Assertion (A) : Nitrogen gas is used to provide inert atmosphere in chemical reaction. Reason (R) : Nitrogen gas has a very little chemical reactivity at ordinary temperature.

Assertion (A) is true as nitrogen gas is widely used to provide an inert atmosphere in chemical reactions, food packaging, and industrial processes to prevent oxidation and unwanted reactions [c1][t3][t6]. Reason (R) is also true and provides the correct explanation for (A). Nitrogen gas (N2) exhibits very little chemical reactivity at ordinary temperatures because of the exceptionally strong triple bond between nitrogen atoms, which requires significant energy to break [t1][t2]. While it can react with specific substances like lithium or magnesium under certain conditions, it remains stable and unreactive for the vast majority of organic and industrial applications at room temperature [t5][t8][t9]. This relative inertness makes it a cost-effective choice for displacing oxygen and moisture to stabilize products and maintain chemical integrity [t3][t7].

Sources

1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 20: Earths Atmosphere > Nitrogen > p. 272
2. [2] https://www.sciencedirect.com/topics/chemistry/inert-atmosphere