Answer: The enthalpy of combustion, per mole, of butane is -2657.4 kJ
Explanation:
The balanced chemical reaction is,
The expression for enthalpy change is,
Putting the values we get :
2 moles of butane releases heat = 5314.8 kJ
1 mole of butane release heat = 
Thus enthalpy of combustion per mole of butane is -2657.4 kJ
I think it’s 2.45, not 100% sure
As you go down a group on the periodic table, atomic radii tend to increase because elements with larger atomic numbers have more occupied electron levels which take up more space surrounding the nucleus.
I hope this helps.