An exothermic reaction X $$ \to $$ Y has an activation energy 30 kJ mol^$$-$$1. If energy change $$\Delta$$E during the reaction is $$-$$20 kJ, then the activation energy for the reverse reaction in kJ is ___________. (Integer answer)

Five moles of an ideal gas at 293 K is expanded isothermally from an initial pressure of 2.1 MPa to 1.3 MPa against at constant external pressure 4.3 MPa. The heat transferred in this process is _________ kJ mol^$$-$$1. (Rounded off to the nearest integer) [Use R = 8.314 J mol^$$-$$1K^$$-$$1]

The reaction of cyanamide, NH₂CN_(s) with oxygen was run in a bomb calorimeter and $$\Delta$$U was found to be $$-$$742.24 kJ mol^$$-$$1. The magnitude of $$\Delta$$H₂₉₈ for the reaction

$$N{H_2}C{H_{(S)}} + {3 \over 2}{O_{2(g)}} \to {N_{2(g)}} + {O_{2(g)}} + {H_2}{O_{(I)}}$$

is _________ kJ. (Rounded off to the nearest integer) [Assume ideal gases and R = 8.314 J mol^$$-$$1 K^$$-$$1]

The ionization enthalpy of Na⁺ formation from Na_(g) is 495.8 kJ mol^$$-$$1, while the electron gain enthalpy of Br is $$-$$325.0 kJ mol^$$-$$1. Given the lattice enthalpy of NaBr is $$-$$728.4 kJ mol^$$-$$1. The energy for the formation of NaBr ionic solid is ($$-$$) ____________ $$\times$$ 10^$$-$$1 kJ mol^$$-$$1.