Balance the following chemical equation and identify the type of chemical reaction?
$Na(s)+S(s)\xrightarrow{heat}N{{a}_{2}}S(s)$.

Hint: The answer to this question is based on the concept of the thermodynamics, that is whether heat is absorbed or heat is evolved and this fact gives which type of reaction it undergoes.

Complete step – by - step answer:
From the lower classes of chemistry, we have studied about balancing a chemical equation and also to find the type of reactions, that is whether endothermic or exothermic.
Let us now refresh the concepts which will lead you to guess the correct answer.
Here, the equation consists of sodium which reacts with sulphur to give sodium sulphide and the sodium sulphide has the formula $N{{a}_{2}}S$ .
Now, for balancing the equation, we must make it in such a way that each of the molecules or atoms are equal in number on both sides of the reaction. That is, the number of atoms or molecules on the reactant side should be the same as that of the product.
Now, since in the above reaction, sodium in the product side has two moles, thus we have to write 2 in the reactant side too.
Therefore, balancing this equation, we can write the reaction as shown below,
\[2Na(s)+S(s)\xrightarrow{heat}N{{a}_{2}}S(s)\]
Now, to find the type of reaction, we can see in the above reaction that there is neither heat evolved in any form nor there is any evolution of gas. Thus the type of reaction which this reactant is undergoing is the endothermic reaction.

Note: Note that balancing the chemical equation plays an important role and according to law conservation of mass, the matter can neither be created nor destroyed and this can be possible only if the total number of atoms on both sides of reactions is balanced.