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igomit [66]
3 years ago
11

Potassium-40 has a half-life of 1.3 billion years. as the potassium-40 isotope decays, it becomes argon. if a rock was formed wi

th 12 g of potassium-40, approximately how long would it take for 75% of the potassium-40 to be replaced by argon?
a. 1.3 billion years
b. 2.6 billion years
c. 5.2 billion years
d. 650 million years
Chemistry
2 answers:
Marina CMI [18]3 years ago
3 0
The half life of a substance is the time taken by a radioactive substance to decay by half its original mass. In this case, the half life of Potassium-40 is 1.3 billion years. 
Original mass of Potassium-40 = 12 g (100%)
New mass after the decay = 3 g ( 25 %, since 75% was replaced by argon)
New mass = Original mass × (1/2)^n ; where n is the number of half lives. 
 3 = 12 × (1/2)^n
(1/2)^n = 1/4 
      n = 2 
Therefore; the time taken will be 1.3 × 2 = 2.6 Billion years
Rom4ik [11]3 years ago
3 0

Answer:Potassium is a crucial element for the healthy operation of the human body. Potassium occurs naturally in our environment (and thus our bodies) as three isotopes: Potassium-39, Potassium-40, and Potassium-41. Their current abundances are 93.26%, 0.012% and 6.728%. A typical human body contains about 3.0 grams of Potassium per kilogram of body mass.

How much Potassium-40 is present in a person with a mass of 80 kg?

If, on average, the decay of Potassium-40 results in 1.10 MeV of energy absorbed, determine the effective dose (in Sieverts) per year due to Potassium-40 in an 80-kg body. Assume an RBE of 1.2. The half-life of Potassium-40 is 1.28 x 109 years.

Explanation:

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Answer:

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Explanation:

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Mass of Sulfur = S × 1 = 32.06 × 1 = 32.06 g

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Mass of Hydrogen = H × 20 = 1.01 × 20 = 20.2 g

Mass of Na₂S0₄.10H₂O = 322.24 g

Secondly, calculate mass of water present in hydrated compound. For this one should look for the coefficient present before H₂O in molecular formula of hydrated compound. In this case the coefficient is 10, so the mass of water is...

Mass of water = 10 × 18.02

Mass of water = 180.2 g

Now, we will apply following formula to find percent of water in hydrated compound,

           %H₂O  =  Mass of H₂O / Mass of Hydrated Compound × 100

Putting values,

                                      %H₂O  = 180.2 g / 322.24 g × 100

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Fofino [41]

Option A is correct. When a person says "<em>I think</em><em> that between an elephant and a monkey that jumped off the cliff, both of them will hit the ground at the same time."</em> the person is stating his Hypothesis

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It is useful at the beginning of an investigation because it serves as the building block for an impending fact or law.

From the statement, we can see that the person is not too sure of the information provided since he "thinks". <em>He said, </em><em>"I think</em><em> that between an elephant and a monkey that jumped off the cliff, both of them will hit the ground at the same time." </em>

<em />

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6 0
2 years ago
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Elena L [17]

After careful consideration your answer is...

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