instruction:
You are given a background paragraph that describes one or more causal or qualitative relationships such as a relationship in economics or a scientific law and a story that makes use of the concepts or the relationship described in the provided paragraph. You need to come up with a question about the story that requires an understanding of the relationship described in the background paragraph. The generated question should not be answerable without both the background and story. Write a question about the story that requires a relationship in the background paragraph to answer. Check whether your question requires both the background paragraph and the story to answer. If your question can be answered by only one of these, try to rewrite your question so that it requires both. Note that "flipping" a word in the question can give rise to a new question where the answer will be different from the original question. Often, "flipping" a word gives rise to flipping the direction of the relationship, for example, from "increase" to "decrease."
question:
Background Paragraph: A major use for petroleum products is fuel for cars, trucks, airplanes, trains, and other vehicles. The chemical used are usually a mixture of compounds containing several carbon atoms in a chain. When the material is ignited, a massive amount of gas is created almost instantaneously. This increase in volume will move the pistons in an internal combustion engine to provide power. A jet plane works on a similar principle. Air comes into the front of the engine and mixes with the jet fuel. This mixture is ignited and the gases formed create a lot of pressure to push the plane forward. The idea can be seen even more clearly in the case of a rocket launch. The ignition of the fuel (either solid-state or liquid) creates gases produced under great pressure that pushes the rocket up. 
Story: Two engineering students learned about petroleum products, While Dan learned more about plastics, Jim learned about fuels.
answer:
Which student learned less about air mixing with the jet fuel?


question:
Background Paragraph: The epidermis also contains melanocytes, which are cells that produce melanin. Melanin is the brownish pigment that gives skin much of its color. Everyone has about the same number of melanocytes, but the melanocytes of people with darker skin produce more melanin. The amount of melanin produced is determined by heredity and exposure to UV light, which increases melanin output. Exposure to UV light also stimulates the skin to produce vitamin D. Because melanin blocks UV light from penetrating the skin, people with darker skin may be at greater risk of vitamin D deficiency. 
Story: Jacob has lived in a city in Sweden for most of his life. His favorite hobbies are reading and playing videogames so he rarely goes outside. Even as a kid, he almost never played outside and instead was in his house most of the time. Martin lives in the middle of the Sahara desert in a small town. The sun almost never stops beating down on Martin during the day and it's hard to find shade where he lives.
answer:
Is Jacob more or less likely than Martin to have a vitamin D deficiency?


question:
Background Paragraph: Collision theory tells us that molecules need to collide in order for a reaction to take place. All else being equal, anything that increases the frequency of collisions would also increase the rate of reaction. One way to do this is to increase the concentrations of one or more of the reactants. Using a real world example, a busy freeway will experience much more frequent car collisions than a fairly empty neighborhood street. Similarly, forcing more randomly moving molecules into the same amount of space will cause an increased number of collisions over a given length of time, providing the reactants with more opportunities to transform into products. 
Story: John is a chemical engineer with a pharmaceutical company. He is trying to develop a drug that can be absorbed by the system in different rates. To that end, he conducted two experiments. In one case, he used lower concentrations of reactants, he called it case A. Then he used the same reactants in a higher concentration. He called it case B.
answer:

In case A, would the frequency of collisions be higher or lower than in case B?