Q: What is the term for a solution that resists dramatic changes in ph? Read this paragraph and choose the correct option from the provided answers: As indicated in Section 12.4 "Strong and Weak Acids and Bases and Their Salts", weak acids are relatively common, even in the foods we eat. But we occasionally encounter a strong acid or base, such as stomach acid, which has a strongly acidic pH of 1.7. By definition, strong acids and bases can produce a relatively large amount of H+ or OHions and consequently have marked chemical activities. In addition, very small amounts of strong acids and bases can change the pH of a solution very quickly. If 1 mL of stomach acid [approximated as 0.1 M HCl(aq)] were added to the bloodstream and no correcting mechanism were present, the pH of the blood would decrease from about 7.4 to about 4.7a pH that is not conducive to continued living. Fortunately, the body has a mechanism for minimizing such dramatic pH changes. The mechanism involves a buffer, a solution that resists dramatic changes in pH. Buffers do so by being composed of certain pairs of solutes: either a weak acid plus a salt derived from that weak acid or a weak base plus a salt of that weak base. For example, a buffer can be composed of dissolved HC2H3O2 (a weak acid) and NaC2H3O2 (the salt derived from that weak acid). Another example of a buffer is a solution containing NH3 (a weak base) and NH4Cl (a salt derived from that weak base). Let us use an HC2H3O2/NaC2H3O2 buffer to demonstrate how buffers work. If a strong basea source of OH(aq) ionsis added to the buffer solution, those OH ions will react with the HC2H3O2 in an acid-base reaction:. Choices: - inert - neutral - stable - buffer A:
buffer

Q: A highway that switches back and forth as it climbs up a steep hillside, yeilding a much gentler slope, is an example of what simple machine? Read this paragraph and choose the correct option from the provided answers: The highway above switches back and forth as it climbs up the steep hillside. The much gentler slope of the road makes it easier for vehicles to reach the top of the mountain. The highway is an example of an inclined plane. Choices: - lever - pulley - wheel - inclined plane A:
inclined plane

Q: The uranium series is a chain constituting one what, which encompass naturally occurring isotopes of the heaviest elements? Read this paragraph and choose the correct option from the provided answers: Radioactive Decay Series The naturally occurring radioactive isotopes of the heaviest elements fall into chains of successive disintegrations, or decays, and all the species in one chain constitute a radioactive family, or radioactive decay series. Three of these series include most of the naturally radioactive elements of the periodic table. They are the uranium series, the actinide series, and the thorium series. The neptunium series is a fourth series, which is no longer significant on the earth because of the short half-lives of the species involved. Each series is characterized by a parent (first member) that has a long half-life and a series of daughter nuclides that ultimately lead to a stable end-productthat is, a nuclide on the band of stability (Figure 21.9). In all three series, the end-product is a stable isotope of lead. The neptunium series, previously thought to terminate with bismuth-209, terminates with thallium-205. Choices: - nuclear decay family - gland decay family - fuel decay family - radioactive decay family A:
radioactive decay family

Q: What is the shorter loop of the cardiovascular system? Read this paragraph and choose the correct option from the provided answers: Pulmonary circulation is the shorter loop of the cardiovascular system. It carries blood between the heart and lungs. Oxygen-poor blood flows from the heart to the lungs. In the lungs, the blood absorbs oxygen and releases carbon dioxide. Then the oxygen-rich blood returns to the heart. Choices: - pulmonary edema - venous circulation - metabolic circulation - pulmonary circulation A:
pulmonary circulation