Problem: Two students were learning about atmospheres and planets. Dan learned about the atmosphere of Earth, while Nate learned about planet Venus and its atmosphere. Which student learned less about the planet with a hotter surface temperature? Hint: Clouds on Earth are made of water vapor. Venus's clouds are a lot less pleasant. They are made of carbon dioxide, sulfur dioxide and large amounts of corrosive sulfuric acid! The atmosphere of Venus is so thick that the pressure on the surface of Venus is very high. In fact, it is 90 times greater than the pressure at Earth's surface! The thick atmosphere causes a strong greenhouse effect. As a result, Venus is the hottest planet. Even though it is farther from the Sun, Venus is much hotter even than Mercury. Temperatures at the surface reach 465C (860F). That's hot enough to melt lead!

A: Dan

Problem: Robert, a baker, has just baked a large batch of cupcakes for his store. He won't be able to sell all of his cupcakes within the next week, so he has decided to store a portion of them in the freezer to preserve them for later. He is trying to decide if he should store the cupcakes at 0 F or at 10 F in the freezer. Which temperature will result in slower growth of micro-organisms on the cupcakes? Hint: Freezing is a common method of food preservation that slows both food decay and the growth of micro-organisms. Besides the effect of lower temperatures on reaction rates, freezing makes water less available for bacterial growth.

A: 0 F

Problem: Two friends went camping and made a fire each. Bill used a few large logs while Tim used kindlings, wood chips and sawdust. they both brought the same volume of wood. Which friend didn't make a fire that burned slower? Hint: A large log placed in a fire will burn relatively slowly. If the same mass of wood were added to the fire in the form of small twigs, they would burn much more quickly. This is because the twigs provide a greater surface area than the log does. An increase in the surface area of a reactant increases the rate of a reaction. Surface area is larger when a given amount of a solid is present as smaller particles. A powdered reactant has a greater surface area than the same reactant as a solid chunk. In order to increase the surface area of a substance, it may be ground into smaller particles or dissolved into a liquid. In solution, the dissolved particles are separated from each other and will react more quickly with other reactants.

A: Tim

Problem: Scientists are observing two of the same gases at different temperatures. They are observing the speed of the particles in the gases to see how fast they are moving. Gas A has particles moving very quickly, but Gas B has particles that are hardly moving at all. Which gas is at a higher temperature? Hint: We discussed earlier some basic principles about the behavior of gases called the kinetic-molecular theory. Among other things, this theory suggests that gas molecules are in constant motion, and the average speed of the individual gas particles is dependent upon temperature the higher the temperature, the faster the molecules move. It is not just gas particles that are in constant motion. The molecules and ions that make up liquids and solutions are also continually moving in nearly random directions. As a result, molecules and ions in a solution will collide with one another fairly frequently. As with gases, a temperature increase will produce an increase in the average particle speed.

A:
Gas A