Chemistry question about gas phase reactions with pressure?

increasing the pressure will increase the quickest reaction, in this case the reaction between NO and Cl2. but, adding argon decreases the chances that NO and Cl2 will meet due to the size of the argon molecule. think of size, speed of reaction, pressure. if the pressure were increased by decreasing the size of the environment, you would definitely get more NOCl. think of the kinetic molecular theory of gas movement