2. A student is writing a report on the properties of fluorine. She decides to include a brief section about other elements that are similar to fluorine. In order to find similar elements, she looks up where fluorine is located on the periodic table of elements shown below.

The student wants to select the elements similar to fluorine.

Which of the following sets of elements should be included?

3. In the 1800s, pure aluminum metal was so valuable that it was worth as much as gold! Now, aluminum is relatively cheap and can be used to make all sorts of products, like the aluminum cans shown below. To avoid using very large numbers, or very small numbers, people choose a unit appropriate to the scale of the object. The mass of only one can could be measured in grams, but the large block of recycled cans would more likely be measured in kilograms.

Which of the following units would be most appropriate for measuring mass at the scale of a single aluminum atom?

4. Limonene is a colorless chemical that is commonly found in citrus fruits. It has two forms: Rlimonene, which smells like oranges, and S-limonene, which smells like lemons. Both forms of limonene have exactly the same number of carbon, hydrogen, and oxygen atoms.

Which of the following is the most likely explanation for why the two forms of limonene smell different?

5. A student was playing with a molecular model kit, and built the molecule shown below. According to her science teacher, she had just built the molecular model for acetone (C₃H₆O), the main chemical in nail polish remover. Her teacher then challenged her to build the molecular model for isopropanol (C₃H₈O), also known as rubbing alcohol.

Using the same colored balls as the ones in the model shown above, how many of each would be needed to build the predicted molecular model for isopropanol?

6. A scientist decides to use X-ray crystallography to examine a sample of sodium chloride (also known as table salt) that he recently made in his laboratory. He also decides to use this technique to look at a sample of sodium chloride that he extracted from seawater.

How will the X-ray crystallography patterns of the two samples compare?

7. While decorating for a family party, a student decides to put floating candles in the backyard fountain. Interested in why the candles can float in the first place, she decides to look at molecular models for candle wax and water.

Which of the following best explains why the candles can float on water?

Investigation A

Two students are interested in seeing how the solubility of sugar and salt in water can be affected by the temperature of the water. For their experiment, each student measures six 100 milliliter samples of water at the following temperatures: 0℃, 20℃, 40℃, 60℃, 80℃, and 100℃. The first student measures how many grams of sugar can be dissolved in his six samples of water, while the second student measures how many grams of salt can be dissolved in her six samples of water. They then plotted their data on the graph shown below.

8. Based on the provided graph, how does the solubility of sugar and salt change as the temperature of water increases?

9. The students have a friend at a different school who they ask to confirm their results by repeating their experiment. He repeats their experiment at his own school by using their procedures. However, he is surprised to find that all of his values are higher than the values reported by his friends at the other school.

Which of the following best describes what the third student can do to obtain results that are more consistent with the data obtained by his friends?

10. Vinegar is an ingredient commonly used by chefs. Scientists also use it as well, although they call it acetic acid. When vinegar is in its liquid or solid (frozen) states, it has a fixed volume. But when vinegar is in its gas state, it takes up the entire volume of whatever container it is in. This is why you can smell an open bottle of vinegar the minute you walk into a kitchen, even though you cannot actually see the gas particles!

Which statement best explains why the volume of vinegar gas is changeable as opposed to the fixed volume of its solid and liquid states?

11. Mercury is a fascinating element. Of all the metal elements, mercury is the only one that is liquid at room temperature; the rest are all solid. However, mercury is also capable of existing in the solid state.

Which set of conditions would most likely cause mercury to exist in the solid state?

13. Kamal is stuck at home on a hot day. The air conditioning system in his home is broken, so he does online research to find another way to cool down the house. One source advises that he open all of the house’s windows, although it also warns him that this idea may not always work.

In which of the following situations would it be most recommended to open all of the house’s windows?

Investigation A

Most people agree that when parking a car in sunlight for several hours, leaving the car windows slightly open can help keep the car’s internal temperature slightly lower than keeping the car windows closed. Two teenagers with identical cars wanted to see if this was also true when parking for shorter periods of time, such as a quick stop at a gas station.

To test this idea out, the teenagers parked their cars outside in direct sunlight. One car kept its windows open and the other car kept its windows closed. They then tracked their cars’ internal temperatures over a period of 30 minutes, and then plotted their data in the graph shown below.

14. According to the provided graph, at what times are the internal temperatures of both cars the same?

15. The teenagers present the data they collected to their science teacher, who compliments them for doing a good job. However, she points out that they should try to improve the design of their experiment to make their data more valid and reliable.

Which of the following changes would make their data more reliable?

16. For a class experiment, a student needs to separate a mixture of salt crystals, sulfur powder, and iron filings. To do this, she first runs a magnet over the mixture to extract the iron. She then adds water to the remaining mixture to dissolve the salt, after which she filters out the sulfur. She finally boils off the water to leave behind salt crystals.

At which point during this procedure did a chemical reaction occur?

17. Based on the provided diagram, which of the following conditions is used to initiate the reaction?

18. The scientist noticed that at the end of the combustion analysis, a colorless and odorless gas was coming out of the device. However, she does not know if that gas is just oxygen gas or a mixture of oxygen and additional gases (that may contain other elements).

What could she do to determine if the gas coming out of the device is just oxygen gas or a mixture of gases?

19. Think about eating and digestion as a model for what happens during chemical reactions. When you eat foods, the foods undergo chemical reactions.

What can you say about the products after digestion compared to the “reactants” (foods) that you ate?

21. An ice pack is activated and placed on a person’s wrist. After the resulting chemical reaction, the average temperature of the hands-icepack system is lower.

Which of the following statements best completes a statement about the transfer of energy in this chemical reaction?

22. When a candle burns, a chemical reaction occurs changing wax and oxygen into carbon dioxide and water vapor. The average temperature of the candle-room system increases.

Which of the following statements best completes a statement about the transfer of energy in this chemical reaction?

23. Pictured below is an electrolysis device used to separate hydrogen and oxygen from water. Notice there is twice as much hydrogen as oxygen in the test tubes. The battery supplies energy to separate the gasses. Later, by burning, the gasses combined back into water vapor.

Which statement best describes the flow of energy in this process?

24. Medications can react with each other to result in negative side-effects. James’ grandfather has just been prescribed a new medication. He asks James for help doing Internet research to find out if his new medicine will react with other medicines he already takes.

Which of the following sources is likely to provide the most reliable information about the medicine?

25. You are verifying the research in the table. You have found three different sources which contain information about these six color additives: a blog run by a chef, a report written by a scientist, and an article in a national newspaper.

Which lists the three sources in order from most to least reliable?

26. Your friend Tyler says that all synthetic color additives contain the same molecules as natural color additives and they only differ in how they are made.

What extra research should you do, and what sources should you use to evaluate her claim?