6. [ea13o03 hslq_ea13o03_g] if gas approaches a black hole, it will often heat up and emit that can be detected telescopically.
a) x-rays
b) white light
c) purple light
d) radio waves

Which of these is an example of land degradation? a. containers designed to store pollutants leak. b. fertilizers provide too many nutrients to crops. c. garbage is buried so the land can be reclaimed later. d. a drought kills all the plants in an area, leaving bare land