Identify arrows pointing to bonding electrons. An upper H is single bonded to an upper C, which is bonded to an upper O with pairs of dots above an below, which is bonded to an upper H. The upper C is double bonded above to an upper O, which has pairs of dots to the right and left. Arrow A points to the double bond, arrow B to the single bond between H and C, Arrow C to the dots below the O, and arrow D to the bond between O and H.

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 -

Heat of fusion= heat/mass  heat of fusion = 12.03kj/36 g= 0.3342 kj/g or 334.2 j/g