Which of the following is an example of a pure substance?
A. beer
C. halo-halo
B. ethyl alcohol
D. silver spoon​

Answer:

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

[tex]n = \frac{N}{L} \\[/tex]

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

From the question

N = 1.505 × 10²³ Na atoms

We have

[tex]n = \frac{1.505 \times {10}^{23} }{6.02 \times {10}^{23} } = \frac{1}{4} \\ [/tex]

We have the final answer as

Hope this helps you

Answer:

epithelium, muscle, connective tissue and nervous tissue.

Explanation:

Explanation:

Epithelial

Connective

Muscle

Nervous

Answer:

286

Explanation:

Add atomic mass of all the Isotopes,

                                          Outcome = 825

divide it by number of isotopes which is 4 because there are 4 isotopes

                       Atomic mass of x = [tex]\frac{825}{4}[/tex]

                       Atomic mass of x is 286

The atomic mass of the unknown element X is 206 amu. Thus option B is correct.

Atomic mass is defined as the relative mass of the element's atom in comparison to the mass of an atom of the C12 isotope.

In an example, the general atomic mass is the average of the atomic masses of a large number of different isotopes.

First we added atomic mass of each isotopes

= 204 + 206 + 207 + 208 = 824

Now to calculate the atomic mass of element X we divide it by 4 as there is four isotopes

So, atomic mass = 824 / 4

                           = 206 amu

Thus, the atomic mass of the unknown element X is 206 amu. Thus option B is correct.

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Answer:

Mass of iron oxide: 79.85 g  

Explanation:

Given data:

Mass of iron = 112 g

Mass of O₂ = 24 g

Mass of iron oxide formed = ?

Solution:

4Fe + 3O₂         →       2Fe₂O₃

Number of moles of Fe:

Number of moles = mass/ molar mass

Number of moles = 112 g/ 55.85 g/mol

Number of moles =  2 mol

Number of moles of O₂:

Number of moles = mass/ molar mass

Number of moles = 24 g/ 32 g/mol

Number of moles =  0.75 mol

Now we will compare the moles of oxygen and iron with iron oxide.

                 Fe           :             Fe₂O₃

                 4             :                2

                 2             :                2/4×2 =  1

                O₂            :             Fe₂O₃

                 3             :                2

                 0.75       :                2/3×0.75 =  0.5

The number of moles of iron oxide formed by oxygen are less thus it will be limiting reactant.

Mass of iron oxide:

Mass = number of moles × molar mass

Mass = 0.5 mol  × 159.69 g/mol

Mass = 79.85 g  

Answer:

136 g Fe2O3

Explanation:

study island

Answer:

Step 1: Find the Total Number of Valence Electrons. ...

Step 2: Find the Number of Electrons Needed to Make the Atoms "Happy" ...

Step 3: Determine the Number of Bonds in the Molecule. ...

Step 4: Choose a Central Atom. ...

Step 5: Draw a Skeletal Structure. ...

Step 6: Place Electrons Around Outside Ato

Explanation:

Answer:

2.322 half-lives have passed to decay down from 150 miligrams to 30 miligrams.

Explanation:

The half of Technetium-99 is approximately 211000 years. The decay of isotopes is represented by the following ordinary differential equation:

[tex]\frac{dm}{dt} = -\frac{m}{\tau}[/tex] (Eq. 1)

Where:

[tex]\frac{dm}{dt}[/tex] - First derivative of isotope mass in time, measured in miligrams per year.

[tex]m[/tex] - Mass of the isotope, measured in miligrams.

[tex]\tau[/tex] - Time constant, measured in years.

Now we proceed to obtain the solution of this differential equation:

[tex]\frac{dm}{m} = -\frac{dt}{\tau}[/tex]

[tex]\int {\frac{dm}{m} } = -\frac{1}{\tau}\int dt[/tex]

[tex]\ln m = -\frac{t}{\tau}+C[/tex]

[tex]m(t) = m_{o}\cdot e^{-\frac{t}{\tau} }[/tex] (Eq. 2)

Where:

[tex]m_{o}[/tex] - Initial mass of the isotope, measured in miligrams.

[tex]t[/tex] - Time, measured in years.

The time passed for isotope is cleared within the equation described above:

[tex]\ln \frac{m}{m_{o}} = -\frac{t}{\tau}[/tex]

[tex]t = -\tau \cdot \ln \frac{m}{m_{o}}[/tex]

In addition, we can obtain the time constant as a function of half-life:

[tex]\tau = \frac{t_{1/2}}{\ln 2}[/tex] (Eq. 3)

If we know that [tex]t_{1/2} = 211000\,yr[/tex], [tex]m_{o} = 150\,mg[/tex] and [tex]m = 30\,mg[/tex], then the time passed is:

[tex]\tau = \frac{211000\,yr}{\ln 2}[/tex]

[tex]\tau \approx 304408.654\,yr[/tex]

[tex]t = -(304408.654\,yr)\cdot \ln \left(\frac{30\,mg}{150\,mg} \right)[/tex]

[tex]t \approx 489926.829\,yr[/tex]

The amount of passed half-lives is that time divided by a half-life. That is:

[tex]n = \frac{489926.829\,yr}{211000\,yr}[/tex]

[tex]n = 2.322[/tex]

2.322 half-lives have passed to decay down from 150 miligrams to 30 miligrams.

Answer:

closely packed cells

many cell junctions

Explanation:

Answer:

A,B

Explanation:

EDGE2021

Answer:

270.77 g of CO2.

Explanation:

We'll begin by writing the balanced equation for the reaction. This is illustrated below:

2C4H10 + 13O2 —> 8CO2 + 10H2O

Next, we shall determine the masses of C4H10 and O2 that reacted and the mass of CO2 produced from the balanced equation. This can be obtained as follow:

Molar mass of C4H10 = (12×4) + (10×1)

= 48 + 10 = 58 g/mol

Mass of C4H10 from the balanced equation = 2 × 58 = 116 g

Molar mass of O2 = 2 × 16 = 32 g/mol

Mass of O2 from the balanced equation = 13 × 32 = 416 g

Molar mass of CO2 = 12 + (16×2)

= 12 + 32 = 44 g/mol

Mass of CO2 from the balanced equation = 8 × 44 = 352 g

Summary:

From the balanced equation above,

116 g of C4H10 reacted with 416 g of O2 to produce 352 g of CO2.

Next, we shall determine the limiting reactant. This can be obtained as follow:

From the balanced equation above,

116 g of C4H10 reacted with 416 g of O2.

From the above, we can see that a higher mass of O2 i.e 416 g than what was given i.e 320 g his needed to react completely with 116 g of O2. Therefore, O2 is the limiting reactant and C4H10 is the excess reactant.

Finally, we shall determine the mass of CO2 produced from the reaction.

In this case, we shall use the limiting reactant because it will give the maximum yield of CO2.

The limiting reactant is O2 and the mass of CO2 produced can be obtained as follow:

From the balanced equation above,

416 g of O2 reacted to produce 352 g of CO2.

Therefore, 320 g of O2 will react to produce = (320 × 352)/416 = 270.77 g of CO2.

Thus, 270.77 g of CO2 were obtained from the reaction.

Answer:

B. Each electron has its own "address."

Explanation:

This is the correct answer.

Good luck with the rest, and have a good day : )

Each electron has its own "address." Therefore, the correct option is option B among all the given options.

The elementary electric charge of the electron is a negative one, making it a subatomic particle. Due to their lack of components or substructure, electrons, which are part of the lepton particles family's first generation, are typically regarded to be elementary particles. The mass of an electron is roughly 1/1836 that of a proton.

The electron has a half-integer intrinsic rotational momentum that is represented in terms of the decreased Planck constant,, among its quantum mechanical features. The rule of exclusion developed by Pauli states that because electrons are fermions, no two of them may be in the same quantum state. Since they're capable of collide against other particles as well as can be bent like light, electrons, like all primary particles, display both wave and particle characteristics.  Each electron has its own "address."

Therefore, the correct option is option B.

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Answer:

It is C

Explanation:

It is because Prokaryotic cells mostly don't have a nucleus.

Answer:

It is C.Eukaryotic cells have nuclei; prokaryotic cells do not

Explanation:

I just watched a video of it.

Answer:

Transfer of heat through direct physical contact

Explanation:

The meaning of conduction is the transfer of heat directly transmitted through a substance when there is the difference between temperature and electrical potential. Hope it helps!

Answer:

B

Explanation:

Answer:

Answer

The answer is option 4

The energy transformation during nutrients transportation across the cell membrane is transformation from chemical energy to kinetic energy, where the uphill and downhill movements of molecules based on concentration gradient carries the whole process.

The total energy in a system is always conserved. However, one form of energy can be transformed into another form. For example we uses electrical devices such as bulbs fan etc, wherever the energy transformation is getting way from electrical energy to light or mechanical energy.

In plant cells nutrient molecules and ions are balanced inside and outside the cell and hence they are transported across the cell membrane by a concentration gradient with a chemical energy produced by the molecules.

The chemical energy inside of the ions and molecules converts to kinetic energy to transport itself through downhill and uphill mechanisms with aid of various enzymes and electron channels.

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Answer:

3 elements

Explanation:

The elements are:

- Chromium

- Hydrogen

- Oxygen

Answer:

Explanation:

Chemistry is the study of matter and the changes that matter undergoes. Matter is anything that has mass and takes up space.

Answer: magnetic field

A field produced by a magnetic object that exerts a force on other magnetic materials or moving electrical charges is called a Magnetic field.

The magnetic subject is the region around a magnet in which the effect of magnetism is felt. We use the magnetic area as a device to describe how the magnetic force is shipped inside the area around and inside something magnetic in nature.

The magnetic area is extremely critical to maintaining lifestyles in the world. without it, we'd be exposed to excessive amounts of radiation from the solar, and our environment would be unfastened to leak into space.

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Answer:

the atoms are rearranged

Explanation:

they are just in a diff order

The particle diagram represents a chemical change because the breaking of old chemical bonds and the formation of new chemical bonds occurs and a completely new substance is formed.

A chemical change is when a chemical substance is completely transformed into one or more different types of substances. Chemical changes occur through chemical reactions and result in substances with different and new chemical and physical properties.

Chemical changes are irreversible in nature and are also known as permanent changes. When chemical responses occur, the molecules are modified and joined by an energy change as new molecules are produced.

Examples of chemical changes: burning of coal, rusting of iron, digestion of food, adding vinegar to baking soda,  germination of seeds, ripening of fruits, cooking an egg, etc.

The given diagram is quite similar to the water formation reaction:

2H₂   + O₂  [tex]\longrightarrow[/tex] 2H₂ O

In which the bond between the hydrogen atoms and oxygen atoms is broken and the formation of the O-H bond, therefore, is a chemical change.

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Answer:

The metal is Copper

Explanation:

Matter is composed of atoms, which is the smallest indivisible particle of an element. The atom of an element consists of three subatomic particles namely: proton, electron and neutron etc.

The proton, which is the positively charged particle, is equal to the electron, which is the negatively charged particle. The proton number of the atom is the ATOMIC NUMBER of an element.

In the periodic table, the element with atomic number 29, which also means proton number 29 is Copper (Cu).

Answer: The formula for magnesium carbonate is MgCO_3.

Explanation:

Answer:

LIGHT

AIR

SHELTER

FOOD

WATER

Answer:

light

air

shelter

food

water

Answer: The answer is D

Explanation: I took the quiz just now and got it right

The correct answer is:

D.(a vesicle encloses over a nutrient molecule)

I took the test, hope this helps!

Answer:

39

Explanation:

Electrons weigh almost nothing, so their mass doesn't really matter for these types of problems. Just subtract 118-79 to find the remaining mass which is for the neutrons.

Answer:

.0924 moles of NaCl

Explanation:

So you know you have 5.4 g of NaCl and you need to know how many moles there are in this amount of NaCl

Add these two together----> 22.99 + 35.45 = 58.44

Now you can calculate for moles

Written-out method:

5.4 grams of NaCl  |   1 mole of  NaCl              

                                | 58.44 grams NaCl                = .0924 moles of NaCl

Plug into calculator method:

(5.4 g of NaCl/ 58.44g NaCl= .0925 moles)

Answer:

I think all of the above

Explanation:

Put as brainliest if you wish

Answer:

D. Directly to The Right

food moves through the mouth by muscle movement

Answer:

You would just put the definition and what it means im pretty sure

Explanation:

I hope this helps!!

Answer:

45N

Explanation:

force=mass×acceleration

Answer:

Supersaturated !

Explanation: