page 10 18. The graph shows how the rate of a reaction varies with the concentration of a reactant. 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0 0 0.001 0.002 0.003 0.004 0.005 0.006 concentration (mol l−1) rate of reaction (1/t) (s−1) When the concentration of the reactant is 0.06 mol l−1, the reaction time is: A 0.004 s B 0.09 s C 17 s D 250 s. 19. Butene reacts with oxygen as shown. C4H8(g)  +  6O2(g)  ↓  4CO2(g)  +  4H2O(g) 100 cm3 of butene was reacted with excess oxygen. Compared with the total volume of gases before reaction, what would be the total volume of gases after complete reaction? A 100 cm3 more B 100 cm3 less C 300 cm3 more D 300 cm3 less