This is known as parasitism.
In biology, parasitism is a relationship between species, where one organism, the parasite, lives on or in another organism, the host, causing it some harm, and is adapted structurally to this way of life.
Each layer of earth has a different density the more in you go with the layers the more density is going to show up.
Crust-2.2g/cm^3
Upper mantle-3.4g/cm^3
Lower mantle-4.4g/cm^3
Outer core-9.9g/cm^3
Inner core-12.8g/cm^3
Hope I helped in something, Sorry if I didn't gave it my best shot:)
Scientific modeling is a scientific activity, the aim of which is also to make something a particular part or feature of the word easier to recognize, define, quantify, visualize, or even simulate by referencing it to an existing and usually commonly accepted knowledge.
For questions 11-15
11. Magnesium Oxide is a combination between Magnesium and oxygen so the formula will be MgO
12. Calcium Chloride is a combination between Calcium and Chlorine, so the formula will be CaCl₂ the ₂ comes from the fact that there is two Chlorine atoms
13. Lithium Sulfide is a combination between Two lithium and a sulfur atoms,
so the formula will be Li₂S The ₂ coming from the two lithium atoms
14. Barium Selenide is a combination between Barium and Selenium so the formula will be BaSe
15. Aluminum Oxide is a combination between Aluminum and Oxygen, there are two Aluminum atoms and three Oxygen atoms, so it will make Al₂O₃
Hope this helps
