Any radical in which the unpaired electron is on a carbon that is attached to a carbon-carbon double bond is an allylic radical. for example, the structure here is an allylic radical. this radical has another resonance structure. complete the other resonance structure by dragging bonds and electrons to their appropriate positions.

It's either 3 or that ,,but if not than choose 4

Answer ozone (o3) is made of three atoms of oxygen, it is a molecule;

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 -