6. Below is a table comparing atoms of different elements. Write your answer for box "a" below
*

And can somebody explain an easy way to solve questions like this?

The answer is true for your question.

Ithink it’s carbon dioxide

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 -