Agem has a mass of 4.50 g. when the gem is placed in a graduated cylinder 12.00 ml of water, the water level rises to 13.45 ml.

Displaced volume :

Final volume - Initial volume

13.45 mL - 12.00 mL => 1.45 mL

Mass =  4.50 g

Therefore:

density = mass / volume

D = 4.50 / 1.45

D = 3.103 g/mL 

Its a hope this

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 -