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

Is the yield of SO3 at equilibrium favored by a higher or lower pressure? By a higher or lower temperature?2 SO2(g) + O2 ⇌ 2 SO3(g) ∆H = -47 kcal/mol

What effect do the listed changes have on the position of the equilibrium in the reaction of carbon with hydrogen?C(s) + 2 H2(g) ⇌ CH4(g) ∆H = -18 kcal/mol (-75kJ/mol)Increasing temperature

What effect do the listed changes have on the position of the equilibrium in the reaction of carbon with hydrogen?C(s) + 2 H2(g) ⇌ CH4(g) ∆H = -18 kcal/mol (-75kJ/mol)Increasing pressure by decreasing volume

What effect do the listed changes have on the position of the equilibrium in the reaction of carbon with hydrogen?C(s) + 2 H2(g) ⇌ CH4(g) ∆H = -18 kcal/mol (-75kJ/mol)Allowing CH4 to escape continuously from the reaction vessel

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 whenA catalyst is added?