Easy. Answer is oxygen because it says which one was missing before any life was on earth. And in order to have life on earth you need oxygen!
:)
Answer:
Roundworms can grow up to 3 meters and can be so small they can't be seen with the naked eye. Some roundworms have hooks to cling to certain body parts without being carried away by blood or other fluid. Roundworms are covered in a strong, but flexible, covering
Explanation:
Yes, They make rapid chirps if it's warmer
Answer:
Volume= 4 cm³
Density= 2 g/cm³
Explanation:
We have the following data:
volume= V= 8 cm³
mass= m= 16 g
The density is the mass per volume of a substance, so the density of the rock is:
density= d= 16 g/8 cm³= 2 g/cm³
When we cut the rock in half, we have a half volume and a half mass:
V= 8 cm³/2= 4 cm³
m= 16 g/2= 8 g
But the density is not altered because it is an intrisic property - it does not change with the amount of subtance. Thus, the density of a half rock is:
d = m/V= 8 g/4 cm³= 2 g/cm³
