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Which of these statements is the best explanation of what happens in the photoelectric effect experiment?

In an experiment done in the early 1900’s, Rutherford used a radioactive source to bombard a thin sheet of gold foil with a narrow beam of alpha particles. He carefully measured where these alpha particles went after they hit the foil. Thomson’s plum pudding model was the model of the atom being used at the time. Which of the following explains what Rutherford expected to happen based on Thomson’s model, and why he expected these results?

When a very large number of electrons are sent through the slits, which of these statements best depicts what is observed?

When a single electron is sent through the slits, which of these images best depicts what is observed?

A beam of light from a red laser is allowed to pass through two very closely spaced narrow slits and then fall on a screen (or photographic film). No attempt to measure the light is made before it hits the screen. It produces a series of red spots separated by areas where there is no light, as this picture shows. What does this experiment and pattern demonstrate about the behavior of light? Image Description Five red spots in a horizontal line. The third spot in the middle is the largest. The two spots on either side of the middle get smaller as you move away from the center.

Electrons are sent one at a time through a single slit. This slit is about the width of an atom. The slit can be adjusted to make it wider or narrower. Each electron is later detected using a screen that produces a spot of light wherever it is hit by a charged particle. If the slit is made narrower in an attempt to know exactly where each electron is when it passes through the slit, how does this affect the results?

  In the picture, a sound wave moves from the top of the page towards the bottom and passes through a small hole in a barrier (point 2 on the diagram).  The light areas represent regions of low pressure, and the dark areas represent high pressure.  The following questions ask you to use your understanding of wave behavior to explain what is happening at certain points.    Image Description horizontal evenly spaced bands of dark and light that extend from the top to a barrier with a hole. The distance between two adjacent white bands is labeled 1, the hole is labeled 2. In the next three questions, use your understanding of wave behavior to explain what is happening at certain points.

When you compare the volumes of Na, Mg, and Li atoms which of these statements is correct?

Almost 70 million animals are sacrificed annually in research labs across the nation. Among these are about half a million dogs, nearly 200,000 cats, and over 30,000 chimps plus millions of mice, rabbits, guinea pigs, goats, sheep, and even birds. Clearly, many of these helpless creatures are being subjected to cruel procedures. Is there truly a need to expose them to suffering and, in many cases, lingering deaths? Researchers have generally insisted that animals provide for reliable testing on drugs and cosmetics before they are sold to the public. Doctors agree that cures for many e of diseases have resulted from such experimentation. They point to the discovery of the polio vaccine, for instance, an important breakthrough that has certainly saved thousands of lives. The polio vaccine was made possible through the use of animal testing. Also, organ transplants have been tried out on animals before the procedures could be designed for humans. Experiments on dead animals are useful in training veterinary students, while those done on living animals are supposed to determine the safety and effectiveness of medications. Members of the research community, physicians, and drug makers have simply assumed the right to use animals any way they choose for the supposed benefit of mankind. Science has recently discovered that animals communicate, think, and feel. Some species even demonstrate altruism within their social groups. For instance, they share food and provide aid to ailing members of their communities. A few chimps and gorillas have learned simple sign language. Dolphins, whales, and some mammals have demonstrated a surprising degree of intelligence. Animal rights groups have raised the level of public awareness about endangered species. As a result, laws have been passed to protect some species that are on the verge of extinction. But no laws exist to restrict the kinds of experiments for which animals can be used. Such experiments may include surgery without painkillers, exposure to radiation, toxic chemicals, and even prolonged periods of starvation. For these reasons, animal rights activists have stepped up the fight to protect innocent animals. What have been the results of many of these tortuous experiments? Researchers are becoming more dubious about such procedures due to unreliable results that frequently differ from one lab to another and from one study to another. Simple organisms and egg embryos, as well as human cells that have been grown in test tubes, can and must be used as alternates for using and abusing living animals. The reader may infer that

  Dehydration is a worldwide problem. Even in the U.S., it has been suggested that nearly ¾ of the population live in a chronically dehydrated condition while being totally unaware of the problem. The effects of dehydration include a slowing down of the metabolism, increased fatigue, joint and back pain, loss of memory, as well as loss of mental focus. Imbibing 8 to 10 glasses of water daily, on the other hand, can mitigate joint pain, improve memory, and relieve some headaches. Drinking a glass of water when hunger pangs occur can even aid in dieting by silencing hunger pangs and speeding up metabolism. Researchers have discovered that taking in 5 or more glasses of water daily cuts the risk of colon cancer by almost 50% and the risk of breast cancer by about 80%.             Coke, on the other hand, is the preferred drink of millions of Americans. They are largely ignorant of the characteristics of this common beverage. Few, for instance, know that steak placed in a container of Coke will be dissolved in two days or less. Coke has been used to clean corrosion off the terminals of car batteries, to remove rust from chrome auto parts, and to remove grease from dirty clothing. Additionally, the citric acid in Coke makes it an ideal toilet bowl cleaner. Phosphoric acid in Coke is able to dissolve nails. In fact, those who consume the most Coke are at significantly greater chance of developing osteoporosis, a bone-wasting disease that makes bones brittle and easy to break. Based on the passage, drinking water