rate of reactions - concentration and reversible reactions

Question 1

what happens if a system is at equilibrium but a change is made to the conditions?

Answer 1

then the system responds to counteract the change. This is Le Chatliers principle

Question 2

2NO2 ⇌ N2O4
what happens if we increase concentration of 2NO2?
what happens if we decrease concentration of N2O4?

Answer 2

1. more N2O4 will react
2. more 2NO2 will form