In a covalent bond between identical atoms, the electrons are shared between the atoms. If the atoms are not identical, the electron distribution is so that the electrons are closer to one atom than the other. This type of bond is called a(n) covalent bond. Listen to the complete question

A.(nh4)(2co3)is the correct answer 

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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 -