Name the reducing agent in the following reaction:

$3{\mathrm{MnO}}_2+4\mathrm{Al}\to 3\mathrm{Mn}+2{\mathrm{Al}}_2{\mathrm{O}}_3$

In the redox reaction, the element or the molecule that loses electrons and gets oxidized is called a reducing agent. On the other hand, the molecule that gains electrons and gets reduced is called an oxidizing agent.

The given equation is:

$$\begin{gathered} 3{\mathrm{MnO}}_2\left(\mathrm{s}\right)+4\mathrm{Al}\left(\mathrm{s}\right)\to 3\mathrm{Mn}\left(\mathrm{s}\right)+2{\mathrm{Al}}_2{\mathrm{O}}_3\left(\mathrm{s}\right) \\ \mathrm{Manganese}\mathrm{Aluminium}\mathrm{Manganese}\mathrm{Aluminium} \\ \mathrm{dioxide}\mathrm{oxide} \end{gathered}$$

In the given reaction, Aluminum (Al) gets oxidized by displacing Manganese (Mn) from Manganese dioxide and Aluminium loses 3 electrons. The oxidation number of Al changes from 0 to +3.

Therefore, Aluminium (Al) is a reducing agent.