Molecular mass of welding gas = 11.6 x 22.4/10 = 25.98
CO2 and H2O are obtained from welding gas combustion in water.
g-atoms of C in gas = 3.38/44 = 0.077
g-atoms of H in gas = 0.690 x 2/18 = 0.077
Ratio of C and H atoms in gas is 1 : 1
Thus, empirical formula of welding gas is CH
Empirical formula mass of welding gas = 13
Molecular mass = (empirical formula mass) x n
n = 25.98/13 = 2
Molecular formula = 2 x empirical formula = 2 x (CH) = C2H2