Question

Formation of Nitric oxide is a/an:
A.Highly exothermic reaction
B.Highly endothermic reaction
C.Both A and B
D.Exothermic reaction

Answer 1

Exothermic reaction is the one in which heat is released after the products are formed and endothermic reaction is the one in which heat is required to convert the reactants into products. Nitric oxide is a gas which has a molecular formula $NO$ and it can be prepared from nitrogen and oxygen as its molecular formula suggests. So, if the breakdown of nitrogen and oxygen is easy or difficult will decide endothermic or exothermic.

Complete step by step answer:
In this question, formation of Nitric oxide is being asked and the type of reaction i.e. whether it is energy consuming or energy releasing which will ultimately tell about exothermic or endothermic. So, Nitrogen oxide, also called nitrogen oxide is a colorless and toxic gas with the molecular formula of $NO$. It has several applications like in medicines and produced also naturally by body and also it is a pollutant which causes pollution and acid rain.
So, from the molecular formula of Nitric oxide we can say that it contains two elements i.e. Nitrogen and Oxygen and therefore it is generally formed by these elements.
If we see the formation of nitric oxide by just Nitrogen and Oxygen gases, the reaction is represented as: -
${N_2}\left( g \right){\text{ }} + {\text{ }}{O_2}\left( g \right) \to {\text{ }}2NO\left( g \right)$
And the heat absorbed by this reaction is about $180{\text{ }}kJ$ and this much amount of heat is required to convert into NO and therefore, the reaction becomes highly endothermic in nature because high amount of heat is required to convert the reactants into products.

Therefore, the correct answer is B i.e. highly endothermic reaction.

Note:
This high amount of heat because the Nitrogen is an inert element and present as ${N_2}$ with triple bond with other Nitrogen atoms and therefore, to break this bond high energy required and same case with oxygen. So, to break these bonds, a high amount of energy is required which ultimately makes the process highly endothermic.