F needs one more electron to complete its octet, since it is the most electronegative element.

Hence, the values of t are $0,-1,+1,2$.