Question

Le-Chatelier principle is not applicable to

• A.
  $H_2\left(g\right)+I_2\left(g\right)\rightleftharpoons 2HI\left(g\right)$
  
• B.
  $Fe\left(s\right)+S\left(s\right)\rightleftharpoons FeS\left(s\right)$
  
• C. $N_2\left(g\right)+3H_2\left(g\right)\rightleftharpoons 2N{H}_3\left(g\right)$
  
• D. $N_2\left(g\right)+O_2\left(g\right)\rightleftharpoons 2NO\left(g\right)$
  

Answer 1

The correct option is B

$Fe\left(s\right)+S\left(s\right)\rightleftharpoons FeS\left(s\right)$

Le- Chatelier principle is applicable only to gases. But it is not necessary that in a certain chemical reaction, all the reactants species must be in gaseous phase.
$Fe\left(s\right)+S\left(s\right)\rightleftharpoons FeS\left(s\right)$ is in solid-solid equilibrium phase hence, Le-chatelier principle is not applicable this.