The increasing order of boiling points of the following compounds is :

Lattice enthalpy and enthalpy of solution of NaCl are 788 kJ mol^–1, and 4 kJ mol^–1, respectively.
The hydration enthalpy of NaCl is :

The rate constant (k) of a reaction is measured at differenct temperatures (T), and the data are plotted in the given figure. The activation energy of the reaction in kJ mol^–1 is :
(R is gas constant)

The compound that has the largest H–M–H bond angle (M = N, O, S, C) is :