Neon has 10 electrons and krypton has 18 electrons which element do you think has a greater chance of forming a momentary dipole and why

krypton has more electrons, and it would have the greater chance of forming a momentary dipole.

The number of electrons in each of the atom affect momentary dipole.

Momentary dipole is one of the London dispersion forces.  It is non-uniform distribution of electrons around a molecule, resulting in a temporary charge difference between its ends.

The number of electron in atom affects its polarization and the higher the number of electrons in an atom, the more easily the electron will move. krypton has more electrons, and it would have the greater chance of forming a momentary dipole.

Learn more about momentary dipole here: link

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.

it's all four options.