Answer the following question given this paragraph: It is hard to overstate the importance of hydrocarbons to modern life. Hydrocarbons have even been called the driving force of western civilization. You saw some ways they are used in Figure above . Several other ways are illustrated in Figure below . Their most important use is as fuels. Gasoline, natural gas, fuel oil, diesel fuel, jet fuel, coal, kerosene, and propane are just some of the hydrocarbon compounds that are burned for fuel. Hydrocarbons are also used to manufacture many products, including plastics and synthetic fabrics such as polyester. Q: What compounds, which serve as fuels and are used in manufacturing, are called the driving force of western civilization? Choices: - forests - fossils - gas - hydrocarbons A:
hydrocarbons
Answer the following question given this paragraph: 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:. Q: What is the term for a solution that resists dramatic changes in ph? Choices: - inert - neutral - stable - buffer A:
buffer
Q: Answer the following question given this paragraph: In catalysis, if a molecule forms strong bonds to the catalyst, then the catalyst may become poisoned. Experiments on various catalysts showed the following results: a. Fe, Ru, and Os form weak bonds with N2; however, O2, alkynes, alkenes, CO, H2, and CO2 interact more strongly. CO2 and H2 form weak bonds with a Co or Ni surface. Rh, Pd, Ir, and Pt form weak bonds with H2 but do not bond with CO2. Cu, Ag, and Au form weak bonds with CO and ethylene. Explain why Fe was chosen as a catalyst to convert nitrogen and hydrogen to ammonia. Why is Fe more suitable than Ru or Os? f. Because alkenes generally interact more strongly with metal surfaces than does H 2, what catalyst would you choose for hydrogenation of an alkene such as ethylene? g. Although platinum is used in catalytic converters for automobile exhaust, it was not found to be a particularly effective catalyst for the reaction of H2 with a mixture of carbon monoxide and carbon dioxide to produce methane. Why? h. If you were interested in developing a catalyst to reversibly bind ethylene, which of the catalysts listed here would you choose? 14. Nonstoichiometric metal oxides can be effective catalysts for oxidationreduction reactions. One such catalyst is Ni1xO, found to be effective for converting CO to CO2when oxygen is present. Why is it so effective? 15. The chemical reactions in an organism can be controlled by regulating the activity of certain enzymes. Efficient regulation results in an enzyme being active only when it is needed. For example, if a cell needed. Q: What happens if a molecule forms strong bonds to the catalyst? Choices: - molecules gets poisoned - surface gets poisoned - membrane gets poisoned - catalyst gets poisoned A:
A: catalyst gets poisoned
Question: Answer the following question given this paragraph: Even compounds with the same number of carbon and hydrogen atoms can have different shapes. These compounds are called isomers . Look at the examples in Figure below . The figure shows the structural formulas of butane and its isomer iso -butane. Both molecules have four carbon atoms and ten hydrogen atoms (C 4 H 10 ), but the atoms are arranged differently. Butane is a straight-chain molecule. Iso -butane is branched. You can see three-dimensional models of these two isomers at the URLs below. You can rotate the molecule models to get a better idea of their shapes. Q: What are compounds with the same number of carbon and hydrogen atoms called? Choices: - alcohols - hydrocarbons - monomers - isomers A:
Answer: isomers
*Question*
Answer the following question given this paragraph: Nails are similar to claws in other animals. They cover the tips of fingers and toes. Fingernails and toenails both grow from nail beds. As the nail grows, more cells are added at the nail bed. Older cells get pushed away from the nail bed and the nail grows longer. There are no nerve endings in the nail. Otherwise cutting your nails would hurt a lot!. Q: Nails cover the tips of what? Choices: - lips and teeth - fingers and lips - ribs and nerves - fingers and toes A:
**Answer**
fingers and toes
*Question*
Answer the following question given this paragraph: Temperature is the quantity measured by a thermometer. Temperature is related to the average kinetic energy of atoms and molecules in a system. Absolute zero is the temperature at which there is no molecular motion. There are three main temperature scales: Celsius, Fahrenheit, and Kelvin. Temperatures on one scale can be converted to temperatures on another scale using the following equations:. Q: What does a thermometer measure? Choices: - oxygen - precipitation - size - temperature A:
**Answer**
temperature