Answer
(a) $C(s)$ being a solid substance there is no effect on equilibrium.
(b) $H_2O$ being a reactant, the reaction shifts to the left side.
(c) $CO$ being a product, the reaction shifts to the left side.
(d) $H_{2}$ being a product, the reaction shifts right side.
Work Step by Step
(a) According to Le Chatelier's Principle when a solid substance(reactant/product) is added to the reaction mixture there is no effect on equilibrium.So the reaction neither shift left nor shift right and remain unchanged.
(b) According to Le Chatelier's Principle, when reactant is removed from reaction mixture the reaction will shift toward left(reactants).Here $H_2O$ is condenced and removed so the reaction will move towards left.
(c) According to Le Chatelier Principle when a product is added to a reaction mixture the equilibrium will move towards left side(reactant).
(d) According to Le Chetelier Principle when a product is removed from a equilibrium mixture then the reaction will move towards right side(product).
