Answer the following question given this paragraph: Summary Chemistry is the study of matter and the changes material substances undergo. It is essential for understanding much of the natural world and central to many other scientific disciplines, including astronomy, geology, paleontology, biology, and medicine. Q: What is the name of the science that studies matter and the changes material substances undergo? Choices: - geology - physics - biology - chemistry A:
chemistry
Answer the following question given this paragraph: This picture shows a thick layer of smog and dust over a very polluted city (Singapore). Smog in the air is a serious health hazard for people living in many big cities around the globe. Smog is one example of air pollution. Q: Smog is one example of what type of pollution? Choices: - light - energy - sound - air A:
air
Q: Answer the following question given this paragraph: Fossils are the remains or traces of living organisms. Q: What is the term for the remains or traces of living organisms? Choices: - remains - ethings - deposits - fossils A:
A: fossils
Question: Answer the following question given this paragraph: Hurricanes are cyclones. Since they form in the tropics, they are called tropical cyclones. These storms form over very warm ocean water in summer and autumn. The temperature of the sea surface must be 28 o C (82 o F) or higher. The air above the water warms and rises. This forms a low pressure cell. The air begins to rotate around the low pressure cell. Water vapor condenses. If conditions are right, the storm will build into a hurricane in two to three days. Q: Hurricanes that form in the tropics are called what? Choices: - rain cyclones - tornados - caribbean cyclones - tropical cyclones A:
Answer: tropical cyclones
*Question*
Answer the following question given this paragraph: All solutions contain at least two substances. Q: All solutions contain at least how many substances? Choices: - one - four - three - two A:
**Answer**
two
(Q).
Answer the following question given this paragraph: 20.5 Alternating Current versus Direct Current Alternating Current Most of the examples dealt with so far, and particularly those utilizing batteries, have constant voltage sources. Once the current is established, it is thus also a constant. Direct current (DC) is the flow of electric charge in only one direction. It is the steady state of a constant-voltage circuit. Most well-known applications, however, use a time-varying voltage source. Alternating current (AC) is the flow of electric charge that periodically reverses direction. If the source varies periodically, particularly sinusoidally, the circuit is known as an alternating current circuit. Examples include the commercial and residential power that. Q: "direct" and "alternating" are two kinds of what, which is associated with electricity? Choices: - time - constant - levels - current A:
(A).
current