I just took a test with this question and got the answer wrong for saying ethane. The correct answer is propane.
Answer:
When the concentration of all the reactants increases, more molecules or ions interact to form new compounds, and the rate of reaction increases. When the concentration of a reactant decreases, there are fewer of that molecule or ion present, and the rate of reaction decreases.
Who cares. Joe can solve his own problem instead of making people do it. (This was not toward you. This was supposed to be funny)