Question

11. Carbon-14 has a half-life of 5760 years. A 1-gram sample of an ancient pine spear contains 1/8 as much carbon-14 as is present in a modern pine branch.

(a) Approximately how old is the spear?

(b) If a spear were 100,000 years old, why would carbon dating be inadequate for dating it?

Answer #1

Part A)
The radioactive element carbon-14 has a half-life of 5750
years. A scientist determined that the bones from a mastodon had
lost 76.176.1% of their carbon-14. How old were the bones at the
time they were discovered?
Part B)
The radioactive element carbon-14 has a half-life of 5750
years. A scientist determined that the bones from a mastodon had
lost 63.763.7% of their carbon-14. How old were the bones at the
time they were discovered?

A branch from a bristlecone pine tree is found in a sedimentary
layer, and its age is to be determined. The branch is a 5.0-gram
piece of cellulose (C6H10O5: molar mass = 162 g/mole). This
specimen is taken and placed between scintillation detectors, and
over a 24-hour period 16,500 decays were recorded. How old is this
branch? When the tree was living, carbon-14 accounted for 1 out of
every 7.2x1011 atoms of carbon. The half-life of carbon-14 is 5730
years.

If the half life of Carbon 14 is about 5,730 years, then a
fossil that has 1/4 the normal proportion of Carbon 14 to Carbon 12
should be how old?
20,900
2,800
17,200
1,400
11,400

The radioactive element carbon-14 has a half-life of 5750
years. A scientist determined that the bones from a mastodon had
lost
64.5% of their carbon-14. How old were the bones at the time
they were discovered?

Carbon-14 has a half-life of 5,730 years. A fossil is found that
has 28% of the carbon-14 found in a living sample. How old is the
fossil? (Round your answer to the nearest year.)

Carbon-14 is unstable and undergoes β- decay, with a
half-life of 5730 years.
(a) What does it decay into?
(b) How much energy is released in the reaction?
(c) If a 1 g sample of carbon contains 0.1% carbon-14, what is the
activity in units of curie (Ci), where 1 Ci
= 3.7 × 1010 decay/s?
(d) What is the activity after 20,000 years have passed?

Q1. Carbon-14 – or 14C – is a radioactive isotope of carbon with
a half-life of 5,730 years. It decays into nitrogen-14 – or 14N – ,
which is a stable isotope of nitrogen.
(a) Which of the three nuclear decay processes describes the decay?
Explain. (Hint: You can get the atomic number of carbon and
nitrogen from a periodic table.)
(b) Write down the equation for the decay.
(c) What is the decay constant for 14C?
All isotopes of...

The half-life of carbon-14 is 5,730 years. An artifact produces
13.3 disintegrations of 14C per minute per gram of carbon in the
sample. Estimate the age of this sample assuming that its original
radioactivity was 15.3 disintegrations per minute per gram of
carbon.

3p An artifact has C-14 ( half life of carbon - 14 is
5,700 years) content that is 50% of that found in living organisms.
what is the approximate age of object?
a 11,000 years
b 17,000 years
c 23, 000 years
d 5,700 years

Carbon 14 (146C, mass of 14.003242u, half-life of 5730 years)
can be used to date things that were once living. When a particular
tree fell, a chunk of that tree would have had an activity of 15
decays/minute. Now, that chunk of the tree has a total of 1x10-12 g
of carbon 14 in it. How long ago did the tree fall? [3436.6
yrs]

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