How does the amount of butane mixed in propane affect container pressure?

Mixing butane with propane can indeed influence the container pressure, particularly at varying temperatures. When butane is added to propane, it can raise the pressure within a container, especially at specific temperatures. This is due to the different properties of butane compared to propane; butane has a higher boiling point (approximately 31°F or -0.5°C) than propane (which boils at about -44°F or -42°C).

As the temperature increases, the vapor pressure of butane contributes to the total pressure in the container. This means that as the temperature rises, the vapor pressure generated by the mixture of propane and butane will result in a higher overall pressure within the tank. Hence, the ability of butane to boil and produce vapor at certain temperatures can lead to an increase in pressure, making this the correct choice.

In the context of the other options, while the addition of butane does impact pressure, it does not decrease it or leave it unaffected. Additionally, while butane can stabilize temperature to some degree due to its different properties, the primary relation of butane affecting container pressure rests on temperature changes rather than temperature stabilization alone.