Question 2:
a C2H4+ b O2 c CO2 + H2O
Les coefficients stoechiométriques a, b, c, d valent:
a = 1; b = 2; c= 2; d = 3
a = 1; b = 3; c= 2; d=2
a=2; b = 1; c= 3; d=1
a=1; b = 2; c= 2; d= 2