Fossil Fuels:
Coal and Oil
How they are formed:
Coal is formed from big plants, from a long time ago. When the big plants died, they formed layers at the bottom of swamps and the dirt began to pile up and it formed Coal.
Oil is a fossil fuel that has been formed from a large amount tiny plants and animals such as algae and zooplankton.
I believe the answer would be lungs
Answer:
20 hertz of frequency produced.
Explanation:

Here we will find frequency and period should be in second, here given: 0.05 seconds
using the formula:

