Atoms are known to form charges due to their ability to gain and lose electrons in reactions. As a result, atoms become ions that are positively or negatively charged depending on the loss or gain of electrons. Which of the following atoms has a charge of +2 given the number of electrons?

The answer for this is a

1) according to the law of conservation of mass ,in all chemical reactions total mass is unchanged

The answer is solid copper 

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 -