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:
current
Answer the following question given this paragraph: Many chemicals that we use on a daily basis are transported in a concentrated form but used in a more diluted form. For example, concentrated cleaners are often diluted before they are used. To perform a dilution , pure solvent is added to a concentrated solution in order to make a less concentrated (more dilute) solution. The resultant solution will contain the same amount of solute but a greater amount of solvent. It will therefore have a lower concentration than the original solution. When performing a simple dilution, the concentration and volume of the initial solution are related to the new concentration and volume as follows:. Q: The resultant solution will contain the same amount of solute but a greater amount of what? Choices: - calcium - liquid - pigment - solvent A:
solvent
Q: Answer the following question given this paragraph: El Nino and La Nina bring about dramatic changes in climate for a year or two. In some locations, one brings rain and the other brings drought. In California, for example, El Nino years are full of snow and rain. La Nina years tend toward drought. These variations can bring tremendous changes to living creatures. Humans are also affected; for example, erosion from storms may be very high some years. Q: What kind of weather change do la nina years usually bring? Choices: - heat - Mass amounts of snow - moisture - drought A:
A: drought
Question: Answer the following question given this paragraph: Figure 6.6 Water behind a dam has potential energy. Moving water, such as in a waterfall or a rapidly flowing river, has kinetic energy. (credit "dam": modification of work by "Pascal"/Flickr; credit "waterfall": modification of work by Frank Gualtieri). Q: Water behind a dam has potential energy. moving water, such as in a waterfall or a rapidly flowing river, has this? Choices: - residual energy - thermal energy - compression energy - kinetic energy A:
Answer: kinetic energy
*Question*
Answer the following question given this paragraph: A third important type of soil is laterite . Laterite forms in tropical areas. Temperatures are warm and rain falls every day ( Figure below ). So much rain falls that chemical weathering is intense. All soluble minerals are washed from the soil. Plant nutrients get carried away. There is practically no humus. Laterite soils are often red in color from the iron oxides. If laterites are exposed to the Sun, they bake as hard as a brick. Q: What causes the red color of laterite soils? Choices: - oxygen - toxins - erosion - iron oxides A:
**Answer**
iron oxides
*Question*
Answer the following question given this paragraph: Overview of Systemic Veins Systemic veins return blood to the right atrium. Since the blood has already passed through the systemic capillaries, it will be relatively low in oxygen concentration. In many cases, there will be veins draining organs and regions of the body with the same name as the arteries that supplied these regions and the two often parallel one another. This is often described as a "complementary" pattern. However, there is a great deal more variability in the venous circulation than normally occurs in the arteries. For the sake of brevity and clarity, this text will discuss only the most commonly encountered patterns. However, keep this variation in mind when you move from the classroom to clinical practice. In both the neck and limb regions, there are often both superficial and deeper levels of veins. The deeper veins generally correspond to the complementary arteries. The superficial veins do not normally have direct arterial counterparts, but in addition to returning blood, they also make contributions to the maintenance of body temperature. When the ambient temperature is warm, more blood is diverted to the superficial veins where heat can be more easily dissipated to the environment. In colder weather, there is more constriction of the superficial veins and blood is diverted deeper where the body can retain more of the heat. The "Voyage of Discovery" analogy and stick drawings mentioned earlier remain valid techniques for the study of systemic veins, but veins present a more difficult challenge because there are numerous anastomoses and multiple branches. It is like following a river with many tributaries and channels, several of which interconnect. Tracing blood flow through arteries follows the current in the direction of blood flow, so that we move from the heart through the large arteries and into the smaller arteries to the capillaries. From the capillaries, we move into the smallest veins and follow the direction of blood flow into larger veins and back to the heart. Figure 20.35... Q: Systemic veins return blood low in what to the right atrium? Choices: - dioxide - nutrients - nitrogen - oxygen A:
**Answer**
oxygen