The most commonly used reducing agent is-

1. AlCl3 

2. PbCl2

3. SnCl4

4. SnCl2



Hint: Element stable in higher oxidation state than lower oxidation state show strong reducing agent

Reducing agents are those substances that reduce other substances and itself oxidises.
In SnCl2, Sn oxidises in +2 oxidation state, thus, acts as a strong reducing agent i.e.,