Answer the following question given this paragraph: Depending on the surrounding conditions, normal matter usually exists as one of three phases: solid, liquid, or gas. A phase change is a physical process in which a substance goes from one phase to another. Usually the change occurs when adding or removing heat at a particular temperature, known as the melting point or the boiling point of the substance. The melting point is the temperature at which the substance goes from a solid to a liquid (or from a liquid to a solid). The boiling point is the temperature at which a substance goes from a liquid to a gas (or from a gas to a liquid). The nature of the phase change depends on the direction of the heat transfer. Heat going into a substance changes it from a solid to a liquid or a liquid to a gas. Removing heat from a substance changes a gas to a liquid or a liquid to a solid. Two key points are worth emphasizing. First, at a substance's melting point or boiling point, two phases can exist simultaneously. Take water (H2O) as an example. On the Saylor URL: http://www. saylor. org/books. Q: Depending on the surrounding conditions, normal matter usually exists as one of three phases: solid, liquid, or this? A:

OPTIONS:
- fluid
- crystal
- ice
- gas

Answer: gas

Answer the following question given this paragraph: Thick fur and a layer of blubber keep polar bears warm in their Arctic ecosystem. Why do you think their fur is white? Why might it be an adaptation in an Arctic biome?. Q: What 2 things keep polar bears warm in their arctic ecosystem? A:

OPTIONS:
- hibernation, thick fur
- colourful fur , blubber
- camouflage, blubber
- thick fur, blubber

Answer: thick fur, blubber

Answer the following question given this paragraph: An object will not change its state of motion (i. e. , accelerate) unless an unbalanced force acts on it. Equal and oppositely directed forces on the same object do not produce acceleration. Q: An unbalanced force on an object in motion causes what? A:

OPTIONS:
- agitation
- velocity
- vibration
- acceleration

Answer: acceleration

Answer the following question given this paragraph: Metal exposed to the outside elements will usually corrode if not protected. The corrosion process is a series of redox reactions involving the metal of the sculpture. In some situations, the metals are deliberately left unprotected so that the surface will undergo changes that may enhance the esthetic value of the work. Q: What process typically occurs to metal exposed to outside elements? A:

OPTIONS:
- shrinkage
- extraction
- explosion
- corrosion

Answer:
corrosion