2hci + na2so4 -> 2 naci + h2so4

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 -

Burned piece of steel wool does not gain mass. so only d could be true.

Moles = mass/molar mass by this formula 458/207+32 you should get your answer the ans. is 1.916 mol to 4 sig. fig.