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.
Answer:
When magma cools underground, it cools very slowly and when lava cools above ground, it cools quickly. When magma and lava cool, mineral crystals start to form in the molten rock. Plutonic rocks, which cool slowly underground, have large crystals because the crystals had enough time to grow to a large size.
Explanation:
It basicly startes to molden the rock, and more.
Answer:
Incomplete Dominance
Explanation:
In terms of the shape of the blood cell shape, sickle cell disease has an incomplete dominance.
Answer:
The correct answer is - segregation.
Explanation:
The law of segregation states that out of two factors or alleles of a gene located in an organism, only one allele or factor is distributed to each sperm cell or egg cell (gamete) randomly, So, the segregation of the alleles are random and only one allele is distributed to each gamete according to this law.
The law of segregation helps in making a different combination of alleles in a particular species or population and leads to variation in genetics. It makes sure that traits distribute to each generation randomly.