Question

Le-Chatelier's principle is not applicable to

• A. \({H}_2(g) + {I}_2(g) \rightleftharpoons 2 {HI}(g)\)
• B. \({Fe}(s) + {S}(s) \rightleftharpoons {FeS}(s)\)
• C. \({N}_2(g) + 3 {H}_2(g) \rightleftharpoons 2 {NH}_3(g)\)
• D. \({N}_2(g) + {O}_2(g) \rightleftharpoons 2 {NO}(g)\)

Hint:

Le-Chatelier's principle is not applicable to pure solids and liquids because their concentrations do not change during chemical equilibrium.

Answer 1

The Correct Option is B

Le-Chatelier's principle applies to systems where changes in temperature, pressure, or concentration cause a shift in equilibrium. However, it does not apply to pure solids and liquids, because their concentrations do not change significantly during a reaction. 
Step 1: {Identifying the Pure Solids and Liquids} 
In reaction (B), Fe and S are pure solids, and thus, their concentrations do not significantly change during the reaction. Therefore, Le-Chatelier's principle is not applicable here. Thus, the correct answer is (B).