Match each term to its description. (inner core, crust, lower mantle, asthenosphere, upper mantle, top layer, outer core)
1. the semi-solid layer between the top layer and the upper mantle
2. the firm layer between the crust and the asthenosphere
3. the earth's outermost layer
4. the layer between the asthenosphere and lower mantle
5. the layer surrounding the inner core
6. the hottest part of the mantle
7. the metallic layer at the earth's center