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Amanda [17]
3 years ago
15

The half-life of C-14 is 5470 years. If a particular archaeological sample has one-quarter of its original radioactivity remaini

ng, what is the best estimate for its age?
5470 years

10940 years

16410 years

21880 years
Chemistry
2 answers:
Sever21 [200]3 years ago
6 0

Answer:

When there remains one-quarter of the sample, the age of the sample is 10940 years

Explanation:

Step 1: Data given

The half- life time is the time required for a quantity to reduce to half of its initial value.

The half-life of C-14 is 5470 years.

This means after 5470 years there remains half of the C-14 sample.

When there will pass another half-life cyclus, half of the sample will remain.

Half of 50 % = 25% = one- quarter

This means 2 half-lives should have passed to remain a quarter of the sample.

<u>Step 2</u>: Calculate it's age

t/(t/1/2) = 2

⇒ with t = the age (or time) of the sample

⇒ with t(1/2) = the half-life time of the sample = 5470 years

⇒ with 2 = the number of half- lives passed  to remain one quarter of sample

t/5470 = 2

t = 2*5470 = 10940 years

When there remains one-quarter of the sample, the age of the sample is 10940 years

-Dominant- [34]3 years ago
3 0
10940? Sorry if it isn’t correct
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Triss [41]

Answer:

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Explanation:

The 1HNMR is the acronym for Proton nuclear magnetic resonance and it is used in chemistry or Chemical laboratory for the analysis and identification of compounds.

In order to be able to answer the question accurately you have to have the tables containing all the values for chemical shift. The Chemical shift is measured in ppm and it occur due to Resonance frequency variation.

From the table, a singlet at 1.15 ppm (9H) is - C(CH3)3.

A singlet at d 0.9 ppm (1H) shows the presence of a secondary amine group, that is -R2NH group.

A triplet at 1.10 ppm (3H) shows that we have;

CH3- CH2-

A quartet at 2.6 ppm (2H) shows that we have;

-CH2 - CH3.

Therefore, joining all together we have;

CH3 - CH2 - NH - C(CH3)3.

Kindly check attached file for the picture of the structure.

5 0
2 years ago
0.65743 In scientific notation
Goryan [66]
202827.0000 is the answer I think idrk
6 0
3 years ago
Sophia was fascinated while studying the role of oceans in the hydrosphere. She decided to illustrate the features of the ocean
ANEK [815]

Answer:

The Major features of the ocean floor are:

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Explanation:

1. Continental Shelf: This refers to the part of the land on every continent that is covered with water that is not too deep. The types of animals that can be found on the continental shelf are:

Crab, Tuna, Lobster, Dungeness cod, etc. Within the Continental shelf, there are permanent rocks that house other organisms such as sponges, anemones, clams, sponges, oysters. The continental shelf also contains the route of migration for bigger animals such as sea turtles dolphins and even whales.

2. Continental Slope: This spans from the shelf break to the continental rise.  It can slope up to 4 degrees. Slopes can be created by faulting, slumping of huge boulders of sediments, rifting, etc.

Some of the aquatic animals that can be found in this region include but are not limited to:

Sablefish, Dover sole rockfish, etc.

3. Continental rise

This part of the ocean floor usually has a very steep gradient or angle slope. It slopes very steeply into the abyssal plain of the ocean.

The following can help form continental rise:

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4. Abyssal Plain.

This is the real bottom of the ocean. There is a very high probability that one would find animals such as nematodes, polychaetes, etc which are all types of worms down there. The Abyssal plain is also home to molluscs,  and echinoderms.

5. Oceanic Trench

Sometimes there is a long and narrow indenture or depression along the seafloor. These are called Trenches. Trenches are sometimes formed by the boundaries between one lithospheric plate and another. The deepest trench on earth is found in the Pacific Ocean. It has been nick-named the Challenger Deep and said to be the deepest point known on earth reaching almost 11 kilometers.

6. Mid-Ocean Ridge

This is a mountain range underneath the ocean. It is formed when there is an upward push by convection currents of the mantle beneath the oceanic crust. When this happens and molten magma is ejected or created at the boundary between the plates, the result is a Mid-Oceanic Ridge.

Cheers

7 0
2 years ago
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Answer:

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Explanation:

The percent volume of the coffee solution can be calculated as follows:

% volume of coffee solution = volume of coffee/total volume of coffee solution × 100

According to this question, a cup of coffee has 71 mL of coffee and 127 mL of water. This means that, the total volume of coffee solution is;

71mL + 127mL = 198mL

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3 years ago
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Sveta_85 [38]

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<h3>What is transfer of energy?</h3>

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To know more about transformation of energy, visit the below link:

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1 year ago
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