Answer:
![\boxed {\boxed {\sf C. \ 2.5 \ grams }}](https://tex.z-dn.net/?f=%5Cboxed%20%7B%5Cboxed%20%7B%5Csf%20C.%20%5C%202.5%20%5C%20grams%20%7D%7D)
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.
![A= A_o(\frac {1}{2})^{\frac{t}{hl}](https://tex.z-dn.net/?f=A%3D%20A_o%28%5Cfrac%20%7B1%7D%7B2%7D%29%5E%7B%5Cfrac%7Bt%7D%7Bhl%7D)
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.
![A= 40 \ g (\frac{1}{2})^\frac{12}{3}](https://tex.z-dn.net/?f=A%3D%2040%20%5C%20g%20%28%5Cfrac%7B1%7D%7B2%7D%29%5E%5Cfrac%7B12%7D%7B3%7D)
![A= 40 \ g (\frac{1}{2})^4](https://tex.z-dn.net/?f=A%3D%2040%20%5C%20g%20%28%5Cfrac%7B1%7D%7B2%7D%29%5E4)
![A= 40 \ g * 0.0625](https://tex.z-dn.net/?f=A%3D%2040%20%5C%20g%20%2A%200.0625)
![\bold {A= 2.5 \ g}](https://tex.z-dn.net/?f=%5Cbold%20%7BA%3D%202.5%20%5C%20g%7D)
After 12 years, <u>2.5 grams </u> of Iron-55 will remain.
Answer:
Explanation:
The switch from glutamic acid to valine in position 6 of hemoglobin (HB) forms the basis of sickle cell anemia disease pathology.
Valine is hydrophobic and it's chain is shorter than glutamic acid. The lack of the carboxylic acid and shortness of valine will result in loss of the ionic interactions formed between the glutamic acid's carboxylic group and other amino acids. A hydrophobic cavity will form in the beta sheet of HB due to the short and hydrophobic structure of valine. For these reasons, the HB molecule will be less stable and insoluble in water. The insolubility is thought to be caused by fibril formation between the valine interacting with hydrophobic pocket residues of the adjacent HB molecule. This would in turn affect binding of oxygen to HB.
Answer:
There are 7 obligate categories included in hierarchical classification The highest rank is the kingdom, followed by division, class, order, family, genus and species.
Explanation:
Hope this help!!
When conducting legal experiments on animals, a researcher needs to obtain consent from the INSTITUTIONAL RESEARCH BOARD.
Each research institution has research board which sees into uses of animals for research purposes, consent must be obtained from the board before experiments involving usage of animals is carried out.
Answer:
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Explanation:
1/4 : 25%
3/4 : 75%
4/4 : 100%
2/4 : 50%
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