Answer:
: reducing agent is CO.
Explanation:
a) ![Fe+Cu^{2+}\rightarrow Fe^{2+}+Cu](https://tex.z-dn.net/?f=Fe%2BCu%5E%7B2%2B%7D%5Crightarrow%20Fe%5E%7B2%2B%7D%2BCu)
The oxidation state of copper reduces from +2 to 0, it is getting reduced. As
gets reduced, it acts as an oxidising agent.
The oxidation state of iron increases from 0 to +2. Thus, it is getting oxidized. As
gets oxidized, it acts as a reducing agent.
b. ![2Na+Cl_2\rightarrow 2NaCl](https://tex.z-dn.net/?f=2Na%2BCl_2%5Crightarrow%202NaCl)
The oxidation state of chlorine reduces from 0 to -1, it is getting reduced. As
gets reduced, it acts as an oxidising agent.
The oxidation state of sodium increases from 0 to +1. Thus, it is getting oxidized. As
gets oxidized, it acts as a reducing agent.
c. ![C+O_2\rightarrow CO_2](https://tex.z-dn.net/?f=C%2BO_2%5Crightarrow%20CO_2)
The oxidation state of oxygen reduces from 0 to -2, it is getting reduced. As
gets reduced, it acts as an oxidising agent.
The oxidation state of carbon increases from 0 to +2. Thus, it is getting oxidized. As
gets oxidized, it acts as a reducing agent.
d. ![NiO+CO\rightarrow Ni+CO_2](https://tex.z-dn.net/?f=NiO%2BCO%5Crightarrow%20Ni%2BCO_2)
The oxidation state of nickel reduces from +2 to 0, it is getting reduced. As
gets reduced, it acts as an oxidising agent.
The oxidation state of carbon increases from +2 to +4. Thus, it is getting oxidized. As
gets oxidized, it acts as a reducing agent.