Cyclopropane and oxygen at partial pressures $170 \ torr$ and $570 \ torr$ respectively are mixed in a gas cylinder. What is the ratio of the number of moles of cyclopropane to the number of moles of oxygen $(n_{C_3H_6}/n_{O_2})$ ?

• A
  $\frac{170 \times 42}{570 \times 32} = 0.39$
• B
  $\frac{170}{42} / (\frac{170}{42} + \frac{570}{32}) \approx 0.19$
• C
  $\frac{170}{740} = 0.23$
• D
  $\frac{170}{570} = 0.30$