Correct: The sun is the center of the solar system. It is mostly gas. It is the most massive object in the solar system.
Answer:
Classification system changes because the scientists find new evidence in their studies.
Explanation: The world is always changing and growing and dying as well as developing, so over time things change. For example, as you grow up do you stay the same? No, you notice the physical changes happening, well thats sort of like how the earth and its ways are always changing as well.
A.
The respiratory system transports oxygen and other nutrients to the heart for the circulatory system.
I hope this helped you hon
For an atom to become a positively charged ion it must lose negatively charged electrons.
