This one is an oxidation-rdcution equation:
H2 + F2 → 2HF
How can you tell?
If the oxidation states of the atoms in the reactans are different from the oxidation states of the same atoms in the products then it is an oxidation-reduction reaction.
Both atoms H and F in the reactants have oxidation states 0.
That is a basic rule: any atom alone or bonded to the same kind of atom has oxidation state 0.
The oxidation states in HF are: H: +1, and F: -1.
So, the H increased its oxidation state, which is that ii is oxydized ; while F reduced its oxidation state so it is reduced.
Answer: H2 + F2 ----> 2HF
