Carbon-11 is used in medical imaging. The half-life of this radioisotope is 20.4 min. What percentage of a sample remains after 60.0 min?34.013.05.2871.22.94
Answers
Answer:
Percentage of a sample remains after 60.0 min is 13.03%.
Explanation:
- It is known that the decay of isotopes of C-11 obeys first order kinetics.
- Also, it is clear that in first order decay the half-life time is independent of the initial concentration.
- Half-life time (t1/2) in first order reaction = 0.693/k, where k is the rate constant.
∴ k = 0.693/(t1/2) = 0.693/(20.4 min) = 0.03397 min⁻¹.
- The integrated law for first order reaction is:
kt = ln[A₀]/[A],
where, k is the rate constant (k = 0.03397 min⁻¹).
t is the time of the reaction (t = 60.0 min).
[A₀] is the initial concentration of C-11 ([A₀] = 100.0 %).
[A] is the remaining concentration of C-11 ([A] = ???%).
∵ kt = ln[A₀]/[A]
∴ (0.03397 min⁻¹)(60.0 min) = ln(100%)/[A]
∴ 2.038 = ln(100%)/[A]
- Taking e for both sides:
∴ 7.677 = (100%)/[A]
∴ [A] = (100%)/(7.677) = 13.03%.
So, percentage of a sample remains after 60.0 min is 13.03%.
Final answer:
The half-life of Carbon-11 is 20.4 minutes, meaning the quantity reduces by half every 20.4 minutes. So, after approximately 60.0 minutes (roughly three half-lives), approximately 12.5% of the original sample would remain.
Explanation:
Carbon-11 is a radioisotope that's widely used in medical imaging due to its radioactive properties. It has a half-life of 20.4 minutes, which means that the quantity of Carbon-11 reduces to half in every 20.4 minutes.
If we denote one half-life as t, after three half-lives (60.0 min or 3t), the ratio of the remaining sample of Carbon-11 would be 1/2 * 1/2 * 1/2 = 1/8. In other words, approximately 12.5% of the original sample would be remaining. This percentage changes a bit due to the fact that 20.4 min is slightly less than 22.2 min (which would be the exact 3 half lives).
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Answers
Answer:
The specific heat capacity of the metal is 1.143 J/g°C
Explanation:
A typical excersise of calorimetry:
Q = m . C . ΔT
ΔT = Final T° - Initial T°
m = mass
In this case, the heat released by the metal is gained by the water to rise its temperature.
Qmetal = Qwater
(We consider that metal was at the same T° of water)
22.5 g . C . (65°C - 25.55°C) = 25 g . 4.184 J/g°C . (35.25°C - 25.55°C)
22.5 g . C . 39.45°C = 25g . 4.184 J/g°C . 9.7°C
887.625 g.°C . C = 1014.62J
C = 1014.62J / 887.625 g.°C
C = 1.143 J/g°C
a. True
b. False?
Answers
Answer : Option A) true
Explanation :
CO which is carbon monoxide is a primary pollutant for air pollution. As it contributes to the major proportion in the air pollutants amongst others. It has 48% percent of pollutants in comparison to other pollutants of air. The source of carbon monoxide is mainly from incomplete combustion of fuel mostly from the older cars.
The rise in atmospheric CO results in fatigue, drowsiness and my also sometimes lead to death of the person exposed to it.
Final answer:
The statement is true. Carbon monoxide (CO) is a primary pollutant, which is directly emitted into the environment from vehicles and machines burning fossil fuels and can negatively impact our health by limiting the oxygen transportation in the body.
Explanation:
Yes, the statement 'CO is a primary pollutant' is True. Primary pollutants are those that are directly emitted into the environment and have a damaging effect. Carbon monoxide (CO) is a significant primary pollutant that is largely produced by vehicles and other machines that burn fossil fuels. It is harmful because, when inhaled, CO can limit your body's ability to transport oxygen in your bloodstream, leading potentially to serious health problems.
Learn more about Primary Pollutants here:
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Answers
Answer:
there are 18.65 grams of sodium nitrate dissolved in 126 grams of the solution that is 14.8% by mass of the compound.
Explanation:
To find the mass of sodium nitrate dissolved in the solution, we can use the concept of percent composition.
First, we need to determine the mass of the solution that is made up of sodium nitrate. Since the solution is 14.8% by mass of the compound, we can calculate this by multiplying the total mass of the solution by the percentage:
Mass of sodium nitrate in solution = (14.8/100) * 126 g
Mass of sodium nitrate in solution = 18.65 g
Therefore, there are 18.65 grams of sodium nitrate dissolved in 126 grams of the solution that is 14.8% by mass of the compound.
Answers
so
the atomic mass of ozone= 16*3=48
ozone=O3
ie,16*3=48
Answers
Answer:
Primary producers
Explanation:
Phytoplankton belong to the primary producers trophic level. Beings of the other levels gain energy from phytoplankton. Phytoplankton are also capable of transforming inorganic carbon into protoplasm.
2Na(s) + ZnF2(aq) + 2NaF(aq) + Zn(s)
O Fe(s) + CuCl2(aq) → FeCl2(aq) + Cu(s)
0 2HCl(aq) + Mg(s) → MgCl2(aq) + H2(g)
Answers
Answer: will not occur.
Explanation:
A single replacement reaction is one in which a more reactive element displaces a less reactive element from its salt solution. Thus one element should be different from another element.
A general single displacement reaction can be represented as :
a)
Flourine is more reactive than chlorine and hence this reaction cannot occur.
b)
Sodium is more reactive than zinc and hence the reaction will occur.
c)
Iron is more reactive than copper and hence the reaction will occur.
d)
Magnesium is more reactive than hydrogen and hence the reaction will occur.