When 1 mole of crystalline NaCl is obtained from sodium and chlorine gas, 410 kJ of heat is released. The heat of sublimation of sodium metal is 108 kJ mol–l and Cl-Cl bond enthalpy is 242 kJ mol–l . If the ionization energy of Na is 493.0 kJ mol–l and the electron affinity of chlorine is 368 kJ mol–l , the lattice energy of NaCl is
a. 764 kJ mol-l
b. -764 kJ mol-l
c. 885 kJ mol-l
d. -885 kJ mol-l