Teacher:Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.
Teacher: Now, understand the problem? Solve this instance: Remember that H2 O is a polar molecule, so it can dissolve many substances (Figure 1.1). Salts, sugars, acids, bases, and organic molecules can all dissolve in water. Where does the salt in seawater come from? As water moves through rock and soil on land it picks up ions. This is the flip side of weathering. Salts comprise about 3.5% of the mass of ocean water, but the salt content, or salinity, is different in different locations. What would the salinity be like in an estuary? Where seawater mixes with fresh water, salinity is lower than average. What would the salinity be like where there is lots of evaporation? Where there is lots of evaporation but little circulation of water, salinity can be much higher. The Dead Sea has 30% salinity nearly nine times the average salinity of ocean water (Figure 1.2). Why do you think this water body is called the Dead Sea? In some areas, dense saltwater and less dense freshwater mix, and they form an immiscible layer, just like oil and water. One such place is a "cenote", or underground cave, very common in certain parts of Central America. Ocean water is composed of many sub- stances, many of them salts such as sodium, magnesium, and calcium chlo- ride. Because of the increased salinity, the wa- ter in the Dead Sea is very dense, it has such high salinity that people can easily float in it! With so many dissolved substances mixed in seawater, what is the density (mass per volume) of seawater relative to fresh water? Water density increases as: salinity increases temperature decreases pressure increases Differences in water density are responsible for deep ocean currents, as will be discussed in the "Deep Ocean Currents" concept. Click image to the left or use the URL below. URL:
Student:
water density increases when