This graph shows variations in temperature over the last 400 thousand years. Image Description Graph of temperature difference versus thousands of years ago. At the start of the graph, the temperature difference line begins at 0 and drops to a negative 9 difference before gradually increasing until it peaks at 5 degrees around 120 thousand years before dropping back down to a negative 9 difference and gradually increasing until it peaks at 240 thousand years. This trend of dropping and increasing continues, with two more peaks seen at 320 thousand years and 410 thousand years. Based on the natural cycles found in the graph, how far in the future will the temperature once again be as warm as it is now?

In her devotional talk, “Finding Your Place in the Universe,” Dr. Stephens compared us to stars. What point was she making with this analogy?

In which of these situations does the entropy of the universe increase?

Global temperatures have increased over the last 100 years. What evidence is there that human activities are at least partially responsible for this increase?

This is the energy diagram for the magnesium–oxygen reaction.    Image Description Graph of the magnesium-oxygen energy curve with energy (y-axis) versus the extent of reaction (x-axis). The energy line starts level then increases before reaching its peak energy around the middle of the reaction, then decreasing in energy and leveling off well below the initial energy level line. Sodium will also react with oxygen. However, unlike magnesium, sodium begins to react as soon as it is exposed to oxygen and produces very little heat and no visible light. Which of these curves best represents the sodium–oxygen reaction compared with the magnesium-oxygen reaction? (The curve for magnesium + oxygen is shown using a dotted line for reference.)    Image Description Five energy diagrams. Diagram A is as follows: The sodium-oxygen energy curve starts by increasing twice as much as the magnesium-oxygen line before reaching its peak and decreasing to below the initial energy line. The final level of sodium-oxygen energy is less than the magnesium-oxygen energy level. Diagram B is as follows: The sodium-oxygen energy curve starts by increasing more than the magnesium-oxygen line, reaching its peak a little after magnesium-oxygen before decreasing and leveling off, with its final energy above the initial energy line. The final level of sodium-oxygen energy is much greater than the magnesium-oxygen energy level. Diagram C is as follows: The sodium-oxygen energy curve starts by increasing a little then going back to the initial energy level by the middle of the reaction. The line keeps decreasing before rounding off and heading back to the initial energy line at the end of the reaction. The final level of sodium-oxygen energy is greater than the magnesium-oxygen energy level. Diagram D is as follows: The sodium-oxygen energy curve starts by increasing, but not as much as the magnesium-oxygen energy line, before rounding off and decreasing to below the initial energy line. The final level of sodium-oxygen energy is above the magnesium-oxygen energy level. Diagram E is as follows: The sodium-oxygen energy curve starts by increasing a little before decreasing a great amount below the initial energy line before rounding back up and increasing in energy back above the initial energy line. It begins to taper back to a decreasing line as the reaction ends. The final level of sodium-oxygen energy is greater than the magnesium-oxygen energy level.

A divergent plate margin bisects the Red Sea. What will happen to the Red sea as a result of the presence of this diverging plate boundary?   

The outer planets are much more massive and much lower density than the inner planets. What conditions in the disk of gas and dust that surrounded the protostar that became the sun led to the difference between the Jovian and Terrestrial planets?

The age provided for rock A is actually the age of what?

For generating nuclear energy, fusion experiments use the smallest nuclei, isotopes of hydrogen, while fission experiments use very large nuclei. Why?

This graph shows nucleon mass versus atomic number. Image Description Graph of average nucleus mass (y-axis) versus the atomic mass number (x-axis). The graph starts off with an average nucleus mass of 1.008 and decreases to 1.001 with an atomic mass number of 5. The line goes back up to 1.0025 until the atomic mass number is 10 before it decreases to just below 0.999 at around an atomic mass number of 55 before gradually increasing to 0.999 at atomic mass number 100, 0.9995 at atomic mass number 150, 1 at atomic mass number 210, and 1.0005 at atomic mass number 250. The next three questions deal with this graph.