Given:
(i) `S+O_2 to SO_2, Delta H=-298.2 kJ`
(ii) `SO_2 + 1/2 O_2 to SO_3, Delta H=-98.7 kJ`
(iii) `SO_3 + H_2 O to H_2 SO_4, Delta H=-130.2 kJ`
(iv) `H_2 + 1/2 O_2 to H_2 O, Delta H=-287.3 kJ` ,
Then the enthalpy of formation of `H_2 SO_4` at 298 K will be _________ .