Why do catalysts not alter the amounts of reactants and products present at equilibrium?

When the following equilibria are disturbed by increasing the pressure, does the concentration of reaction products increase, decrease, or remain the same?2 CO2(g) ⇌ 2 CO(g) + O2(g)

For the following equilibria, use Le Châtelier's principle to predict the direction of the reaction when the pressure is increased by decreasing the volume of the equilibrium mixture.C(s) + H2O(g) ⇌ CO(g) + H2(g)

The reaction CO(g) + H2O(g) ⇌ CO2(g) + H2(g) has ∆H = -9.8 kcal/mol (-41 kJ/mol). Does the amount of H2 in an equilibrium mixture increase or decrease when the temperature is decreased?

The reaction H2(g) + I2(g) ⇌ 2 HI(g) has ∆H = -2.2 kcal/mol (-9.2 kJ/mol). Will the equilibrium concentration of HI increase or decrease whenH2 is removed?

The reaction Fe 3+(aq) + Cl -(aq) ⇌ FeCl 2+(aq) is endothermic. How will the equilibrium concentration of FeCl 2+ change whenCl - is precipitated by addition of AgNO3?

Many carbonate minerals are insoluble in water and appear in water pipes as 'scale.'Why is scale formation typically only a problem in hot water pipes?