Q: I read this background article the other day: Of the 94 naturally occurring elements, those with atomic numbers 1 through 82 each have at least one stable isotope (except for technetium, element 43 and promethium, element 61, which have no stable isotopes). Isotopes considered stable are those for which no radioactive decay has yet been observed. Elements with atomic numbers 83 through 94 are unstable to the point that radioactive decay of all isotopes can be detected. Some of these elements, notably bismuth (atomic number 83), thorium (atomic number 90), and uranium (atomic number 92), have one or more isotopes with half-lives long enough to survive as remnants of the explosive stellar nucleosynthesis that produced the heavy metals before the formation of our Solar System. At over 1.91019 years, over a billion times longer than the current estimated age of the universe, bismuth-209 (atomic number 83) has the longest known alpha decay half-life of any naturally occurring element, and is almost always considered on par with the 80 stable elements. The very heaviest elements (those beyond plutonium, element 94) undergo radioactive decay with half-lives so short that they are not found in nature and must be synthesized. I am facing a new situation today: David was studying for his chemistry exam. To understand the elements of the periodic table better he categorized them into three groups, cat A, cat B, and cat C. In cat A he placed all the elements with atomic numbers lower than 83. In cat B he put the elements with atomic numbers from 83 to 94. Finally, in cat C he placed the elements with atomic numbers over 94. He found it easier to see their differences after he categorized them. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which category would have shorter half-lives, cat B or cat C?
A: cat C
Question: I read this background article the other day: Electrons can be removed from some objects using friction, simply by rubbing one substance against another substance. There are many examples of objects becoming charged by friction, including a rubber comb through hair, and a balloon on a sweater. In both these instances, the electrons move from the second object to the first, causing the first object to become negatively charged and the second one positively charged. Friction between the tires on a moving car and the road cause the tires to become charged, and wind causes friction between clouds and air which causes clouds to become charged and can result in tremendous bolts of lightning. I am facing a new situation today: Dorothy is riding an elevator. The elevator has bristles running up the side of the tracks so her jeans are rubbing against them. When he gets to the top of the elevator she accidentally brushes a piece of metal and gets a small electric shock from it. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Will objects moving from one object to anothr cause the first to become positively charged or negatively charged?
Answer: positively
[Q]: I read this background article the other day: Demographic stochasticity refers to variability in population growth arising from sampling random births and deaths in a population of finite size. In small populations, demographic stochasticity will decrease the population growth rate, causing an effect similar to the Allee effect, which will increase the risk of population extinction. Whether or not demographic stochasticity can be considered a part of Allee effect is somewhat contentious however. The most current definition of Allee effect considers the correlation between population density and mean individual fitness. Therefore, random variation resulting from birth and death events would not be considered part of Allee effect as the increased risk of extinction is not a consequence of the changing fates of individuals within the population.Meanwhile, when demographic stochasticity results in fluctuations of sex ratios, it arguably reduces the mean individual fitness as population declines. For example, a fluctuation in small population that causes a scarcity in one sex would in turn limit the access of mates for the opposite sex, decreasing the fitness of the individuals within the population. This type of Allee effect will likely be more prevalent in monogamous species than polygynous species. I am facing a new situation today: Two small cities of identical population are both having elections this year. Although they have the same small amount of people, the city of Kilmar is experiencing demographic stochasticity while the city of Plano is not. Every time an election arises, both cities become very active with citizens coming out in droves to listen to the candidates speak at town hall meetings through the months leading up to the election. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which town is less likely to still be around several years from now?
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[A]: Kilmar
Question: I read this background article the other day: Many respiratory diseases are caused by pathogens. A pathogen is an organism that causes disease in another organism. Certain bacteria, viruses, and fungi are pathogens of the respiratory system. The common cold and flu are caused by viruses. The influenza virus that causes the flu is pictured below ( Figure below ). Tuberculosis, whooping cough, and acute bronchitis are caused by bacteria. The pathogens that cause colds, flu, and TB can be passed from person to person by coughing, sneezing, and spitting. Illnesses caused by bacteria can be treated with antibiotics. Those caused by viruses cannot. I am facing a new situation today: Martin and David are roommates in their dorm room. Martin comes down with the flu and is very sick coughing and sneezing a lot. David opts to take care of Martin, spending a lot of time with him to make sure he gets well soon. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Given David decides to stay with his parents instead of taking care of Mathew, will his chances of getting the flu increase or decrease?
Answer:
decrease