Q: The ordovician-silurian extinction event is the first recorded mass extinction and the second largest. during this period, about what percent of marine species went extinct? Read this paragraph and choose the correct option from the provided answers: The Ordovician-Silurian extinction event is the first recorded mass extinction and the second largest. During this period, about 85 percent of marine species (few species lived outside the oceans) became extinct. The main hypothesis for its cause is a period of glaciation and then warming. The extinction event actually consists of two extinction events separated by about 1 million years. The first event was caused by cooling, and the second event was due to the subsequent warming. The climate changes affected temperatures and sea levels. Some researchers have suggested that a gamma-ray burst, caused by a nearby supernova, is a possible cause of the Ordovician-Silurian extinction. The gamma-ray burst would have stripped away. Choices: - 10 percent - 99 percent - 40 percent - 85 percent A:
85 percent

Q: Gases are most ideal at high temperature and what pressure? Read this paragraph and choose the correct option from the provided answers: Under what conditions then, do gases behave least ideally? When a gas is put under high pressure, its molecules are forced closer together as the empty space between the particles is diminished. A decrease in the empty space means that the assumption that the volume of the particles themselves is negligible is less valid. When a gas is cooled, the decrease in kinetic energy of the particles causes them to slow down. If the particles are moving at slower speeds, the attractive forces between them are more prominent. Another way to view it is that continued cooling the gas will eventually turn it into a liquid and a liquid is certainly not an ideal gas anymore (see liquid nitrogen in the Figure below ). In summary, a real gas deviates most from an ideal gas at low temperatures and high pressures. Gases are most ideal at high temperature and low pressure. Choices: - absolute - high - stable - low A:
low

Q: Q: A fish's stream-lined body that reduces water resistance is an example of what kind of response to an aquatic lifestyle? Read this paragraph and choose the correct option from the provided answers: Many structures in fish are adaptations for their aquatic lifestyle. For example, fish have a stream-lined body that reduces water resistance while swimming. Choices: - natural selection - retraction - evolution - adaptation A:
A: adaptation

Question: Q: What type of waves start when a source of energy causes a disturbance in the medium? Read this paragraph and choose the correct option from the provided answers: Mechanical waves are waves that transfer energy through matter, called the medium. Mechanical waves start when a source of energy causes a disturbance in the medium. Types of mechanical waves include transverse, longitudinal, and surface waves. Choices: - fluid waves - mechanical currents - magnetic waves - mechanical waves A:
Answer: mechanical waves

*Question*
Q: What are the most dramatic, sudden, and dangerous types of mass wasting? Read this paragraph and choose the correct option from the provided answers: Landslides are the most dramatic, sudden, and dangerous types of mass wasting. Landslides are sudden falls of rock; by contrast, avalanches are sudden falls of snow. Choices: - earthquakes - monsoons - volcanoes - landslides A:
**Answer**
landslides

*Question*
Q: What creates charged regions in a water molecule? Read this paragraph and choose the correct option from the provided answers: Choices: - nonpolar bonds - ionic bonds - noncovalent bonds - polar covalent bonds A:
**Answer**
polar covalent bonds