Answer the following question given this paragraph: Isotopes of Hydrogen Hydrogen, the most abundant element in the universe, is the ultimate source of all other elements by the process of nuclear fusion. (For more information on nuclear fusion, seeChapter 20 "Nuclear Chemistry". ) Table 21.2 "The Isotopes of Hydrogen" compares the three isotopes of hydrogen, all of which contain one proton and one electron per atom. The most common isotope is protium (1H or H), followed by deuterium (2H or D), which has an additional neutron. The rarest isotope of hydrogen is tritium (3H or T), which is produced in the upper atmosphere by a nuclear reaction when cosmic rays strike nitrogen and other atoms; it is then washed into the oceans by rainfall. Tritium is radioactive, decaying to 3He with a half-life of only 12.32 years. Consequently, the atmosphere and oceans contain only a very low, steadystate level of tritium. The termhydrogen and the symbol H normally refer to the naturally occurring mixture of the three isotopes. Table 21.2 The Isotopes of Hydrogen. Q: What is the most abundant element in the universe? Choices: - carbon - helium - nitrogen - hydrogen A:
hydrogen
(Question)
Answer the following question given this paragraph: From the stirrup, the vibrations pass to the oval window . This is another membrane like the eardrum. Q: How many pi bonds are found in a triple bond? Choices: - 10 - six - four - two A:
(Answer)
two
Ques: Answer the following question given this paragraph: Plants maintain the atmosphere. They produce oxygen and absorb carbon dioxide during photosynthesis. Oxygen is essential for cellular respiration for all aerobic organisms. It also maintains the ozone layer that helps protect Earth's life from damaging UV radiation. Removal of carbon dioxide from the atmosphere reduces the greenhouse effect and global warming. Q: The ozone layer protects the earth from what? Choices: - pollution - light waves - radio waves - uv radiation A:
Ans: uv radiation
(Q).
Answer the following question given this paragraph: The Linnaean system of classification consists of a hierarchy of groupings, called taxa (singular, taxon). Taxa range from the kingdom to the species (see Figure below ). The kingdom is the largest and most inclusive grouping. It consists of organisms that share just a few basic similarities. Examples are the plant and animal kingdoms. The species is the smallest and most exclusive grouping. It consists of organisms that are similar enough to produce fertile offspring together. Closely related species are grouped together in a genus. Q: What do we call the system of classification consisting of a hierarchy of groupings called taxa? Choices: - lamarckian system - linchpin system - crocodilian system - linnaean system A:
(A).
linnaean system
Ques:Answer the following question given this paragraph: Not really. Like all mammals, polar bears maintain a stable internal temperature. They do not need to stay warm by lying in the sun. This allows them to live in cold climates. Q: The ability to maintain a stable internal temperature, despite the climate, is exhibited by members of what animal group? Choices: - fish - parasites - reptiles - mammals A:

Ans:mammals
Ques:Answer the following question given this paragraph: Q: What are the poles labeled? Choices: - west and south - southwest and south - east and west - north and south A:

Ans:
north and south