Question

The half-life of 199Au is 3.14 days.

a.)Convert the half-life to units of seconds.

b.) What is the decay constant (in s^{−1}) for this
isotope?

c.) Suppose a sample of ^{199}Au has an activity of
0.360 µCi. What is this activity expressed in the SI unit of
becquerels (Bq)?

d.) Suppose a sample of ^{199}Au has an activity of
0.360 µCi. What is this activity expressed in the SI unit of
becquerels (Bq)?

e.) Now suppose that a new sample of ^{199}Au has an
activity of 7.00 mCi at a given time.

How many half-lives will the sample go through in next 40.2 days? (Enter your answer for the number of half-lives to at least one decimal place.)

f.) What is the activity of this sample (in mCi) at the end of 40.2 days?

Answer #1

The half-life of 222Rn is 3.82 days.
(a) Convert the half-life to seconds.
s
(b) Calculate the decay constant for this isotope.
s?1
(c) Convert 0.650 ?Ci to the SI unit the becquerel.
Bq
(d) Find the number of 222Rn nuclei necessary to produce
a sample with an activity of 0.650 ?Ci.
222Rn nuclei
(e) Suppose the activity of a certain 222Rn sample is
6.20 mCi at a given time. Find the number of half-lives the sample
goes through in...

The half-life of 131I is 8.04 days. (a) Convert the
half-life to seconds. (b) Calculate the decay constant
for this isotope. (c) Convert 0.500 mCi to the SI unit
the becquerel. (d) Find the number of 131I nuclei necessary
to produce a sample with an activity of 0.500 mCi.
(e) Suppose the activity of a certain 131I sample is
6.40 mCi at a given time. Find the number of half-lives
the sample goes through in 40.2 d and the activity...

The radioactive isotope 198Au has a half-life of 64.8 hr. A
sample containing this isotope has an initial activity (t = 0) of
1.5x 10^12 Bq. Calculate the number of nuclei that decay in the
time interval between t1 = 10 hr and t2 = 12 hr.
Please show and explain work, and do not use calculus to solve
it.

How many atoms of isotope were contained in the freshly prepared
sample? Answer in units of nuclei. What is the sample’s activity 26
h after it is prepared? Answer in units of mCi. (info to answer
this below)
A freshly prepared sample of a certain radioactive isotope has
an activity of 9.2 mCi. After 3.46 h, the activity is 7.5 mCi. Find
the decay constant. Answer in units of h?1 . (The answer to this is
.059) 003 (part 2...

The radioactive isotope 32P decays by first-order kinetics and
has a half-life = 14.3 days. How many atoms of a 1.0000 ug sample
of 32P would decay in 1.0000 second? (Assume 1 decay per atom.)

The radioactive plutonium isotope, 239Pu, has an half-life of 24
100 years and undergoes alpha decay. The molar mass of 239Pu is
239.0521634 amu. The sample initially contains 10.0 g of 239Pu.
(a) Calculate the number of moles of 239Pu that are left in the
sample after 15 000 years. (4)
(b) Determine the activity of 239Pu after 15 000 years, in units
of Bq.

The radioactive plutonium isotope, 239Pu, has an
half-life of 24 100 years and undergoes alpha decay. The molar mass
of 239Pu is 239.0521634 amu. The sample initially
contains 10.0 g of 239Pu. (a) Calculate the number of
moles of 239Pu that are left in the sample after 15 000
years. (4) (b) Determine the activity of 239Pu after 15
000 years, in units of Bq.

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

The gold nucleus Au(198,79) undergoes alpha decay with a
half-life of 2.70 days.
A. ) Find how many neutrons and protons are in the
daughter nucleus produced by this decay.
B.) Find the activity in Bq (decays/sec) of a sample that
contains 5.0 grams of Au(198,79) nuclei.
C.) A 2.5 kg suitcase at an airport absorbs 2.0 × 10−3 J/kg from
100 keV x-rays. How many photons are absorbed?

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!

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