What mass of MgO is produced from 170 grams of Mg? molar masses: Mg = 24.31 g/mol, O2 = 32 g/mol, MgO = 40.31 g/mol

That is a lot of moles that you have

Answer is: the equilibrium  shifts toward the reactants, to the left side of chemical reaction.it is because lead(ii) nitrate dissociates in water: pb(no₃)₂ → pb²⁺(aq) + 2no₃⁻(aq).according to lechatelier's principle, the position of equilibrium moves to counteract thechange (more lead cations, common ion), the position of equilibrium will move so that the concentration ofproducts decrease and concentration of reactants of chemical reaction increase.read more on -