Class 8 fossil fuels are

Answer:

the quantum mechanical model VS. Neils Bohr of the atom

Explanation:

The Bohr model and quantum model are models that explain the structure of an atom. ... The key difference between Bohr and quantum model is that Bohr model states that electrons behave as particles whereas quantum model explains that the electron has both particle and wave behavior.

Answer:

Correct option is

A

Explanation:

The number of molecules of CO involves in the slowest step will be 0 because CO is not involve in the slowest step i.e. rate determing step.

Answer:

[tex]X=6[/tex]

Explanation:

From the question we are told that:

Energy levels [tex]n=4[/tex]

Generally, the equation for spectral lines is mathematically given by

 [tex]X=\frac{n(n-1)}{2}[/tex]

 [tex]X=\frac{4(4-1)}{2}[/tex]

 [tex]X=6[/tex]

Answer:

I don't know What can I do.

Answer:

Have you ever touched a fish? Most fish will feel a bit rough - due to their scales. Some, like sharks, will feel like sandpaper. Even fish with small, smoother scales will feel a bit like that. Amphibians don’t have scales, and most species will be wet to some degree - they have to keep their skin moist or they’ll die. A few groups, like toads and newts, have rougher skin, which is heavier and thicker, which allows them to retain moisture better away from water.

Functionally, the big thing about amphibian skin is that it is semi-permeable. Amphibians can breathe through their skin - all amphibians can get some oxygen through their skin, but some species of salamanders get all their oxygen that way - they have no lungs or gills. The skin can also allow water in - sort of like a paper towel. The bad thing is that other chemicals can pass through the skin, too - pollutants and other chemicals tend to affect amphibians far more than they do other groups.

Amphibians also shed their skin - fish do not. People don’t tend to see frogs shedding their skin often, though, since they eat it to regain nutrients and other resources in the skin.

Finally, since amphibian skin offers no defense against predators in the way that scales do, and limited barrier against disease the way non-amphibian skin does (shedding helps), the skin of many amphibians contain toxins, and some of them have anti-fungal properties (typically due to symbiotic bacteria). Many species have evolved chemical defenses in the skin, while others have glands that produce toxins that can be secreted outside of the skin.

The skin can withstand dessication more than the fish.

They have moist skin used as respiratory surface during deep sleep / hibernation.

They have moist skin due to secretion of mucus by glands under the skin.

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Answer:

TATGGCGTT

Explanation:

Complimentary base pairs:

A-T

C-G

Use the other letter for complimentary strands

Answer:

An ecosystem encompasses living organisms and the nonliving elements of their environments. Hence, the components of an ecosystem include animals, plants, microorganisms, rocks, soil, minerals, atmosphere, and the surrounding water masses. An ecosystem can be huge, cutting across several nations, or it can be relatively small, such as the body of an animal, which is home to numerous microorganisms.

We can describe ecosystems under two headings – natural ecosystems and unnatural ecosystems. Unnatural ecosystems, which include agricultural and urban areas, are greatly modified and maintained by human activity. Conversely, natural ecosystems are self-sufficient, balanced ecological units, with a high proportion of native biodiversity and minimal human disruption.

The natural ecosystem is broad. It is divided into two major groups – terrestrial and aquatic ecosystems. These are further divided into many other smaller types of ecosystems as outlined in this article.

Explanation:

Hope it helps.. if yes, plz mark me as brainliest

Answer:

As you know, one mole of any substance contains exactly

6.022

⋅

10

23

molecules of that substance - this is known as Avogadro's number.

Notice that you're dealing with more than

6.022

⋅

10

23

molecules of carbon dioxide, which means that you'll also be dealing with more than one mole of the compound.

More specifically, you'll have

1.5

⋅

10

26

molecules

⋅

1 mole CO

2

6.022

⋅

10

23

molecules

=

2.491

⋅

10

2

moles CO

2

Now, a substance's molar mass tells what the mass of one mole of that substance is. In carbon dioxide's case, its molar mass is equal to

44.01 g/mol

, which means that every mole of

CO

2

will have a mass of

44.01 g

.

In your case,

2.491

⋅

10

2

moles of

CO

2

would have a mass of

2.491

⋅

10

2

moles CO

2

⋅

44.01 g

1

mole CO

2

=

109.63 g

Rounded to two sig figs, the number of sig figs you have for the number of molecules of

CO

2

, the answer will be

m

C

O

2

=

110 g

Answer:

See explanation

Explanation:

The average speed of the molecules of a gas depends on the temperature of the gas and its molar mass and not on the volume of the gas.

The average velocity of a gas is given by; vrms=√3RTM

R= gas constant

T= Absolute temperature

M= molar mass of the gas

Where the temperature of the gas is held constant, the average velocity of gas molecules depends on the molar mass of the gas. Hence, if a sample of gas is slowly compressed to one-half of its original volume with no change in temperature, the average speed of the molecules in the sample of gas remains the same.

Answer:

Cs> Ba> Pb>Si> P>O

Explanation:

Recall that atomic size decreases across a period and increases down the group.

As we move from Cs to Ba, the atomic size decreases across the period. Lead is larger than silicon since atomic size increases down the group.

Between phosphorus and oxygen, phosphorus is larger than oxygen as you move across the period.

Answer:

Molarity is a measure of concentration

I Hope its right if not so advance sorry :)

The molarity measures the number of moles of the solute present per liter of the solution and it measures the concentration of the solution. option D is correct.

Molarity is the amount or the number of moles present in per liter of the solution it is the unit to measure the concentration of the moles.

Unit of molarity will be moles per liter and the temperature does not affect the molarity of the solution. molarity can be calculated by dividing the concentration of the solution by the molar mass of the given element.

molarity = weight / mass ×  1000/ volume in liters.

With the help of this formula, we can calculate the molarity.

Therefore,  molarity measures the number of moles of the solute present per liter of the solution and it measures the concentration of the solution. option D is correct.

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The compound in this reaction which is having the elemental ratio of 1:4:1 is NH₄Cl where nitrogen and chlorine are of one mole each with 4 hydrogens.

Elemental ratio of a compound is the ratio of number of atoms  of each  elements in that compound. The elemental ratio can be determined from the molecular formula of compounds.

The given reaction is a double displacement reaction. Here, the Cl group is replaced to the ammonia and OH group is replaced to the water. Thus, two species is replaced in the reaction.

In NH₄Cl, there are one nitrogen, 4 hydrogens and one chlorine atom. Therefore, the elemental ratio of the compound is 1:4:1. The elemental ratio of water is 2:1 and HCl is 1:1 and that in NH₄OH is 1:5:1. Hence, option b is correct.

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Answer:

gahwidsuacsgsuacayau1joagavahiq8wtw8quavakiafabajozyavqhaigavayquata

Explanation:

vahaiqgahiavavqugafayqigqvsbjsiagwyeiwvvs

Answer:

A white gelatinous precipitate is observed in each case.

Explanation:

Qualitative analysis in chemistry is mostly used to identify the ions present in a sample by adding certain reagents. The observation after adding the reagent often leads to an inference.

When NaOH is added to a solution containing Zn^2+ in drops, a white gelatinous precipitate is observed.

When NH3(aq) is added in drops to a solution containing Zn^2+, a white gelatinous precipitate is also observed.

Answer:

duw8 Wert gsi

Explanation:

pues pues y 8y1rcuecisscfjfj3eoeu xv cihskdkkd HD jekifeuifkeñ elijo eh fh FC eh SSH DJ djdvheshdhs

The mass percent of antimony in the sulfide is 71.7% and the mass of Sb2S3 is 0.148 g.

Mass percent is defined as a way of expressing a concentration or describing a component in a particular mixture.

To calculate the mass percent of an element in a compound, divide the mass of the element in 1 mole of the compound by the molar mass of the compound and multiply the result by 100.

Mass percent = Mass of chemical / Total mass  of compound x 100

Mass of ore = 10 kg

% antimony in ore = 10.6%

                              = 10.6 / 100 = 0.106 g

Mass of antimony = 0.106 g

Mass percent = Mass of antimony / Mass of stibnite x 100

71.7% = 0.106 / X x 100

X = 0.106 x 1000 / 71.7 x 1000

  = 106 / 717 = 0.148 g

Thus, the mass percent of antimony in the sulfide is 71.7% and the mass of Sb2S3 is 0.148 g.

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Answer:

here's your answer

Explanation:

Molar mass of CH3CH2OH = 46.06844 g/mol

This compound is also known as Ethanol.

Convert grams CH3CH2OH to moles  or  moles CH3CH2OH to grams

Molecular weight calculation:

12.0107 + 1.00794*3 + 12.0107 + 1.00794*2 + 15.9994 + 1.00794

Percent composition by element  

Hydrogen H 1.00794 6 13.128%

Carbon C 12.0107 2 52.143%

Oxygen O 15.9994 1 34.730%

The mass percentage of C in CH₃CH₂OH is 52.14% (to two decimal places)

To calculate the mass percentage of C (Carbon) in CH₃CH₂OH (Ethanol),

First, we will determine the mass of CH₃CH₂OH

Molar mass of CH₃CH₂OH = 46.07 g/mol

Mass of C = 12.01 g/mol

Now, for the mass percentage of C in CH₃CH₂OH,

We will determine the ratio of the total mass of C to the mass of CH₃CH₂OH, and then multiply by 100%

Since we have 2C in CH₃CH₂OH

Then, total mass of C in CH₃CH₂OH = 2 × 12.01 g/mol = 24.02 g/mol

That is,

Mass percentage of C in CH₃CH₂OH = [tex]\frac{24.02}{46.07} \times 100\%[/tex]

Mass percentage of C in CH₃CH₂OH = 0.5213805 ×100%

Mass percentage of C in CH₃CH₂OH = 52.13805%

Mass percentage of C in CH₃CH₂OH ≅ 52.14%

Hence, the mass percentage of C in CH₃CH₂OH is 52.14% (to two decimal places)

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The name of the compound shown below is 1- pentene. The correct answer is option D.

A compound is a substance made up of two or more different elements chemically bonded together in a fixed ratio.

1-pentene is an unsaturated hydrocarbon with the chemical formula [tex]\rm C_5H_{10}[/tex]. It is an alkene, which means it contains a carbon-carbon double bond.

Therefore, option D. 1-pentene is the name of the compound shown.

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The correct order of the substances in order of decreasing boiling point is,

KF , CH30OH , CO2 , Ne

Boiling point, the temperature at which the force exerted by the surroundings upon a liquid exists equaled by the pressure exerted by the vapor of the liquid; under this situation, the addition of heat affects the transformation of the liquid into its vapor without increasing the temperature.

The main difference between the boiling point and the melting point stands that the melting point is determined as the temperature at which solid and liquid phases exist in equilibrium, whereas the boiling point stands as the temperature at which the vapor pressure of a liquid stands equal to the external pressure.

Hence, The correct order of the substances in order of decreasing boiling point is,

KF , CH30OH , CO2 , Ne

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Your answer is CaO.I hope that my answer helped you..

Answer:

21.5mL of a 0.100M HCl are required

Explanation:

The sodium phenoxide reacts with HCl to produce phenol and NaCl in a 1:1 reaction.

To solve this question we need to find the moles of sodium phenoxide. These moles = Moles of HCl required to reach equivalence point and, with the concentration, we can find the needed volume as follows:

Mass NaC6H5O:

1.000g * 25% = 0.250g NaC6H5O

Moles NaC6H5O -116.09g/mol-

0.250g NaC6H5O * (1mol/116.09g) = 2.154x10⁻³ moles = Moles of HCl required

Volume 0.100M HCl:

2.154x10⁻³ moles HCl * (1L/0.100mol) = 0.0215L =

The correct answer is option c. Both A and B: An ion is a charged particle that is formed when an atom gains electrons or an atom loses electrons.

First you need to know the definition of ion. An ion is a molecule or atom that has a positive or negative electrical charge.

That is, an ion is an atom whose electric charge is not neutral. This charged particle can be positive or negative.  

Ionization is the chemical or physical process by which ions are produced. In this process, negatively charged ions are produced by gaining electrons and are known as anions.

The positively charged are produced by the loss of electrons and are known as cations.

In summary, an ion is a charged particle that is formed when  an atom gains electrons or an atom loses electrons, and they are known as cations and anions respectively.

The correct answer is both A and B.

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Answer:

361.4 pm is the length of the edge of the unit cell

Explanation:

First, let's calculate the average volume each atom is taking. Start with calculating how many moles of copper we have in a cubic centimeter by looking up the atomic weight. Atomic weight copper = 63.546 Now divide the mass by the atomic weight, getting 8.94 g / 63.546 g/mol = 0.140685488 mol And multiply by Avogadro's number to get the number of atoms: 0.140685488 * 6.022140857x10^23 = 8.472278233x10^22 Now examine the face-centered cubic unit cell to see how many atoms worth of space it consumes. There is 1 atom at each of the 8 corners and each of those atoms is shared between 8 unit cells for for a space consumption of 8/8 = 1 atom. And there are 6 faces, each with an atom in the center, each of which is shared between 2 unit cells for a space consumption of 6/2 = 3 atoms. So each unit cell consumes as much space as 4 atoms. Let's divide the number of atoms in that cubic centimeter by 4 to determine the number of unit cells in that volume. 8.472278233x10^22 / 4 = 2.118069558x10^22 Now calculate the volume each unit cell occupies. 1 cm^3 / 2.118069558x10^22 = 4.721280262x10^-23 cm^3 Let's get the cube root to get the length of an edge. (4.721280262x10^-23 cm^3)^(1/3) = 3.61426x10^-08 cm Now let's convert from cm to pm. 3.61426x10^-08 cm / 100 cm/m * 1x10^12 pm/m = 361.4 pm Doing an independent search for the Crystallographic Features of Copper, I see that the Lattice Parameter for copper at at 293 K is 3.6147 x 10^-10 m which is in very close agreement with the calculated amount above. And since metals expand and contract with heat and cold, I assume the slight difference in values is due to the density figure given being determined at a temperature lower than 293 K.

Answer:

rrgggf in the world of the world of the world of the up the good morning I will take a user and pass it on the

Explanation:

Hey there!

Charles law states that the volume of gas is directly proportional to the absolute temperature at constant pressure.

As the fact is, at a constant pressure the volume of fix amount of dry gas is directly proportional to absolute temperature from Charles law.

Since V and T are directly varying directly, we can write the equation using constant "k".

V/T = k

In this case the value of k depends on the pressure of gas, the amount of gas and also unit volume.

V/T = k .........(i)

Let us consider V1 and T1 the Volume and temperature of the ideal gases.

Then the equation is;

V1/T1 =k........(ii)

After this let change the temperature and volume be T2 and V2, respectively.

Then the equation is:

V2/T2 = k.......(iii)

Now; Equating equation (ii) and (iii)…

V1/T1 = V2/T2

So, this the formula. (i.e V1/T1 = V2/T2).

Hope it helps!

Answer:

[tex]x=54g[/tex]

Explanation:

From the question we are told that:

Content of Sterling silver:

Let x be sterling silver

Silver [tex]S=0.9x[/tex]

Copper [tex]C=0.1x[/tex]

Total  silver available [tex]T=48.3[/tex]

Generally the equation for Total amount to be made is mathematically given by

[tex]T=\frac{x*90}{100}[/tex]

[tex]x=\frac{48.3*100}{90}[/tex]

[tex]x=54g[/tex]

Answer:

43) protein

44) oxidoreductase

Answer:

-800 kJ/mol

Explanation:

To solve the problem, we have to express the enthalpy of combustion (ΔHc) in kJ per mole (kJ/mol).

First, we have to calculate the moles of methane (CH₄) there are in 2.50 g of substance. For this, we divide the mass into the molecular weight Mw) of CH₄:

Mw(CH₄) = 12 g/mol C + (1 g/mol H x 4) = 16 g/mol

moles CH₄ = mass CH₄/Mw(CH₄)= 2.50 g/(16 g/mol) = 0.15625 mol CH₄

Now, we divide the heat released into the moles of CH₄ to obtain the enthalpy per mole of CH₄:

ΔHc = heat/mol CH₄ = 125 kJ/(0.15625 mol) = 800 kJ/mol

Therefore, the enthalpy of combustion of methane is -800 kJ/mol (the minus sign indicated that the heat is released).

Answer:

True

Explanation:

Copper has the highest electrical conductivity rating of all non-precious metals: the electrical resistivity of copper = 16.78 nΩ•m at 20 °C. Specially-pure Oxygen-Free Electronic (OFE) copper is about 1% more conductive (i.e., achieves a minimum of 101% IACS).

True is the correct answer.