In a closed system, how will a decrease in pressure affect the following reaction: 2a(g) +2b(g) ⇌ 2c(g) + 2d(g)?
a. equilibrium will shift towards compound a.
b. no change will occur.
c. equilibrium will shift towards compound d.
d. equilibrium will shift towards the reactants.

B. No change will occur.

Explanation:

Notice that the two moles of gas on the side of the reactants also reflects on the side of the products (i.e. there are also two moles of gas on the side of the products).

This translates to there won't be any change in the equilibrium if the pressure is increased.

The only important factor to take note of is that altering the pressure can only result in a significant change for equilibrium reactions between gases, when the reaction features a change in the number of moles of gas.