Define oxidising and reducing agents by giving suitable example.
$$Oxidizing \ agent$$
$$\text{: An oxidizing agent is an element that gains electrons. Since the oxidizing agent means to}$$ $$\text{gain electrons; it is said to have been reduced.}$$
$$\text{The element which undergoes reduction (gets reduced) is called an oxidizing agent.}$$
For example: $$2Mg + O_2 \rightarrow 2MgO$$
$$\text{In the given reaction,}$$ $$O_2$$ $$\text{is reduced by losing oxygen atoms. Thus,}$$ $$O_2$$ $$\text{is an oxidizing agent as it undergoes reduction.}$$
$$Reducing\ agent:$$
$$\text{A reducing agent is an element that loses electrons. The reducing agent means to lose}$$ $$\text{electrons; it is said to have been oxidized.}$$
$$\text{The element which undergoes oxidation (gets oxidized) is called the reducing agent.}$$
For example:
$$4NH_3 + 5O_2 \rightarrow 4NO + 6H_2O$$
$$\text{In the given reaction, nitrogen is oxidized to}$$ $$NO$$ $$\text{by gaining oxygen atom. Thus,}$$ $$NH_3$$ $$\text{is reducing agent as it undergoes oxidation.}$$