Which answer best describes the transfer of heat that occurs when 1.40 mol of H2 reacts?

In order to determine the energy changes involved, we require the reaction. The reaction under consideration in this question is

2H₂ + O₂ → 2H₂O, ΔH = - 484 kJ/mol

We see that if 2 moles of hydrogen react, 484 kJ of energy are released. We may use a ratio to determine the amount of energy released when 1.8 moles of hydrogen react:

2 : 484

1.8 : x

x = 435.6

435.6 kilojoules of energy are released when 1.8 moles of hydrogen react.