Consider the balanced equation.

n2 + 3h2 --> 2nh3

what is the percent yield of nh3 if the reaction of 26.3 g of h2 produces 79.0 g of nh3?

 The balanced reaction that describes the reaction between hydrogen and nitrogen to produce ammonia is expressed 3H2 + N2 = 2NH3. The yield of the reaction is equal to the actual amount of product divided to the theoretical amount of product multiplied by 100 percent. 26.3 grams of H2 theoretically produces149 grams. The yield is 79 divided by 149 equal to 53.02 percent. 

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 think it's c. i'm not sure but i think so.