Pressure

For reacting gases, increasing the pressure usually increases the rate, while decreasing it usually slows the reaction. Pressure is the relevant factor here because it changes how closely the gas particles are packed together. It is not the same as changing the concentration of a solution.

Pressure matters when reacting gases are involved. Increasing their pressure usually increases the rate; decreasing it usually lowers the rate. Pressing on a mixture of a solid and a solution is not the same comparison: changing gas pressure is the relevant condition here.

Cooling a reaction, diluting a reacting solution, lowering the pressure of reacting gases or reducing the exposed surface area of a solid makes the reaction slower.