Changes of state from solid to liquid and from liquid to gas occur when matter gains energy. The energy allows individual molecules to separate and move apart from one another. It takes more energy to bring about these changes of state for polar molecules. Although hydrogen bonds are weak, they add to the energy needed for molecules to move apart from one another, so it takes higher temperatures for these changes of state to occur in polar compounds. This explains why polar compounds have relatively high melting and boiling points. The Table below compares melting and boiling points for some polar and nonpolar covalent compounds. Andrew is thirsty and wants some cold water. He puts a bottle in the freezer but leaves it in too long so it freezes. Being impatient he then takes the bottle and runs it under soe hot water for a few minutes. Will the water molecules lose energy or gain energy when put in the freezer?
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Answer: lose

Rain dissolves fertilizer in the soil. Runoff carries it away. The fertilizer ends up in bodies of water, from ponds to oceans. Nitrogen is a fertilizer in the water. Since there is a lot of nitrogen, it causes algae to grow out of control. Pictured below is a pond covered with algae ( Figure below ). Algae use up carbon dioxide in the water. After the algae die, decomposers break down the dead tissue. The decomposers use up all the oxygen in the water. This creates a dead zone. A dead zone is an area in a body of water where nothing grows because there is too little oxygen. There is a large dead zone in the Gulf of Mexico ( Figure below ). The U.S. states outlined on the map have rivers that drain into the Gulf of Mexico. The rivers drain vast agricultural lands. The water carries fertilizer from these areas into the Gulf. Park farm and Fiddle farm provided Red city with tonnes of produce annually. Fiddle farm used and abundance of fertilizers and pesticides, while Park farm didn't use any of those substances. Which farm caused more fertilizer to dissolve in the soil because of rain?
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Answer: Fiddle

Mass is a measure of the amount of matter in a substance or an object. The basic SI unit for mass is the kilogram (kg), but smaller masses may be measured in grams (g). To measure mass, you would use a balance. In the lab, mass may be measured with a triple beam balance or an electronic balance, but the old-fashioned balance pictured below may give you a better idea of what mass is. If both sides of this balance were at the same level, it would mean that the fruit in the left pan has the same mass as the iron object in the right pan. In that case, the fruit would have a mass of 1 kg, the same as the iron. As you can see, however, the fruit is at a higher level than the iron. This means that the fruit has less mass than the iron, that is, the fruit's mass is less than 1 kg. Johnathan is trying to find two blocks of wood with the same mass for a project he is working on. He doesn't have a balance, so he makes a crude one out of materials he has on hand. He put a block of wood on either side and the block on the left side was at a lower level than the block on the right. If Johnathan wanted to both sides to be at an equal level would he need more or less mass on the left side?
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Answer:
less