On increasing the pressure, the direction in which gas phase reaction proceeds to re-establish equilibrium is predicted by applying the Le-Chatelier's principle. Consider the reaction,

N2(g)+3H2(g)2NH3(g)

If the total pressure at which the equilibrium is established is increased without changing the temperature, then the correct option is:

1. K will remain same.
2. K will decrease.
3. K will increase.
4. K will increase initially and decrease when pressure is very high.

Hint: K is only temperature dependent.

Explanation: 

In the reaction, N2(g)+3H2(g)2NH3(g)
If the total pressure at which the equilibrium is established, is increased without changing the temperature, K will remain same. K changes only with change in temperature.