Magnesium has 2 valence electrons, and oxygen has 6 valence electrons. which type of bonding is likely to occur between a magnesium atom and an oxygen atom?
ionic—magnesium will give 2 electrons to oxygen, and both will become ions.
ionic—oxygen will give 2 electrons to magnesium, and both will become ions.
metallic—oxygen and magnesium atoms will be surrounded by a pool of electrons.

answer: the enthalpy of the overall chemical reaction is +87.88 kj or +88 kj.

according to hess's law, the overall enthalpy of a reaction is the difference between the sum of enthalpy values of all the products and the sum of enthalpy values of all the reactants.

δh(reaction) = ∑nδh(products) - ∑nδh(reactants)

δh(reaction) = [δh +δh] - [δh]

δh(reaction) = [1(-287.02) + 1(0) ] - [1(-374.9)] kj = +87.88 kj

here, δh (pcl3) = -287.02 kj, δh(cl2) = 0, δh(pcl5) = -374.9 kj

therefore, enthalpy of the overall reaction is +87.88 kj or +88 kj.

the correct answer to this question is 2