Select the correct answer from the drop-down menu. a scientist digs up sample of arctic ice that is 458,000 years old. he takes it to his lab and finds that it contains 1.675 grams of krypton-81. if the half-life of krypton-81 is 229,000 years, how much krypton-81 was present when the ice first formed? use the formula n = n0 . the ice originally contained grams of krypton 81.

Answers

Answer 1

The original mass of krypton 81 that is present in the ice is 6.70 grams.

How do we calculate original mass?

Original mass of any substance will be calculated as below for the decomposition reaction is:

N = N₀(1/2)ⁿ, where

N = remaining mass of krypton-81 = 1.675g

N₀ = original mass of krypton-81 = ?

n will be calculated as:
n = T/t, where

T = total time period = 458,000 years

t = half life time = 229,000 years

n = 458,000/229,000 = 2

Now putting all these values on the above equation, we get

N₀ = 1.675 / (1/2)²

N₀ = 6.70 g

Hence required mass is 6.70 g.

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Related Questions

What happens to the density of group 1 when you go down the group

Answers

the density increases down the group.

What is the name of the molecule shown below?

Answers

A 2-octene. The feature is the double bond its an alkene. 8 carbons so (oct) attached to 2nd carbon.

A.2-octene  is the name of the molecule shown below.

How many carbons does 2-octene have?

The oct part of the name indicates the parent chain. In this case, oct- is an abbreviation for octane, which means that there are 8 carbons in the parent chain. The first part of the name, cis-2. 2 is used to indicate the first atom that forms the double bond above.

Alkenes are classified into higher olefins and alpha olefins. This means that the double bond is in the alpha (primary) position, which makes the compound more reactive and provides useful chemistry.

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How is permeability related to the size of the grains that make up the sediment?

Answers

Answer:

In poorly sorted sediments, those with a larger range of grain sizes, the finer grains tend to fill the spaces between the larger grains, resulting in lower porosity. Primary porosity can range from less than one percent in crystalline rocks like granite to over 55% in some soils.

Explanation:

Which compound has the longest carbon-carbon bond length?.

Answers

Hokkaido University researchers have synthesized an organic compound with a longer bond between carbon atoms than ever before - exceeding the assumed limit for carbon-carbon single bond (C-C) lengths. The researchers termed it a "hyper covalent bond." The novel polycyclic hydrocarbon named 10c is stable, and an X-ray analysis showed that its C-C bond lengths was as long as 1.806 angstroms, longer than the previously reported world records for hydrocarbons.

A mixture of three gases (N2, Ar, and O2) at 2.6 atm is found to contain 23% N2 and 3.0% Ar by mass. What is the partial pressure of O2

Answers

Given that the mixture of the three gases has a pressure of 2.6 atm, the partial pressure of O₂ is 1.924 atm

Dalton's law of partial pressure

This law states that at contact temperature, the total pressure of a mixture of gases is equal to the sum of the partial pressure exerted by each gas. Mathematically, it is expressed as

Total pressure = partial pressure of A + partial pressure of B

How to determine the partial pressure of O₂Percentage of N₂ = 23%Percentage of Ar = 3%Percentage of O₂ = 100 – (23 + 3) = 74%Total pressure = 2.6 atmPartial pressure of O₂ =?

Partial pressure of O₂ = (percentage of O₂) × total pressure

Partial pressure of O₂ = 74% × 2.6

Partial pressure of O₂ = 0.74 × 2.6

Partial pressure of O₂ = 1.924 atm

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what are two transition metals in the periodic table?

Answers

Answer:

two transitions elements are iron and cobalt

What role does sulfuric acid play in the fischer esterification?.

Answers

Answer:

It plays the role of a catalyst.

Type of force when you open the door. *
1 point
A. applied force
B. friction
C. gravity
D. magnetism

Answers

A. applied force

force applied to an object

Answer:

A. Applied force

Explanation:

A. should be the answer because you applied force onto an object to make it move or do what you’d like.


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identify a human activity that impacts the land negatively then describe a positive action that can help rude effects caused by the activity

giving brainiest

Answers

the number of trips one takes in a car should be reduced.

reduce or eliminate fireplace and wood stove use.

burning leaves, trash, and other materials should be avoided.

using gas-powered lawn and garden equipment should be also be avoided.

What is a DNA fingerprint and why is it considered individual evidence?

Answers

Answer:

DNA fingerprinting is a laboratory technique used to establish a link between biological evidence and a suspect in a criminal investigation.

A DNA sample taken from a crime scene is compared with a DNA sample from a suspect. If the two DNA profiles are a match, then the evidence came from that suspect.

Name and title:include your name, instructor's name, date, and name of lab.objectives(s):in your own words, what is the purpose of this lab?hypothesis:in this section, please include the if/then statements you developed during your lab activity. these statements reflect your predicted outcomes for the experiment.if the mass of the sun is 1x, at least one planet will fall into the habitable zone if i place a planet in orbits___, ____, ____, and ____, and all planets will orbit the sun successfully.if the mass of the sun is 2x, at least one planet will fall into the habitable zone if i place a planet in orbits___, ____, ____, and ____, and all planets will orbit the sun successfully.if the mass of the sun is 3x, at least one planet will fall into the habitable zone if i place a planet in orbits___, ____, ____, and ____, and all planets will orbit the sun successfully.procedure:the materials and procedures are listed in your virtual lab. you do not need to repeat them here. however, you should note if you experienced any errors or other factors that might affect your outcome.using the summary questions at the end of your virtual lab activity, please clearly define the dependent and independent variables of the experiment.data:record your observation statements from space academy.when the mass of the sun is larger, earth moves around the sun at a ______ (faster, slower) pace.when the mass of the sun is smaller, earth moves around the sun at a ______ (faster, slower) pace.when earth is closer to the sun, its orbit becomes _____ (faster, slower).when earth is farther from the sun, its orbit becomes _____ (faster, slower).for each trial, record the orbit number of each planet from the sun. be sure to indicate the number of planets in the habitable zone after each trial. create a different configuration of planets for each trial. an example has been supplied for you. orbit numberplanet one orbit numberplanet two orbit numberplanet three orbit numberplanet four number of planets in the habitable zone number of planets left in successful orbitexample: sun's mass 1x 135612sun's mass 1x—trial one sun's mass 1x—trial two sun's mass 2x—trial one sun's mass 2x—trial two sun's mass 3x—trial one sun's mass 3x—trial two conclusion:your conclusion will include a summary of the lab results and an interpretation of the results. please answer all questions in complete sentences using your own words.using two to three sentences, summarize what you investigated and observed in this lab.you completed three terra forming trials. describe the how the sun's mass affects planets in a solar system. use data you recorded to support your conclusions.in this simulation, the masses of the planets were all the same. do you think if the masses of the planets were different, it would affect the results? why or why not?how does this simulation demonstrate the law of universal gravitation?it is the year 2085, and the world population has grown at an alarming rate. as a space explorer, you have been sent on a terraforming mission into space. your mission to search for a habitable planet for humans to colonize in addition to planet earth. you found a planet you believe would be habitable, and now need to report back your findings. describe the new planet, and why it would be perfect for maintaining human life.

Answers

If the mass of the sun is 1x, at least one planet will fall into the habitable zone if I place a planet in orbits 2, 6, and 75, and all planets will orbit the sun successfully.

If the mass of the sun is 2x, at least one planet will fall into the habitable zone if I place a planet in orbits 84 , 1, and 5, and all planets will orbit the sun successfully.

If the mass of the sun is 3x, at least one planet will fall into the habitable zone if I place a planet in orbits 672 and 7, and all planets will orbit the sun successfully.

When the mass of the sun is larger, Earth moves around the sun at a faster pace.When the mass of the sun is smaller, Earth moves around the sun at a slower pace.When Earth is closer to the sun, its orbit becomes faster.When Earth is farther from the sun, its orbit becomes slower.

What would occur if the Earth was closer to the sun?

When Earth is closer to the sun, there will be hotter climate. A little movement that takes one closer to the sun could lead to a huge impact.

Due to the fact that there is warming that can make the glaciers to melt, there is an increase in the sea levels and flooding occurs in a lot of areas of the planet and when there is no land to absorb some of the sun's heat, the temperatures on Earth would tend to rise more.

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How are dams and levees alike?

Answers

Answer:

they are bigg has water in then and they a deep

What is a technique for gene therapy?

Answers

Answer:

For gene therapy, stem cells can be trained in a lab to become cells that can help fight disease. Liposomes. These fatty particles have the ability to carry the new, therapeutic genes to the target cells and pass the genes into your cells' DNA.

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What is the density of a substance with a volume of 5.0 mL and a mass of 15.0g?

A.) .33 g/mL
B.) 3.0 g/mL
C.) 10.0 g/mL
D.) 20.0 g/mL

Answers

Answer:

B) 3.0 g/mL

Explanation:

density formula: mass/volume

15/5=3

which of the following is lewis acid a. Bacl. b.kcl c.Becl2 d.Licl​

Answers

Answer:

becl2

Explanation:

because

a it has incomplete outer

b it accept electron pair

Consider the following reactions Ca(OH)2 + 2NH4Cl - Cacl2 + 2H₂O + 2NH2 a) how many grams of cacl2 will be formed from the if . 1)40 gram of nh4cl?​

Answers

Answer:

41.495

Explanation:

107 gm of 2NH4Cl gives 111 gm of CaCl2

40 gm of 2 NH4Cl gives =(111*40)/107

=41.495 gm of CaCl2

The concentration of A is initially 0.150 M before it proceeds to equilibrium. The system is at 298 K. What is the equilibrium concentration of B

Answers

For a  concentration of  is initially 0.150 M before it proceeds to equilibrium, the equilibrium concentration of B  is mathematically given as

x=3.0*10^{-7}m

What is the equilibrium concentration of B?

Generally, the equation for the  change in Gibbs free energy   is mathematically given as

dG=-RTInK

Therefore

31.5*10*^{3}=-(8.314)(298)(ink)

K=3*10^(-6)

Eqution

A--->B

K=x/0.1-x

x=3.0*10^{-7}m

In conclusion, the equilibrium concentration

x=3.0*10^{-7}m

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How will you use simple filter paper to demonstrate chromatography. Show with diagram.​

Answers

Answer:

1. Draw a pencil line across the filter paper, 1 - 2 cm from the bottom.

2. Use a pipette or capillary tube to add small spots of each ink to the line on the paper.

3. Place the paper into a container with a suitable solvent in the bottom. For example, water. Make sure the water level is below the pencil line.

4. Allow the solvent to move through the paper, but remove the chromatogram before it reaches the top.

5. Allow the chromatogram to dry.

Extras : preferably use a lid to prevent evaporation and use a pencil or any suitable device to prop the paper in place, make sure the sides of the paper doesn't touch the sides of the beaker.

Label the equivalence point on the graph of pH versus volume of the titration of a strong acid and strong base shown below
no bots please!

a. What volume of base was needed to neutralize the acid?
b. What is the pH at the equivalence point?
c. How does the number of moles of hydronium ions and hydroxide ions compare at the
equivalence point?

Answers

For C, they would be the same. At the equivalence, you have equal moles of both the acid and the base.

How many liters of 1.0 M NaCl solution are needed to react with 5 M of the solute

Answers

That should be 5mols of solute

Now

Let that volume be V

Molarity=Moles of solute/Volume in L1M=5/VV=5L

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Bromthymol blue is an acid-base indicator that changes color around pH 7. Adding a small amount of bromthymol blue to a basic solution would be most helpful in _____.
A. determining the identity of the base in the solution
B. tracking the pH as the solution is gradually acidified
C. precisely measuring the pH of the solution
D. calculating the concentration of the base in the solution

Answers

Answer:

B) tracking the pH as the solution is gradually acidified

Explanation:

Got it right on the quiz!

hope this helped!

brainliest please!

Answer:

B. tracking the pH as the solution is gradually acidified

Why does the entropy of a gas increase when it expands into a vacuum?.

Answers

Answer:

When a gas expands into a vacuum, its entropy increases because the increased volume allows for greater atomic or molecular disorder. The greater the number of atoms or molecules in the gas, the greater the disorder.

Explanation:

Flammable liquids are those that have a flashpoint of:.

Answers

Answer:

Flammable liquid is any liquid having a flashpoint at or below 199.4 °F (93 °C).

Explanation:

:)

Flashpoints for flammable liquids are at 100°F. Lower flash points allow for easier ignition of liquids. A liquid's flash point is the lowest temperature at which a concentrated enough layer of vapor accumulates on top of its surface to allow for ignition.

A liquid that is flammable has a flash point* below 37.8 ° C (100 ° F). A flammable liquid has a flash point that ranges from 37.8 to 93.3° C (100 to 200° F), which is above the standard working temperature. Flammable liquids emit a vapor that, at standard working temperatures, is easily ignitable.

The substance ignites more readily the lower the flash point. For instance, petrol is more flammable than ethylene glycol and has a flash point of about -40 degrees C (-40 °F).

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Does gravity give objects their mass

Answers

Answer:

No

Explanation:

Mass affects the amount of gravity that acts on an object.

Answer:

Mass is determined by the quantity of matter in a physical object.

Mass is how much space something takes up, while weight is how much an object is acted on by a force because of gravity.

Explanation:

Gravity does not determine the mass of an object. For example, an object on the Moon would weigh less than it does on Earth because of the lower gravity, but it would still have the same mass. This is because weight is a force, while mass is the property that determines the strength of this force.

A(n) reaction is a self-sustaining series of chemical reactions in which the products of one reaction are the reactants in the next reaction.

Answers

The reaction which is a self-sustaining series of chemical reactions in which the products of one reaction are the reactants in the next reaction is chain reactions.

What are reactants and products?

Reactants are those species which are present at the initial state of the reaction and at the end of the reaction we obtain products.

If in any chemical reactions, reactants are combined for the formation of products and for the further process obtained product will act as reactant and that chemical reactions are known as chain reactions. Because this process continues for long time.

Hence correct option is chain reactions.

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Answer:

chain

Explanation:

edge 2023

A car is accelerating from rest at a rate of 2 (m/s)/ s. How fast will it be going after 4 seconds?​

Answers

Answer:

8 m/s

Explanation:

The Formula

v = u + at

⇒ v = final velocity

⇒ u = initial velocity

⇒ a = acceleration

⇒ t = time taken

Given

u = 0 [rest]a = 2 m/st = 4 s

Solving

v = u + atv = 0 + 2(4)v = 8 m/s

what is the pH of 3.65 grams of HCl dissolved in 1250 mL distilled H2O

Answers

Considering the definition of pH, the pH of 3.65 grams of HCl dissolved in 1250 mL distilled H₂O is 1.0969.

Definition of pH

pH is the Hydrogen Potential. It is a measure of acidity or alkalinity that indicates the amount of hydrogen ions present in a solution or substance.

Mathematically, pH is calculated as the negative base 10 logarithm of the activity of hydrogen ions:

pH= - log [H⁺]

The numerical scale that measures the pH of substances includes the numbers from 0 to 14. The pH value 7 corresponds to neutral substances. Acidic substances are those with a pH lower than 7, while basic substances have a pH higher than 7.

Concentration of HCl

Molar concentration or molarity is a measure of the concentration of a solute in a solution and indicates the number of moles of solute that are dissolved in a given volume.

The molarity of a solution is calculated by dividing the moles of solute by the volume of the solution:

[tex]Molarity=\frac{number of moles}{volume}[/tex]

In this case, you know:

number of moles=[tex]3.65 grams x\frac{1 mole}{36.45 grams} =[/tex] 0.1 moles (being 36.45 g/mole the molar mass of HCl)volume= 1250 mL= 1.250 L (being 1000 mL= 1 L)

Replacing in the definition of molarity:

[tex]Molarity=\frac{0.1 moles}{1.250 L}[/tex]

Solving:

Molarity= 0.08 [tex]\frac{moles}{liter}[/tex]= 0.08 M

pH of the solution

Hydrochloric acid is a strong acid, so in aqueous solution it will be totally dissociated. So the concentration of protons is equal to the initial concentration of acid. This is: [H⁺]= [HCl]= 0.08 M

Replacing in the definition of pH:

pH= - log (0.08 M)

Solving:

pH= 1.0969

Finally, the pH of 3.65 grams of HCl dissolved in 1250 mL distilled H₂O is 1.0969.

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pH:

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molarity:

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3. describe natural sources of radiation. infer some of the dangers that radiation can impose.

Answers

Answer:

All of us are exposed to radiation every day, from natural sources such as minerals in the ground, and man-made sources such as medical x-rays. According to the National Council on Radiation Protection and Measurements (NCRP), the average annual radiation dose per person in the U.S. is 6.2 millisieverts (620 millirem).

Explanation:

Which of the following is the molecule with the highest number of covalent bonds?
1. O2
2. N2
3. NH3
4. CO2

Answers

Answer:

N2 and NH3 both have 3 so try one of those ones

what factors determine the amount of radiant energy we will receive on earth?

Answers

I don’t know is this science ??
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