input: OPTIONS:
- bottom to top
- right to left
- left to right
- top to bottom Now, answer this question: Answer the following question given this paragraph: The halogens are among the most reactive of all elements, although reactivity declines from the top to the bottom of the halogen group. Because all halogens have seven valence electrons, they are "eager" to gain one more electron. Doing so gives them a full outer energy level, which is the most stable arrangement of electrons. Halogens often combine with alkali metals in group 1 of the periodic table. Alkali metals have just one valence electron, which they are equally "eager" to donate. Reactions involving halogens, especially halogens near the top of the group, may be explosive. You can see some examples in the video at the URL below. ( Warning: Don't try any of these reactions at home!). Q: In which order does the reactivity of halogen group decline? A:
A:
output: top to bottom

Answer the following question given this paragraph: Chemical reactions follow the laws of thermodynamics. Q: Chemical reactions follow the laws of what? A:

OPTIONS:
- Newton
- quantum physics
- photosynthesis
- thermodynamics

Answer: thermodynamics

Problem: OPTIONS:
- hydrogen
- oxygen
- monoxide
- carbon
Q: Answer the following question given this paragraph: Carbon is one of the most common elements found in living organisms. Chains of carbon molecules form the backbones of many organic molecules, such as carbohydrates, proteins, and lipids. Carbon is constantly cycling between living organisms and the atmosphere ( Figure below ). The cycling of carbon occurs through the carbon cycle . Q: Which common element is the most found in living organisms? A:
Answer: carbon

Problem:OPTIONS:
- density dependent limitation
- containing capacity
- niche
- carrying capacity

Answer the following question given this paragraph: Overcoming Density-Dependent Regulation Humans are unique in their ability to alter their environment with the conscious purpose of increasing its carrying capacity. This ability is a major factor responsible for human population growth and a way of overcoming density-dependent growth regulation. Much of this ability is related to human intelligence, society, and communication. Humans can construct shelter to protect them from the elements and have developed agriculture and domesticated animals to increase their food supplies. In addition, humans use language to communicate this technology to new generations, allowing them to improve upon previous accomplishments. Other factors in human population growth are migration and public health. Humans originated in Africa, but have since migrated to nearly all inhabitable land on the Earth. Public health, sanitation, and the use of antibiotics and vaccines have decreased the ability of infectious disease to limit human population growth. In the past, diseases such as the bubonic plaque of the fourteenth century killed between 30 and 60 percent of Europe's population and reduced the overall world population by as many as 100 million people. Today, the threat of infectious disease, while not gone, is certainly less severe. According to the World Health Organization, global death from infectious disease declined from 16.4 million in 1993 to 14.7 million in 1992. To compare to some of the epidemics of the past, the percentage of the world's population killed between 1993 and 2002 decreased from 0.30 percent of the world's population to 0.24 percent. Thus, it appears that the influence of infectious disease on human population growth is becoming less significant. Q: Humans are unique in their ability to alter their environment with the conscious purpose of increasing what, which acts as a limiting factor on populations in general? A:
****
A: carrying capacity

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? A:
OPTIONS:
- carbon
- helium
- nitrogen
- hydrogen
hydrogen

Answer the following question given this paragraph: Making healthy lifestyle choices can help prevent some types of cancer. For example, you can reduce your risk of lung cancer by not smoking. You can reduce your risk of skin cancer by using sunscreen (see Figure below ). Q: Choosing to not smoke and using sunscreen are examples of lifestyle choices that help prevent forms of what disease? A:
OPTIONS:
- pnemonia
- bacterial disease
- viral disease
- cancer

Answer:
cancer