Answer:
The atomic model is our understanding of how the atom is structured. At one point in history, people believed that any substance was simply made of that substance and would retain that property no matter how small a quantity it was reduced to. Later, some argued that all matter was made of tiny particles called atoms. While this is correct, later researchers found that even the atoms were made of smaller particles called electron, protons, and neutrons. More recently, scientists have discovered quarks, tiny particles that makeup protons and neutrons.
Answer:

Explanation:
We are asked to find how much of a 40 gram sample remains after 12 years.
Iron-55 has a half-life of 3 years. Therefore, after 12 years, 4 half-lives have been completed.
- 12 years/3 years = 4 half-lives
Every time a half-life is completed, half of the sample's mass decays. Remember we start with a 40 gram sample.
- 1 half- life: 40 g / 2 = 20 g
- 2 half-lives: 20 g / 2= 10 g
- 3 half-lives: 10 g / 2 = 5 g
- 4 half-lives: 5 g / 2 = 2.5 g
There is also a formula that can be used to solve this problem.

Where A₀ is the initial amount, t is the time, and hl is the half-life.
We know 40 grams is the inital amount, 12 years is the time, and 3 years is the halflife.




After 12 years, <u>2.5 grams </u> of Iron-55 will remain.
when there are dented cans
X: Ozone layer destruction
Y: Mass extinction
Answer:
False
Explanation:
Thats a fact you can thank me later