Answer
(a) Shifts to left.
(b) Shifts to right.
(c) Shifts to left.
(d) Do not affect.
(e) Shifts to right.
Work Step by Step
(a) Exothermic reaction, increasing temperature favors reactants.
(b) Increasing pressure favors the side with the least amount of moles of gases, which is the products in this case.
(c) Adding a reactant favors products.
(d) A catalyst do not affect equilibrium.
(e) Since volume is constant, helium is increasing the amount of molecules in that space, leaving less room for the reactants and products, which will increase the total pressure. Increasing the pressure in this case favors products, as explained in (b).
$$PV = nRT$$
If V and T are constant, if n increases, P must increase as well.
