Which of the following equations represents the correct thermochemical reaction for the combustion of 1 mole of ethyne?
a) C2H2 + 2.5 O2 -> 2 CO2 + H2O
b) 2 C2H2 + 5 O2 -> 4 CO2 + 2 H2O
c) C2H2 + 3 O2 -> 2 CO2 + H2O
d) C2H2 + 2 O2 -> 2 CO2 + 2 H2O