Well we are not able to see the internal structure of the Earth directly because we can't get at it! The thinnest crust is under the oceans but even that is around 7kms thick, way deeper than we can drill. We have to use indirect methods like earthquakes, and infer the structure from the way the pressure and shear waves produced travel through the Earth.
A book series that a 14-18 year old would read could be the books by Sarah Mlynowski. A book that I have read that is really good it Gimme A Call. It is based on a girls point of view. It is fiction because of the idea that the book revolves around the character getting a call from her future self telling her to do things differently with her life. The book isn't mainly about romance, but it does have some really good topics that teens can deal with. Also, when you are looking for a romance novel keep in mind that there are different levels of romance books. There are the type of books where there is only flirting and the usual teenage dating, but then there are books with very, and I mean very, unpleasing scenes.
Answer:
500 years
Explanation:
The original carbon-14 was 100%, and after 100 years, it decays 1.202%. So after 100 years it goes to 98.798%, after more 100 years (200 years), it will be 97.596% (98.798 - 1.202), thus, after n 100 years "package", the percenatge will be:
100% - actual% = n*1.202
n = (100% - actual%)/1.202
n = (100% - 94%)/1.202
n = 4.992
So, the number of years is n*100 = 4.992*100 = 499.2 ≅ 500 years.
139.850 there ya go hope u ace it
A.atomic mass(a)=16
atomic mass(b)=18
b.a and b are isotopes
c.(a)=2,6
(b)=2,6
