Answer:
93%
Explanation:
First write the balanced reaction
C3H8 + 5O2 --> 3CO2 +4H2O
2nd, find the theoretical yield
2L C3H8 (1mol/22.4L) (3 mol CO2/1 molC3H8) (22.4 L/ 1mol) = 6L
3rd, Find percent yield
%yield = (actual / theoretical) x100 = (5.7/6) x 100 = 93%