Answer the following question given this paragraph: Radioactive decay is the breakdown of unstable isotopes into stable elements. For example, carbon-14 is an unstable isotope of carbon that decays to the stable element nitrogen-14. The rate of decay of an isotope is measured in half-lives. A half-life is the time it takes for half a given amount of an isotope to decay. Q: What is the term for the breakdown of unstable isotopes into stable elements? Choices: - isotopic decay - radioactive decrease - secondary decay - radioactive decay A:
radioactive decay
Answer the following question given this paragraph: Temperature decreases in the mesosphere with altitude. This is because the heat source is the stratosphere. Q: What part of the atmosphere is the heat source? Choices: - troposphere - magnetosphere - ionosphere - stratosphere A:
stratosphere
Q: Answer the following question given this paragraph: Most protists are aquatic organisms. They need a moist environment to survive. They are found mainly in damp soil, marshes, puddles, lakes, and the ocean. Some protists are free-living organisms. Others are involved in symbiotic relationships. They live in or on other organisms, including humans. Q: Most protists are aquatic organisms and need what kind of environment to survive? Choices: - dry - warm - cold - moist A:
A: moist
Question: Answer the following question given this paragraph: Both temperature and pressure have an effect on the phase in which a given substance exists. A plot of temperature vs. pressure that indicates the states of matter present at each point is known as a phase diagram . Figure below shows the phase diagram for water. Q: A phase diagram plots temperature and what else? Choices: - friction - power - movement - pressure A:
Answer: pressure
*Question*
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? Choices: - two - none - three - one A:
**Answer**
one
Answer the following question given this paragraph: The branch of biology that studies animal behavior is called ethology. Ethologists usually study how animals behave in their natural environment. They try to determine the cause of behaviors, how behaviors develop, and how and why behaviors evolve. Q: Which branch of biology studies animal behavior? Choices: - microbiology - anthropology - embryology - ethology A:
ethology