Problem: Given the question: John is a nuclear scientist who works at the Fermi lab. Today, in front of him he has four samples, sample A, sample B, sample C, and sample D. Sample A is the naturally occurring uranium. Sample B is enriched uranium. Sample C is the U-238, and sample D is the U-235. He needs to figure out how to best use them. Which smaple would not be fissionable, sample C or sample D? Hint: Naturally occurring uranium is composed almost entirely of two isotopes, uranium-238 (99%) and uranium-235 (1%). It is the uranium-235 that is fissionable (will undergo fission) and therefore, this is the uranium isotope than can be used for fuel in a nuclear reactor. For uranium to be used as fuel, the percent of uranium-235 must be increased to at least 3%. Uranium in which the U-235 content is more than 1% is called enriched uranium. Somehow, the two isotopes must be separated so that enriched uranium is available for use as fuel. Separating the isotope by chemical means (chemical reactions) is not successful because the isotopes have exactly the same chemistry. The only essential difference between U-238 and U-235 is their atomic masses; as a result, the two isotopes are separated by a physical means that takes advantage of the difference in mass.
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The answer is:
sample C

input question: Dan studied two islands. Loon island had a very stable environment, and there weren't many diverse species of plants and animals. Wolf island displayed lots of evidence for natural selection, and had a large variety of species inhabiting it. Which island had animals that displayed more beneficial heritable traits? Hint: New species develop naturally through the process of natural selection . Due to natural selection, organisms with traits that better enable them to adapt to their environment will tend to survive and reproduce in greater numbers. Natural selection causes beneficial heritable traits to become more common in a population and unfavorable heritable traits to become less common. For example, a giraffe's neck is beneficial because it allows the giraffe to reach leaves high in trees. Natural selection caused this beneficial trait to become more common than short necks.???
output answer: Wolf

Two countries are situated on the shores of the same sea. Turkey is a nation of farmers, they use conventional agricultural methods to produce food, including lots of fertilizers. Greece's economy is mostly based on tourism. Which country causes the entry into the sea of more potentially hazardous particles? Hint: Marine pollution is a generic term for the entry into the ocean of potentially hazardous chemicals or particles. The biggest culprits are rivers and with them many agriculture fertilizer chemicals as well as livestock and human waste. The excess of oxygen-depleting chemicals leads to hypoxia and the creation of a dead zone.Marine debris, which is also known as marine litter, describes human-created waste floating in a body of water. Oceanic debris tends to accumulate at the center of gyres and coastlines, frequently washing aground where it is known as beach litter.
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Answer: Turkey

Q: Barbara and Jane are two students. They both like meteorology. Barbara studies the formation of the ozone layer, while Jane studies about the stratosphere. Which student learned more about temperature inversion? Hint: The mechanism describing the formation of the ozone layer was described by British mathematician Sydney Chapman in 1930. Molecular oxygen absorbs high energy sunlight in the UV-C region, at wavelengths shorter than about 240 nm. Radicals produced from the homolytically split oxygen molecules combine with molecular oxygen to form ozone. Ozone in turn is photolysed much more rapidly than molecular oxygen as it has a stronger absorption that occurs at longer wavelengths, where the solar emission is more intense. Ozone (O3) photolysis produces O and O2. The oxygen atom product combines with atmospheric molecular oxygen to reform O3, releasing heat. The rapid photolysis and reformation of ozone heats the stratosphere resulting in a temperature inversion. This increase of temperature with altitude is characteristic of the stratosphere; its resistance to vertical mixing means that it is stratified. Within the stratosphere temperatures increase with altitude (see temperature inversion); the top of the stratosphere has a temperature of about 270 K (3C or 26.6F). This vertical stratification, with warmer layers above and cooler layers below, makes the stratosphere dynamically stable: there is no regular convection and associated turbulence in this part of the atmosphere. However, exceptionally energetic convection processes, such as volcanic eruption columns and overshooting tops in severe supercell thunderstorms, may carry convection into the stratosphere on a very local and temporary basis. Overall the attenuation of solar UV at wavelengths that damage DNA by the ozone layer allows life to exist on the surface of the planet outside of the ocean. All air entering the stratosphere must pass through the tropopause, the temperature minimum that divides the troposphere and stratosphere. The rising air is literally freeze dried; the stratosphere is a very dry place. The top of the stratosphere is called the stratopause, above which the temperature decreases with height.
A: Jane

Question: Due to increased carbon dioxide in the atmosphere more an more carbon dioxide is mixing with ocean water - thus increasing the acidity of the world's oceans. Rob is a climate scientist. He is measuring the acidity of the Atlantic ocean and the Pacific Ocean. To determine ocean water acidity he performed an acid-base titration. His conclusion is that Atlantic Ocean's acidity reached higher level than Pacific Ocean's acidity. In which ocean's acidity test Rob would have to add less base, Atlantic Ocean or Pacific ocean? Hint: To determine the concentration of an acid in an aqueous solution, an acid-base titration is commonly performed. A strong base solution with a known concentration, usually NaOH or KOH, is added to neutralize the acid solution according to the color change of the indicator with the amount of base added.[7] The titration curve of an acid titrated by a base has two axes, with the base volume on the x-axis and the solution's pH value on the y-axis. The pH of the solution always goes up as the base is added to the solution.
Answer: Pacific Ocean

Please answer this: John an Keith are coworkers in a chemistry lab. Yesterday, they conducted there tests, test A, test B, and test C. In test A, John kept a substance in solid state, but Keith changed the same substance from solid to liquid state. In test B, John conducted a chemical reaction in low temperature, but Keith conducted the same chemical reaction in high temperature. Finally, in test C, John kept an unstable material in room temperature, but Keith kept the same unstable material in a cool container. In test A, whose substance would have higher temperature, John or Keith? Hint: Temperature is a measure of the average kinetic energy of the particles in matter. In everyday usage, temperature indicates a measure of how hot or cold an object is. Temperature is an important parameter in chemistry. When a substance changes from solid to liquid, it is because there was an increase in the temperature of the material. Chemical reactions usually proceed faster if the temperature is increased. Many unstable materials (such as enzymes) will be viable longer at lower temperatures.
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Answer:
Keith