Selenium-81 has an abundance of 21.91% and a mass of 80.65 amu.
Selenium-84 has an abundance of 23.35% and a mass of 83.67 amu.
Selenium-80 has an abundance of 54.74% and a mass of 79.64 amu.
What is the average atomic mass of Selenium according to these values?

Answers

Answer 1

Answer:

80.80amu

Explanation:

multiple each value by its percentage (in decimal form) and take the sum.

80.65x.2191 + 83.67x.2335 + 79.64x.5474 = 80.802296 sig figs = 80.80


Related Questions

5) Which of these are intensive properties?
a substance has a volume of 5.4 mL
a substance has a mass of 1.25 g
a substance has a density of 4.13 g/cm3
a substance has a melting point of 40°C
a substance is very malleable (it can be hammered into a shape)



6) Which of these are extensive properties?
a substance has a melting point of 40°C
a substance is very malleable (it can be hammered into a shape)
a substance has a volume of 5.4 mL
a substance has a mass of 1.25 g
a substance has a density of 4.13 g/cm3

Answers

Answer:

For number 5 it is the 2nd one some stants has a mass of 1.25 g And the 2nd 1 number 6It is the 1st 1A subject has a melting point of 40

What is the enthalpy of reaction for the decomposition of calcium carbonate?

CaCO3(s) Right arrow. CaO(s) + CO2(g)

Answers

Answer:

Explanation:

You will need to look up the Standard Heats of Formation* for each substance and apply Hess's Law Equation.

ΔH⁰(rxn) = ∑ΔH⁰(Products) - ∑ΔH⁰(Reactants)

*Std Heats of Formation can be found in the appendix of most college chem texts.

For this problem:

Given               CaCO₃(s)       =>           CaO(s)        +      CO₂(g)

∑ΔH⁰:          -635.1 Kj/mole            -393.5Kj/mole         -1206.9

ΔH⁰(rxn) = [(-393.5 Kj/mole) + (-393.5Kj/mole)] - (-1206.9Kj/mole)

= (-635.1 -393.5 + 1206.9) Kj/mole

= +178.3 Kj/mole

Answer:

656.3 kJ

This reaction is endothermic

Explanation:

edge 2020

A compound has the following composition by mass:
32% carbon, 6.7% hydrogen, 42.6% oxygen and 18.7% nitrogen
What is the empirical formula of the compound?

Answers

Answer:

i cry when im alone

Explanation:

The table lists some compounds found in foods and their formulas.
Based on this information, which of these statements is NOT true?
CLEAR

Answers

Answer:

A

Explanation:

the number of molecule won't be twice as fructose has 12 hydrogen molecules and lactose has 22 hydrogen molecules

From the given statements, the statement saying that the number of atoms in Lactose is twice the number of atoms in Fructose is not correct. Thus option A is correct.

The given molecules in the list are Glutamine, Lactose, fructose, and Sorbitol.

The number of atoms in the following compounds is:

Glutamine = 20 atomsLactose = 45 atomsFructose = 24 atomsSorbitol = 26 atoms.

Statement A says that the number of atoms in Lactose is twice the number of atoms in Fructose. The twice atoms of Fructose are 48 atoms. The number of atoms of lactose is 45.

Thus statement A is incorrect. Thus option A is correct.

For more about the atoms in a molecule, refer to the link:

https://brainly.com/question/25617532

What allows a liquid to take the form of the container it is in?
A.
strong intermolecular forces
B.
low temperature
C.
weak intermolecular forces
D.
low kinetic energy

Answers

Answer:

It's probably C

The forces between liquid particles are weaker than the forces between solid particles. This means that liquid particles are further apart and can move about more easily. Since the particles can move, the liquid can flow and take the shape of its container

Sorry if the answer is wrong!!!!!!

Which pair has the stronger ionic bond:

- MgCl2 vs. NaCl2
- NaCl vs. LiCl

Answers

Answer:

- NaCl vs. LiCl

What is the density (g / mL) of a substance that has a mass of 8.11 g and, when placed into a graduated cylinder, causes the water level to rise from 25.26 mL to 44.72 mL?

Answers

Answer:

The answer is 0.42 g/mL

Explanation:

The density of a substance can be found by using the formula

[tex]density = \frac{mass}{volume} \\[/tex]

From the question

mass = 8.11 g

volume = final volume of water - initial volume of water

volume = 44.72 - 25.26 = 19.46 mL

We have

[tex]density = \frac{8.11}{19.46} \\ = 0.416752312...[/tex]

We have the final answer as

0.42 g/mL

Hope this helps you

✓7
Is it rational or irrational

Answers

Answer:

Irrational

Explanation:

:)

Answer:

It is irrational

Explanation:

Since 7 is a prime number, it has no square factors and its square root cannot be simplified.

Which is a feature of a single replacement reaction?
Substance XYZ breaks down into X and YZ.
Substance G reacts with compound XY to form GY and X.
Substance X burns rapidly in the presence of oxygen.
Substance QR and GT exchange ions with each other.

Answers

Answer:

Its B

Explanation:

Because im just built different

The statement  featuring the single replacement reaction has been statement B.

The single replacement reaction has been defined as the reaction of the highly reactive element with the compounds, that results in the formation of the new compound with the replacement of the less reactive element.

The single replacement reaction can be given as:

G + XY [tex]\rightarrow[/tex] GY + X

In the reaction, G being more reactive than X has been able to displace X and forms bond with Y. Thus, statement  featuring the single replacement reaction has been B.

For more information about the single replacement reaction, refer to the link:

https://brainly.com/question/8625202

What do organs combine to form? organ systems cells tissues organisms

Answers

Answer:

the answer is {organisms}

Answer:

organisms

Explanation: I took the test

If 298 mL of 0.575 M CuCl2 is diluted into 750 mL, what is the concentration of new solution?

Answers

Answer:

The answer is 0.228 M

Explanation:

To find the concentration of new solution we use the formula

[tex]C_1V_1 = C_2V_2[/tex]

where

C1 is the concentration of the stock solution

V1 is the volume is the volume of the stock solution

C_2 is the concentration of the diluted solution

V2 is the volume of the diluted solution

Since we are finding the the concentration of new solution

[tex]C_2 = \frac{C_1V_1}{V_2} \\[/tex]

From the question

C1 = 0.575 M

V1 = 298 mL

V2 = 750 mL

We have

[tex]C_2 = \frac{0.575 \times 298}{750} \\ = 0.228466666...[/tex]

We have the final answer as

0.228 M

Hope this helps you

Which of the following is a common sign that a chemical change has occurred?

Answers

A chemical has changed into a different state

Marcy tests a solution with a strip of blue litmus paper. The paper turns red. The solution is _____.
acidic
basic
neutral

Answers

Acidic is the correct answer

Which of the statements below about buoyancy is true?
A.if the buoyant force is greater than the force of gravity,the object will sink
B.buoyancy is a force that acts on objects that are placed in a fluid
C.all objects that experience the force of buoyancy float
D.buoyancy pushes objects down in the same direction as gravity

(answer asap plz I will give brainliest to who helps me )​

Answers

Buoyancy is a force that acts on objects that are placed in a fluid is the correct answer
Let me know if I agit it!

Answer:

it's A. if the force of gravity is greater than the buoyant force, the object will sink.

Explanation:

just took the quiz on a p e x

What is the term for an object's strength of motion?
O Momentum
O Acceleration
O
Force
O
Velocity

Answers

I'm pretty sure its momentum

How can the total energy of an open system be changed? Enter your answer in the space provided.

Answers

yes they can be changed becasue they are expose to the environment

That's why it's improtant to have a calorimeter so the energy and heat are contained

The total energy of an open system be changed if:

There is an exchange between matter and energy

According to the First Law of Thermodynamics, energy cannot be created or destroyed, it can only change form.

An open system is a system that has an interaction with its environment where matter or energy can be added or removed from the environment.

As a result of this, the total energy of an open system can be changed if there is an exchange between matter and energy and they remain constant.

Therefore, the correct answer is an exchange has to take place for the total energy in an open system to be changed.

Read more here:

https://brainly.com/question/20319024

A testable explanation of or answer to a scientific question that is based on prior knowledge or research is a(n)

Answers

Answer:

the answer is HYPOTHESIS your welcome

Explanation:

Calculate the number of grams of CuSO4 found in 3.29 mL of a 4.00 M CuSO4 solution. ______ grams CuSO4

Answers

Answer:

2.08g

Explanation:

Given parameters:

  Volume of CuSO₄  = 3.29mL

  Molarity  = 4M

Unknown:

Mass of CuSO₄ = ?

Solution:

Let us find the number of moles from the given parameters first;

     Number of moles  = molarity x volume

           1000mL = 1L

Express the volume of the given CuSO₄ in L = 3.29 x 10⁻³L

   Number of moles  = 4 x 3.29 x 10⁻³ = 0.013mol

So;

  Mass of CuSO₄ = number of moles x molar mass

      Molar mass of  CuSO₄  = 63.6 + 32 + 4(16) = 159.6g/mol

 Mass of CuSO₄  = 0.013mol  x 159.6g/mol

 Mass of CuSO₄  = 2.08g

PLEASE HELP!!!!!
What happens to the transfer of thermal energy when thermal equilibrium is reached?

Answers

Answer:

During the process of reaching thermal equilibrium heat is transferred between the object. heat is always transferred from the object at the higher temperature to the object with lower temperature. For a gas, the heat transfer is related to a change in temperature.

How could the continents have gotten so far apart and how long did it take for this to happen

Answers

Pangaea existed about 240 million years ago. By about 200 million years ago, this supercontinent began breaking up. Over millions of years, Pangaea separated into pieces that moved away from one another. These pieces slowly assumed their positions as the continent we recognize today.

Where can you find most of Earth's liquid freshwater?

Answers

Answer:

Where can you find most of Earth's liquid freshwater?

Explanation:

Over 68 percent of the fresh water on Earth is found in icecaps and glaciers, and just over 30 percent is found in ground water. Only about 0.3 percent of our fresh water is found in the surface water of lakes, rivers, and swamps.

Hope that helped, i also have snap if you need me.

Over 68 per cent of the fresh water on Earth is found in icecaps and glaciers, and just over 30 per cent is found in groundwater. Only about 0.3 per cent of our freshwater is found in the surface water of lakes, and rivers.

What is the per cent of the water on this earth?

The Earth is a watery place. About 71 per cent of the Earth's surface is water-covered, and the oceans hold about 96.5 per cent of all Earth's water.

The majority of Earth’s fresh water is stored in underground aquifers.

Aquifers are layers of sedimentary formations such as sandstone and fractured hard rocks where water after infiltration from soil reaches and fill the interstitial spaces.

Aquifers are huge in size in basins and contain a huge amount of underground water of fresh quality.

So, over 68 per cent of the freshwater is present on Earth.

Learn more about the freshwater here:

https://brainly.com/question/4381433

#SPJ2

Ionic crystals have high boiling points because:
A. They do not have high boiling points.
B. breaking ionic bonds requires a large amount of energy.
C. the structure has a large surface area to absorb heat quickly.
D. the positive and negative charges prevent them from absorbing heat quickly.

Answers

The answer would be B.

Which organ produces the female hormone estrogen?

A. Hypothalamus

B. Ovary

C. Pancreas

D. Testicle

Answers

Answer:

b-ovaries

Explanation:

Answer:

ovaries

Explanation:

i just know trust me tell me if its wrong

A scientist is studying two types of worms. Worm X has DNA identical to its parent. Worm Y has a combination of DNA from two parents. The scientist determines that one of the worms has a survival advantage over the other worm. Which statement correctly summarizes this conclusion? Worm X reproduces asexually, which gives it genetic variation. Worm Y reproduces sexually, which gives it genetic variation. Worm Y reproduces asexually, which gives it more DNA. Worm X reproduces sexually, which gives it more DNA.

Answers

Answer:

2. Worm Y reproduces sexually, which gives it genetic variation.

Answer:

B      Worm Y reproduces sexually, which gives it genetic variation.

Explanation:

hope you all have a good day

7. Which of the following units would be MOST appropriate for measuring
the volume of a small can of soda? *
1 point
A. Liters
B. Milliliters
C. Grams
D. Kilograms
Use the metric ruler to answer questions 8 and 9.

Answers

Answer:

im pretty sure the answer is b

[tex]\huge\underline\mathbb\pink{ANSWER\::}\\\\[/tex]B. Milliliters

[tex]\\\\\\[/tex]

HOPE IT HELPS

PLEASE MARK ME BRAINLIEST ☺️

16.4 A cylinder of water contains oxygen in solution. The cross- sectional area of the cylinder is 2 cm2 and the length of the cylin- der is 5 cm. At one end of the cylinder the concentration of oxygern is maintained at 0.2 mol m-3, this concentration falls linearly to 0.05 mol m-3 at the other end of the cylinder. The diffusion con- stant of oxygen in water is 8 × 10-10 m2 s-1. How many moles of oxygen pass down this cylinder every second? What mass of oxy- gen passes down the cylinder each second?

Answers

Answer:

A) oxygen moles/sec = 48 * 10 ^-14  mol/sec

B) mass of oxygen = 1536*10^-14 grams

Explanation:

cross sectional area of cylinder = 2cm^2 = 2 * 10^-4 m^2

length of cylinder = 5 cm = 0.05 m

concentration at one end = 0.2 mol m^-3

concentration falls linearly at other end = 0.05 mol m^-3

Diffusion constant of oxygen = 8 * 10^-10  m^2 s^-1

A ) Number of moles of oxygen passing every second

 N = A * D * [tex]\frac{dc}{dt}[/tex]   ------- ( 1 )

A = area , D = diffusion constant,  [tex]\frac{dc}{dt}[/tex] = rate of change of diffusion

dc /dt = ( 0.2 - 0.05 ) / 0.05  = 3 mol m^-4

back to the equation

N = ( 2 * 10^-4 ) * ( 8 * 10^-10 ) * ( 3 ) = 48 * 10 ^-14  mol/sec

B) Mass of oxygen passing down the cylinder each second

This can be obtained by converting : 48 * 10^-14 moles to grams

1 mole of oxygen  =  32 grams of oxygen

therefore : 48 * 10^-14 moles of oxygen = ( 32 * (48*10^-14) = 1536*10^-14 grams

Is a venus fly trap non-living?

Answers

It is a plant so it is considered living.

What is the density if the mass is 25 g and the volume is 114 mL?

Answers

Answer:

0.219 g/mL.

Explanation:

From the question given above, the following data were obtained:

Mass = 25 g

Volume = 114 mL

Density =.....?

Density of a substance is simply defined as the mass of the substance per unit volume of the substance. Mathematically, it is expressed as:

Density = mass /volume

With the above formula, we can obtain the density of the substance given in the question above as follow:

Mass = 25 g

Volume = 114 mL

Density =.....?

Density = mass /volume

Density = 25/114

Density = 0.219 g/mL

Therefore, the density of the substance is 0.219 g/mL

what istope of an atom if it has 29 protons and 36 neutrons?

Answers

Answer:

Copper Atoms

Explanation:

All copper atoms have atomic number 29: all their nuclei contain 29 protons. But they also contain uncharged particles called neutrons. In natural copper, the atoms are of two kinds. One has 29 protons and 34 neutrons in the nucleus; the other has 29 protons and 36 neutrons

How many lead (Pb) atoms are in a 5.32 g sample of pure lead?

Answers

Answer:

1.55×10²² molecules.

Explanation:

We'll begin by calculating the number of mole in 5.32 g of pure lead (Pb). This can be obtained as follow:

Mass of Pb = 5.32 g

Molar mass of Pb = 207 g/mol

Mole of Pb =?

Mole = mass /molar mass

Mole of Pb = 5.32/207

Mole of Pb = 0.0257 mole

Finally, we shall determine the number of molecules in 0.0257 mole of Pb. This can be obtained as follow:

From Avogadro's hypothesis,

I mole of Pb contains 6.02×10²³ molecules.

Therefore, 0.0257 mole will contain = 0.0257 × 6.02×10²³ = 1.55×10²² molecules.

Therefore, 5.32 g of pure lead (Pb) contains 1.55×10²² molecules.

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