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anzhelika [568]
3 years ago
14

a rock sample contains 25 percent k-40 and 75 percent daughter product ar-40. if k-40 has a half-life of 1.3 billion years, how

old is the rock?
Biology
1 answer:
RoseWind [281]3 years ago
7 0

Answer:

2.6 billion years old

Explanation:

Initial:

 100% k-40

 0% ar-40

After 1.3 billion years:

 50% k-40

 50% ar-40

After 2.6 billion years:

 25% k-40

 75% ar-40

So the rock is 2.6 billion years old.

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3 years ago
What is the volume of 0.25 mol of ammonia gas at 1.00 atm and 273 K? (R= 0.0821 Latm/molK)What is the volume of 0.25 mol of ammo
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Answer:

5.6L

Explanation:

Given parameters:

number of moles  = 0.25mol

pressure on gas  = 1atm

temperature  = 273K

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Unknown:

Volume of gas  = ?

Solution:

Using the ideal gas equation, we can solve this problem. The equation is a combination of the three gas laws: Boyle's law, Charles's law and Avogadro's law.

It is mathematically expressed as;

             PV = nRT

where P is the pressure

           V is the volume

          R is the gas constant

          T is the temperature

          n is the number of moles

All the parameters are in the appropriate units and we simply solve for the volume of the gas;

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4 0
3 years ago
Relate the analogy of “tug of war” to a water molecule.
ipn [44]

Answer:

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Explanation:

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2 years ago
In order to keep all other things the same and isolate the effects of one particular variable in the biology experiment, Kate wi
miskamm [114]

Answer:

Make sure all tested rats are the same age.

Offer the same type of food to the rats in each trial.

Explanation:

<em>In order to be able to isolate the effects of one particular variable during a research, all the subjects in each trial must be subjected to the same conditions except the variable whose effects is being isolated.</em>

Hence, Kate must offer the same type of food to the rats in each trial as well as make sure that all tested rats are the same age.

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