(i) Cis - 2 - butene → trans-2-butene, △H1
(ii) Cis - 2 - butene → 1 - butene, △H2
(iii) Trans-2-butene is more stable than cis - 2 - butene.
(iv) Enthalpy of combustion of 1 - butene, △H=−649.8 kcal/mol
(v) 9△H1+5△H2=0
(vi) Enthalpy of combustion of trans 2 - butene, △H=−647.0 kcal/mol.
The value of △H1 and △H2 in kcal/mol are