For the following reaction ΔH° = 176 kJ and ΔG° = 91.2 kJ at 298 K. What is the value of ΔG at 1000 K? NH₄Cl(s) → NH₃(g) + HCl(g)
a) -64 kJ
b) 64 kJ
c) 109 kJ
d) -109 kJ