An atom's mass number indicates a
the number of protons in the nucleus of an atom.
b
the number of neutrons in the nucleus of an atom.
c
the sum of the neutrons and electrons in the nucleus of an atom.
d
the sum of the neutrons and protons in the nucleus of an atom.
e
the charge of that atom's ion.

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.

i would say b

explanation:

but i think i would need more information than that