Scientists are finding more and more evidences of water in the outer space. Earth has mostly liquid water. But that's not the case with other celestial objects. Venus has some water, but it is in gaseous state. On the other hand, water in Jupiter's moon Europa is in frozen state. In which place the state of water is in lower density, Earth or Europa? Hint: Hydrogen bonds cause water to have a relatively high boiling point of 100C (212F). Because of its high boiling point, most water on Earth is in a liquid state rather than in a gaseous state. Water in its liquid state is needed by all living things. Hydrogen bonds also cause water to expand when it freezes. This, in turn, causes ice to have a lower density (mass/volume) than liquid water. The lower density of ice means that it floats on water. For example, in cold climates, ice floats on top of the water in lakes. This allows lake animals such as fish to survive the winter by staying in the water under the ice.
Ans: Europa

Rob is competing in a cross country race. After running about a mile he reached a place with two signs, sign A and sign B. Sign A says that it's a quicksand. But sign B says that it's not a quicksand. He has to decide which way to go. Would sign B have liquefied soil or not have liquefied soil? Hint: Quicksand forms in saturated loose sand when the sand is suddenly agitated. When water in the sand cannot escape, it creates a liquefied soil that loses strength and cannot support weight. Quicksand can form in standing water or in upwards flowing water (as from an artesian spring). In the case of upwards flowing water, forces oppose the force of gravity and suspend the soil particles. The saturated sediment may appear quite solid until a sudden change in pressure or shock initiates liquefaction. This causes the sand to form a suspension and lose strength. The cushioning of water gives quicksand, and other liquefied sediments, a spongy, fluid-like texture. Objects in liquefied sand sink to the level at which the weight of the object is equal to the weight of the displaced soil/water mix and the submerged object floats due to its buoyancy.
Ans: not have liquefied soil

Austria had two distinct climactic regions. The eastern region was exposed to a wet climate and had thriving vegetation, while the western region was exposed to drought. Which region had more plants consistently exposed to drought? Hint: One interesting thing that has been found in plants that are consistently exposed to drought, is their ability to form a sort of "memory". In a study by Tombesi et al., they found plants who had previously been exposed to drought were able to come up with a sort of strategy to minimize water loss and decrease water use. They found that plants who were exposed to drought conditions actually changed they way the regulated their stomates and what they called "hydraulic safety margin" so as to decrease the venerability of the plant. By changing the regulation of stomata and subsequently the transpiration, plants were able to function better in situations where the availability of water decreased.
Ans: western

Ted and Larry studied environmental sciences. They are learning about greenhouse gasses this week. Ted reads about carbon dioxide, while Larry reads about methane gas. Which student read less about ocean acidification? Hint: Carbon dioxide is the most significant long-lived greenhouse gas in Earth's atmosphere. Since the Industrial Revolution anthropogenic emissions primarily from use of fossil fuels and deforestation have rapidly increased its concentration in the atmosphere, leading to global warming. Carbon dioxide also causes ocean acidification because it dissolves in water to form carbonic acid.
Ans: Larry