Answer: Le Chatleir Principle
Explanation: The answer of this question can be easily explanied through the Le Chatleir Principle which states that In order to maintain the equilibrium of the reaction, the stress applied to that particular direction will move the equilibrium to the opposite direction in which the stress has been applied.
The given reaction is -
[tex]N_{2}(g)+O_{2}(g)\rightleftharpoons 2NO(g)[/tex]
If the amount of the oxygen is reduced to half and is being doubled, then the reaction will move in froward direction that is a rightward shift. Same situation will arise in option c and d.
If the amount of nitrogen monoxide is reduced to half or being doubled, the reaction will move towards backward direction that is a leftward reaction.