[ 7 ] Earth and Space Science GED ® TEST SCIENCE FLASH REVIEW • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Compared to Earth’s crust, the inner core is A. hotter and contains more molten iron. B. hotter and contains more solid iron. C. hotter and contains most of Earth’s mass. D. hotter and contains mostly sand and rock. Solar power refers to the conversion of solar energy to another, more useful form. Sunlight can be harnessed and collected in special greenhouses. Photovoltaic cells can produce electricity when sunlight hits them. The amount of energy from the sun that reaches Earth is about 8,000 times the energy humans use. Many scientists are convinced that this form of energy will one day replace ordinary fossil fuels. In 2012, about 0.14% of all electricity generation was from solar power. This may seem like a small percentage of overall energy production, but it represents a 58% increase over 2011. Why don’t we see more of our energy coming from solar power? A. Sunlight is always available. B. Fossil fuels are still cheaper. C. Fossil fuels will never run out. D. We do not know how to produce solar power.