If a rock sample originally contained 12 g of uranium 235, how much will be left after 2 half lives?

Answers

Answer 1

Answer:

3 g

Explanation:

new mass = (1/2)^n * original mass

where n = number of half lives

(1/2) ^2 * 12

= 3 g


Related Questions

The diagram shows three steps in the carbon cycle.
The Carbon Cycle

Which two phrases best summarize the events taking place in Step 2?

A. Cellular respiration

B. Storing carbon dioxide in living organisms

C. Photosynthesis

D. Releasing carbon dioxide into the atmosphere

Answers

According to the diagram, cellular respiration and photosynthesis are the phrases that best summarize the events taking place in Step 2.

What is the Carbon Cycle?

It is the way carbon circulates through the atmosphere, the oceans, and the Earth's surface and interior.

Cellular respiration and photosynthesis respectively release and capture carbon dioxide from the atmosphere, as a by-product or input of their biochemical pathways, carbon from CO2 is absorbed by plants and released along with water vapor during animal respiration.

Therefore, we can conclude that according to the diagram, cellular respiration and photosynthesis are the phrases that best summarize the events taking place in Step 2.

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I'd say Photosynthesis and Storing carbon dioxide in living organisms.

But the person above me shows alot more detail than I have.

Niels Bohr adapted the nuclear model.
Describe the change that Bohr made to the nuclear model.

Answers

Answer:

To remedy the stability problem, Bohr modified the Rutherford model by requiring that the electrons move in orbits of fixed size and energy.

If atom a gives up electrons to atom b what will the elecrical charge of atom a be

Answers

Answer:

The electric charge of the atom 'a' will be "+1".

Explanation:

When an atom gains/loses an electron, the atom becomes charged, and is called an ion. Gaining an electron results in a negative charge, so the atom is an anion. Losing an electron results in a positive charge, so atom ion is a cation.

It means that the 'Atom A' is giving that is, losing the electrons

Alpha Centauri IS
star that is about the same size as the IS Sun. John is using tennis balls to model how the Sun and Alpha
Centauri appear from Earth. He places one tennis ball one meter to his right to model the Sun. He places another tennis ball ten
meters to his left to model Alpha Centauri.
What does John notice about the tennis ball that is ten meters to his left?
es
It looks wider than the other tennis ball.
BI
It looks smaller than the other tennis ball
It looks different in color than the other tennis ball
It looks different in shape than the other tennis ball

Answers

Answer:

it looks smaller for sure ^_^

7)What mass of hydrogen gas is produced when 8.56grams of lithium reacts with water to also produce lithium
hydroxide?
2Li + 2H20 - H2 + 2LIOH

Answers

i guess this is the answer .

Please help
Calculate the molarity of an HCl solution if 41.73 mL of HCl reacts with 7.8111 grams of sodium carbonate (106 g/mol) according to

2 HCl + Na2CO3 → 2 NaCl + H2O + CO2
Answer in units of mol/L.

Answers

The molarity of an HCl solution if 41.73 mL of HCl reacts with 7.8111 grams of sodium carbonate is 1.77M. Details about molarity can be found below.

How to calculate molarity?

The molarity of a solution can be calculated by dividing the number of moles of the substance by its volume.

According to this question, 7.8111 grams of sodium carbonate (106 g/mol) is given. The number of moles of sodium carbonate is calculated as follows:

no of moles = 7.811g ÷ 106g/mol = 0.074mol

Molarity of HCl = 0.074mol ÷ 0.04173L

Molarity of HCl = 1.77M

Therefore, the molarity of an HCl solution if 41.73 mL of HCl reacts with 7.8111 grams of sodium carbonate is 1.77M.

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8Li2S --> 16Li +S8 how many moles of Li would be produced when 5 moles of Li2S react?

Answers

Answer:

10moles

Explanation:

mole ratio = 8:16

therefore

1 mole Li2S forms 2 moles Li

when 5 moles Li2S reacts

5 moles Li2S = 5 x 2 moles Li

= 10 moles Li

Why is knowing density important to us? Give a reasonable answer please don’t copy what the internet has I already tried doing that I can’t

Answers

It’s important bc it helps know how dense things can be

Select the correct structure that
corresponds to the name.
3,3-dimethylcyclopentene
A. CH3,
B
CH3
C. both
CH3
CH3
Please help me asap!!

Answers

Answer:

B

Explanation:

The naming of the compound is given by IUPACNumbering of the carbon atoms start from the double bondThe methyl groups lie at the 3rd positionHence, its name will be :3,3 - dimethylcyclopentaneOption B shows the correct structure

What kind of waves do light waves travel in and how do they move

Answers

Light is one form of energy that travels in electromagnetic waves. This energy is both magnetic and electrical. There are many different types of electromagnetic (EM) waves.

A sample of helium gas is
sealed in a container with a lid
that can be moved up and down.

Select all of the following that will result in an increase in pressure inside the container.

A. Decreasing volume

B. Increasing volume

C. Decreasing temperature

D. Increasing temperature

E. Adding one more mole of helium gas

F. Removing one mole of helium gas

Answers

P=nRT/V

P ≈ 1/V = decreasing volume

P ≈ T = increasing temperature

P ≈ n = adding one more mole of helium

What is the maximum mass of ethyl alcohol you could boil with 1000 j of heat, starting from 20°c?

Answers

The amount of maximum mass of ethyl alcohol that could we boil with 1000 J of heat, starting from 20°C is 7.08 grams.

How do we calculate the mass?

Mass of the ethyl alcohol will be calculated by using the below equation as:

Q = mcΔT, where

Q = absorbed heat = 1000 Jm = mass of ethyl alcohol = ?c = specific heat of ethyl alcohol = 2.42 J/g.°CΔT = change in temperature = (78.37°C - 20°C) = 58.37°C

On putting all these values, we get

m = 1000 / (2.42)(58.37) = 7.079 = 7.08g

Hence required mass of ethyl alcohol is 7.08grams.

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Solid potassium fluorine gas → solid potassium fluoride balanced

Answers

The balanced symbol equation for Solid potassium fluorine gas → solid potassium fluoride is 2 K + F₂ → 2 KF ⁻.

What is a balanced equation?

The reactants are on the left side of the arrow in a balanced equation, while the products are on the right.

The moles in a compound are indicated by the number in front of the chemical formula. Subscripts indicate the number of atoms in a single molecule (numbers below an atom).

Thus, the balanced equation is 2 K + F₂ → 2 KF ⁻.

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Why did the Marshall Plan include aid for the defeated Axis powers?
Question

Answers

Answer:

One of the purposes of the Marshall Plan was to aid nations in economic recovery from WWII.

Explanation:

The Marshall Plan aided the defeated Axis powers because that's one of the reasons it was created, The Marshall Plan was supposed to rehabilitate the economies of the 17 western and southern European countries in order to create stable conditions for democracy to continue.

Please help me? I am not understanding any of this

Answers

Answer:

Hydrogen

Explanation:

These are what hydrogen isotopes look like

SO2+02➡SO3
balance chemical equation​

Answers

Answer:

2S02 + O2 ---> 2SO3

Its balanced now as Reactants = Products.

When the temperature and number of particles of a gas are constant, which of the following is also constant?
a. the product of the pressure and volume
b. the sum of the pressure and volume
c. the ratio of the pressure and volume
d. the difference of the pressure and volume

Answers

The answer is A the product of the pressure and volume

If 70 grams of nitrogen gas will dissolve in a liter of solution at 1 atm of external
pressure. If the pressure is increased to 3 atmospheres, what would the solubility be?

Answers

Answer: Empirical formula, CH; Molecular formula, C2H2

Explanation:

CHEMISTRY PLS HELPPP
Which of the following molecules is optically active?
A. 3,3-dichloropent-1-ene
B. Butan-1-ol
C. 2-methylbutane
D. 2-bromopropanoic acid

Answers

Answer:

D

Explanation:

2-bromopropanoic acid is optically active because it contains chiral carbon bonded with 4 different atom ( CH3,H,COOH,Br).

How many formula units of silver fluoride, AgF, are equal to 42.15 g of this substance?
Hurry please.

Answers

2.05 × 10²³ formula units

Given data:Mass of AgF =  43.15 gNumber of formula units = ?Solution:Number of moles of AgF:Number of moles = mass/ molar massNumber of moles = 43.15 g/ 126.87 g/molNumber of moles = 0.34 molNow Number of formula units will be determine by using Avogadro number.It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.The number 6.022 × 10²³ is called Avogadro number1 mole = 6.022 × 10²³ formula units0.34 mol × 6.022 × 10²³ formula units2.05 × 10²³ formula units

Consider the following reaction. Zn(s) 2agno3(aq) --> 2ag(s) zn(no3)2(aq)when 16. 2 g of silver was produced, _____ mole(s) of silver nitrate would be required

Answers

The required amount of silver nitrate to produce 16.2g of silver is 25.48 grams.

What is the relation between mass & moles?

Relation between the mass and moles of any substance will be represented as:

n = W/M, where

W = given massM = molar mass

Moles of silver = 16.2g / 107.8g/mol = 0.15mol

From the stoichiometry of the given reaction it is clear that, same moles of silver nitrate is required to produce same moles of silver. So 0.15 moles of silver nitrate is required.

Mass of silver nitrate = (0.15mol)(169.87g/mol) = 25.48g

Hence required mass of silver nitrate is 25.48g.

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Which periodic trend quantifies the amount of energy required to remove an electron from a neutral, gaseous atom?.

Answers

Ionization energy refers to the amount of energy needed to remove an electron from an atom. Ionization energy decreases as we go down a group. Ionization energy increases from left to right across the periodic table.

What is ionization energy?

Ionization is the process by which ions are formed by the gain or loss of an electron from an atom or molecule.

Ionization energy is defined as the energy required to remove the most loosely bound electron from a neutral gaseous atom.

When we move across a period from left to right then there occurs a decrease in atomic size of the atoms. Therefore, ionization energy increases along a period but decreases along a group.

Smaller is the size of an atom more will be the force of attraction between its protons and electrons. Hence, more amount of energy is required to remove an electron.

Thus, we can conclude that the energy required to remove an electron from a gaseous atom is called ionization energy.

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what whould happend if humans used all the fossil fuels on the earth​

Answers

There are several things that would happens,if all of the fossil fuels were used.The most important is in bold,but I made a quick list below to note.<3

The biggest affects would be that humans would have to find other sources of energy in order to survive. An increase of renewable as well as nuclear energy will be used in order to help build back society.

-War Would Break Out

-The Earth's Climate Would Be Far From Safe & Would Cause A Huge Decrease In Population

-A Huge Portion Of The World Would Be Living In Poverty

-Failing Economies

-A Worthless Planet

-Also want to not that it is almost impossible to run out of fossil fuels, but if we do,it won't be thousands of years in the future.

I HOPE THIS HELPS! & and good luck on your assignment.

Name the factors that liquefy atmospheric gas depend

Answers

Atmospheric gases can be liquefied by applying pressure and lowering temperature.

Plsss helpssssssssSSS

Answers

The booming prosperity of the 1950s helped to create a widespread sense of stability, contentment and consensus in the United States. However, that consensus was a fragile one, and it splintered for good during the tumultuous 1960s.

how is energy involved in phase changes ?

Answers

Answer: It is either through the addition of energy by heat and the transition to a more energetic state or from the removal of energy by heat and the transition to a less energetic state.

Explanation:

Answer:

During phase changes, matter changes from one phase to another one, either through the addition of energy by heat or transmission or the removal of energy with the same process.

Explanation:

_7 A teacher has a bottle of 12.0 M hydrochloric acid. She wants to make 2.0 L of 3.0 M HCl for her chemistry classes. How much of the 12.0 M HCI will she need to use?
А. 0.5 L
B 2L
C 20 L
D 50 L

Show your work in this box. No work, no credit.​

Answers

Answer:

C 20 L

Explanation:

Apply the formula C1 × V1 = C2 × V2 where, C1 = initial concentration , 12M V1 = initial Volume , ? C2 = Final concentration,0.25M V2 = Final Volume , 1.0L V1 = C2 x V2

Name these compounds according to IUPAC. (ASAPP)

Answers

The IUPAC name of the compound is propanal and acetone.

What is propanal and acetones?

Propanal is also called propanaldehyde, and it is an aldehyde which has one double bond and oxygen.

Acetone is a ketone. Ketones have functional group of R2CO.

Thus, the IUPAC name of the compound is propanal and acetone.

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4 pt
Question 6
(05.06 LC)
The actual yield of a product in a reaction was measured as 2.80 g. If the theoretical yield of the
product for the reaction is 3.12 g, what is the percentage yield of the product? (4 points)
82.7%
85.2%
87.3%
89.7%

Answers

89.74% is the percentage yield of the product. Hence, option D is correct.

What is the meaning of percentage?

The percentage can be calculated by dividing the value by the total value and then multiplying the result by 100.

Given data:

Actual yield of product = 2.80 g

Theoretical yield = 3.12 g

Percent yield = ?

Formula:

Percent yield =  [tex]\frac{\;actual \;yield \;X \;100}{theoretical \;yield}[/tex]

by putting values in the formula,

Percent yield =[tex]\frac{2.80 g X 100}{ 3.12 g}[/tex]

Percent yield = 89.74%

Hence, option D is correct.

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16. How many moles of aluminum are needed to react completely with 1.2 mol of FeO?l
2 Al (s) + 3 FeO (s) → 3 Fe (s) + Al₂O, (s)
a. 1.2 mol
0.8 mol
c. 1.6 mol
d. 2.4 mol

Answers

the answer would be 1.2 mol
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