For them following reactions, the δh° rxn is not equal to δh°f for the product except for

a) 3mg(s)+n2(g)—> mg3n2(s)
b) 2ca(s)+o2(g)—> 2cao(s)
c)c2h2(g)+h2(g)—> c2h4(g)
d) 2c(graphite)+o2(g)—> 2co(g)
e) c(diamond)+o2(g)—> co2(g)

ill try to . no promises tho.

explanation:

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%