Question

Complete the following reaction.
______+${O_2} \to 2N{a_2}O$ .
A. $4Na$
B. $2N{a_2}$
C. $Na$
D. $N{a_4}$

Answer 1

During redox reactions, atoms' oxidation states are changed. The actual or formal transfer of electrons between chemical species is characterised by redox reactions, with one species usually undergoing oxidation while the other undergoes reduction.

Complete answer:
When sodium is heated in an excess of air, the main product is sodium peroxide $(2N{a_2}O)$ . The first intermediate product is sodium monoxide. The peroxide is a solid that is yellowish in colour. It melts at $460^oC$ and then decomposes. When it comes into contact with water, it responds violently. The formation of hydrates and ${H_2}{O_2}$ adducts is a common feature of ionic peroxides.
When a material loses its electrons or has oxygen added to it, it is said to be oxidised. The term oxidation refers to reactions in which an element reacts with oxygen. Oxidation was the process of gaining oxygen, while reduction was the process of removing oxygen. A redox reaction is described as a reaction that involves both oxidation and reduction.
In the above given reaction - $4Na + {O_2} \to 2N{a_2}O$
$Na$ is a reducing agent, $O{\;_2}$ is an oxidizing agent.
So, the correct option is (A) $4Na$.

Note:
The oxidation number of sodium in sodium peroxide $(2N{a_2}O)$ is +1. It can't go up, so it can just go down in oxidation state from +1 to 0. (zero). Reduction is the decrease of the oxidation number, and the element that undergoes reduction is known as the oxidising agent. It is a powerful oxidising agent.