The table shows bond energies for some diatomic molecules. Deuterium, D, is an isotope of hydrogen. [Table with columns "bond", "energy /kJ mol⁻¹" and rows "F-F 158", "Cl-Cl 242", "Br-Br 193", "I-I 151", "H-H 436", "D-D 442"] Which statements are correct? 1 Diatomic molecules have exact values for their bond energies, which are always positive. 2 The trend in Group 7 bond energies can be explained by the variation in instantaneous dipole-induced dipole (id-id) forces. 3 A value for the enthalpy change for the reaction between deuterium and chlorine can be calculated using these data alone.