The correct answer is Metal.
Sound waves are vibrations which need medium to propagate. Higher the density of medium, the sound travels fastest. Sound travels fastest in solid than liquid and gas. Therefore, in this question sound will travel faster in metal because metal has higher density than air and water and it will not travel in vacuum as sound needs medium to travel.
1 - introduced to a habitat similar to their own
3 - outcompete native species
4 - generally have no native predators
6 - often have high reproductive rates
8 - can tolerate a range of conditions
D because gravitational force cannot pull or push
The answer is; desertification
Topsoil is usually the riches soil in terms of nutrient is important in support of plant vegetation. It is rich because it contains humus and other decomposed materials that recycle nutrients. When the topsoil is washed away, the local region becomes barren in that it cannot support vegetation. This causes the area to turn into a desert.
Both use oxygen, both produce energy, both give out carbon dioxide as the result and the overall chemical reactions are the same.
Hope this helps :)
