Which of the following is a term used to describe the shallow location near the shore where water covers the continent? (2 points)

Which statement about the density of warm water is most likely correct? (2 points)

The Dead Sea is a location where high evaporation rates occur. What can you conclude about the water in the Dead Sea? (2 points)

The graph below shows the number of radioactive atoms present in four radioactive materials at different time intervals. Which of these statements is correct about the half life of materials plotted on the graph? (4 points)

A substance has a half-life of 10,000 years and an initial mass of 1,000 grams. How many years will pass before only 250 grams of the substance’s parent material is left? (2 points)

Carbon-14 has a half-life of approximately 5,730 years. How many half-lives have occurred in a sample that contains 25 percent of the original amount of the parent isotope? (2 points)

A potassium isotope has a half-life of 1.25 billion years. Given that scientists estimate Earth’s age to be 4.6 billion years, what is the most likely percentage of parent to daughter isotopes of this element currently existing on Earth? (2 points)

As potassium-40 decays, it becomes argon-40, as shown in the following graph. Public Domain Potassium-40 has a half-life of approximately 1.25 billion years. Approximately how many years will pass before a sample of potassium-40 contains one-sixteenth the original amount of parent isotope? (2 points)

Which of the following reduces the number of protons in the nucleus of an atom by 2? (2 points)

The following table shows the currently accepted half-life values for six parent isotopes. Parent Isotope Currently Accepted Half-Life Values Uranium-238 4.5 billion years Uranium-235 704 million years Thorium-232 14.0 billion years Rubidium-87 48.8 billion years Potassium-40 1.25 billion years Samarium-147 106 billion years Earth is approximately 4.5 billion years old. Given this information and the data in the table, which of the following isotopes could today contain less than 50 percent of its parent isotope? (2 points)