[ 149 ] Earth and Space Science GED ® TEST SCIENCE FLASH REVIEW • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Some of the responses to oceanic acidification include reducing CO 2 emissions, climate engineering, iron fertilization, and using carbon-negative fuels. Which of these is a practice that is already being done? Earth’s inner core is a solid mass of iron with a temperature of about 7,000°F. The high heat at Earth’s core is a combination of which three of the following factors? • residual heat from the moon’s formation • residual heat from Earth’s formation • frictional heating, caused by the tectonic plates moving against each other • frictional heating, caused by denser parts of the core moving toward the center • decay of radioactive elements, such as uranium, in the core. The inner core is approximately 1,500 miles in diameter. Which of the following is NOT part of the rocky mantle? • silicon • oxygen • magnesium • iron • aluminum • calcium • meteors • water