Which compound acts as an oxidising as well as reducing agent?

$Cu^{2+}$ does not form $CuI_2$. This is because $Cu^{2+}$

Which of the following can act as both an oxidizing and a reducing agent?

Consider the following reaction:
$BrCH_2CH_2F + SbF_5 \xrightarrow{SO_2, -60^{\circ}C} CH_2-CH_2-Br^+ + SbF_6^-$
In this reaction,$SbF_5$ acts as:

Which of the following can act both as an oxidising as well as reducing agent?

The element which never acts as a reducing agent in a chemical reaction is