Answer:
This means that the isotope of silicon with a mass number of 28 is by far the most common of these three isotopes.
Explanation:
The abundance of Si-28 is 92.23%. Si-29 is 4.68% and Si-30 is 3.09%.
Because most Si atoms have a mass of 28 amu, the average mass of all silicon atoms is very close to 28.
Here is a video which summarizes how to calculate average atomic mass from data about mass and relative abundance.
Answer:
Explanation:
Given,
The density of Helium is 
We need to find the density in Dg/μm
We know that,
1 g = 10 dg
1 cm³ = 10¹² μm³
So,
So, the density of Helium is equal to 
.
Answer:
After Eris was discovered, they had to decide whether Eris was a planet or not. If they decided it wasn't a planet, they had to also decide whether Pluto should be counted as a planet since Eris and Pluto were quite similar. They were the same size, and they were both part of the Kuiper Belt.
Explanation:
After 3 half-lives, 125 grams of the parent isotope will remain.
