$Br^{-}$ is converted into $Br_2$ by using:

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:

Identify the reductant in the following reaction: $C_2O_4^{2-} + MnO_4^{-} + H^{+} \longrightarrow Mn^{2+} + CO_2 + H_2O$

Which of the following mixtures is chromic acid?

What is a reducing agent?

In the following reaction,how does sulfuric acid act?
${H_2}SO_4 \to SO_2$