Answer the following question given this paragraph: Whether or not a given isotope is radioactive is a characteristic of that particular isotope. Some isotopes are stable indefinitely, while others are radioactive and decay through a characteristic form of emission. As time passes, less and less of the radioactive isotope will be present, and the level of radioactivity decreases. An interesting and useful aspect of radioactive decay is half-life, which is the amount of time it takes for one-half of a radioactive isotope to decay. The half-life of a specific radioactive isotope is constant; it is unaffected by conditions and is independent of the initial amount of that isotope. Consider the following example. Suppose we have 100.0 g of tritium (a radioactive isotope of hydrogen). It has a half-life of 12.3 y. After 12.3 y, half of the sample will have decayed from hydrogen-3 to helium-3 by emitting a beta particle, so that only 50.0 g of the original tritium remains. After another 12.3 y making a total of 24.6 yanother half of the remaining tritium will have decayed, leaving 25.0 g of tritium. After another 12.3 ynow a total of 36.9 yanother half of the remaining tritium will have decayed, leaving 12.5 g. This sequence of events is illustrated in Figure 15.1 "Radioactive Decay". Figure 15.1 Radioactive Decay. Q: Some isotopes are stable indefinitely, while others are radioactive and do what through a characteristic form of emission? Choices: - replicate - bond - expand - decay A:
decay
Answer the following question given this paragraph: Distance Although displacement is described in terms of direction, distance is not. Distance is defined to be the magnitude or size of displacement between two positions. Note that the distance between two positions is not the same as the distance traveled between them. Distance traveled is the total length of the path traveled between two positions. Distance has no direction and, thus, no sign. For example, the distance the professor walks is 2.0 m. The distance the airplane passenger walks is 4.0 m. Misconception Alert: Distance Traveled vs. Magnitude of Displacement It is important to note that the distance traveled, however, can be greater than the magnitude of the displacement (by magnitude, we mean just the size of the displacement without regard to its direction; that is, just a number with a unit). For example, the professor could pace back and forth many times, perhaps walking a distance of 150 m during a lecture, yet still end up only 2.0 m to the right of her starting point. In this case her displacement would be +2.0 m, the magnitude of her displacement would be 2.0 m, but the distance she traveled would be 150 m. In kinematics we nearly always deal with displacement and magnitude of displacement, and almost never with distance traveled. One way to think about this is to assume you marked the start of the motion and the end of the motion. The displacement is simply the difference in the position of the two marks and is independent of the path taken in traveling between the two marks. The distance traveled, however, is the total length of the path taken between the two marks. Q: What property is defined as the magnitude or size of displacement between two positions? Choices: - gravity - Distance - passing - distance A:
distance
Q: Answer the following question given this paragraph: Q: Glucocorticoids and mineralocorticoids are the two main types of what in humans? Choices: - carotenoids - metabolites - hormones - corticosteroids A:
A: corticosteroids
Question: Answer the following question given this paragraph: The Levels of Organization To study the chemical level of organization, scientists consider the simplest building blocks of matter: subatomic particles, atoms and molecules. All matter in the universe is composed of one or more unique pure substances called elements, familiar examples of which are hydrogen, oxygen, carbon, nitrogen, calcium, and iron. The smallest unit of any of these pure substances (elements) is an atom. Atoms are made up of subatomic particles such as the proton, electron and neutron. Two or more atoms combine to form a molecule, such as the water molecules, proteins, and sugars found in living things. Molecules are the chemical building blocks of all body structures. Q: All matter in the universe is composed of one or more unique pure substances called what? Choices: - atoms - molecules - compounds - elements A:
Answer: elements
*Question*
Answer the following question given this paragraph: Molar mass is equal to density multiplied by molar volume. Q: Molar mass is equal to density multiplied by what? Choices: - molar energy - molar weight - molar gravity - molar volume A:
**Answer**
molar volume
*Question*
Answer the following question given this paragraph: When additional water is added to an aqueous solution, the concentration of that solution decreases. This is because the number of moles of the solute does not change, while the volume of the solution increases. We can set up an equality between the moles of the solute before the dilution (1) and the moles of the solute after the dilution (2). Q: When additional water is added to an aqueous solution, what happens to the concentration of that solution? Choices: - doubles - no change - increases - decreases A:
**Answer**
decreases