Question

Bismuth-210 has a half-life of 5 days. A sample originally has a mass of 160mg

a) Find a formula for the mass remaining after t days

b) Find a mass remaining after 20 days.

c) When is the mass reduced to 1 mg? You may leave your answer in terms of logarithms

I Will like and comment. Thank you!

Answer #1

Bismuth-210 is beta emitter with a half-life of 5.0 days.
Part A
If a sample contains 1.3 g of Bi-210 (atomic mass = 209.984105
amu), how many beta emissions occur in 14.0 days? Express your
answer using two significant figures. betadecays
Part B
If a person's body intercepts 5.5
% of those emissions, to what dose of radiation (in Ci) is the
person exposed? Express your answer using two significant figures.
Dose of radiation = Ci

The half-life of Palladium-100 is 4 days. After 16 days a sample
of Palladium-100 has been reduced to a mass of 3 mg. What is the
mass 6 weeks after the start?

Radium decays exponentially; it has a half-life of 1,600 years.
Find a formula for the amount,
q(t),
remaining from 70 mg of pure radium after t years.
q(t) =
After how many years will there be 20 mg left? (Round your
answer to the nearest year.)
yr

A certain radioisotope has a half-life of 8.96 days. What
percentage of an initial sample of this isotope remains after 20
days?

A) Radon gas has a half-life of 3.83 days. If 3.18 g of radon
gas is present at time t = 0, what mass of radon will
remain after 2.10 days have passed?
____ g
B) A drug tagged with 9943Tc (half-life =
6.05 h) is prepared for a patient. If the original activity of the
sample was 1.2 104 Bq, what is its activity
(R) after it has been on the shelf for 1.2 h?
_____Bq

Phosphorus-32 (P-32) has a half-life of 14.2 days. If 450 g of
this substance are present initially, find the amount Q(t) present
after t days. (Round your growth constant to four decimal places.)
Q(t) =
What amount will be left after 17.6 days? (Round your answer to
three decimal places.)

The unstable isotope 234Th decays by beta emission
with a half-life of 24.5 days.
a) What mass of 234Th will produce
9.9x1016 decays per second? (Note: 1u =
1.66x10-27 kg). Answer:1.2x10-4kg
b) If the initial decay rate of the sample is
9.9x1016 decays per second, what is the decay rate after
59 days? Answer: 1.4x1013kg decays/second
Must show all work to get to the answers I provided. Thank
you!

A certain radioisotope has a half-life of 10.1 days. What
percentage of an initial sample of this isotope remains after 37
days?

The isotope 79Au198 (atomic mass 197.968 u) of gold, which has a
half-life of 2.69 days, is used in cancer therapy. What mass (in
grams) of this isotope is required to produce an activity of 393
Ci?

A certain drug has a half-life in the bloodstream of 2 hours.
Doses of D mg will be administered every 6 hours, with D to be
determined. a) What percentage of a single dosage remains after 6
hours?; after 12 hours?
b) Express the number of milligrams of drug in the bloodstream
after the nth dose has been administered as a geometric series.
c) What is the long-run level of the drug in the bloodstream,
assuming that D mg continue...

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