input: OPTIONS:
- erosion fuels
- renewable fuels
- greenhouse gases
- fossil fuels Now, answer this question: Answer the following question given this paragraph: Outdoor air pollution is made of chemical particles. When smoke or other pollutants enter the air, the particles found in the pollution mix with the air. Air is polluted when it contains many large toxic particles. Outdoor air pollution changes the natural characteristics of the atmosphere. Primary pollutants are added directly to the atmosphere. Fires add primary pollutants to the air. Particles released from the fire directly enter the air and cause pollution ( Figure below ). Burning of fossil fuels such as oil and coal is a major source of primary pollutants ( Figure below ). Q: A major source of primary pollutants is the burning of oil and coal, which are types of what? A:
A:
output: fossil fuels

Answer the following question given this paragraph: Fish also have a centralized nervous system with a brain. Fish brains are small compared with the brains of other vertebrates, but they are large and complex compared with the brains of invertebrates. Fish also have highly developed sense organs that allow them to see, hear, feel, smell, and taste. Sharks and some other fish can even sense the very low levels of electricity emitted by other animals. This helps them locate prey. Q: Why do sharks sense low levels of electricity? A:

OPTIONS:
- to locate mates
- to sleep
- to reproduce
- to locate prey

Answer: to locate prey

Problem: OPTIONS:
- two
- none
- three
- one
Q: Answer the following question given this paragraph: Our solar system has only one star. But many stars are in systems of two or more stars. Two stars that orbit each other are called a binary star system . If more than two stars orbit each other, it is called a multiple star system. Figure below shows two binary star systems orbiting each other. This creates an unusual quadruple star system. Q: How many stars are in our solar system? A:
Answer: one

Problem:OPTIONS:
- no purpose
- attracting mates
- attracting predators
- warning predators

Answer the following question given this paragraph: Poison dart frogs have toxins in their skin. Their bright colors warn potential predators not to take a bite!. Q: The bright color of poison dart frogs serves what purpose? A:
****
A: warning predators

Answer the following question given this paragraph: Pure Substances and Mixtures A pure chemical substance is any matter that has a fixed chemical composition and characteristic properties. Oxygen, for example, is a pure chemical substance that is a colorless, odorless gas at 25C. Very few samples of matter consist of pure substances; instead, most are mixtures, which are combinations of two or more pure substances in variable proportions in which the individual substances retain their identity. Air, tap water, milk, blue cheese, bread, and dirt are all mixtures. If all portions of a material are in the same state, have no visible boundaries, and are uniform throughout, then the material is homogeneous. Examples of homogeneous mixtures are the air we breathe. Q: What type of substance is any matter that has a fixed chemical composition and characteristic properties? A:
OPTIONS:
- physical substance
- versatile chemical substance
- seawater chemical substance
- pure chemical substance
pure chemical substance

Answer the following question given this paragraph: Outdoor air pollution is made of chemical particles. When smoke or other pollutants enter the air, the particles found in the pollution mix with the air. Air is polluted when it contains many large toxic particles. Outdoor air pollution changes the natural characteristics of the atmosphere. Primary pollutants are added directly to the atmosphere. Fires add primary pollutants to the air. Particles released from the fire directly enter the air and cause pollution ( Figure below ). Burning of fossil fuels such as oil and coal is a major source of primary pollutants ( Figure below ). Q: A major source of primary pollutants is the burning of oil and coal, which are types of what? A:
OPTIONS:
- erosion fuels
- renewable fuels
- greenhouse gases
- fossil fuels

Answer:
fossil fuels