Answer
The element that is oxidized is Si and the one that is reduced is F₂.
Step-by-step explanation
Si + 2F₂ → SiF₄
The given reaction is an oxidation-reduction (redox) reaction:
Oxidation: Si → Si⁴⁺ + 4e⁻
Reduction: 2F₂ + 4e⁻ → 4F⁻
Si is a reducing agent, and F₂ is an oxidizing agent.
An oxidizing agent gains electrons and is reduced in a chemical reaction.
A reducing agent loses electrons and is oxidized in a chemical reaction.
Therefore, the element that is oxidized is Si and the one that is reduced is F₂.