Bond enthalpies (kJ/mol): H-H 436; F-F 159, Cl-Cl 243, Br-Br 193, I-I 151; H-F 568, H-Cl 431, H-Br 366, H-I 299. For $\mathrm{H}{}_2(\mathrm{g})+\mathrm{X}{}_2(\mathrm{g})\to 2\mathrm{HX}(\mathrm{g})$, select the correct statement(s).

1. AThe enthalpy change for $\mathrm{X}=\mathrm{F}$ is more negative than $-500\mathrm{kJ}$.
2. BThe reaction is endothermic for $\mathrm{X}=\mathrm{I}$.
3. CThe enthalpy change for $\mathrm{X}=\mathrm{Cl}$ is more negative than $-200\mathrm{kJ}$.
4. DThe enthalpy change becomes progressively less negative from $\mathrm{X}=\mathrm{F}$ to $\mathrm{X}=\mathrm{I}$.