Erosion of sand n dirt and it ca cause sinkholes
Answer:
The answer is most likely the 3rd option.
The earth rotates on its axis
If a zebra mussel is discovered in a lake in Pennsylvania, then the ecologist would be worried because it is an invasive species. The zebra mussel is native to Ukraine and Russia, but if it has been found in Pennsylvania, than it means that it has been introduced in this area. As an invasive species, the zebra mussel can be very dangerous for the native species in the lake. The invasive species usually are more competitive for food sources than the native species, manage to reproduce quicker, bring in diseases, and the native species tend to not have defense mechanisms for them. This leads to rapid decline or even extinction in the native species, while the invasive spreads out quickly and takes over, resulting in dramatic change in the whole ecosystem.
<span>The culture contains 2*10^8 bacteria before it was exposed to ionizing radiation which kills 99.99% of the bacteria. The number of bacteria left after the radiation would be:
final number= initial number * (100%- radiation kill rate)
</span>final number= 2*10^8<span> *(100%-99.99%)
</span>final number= 2*10^8 *(0.01%)
final number= 2*10^8 * 10^-6
final number= 2*10^(8-6)
final number= 2*10^2
