An emission line of sodium has a wavelength of 330 nm. Calculate the energy of a photon of light emitted in J/atom, and the energy emitted per mole of Na atoms in kJ/mol at this wavelength.

4) Ne

Chemistry

Atomic Structure

The most stable (unreactive) elements are found in group 18. They are known as the Noble Gases.

Noble Gases are inert, meaning they do not react easily with other elements. The reason is because their valence electron shells are filled.

Therefore, our best answer is 4) Ne.

Answer:

\(\boxed {\boxed {\sf 4. \ Ne }}\)

Explanation:

On the Periodic Table, the last group of elements are the Noble Gases. These are the most unreactive or stable elements.

According to the Octet Rule, atoms always want to have 8 valence electrons. The Noble Gases already satisfy this rule and have full outer shells, therefore they don't react with other elements often.

The Noble Gases are helium (He) , neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and oganesson (Og).

The only answer choice that is a Noble Gas is 4. Ne

Explanation:

Write the balance equation for the reaction taking place:

CO(g) + 2H2(g) ==> CH3OH ... balanced equation

Find the limiting reactant:

Because according to the balanced equation it takes 2 moles H2 for every 1 mole CO, there isn't enough H2, so it is limiting and will dictate how much CH3OH can be made.

Mass of CH3OH produced = 0.75 moles H2 x 1 mol CH3OH / 2 mol H2 x 32 g CH3OH / mol = 12 g CH3OH

The student's absolute error, given the data from the question is 0.09 mL

We'll begin by obtainig the volume of the water the student measured. This can be obtained as follow:

Density = mass / volume

Thus,

Volume = mass / density

Volume of water = 30 / 0.997

Volume of water = 30.09 mL

The absolute error can be obatined as illustrated below:

Absolute error = Measured value - accepted value

Absolute error = 30.09 - 30

Absolute error = 0.09 mL

Thue, the student's absolute error is 0.09 mL

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According to the balanced reaction, one mole of N₂O₄ produce 3 moles of N₂. Thus  750 g of N₂O₄will produce 684.7 g of N₂. If the actual yield of N₂ is 650 g, the percent yield is 94.9 %.

The percent yield of a reaction is the ratio of actual yield to the theoretical yield multiplied by 100.

According to the given balanced reaction, one mole of N₂O₄ produce 3 moles of N₂. The molar mass of N₂O₄ is 92 g/mol and the molar mass of 3 moles of N₂ is 84 g. Thus 92 g of N₂O₄ produce 84 g of N₂.

The mass of N₂ produced from 750 g of N₂O₄ is then calculated as follows:

mass of N₂ = ( 750 × 84 /92)

                  = 684.7 g.

The actual yield of N₂ is given 650 g. Thus the percent yield of N₂ is calculated as:

Percent yield = (650 / 684.7) × 100

                      = 94.9 %.

Hence, the amount of N₂ produced from 750 g of N₂O₄ is 684.7 g and the percent yield is 94.9%.

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Answer:

Two.

Explanation:

Hello!

In this case, considering the attached picture wherein you can see the presence of the parent chain as aniline, we can see radicals at the nitrogen, named by N-ethyl and N-methyl which are the present alkyl substituents. In such a way, the benzene ring is not considered an alkyl radical because it belongs to the parent chain on aniline and therefore, N-ethyl-N-methylaniline has two alkyl substituents.

Best regards!

There are two alkyl substituents attached to the nitrogen; one ethyl and one methyl group

Aniline consists of a benzene ring to which an -NH2 moiety is attached. Usually, it is possible for the any of the two hydrogen atoms in the -NH2 moiety to become substituted leading to N-alkylated product.

In the compound N-ethyl-N-methylaniline, there are two alkyl substituents attached to the nitrogen; one ethyl and one methyl group as shown in the image attached to this answer.

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A rainbow is produced through a proces that includes refraction, reflection, and dispersion of  sunlight.

A rainbow is formed when sulinght is refracted and reflected by rain drops in the atmospher.

The sunlight is split into its component colors, which is why rainbows appear as having an array of colors. This is due to each color being bent by a different amount during refraction.

The colors of a rainbow are always in the same order, with red on the outside and violet on the inside.

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Answer:

The answer given by the student is not totally correct.

Explanation:

Law of multiple proportions states that an element Q will react with different volume of Fluorine to produce two non-similar compounds. Hence, the ratio of the masses(Fluorine only) needs to be an absolute reduced value.

Given that:

3.2 g of a sample of Q reacts with Fluorine to form 10.8 g of the unknown fluoride A.

This means the mass of Fluorine present in the compound = 10.8 g - 3.2 g = 7.6 g

Thus, 3.2 g of a sample of Q reacts with 7.6 g of Fluorine.

Also, 6.4 g sample of Q reacts with Fluorine to form 29.2 g of unknown fluoride B.

If we divide the samples by (2), we have 3.2 g sample of Q reacting with Fluorine to form 14.6 g of unknown fluoride B.

This means the mass of Fluorine present in the compound = 14.6 g - 3.2 g = 11.4 g

Thus, 3.2 g Q reacted here with 11.4 g fluorine.

Hence, 11.4/7.6 = 1.5 = 3/2

This above therefore satisfies the law of multiple proportions.

This is not aligned with what the student did, what the student did was to relate the amount of Q used to make A and B. Suppose, we start with twice amount of Q, the ratio would have been smaller(i.e. the ratio of Q).

So, this doesn't relate to the law of multiple proportions.

The law of multiple proportions is specifically concerned with the mass of the element rather than Q that can react with Q. Therefore, there is more reason to relate the two samples of equal masses of Q that react with different masses of Fluorine. The ratios of Fluorine will then be small whole numbers.

Answer:

July/the winter

Explanation:

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July, I just took the test

Answer:

Answer C

Explanation:

Chemical Bonds

In the J = 0 state, the BrF molecule does not undergo any revolutions per second. In the J = 1 state, it undergoes approximately 0.498 revolutions per second, and in the J = 10 state, it undergoes approximately 15.71 revolutions per second.

To calculate the rotational constant B, we can use the formula:

B = 1 / (2 * π * Δν)

Where:

B = rotational constant

Δν = spacing between consecutive lines in the rotational spectrum

Given that the spacing between consecutive lines is 0.71433 cm^(-1), we can substitute this value into the formula:

B = 1 / (2 * π * 0.71433 cm^(-1))

B ≈ 0.079 cm^(-1)

The moment of inertia (I) of the molecule can be calculated using the formula:

I = h / (8 * π^2 * B)

Where:

h = Planck's constant

Given that the value of Planck's constant (h) is approximately 6.626 x 10^(-34) J·s, we can substitute the values into the formula:

I = (6.626 x 10^(-34) J·s) / (8 * π^2 * 0.079 cm^(-1))

I ≈ 2.11 x 10^(-46) kg·m^2

The bond length (r) of the molecule can be determined using the formula:

r = sqrt((h / (4 * π^2 * μ * B)) - r_e^2)

Where:

μ = reduced mass of the molecule

r_e = equilibrium bond length

To calculate the wavenumber (ν) of the J = 9+ to J = 10 transition, we can use the formula:

ν = 2 * B * (J + 1)

Substituting J = 9 into the formula, we get:

ν = 2 * 0.079 cm^(-1) * (9 + 1)

ν ≈ 1.58 cm^(-1)

To determine the most intense spectral line at room temperature (300 K), we can use the Boltzmann distribution law. The intensity (I) of a spectral line is proportional to the population of the corresponding rotational level:

I ∝ exp(-E / (k * T))

Where:

E = energy difference between the levels

k = Boltzmann constant

T = temperature in Kelvin

At room temperature (300 K), the population distribution decreases rapidly with increasing energy difference. Therefore, the transition with the lowest energy difference will have the most intense spectral line. In this case, the transition from J = 0 to J = 1 will have the most intense spectral line.

To calculate the number of revolutions per second, we can use the formula:

ω = 2 * π * B * J

Where:

ω = angular frequency (in radians per second)

J = rotational quantum number

For J = 0:

ω = 2 * π * 0.079 cm^(-1) * 0 = 0 rad/s

For J = 1:

ω = 2 * π * 0.079 cm^(-1) * 1 ≈ 0.498 rad/s

For J = 10:

ω = 2 * π * 0.079 cm^(-1) * 10 ≈ 15.71 rad/s

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Answer:

false

Explanation:

Organic transformation sequential equation using catalysts will be as follows:

2CH3-CH2-O => (alc. KOH) => CH2=CH2 + KCl + H2O => (Br2/CCl4) => CH2Br-CH2Br + Zn

CH2Br-CH2Br + Zn => (HBr /Pd) => CH2=CH2+ZnBr2

As can be visualized from above organic transformation equation, conversion of dry ether in presence of alkaline potassium hydroxide results in formation of unstable ethene. This dry unsaturated compound of ethene is stabilized by reaction that happens in presence of bromine or calcium tetrachloride as the catalyst which results in formation of ethylene bromide which in presence of highly efficient palladium as catalyst results in formation of stable ethene as byproduct. Thereby with formation of stable compound of ethylene, it releases zinc bromide as byproduct resulting completion of reaction equation. This stable product ethene is a double bonded carbon structure that is chemically extremely flammable and has planar structure.

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The  volume of acetone would be required to purify a 5.0g sample of compound is 58.82ml

Let use the solubility data of acetone provided to calculate the volume.

First we will need to calculate the solubility of Y in 25 degree.

   Solubility of Y= 0.12g/10ml= 0.012g/ml.

Solubility of y in boiling acetone = 0.85g/10ml =0.085g/ml.

In order to purify y, we need to dissolve the amount of y in the 5.0g sample.

The amount of acetone needed to dissolve y in the sample is

amount acetone= mass of y/ solubility of y in boiling acetone.

amount acetone= 5.0g/0.085g/ml= 58.82ml.

Therefore, the  volume of acetone would be required to purify a 5.0g sample of compound is 58.82ml

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Taking into account the Boyle's law, 3.377 L of helium the tank will be able to  produce at a pressure of 94.2 kPa.

The gas laws are a set of chemical and physical laws that allow determining the behavior of gases in a closed system. The parameters evaluated in these laws are pressure, volume, temperature, and moles.

Boyle's law is one of the gas laws that relates the volume and pressure of a certain quantity of gas kept at constant temperature.

This law states that the pressure of a gas in a closed container is inversely proportional to the volume of the container, when the temperature is constant. That is, if the pressure increases, the volume decreases; while if the pressure decreases, the volume increases.

Mathematically, Boyle's law states that the product of pressure and volume is constant:

P×V= k

Studying two different states, an initial state 1 and a final state 2, it is satisfied:

P1× V1= P2×V2

In this case, you know:

Replacing in Boyle's law:

101 kPa× 3.15 L= 94.2 kPa× V2

Solving:

\(V2=\frac{101 kPa x3.15 L}{94.2 kPa}\)

V2= 3.377 L

In summary, 3.377 L of helium the tank will be able to  produce at a pressure of 94.2 kPa.

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The arrow in a chemical reaction can be translated as the following:

A. yields

C. react to form

The volume of \(N_2O_5\) needed to produce 9.64 L of \(NO_2\) is 4.97 L, calculated using stoichiometry and the ideal gas equation.

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The density of the metal palates is 2.29 g/mL.

The term density refers to the ratio of the mass to the volume of a body. We know that the volume of a solid can easily be obtained by the use of the displacement method in which water is ejected from the vessel.

Hence;

Mass of the metal pellets is =  75.440 grams - 46.304 grams= 29.136 grams

Volume of the water = 25.5 mL - 12.8 mL = 12.7 mL

Hence density = mass/volume = 29.136 grams/12.7 mL = 2.29 g/mL

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Answer:

Ionic bonding is the attraction between positively- and negatively-charged ions. These oppositely charged ions attract each other to form ionic networks (or lattices). Electrostatics explains why this happens: opposite charges attract and like charges repel.

Explanation:

Ionic compounds form because opposite charges attract.

In an ionic compound, positive and negative ions come together to form a stable structure. This occurs when an atom loses electrons to become a positively charged ion (cation) and another atom gains those electrons to become a negatively charged ion (anion). The positive and negative charges of the ions attract each other, resulting in the formation of an ionic bond.

This attraction between positive and negative charges is what holds ionic compounds together. The strong electrostatic forces of attraction between ions result in a lattice structure, where each ion is surrounded by oppositely charged ions.

Thus, ionic compounds are formed because opposite charges attract.

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The ozone layer is present in the stratosphere layer of the Earth's atmosphere. Therefore, option (C) is correct.

An atmosphere can be defined as layers of gases that envelop a planet and is held in place due to the gravity of the planetary body. A planet contains an atmosphere when the gravity is great and the temperature of the atmosphere of any planet is low.

Earth's atmosphere is made of Nitrogen (78 %), Oxygen (21%), Argon (0.9%), and Carbon dioxide (0.04 %).  The troposphere can be defined as the lowest layer of the atmosphere. The troposphere contains 75 to 80 % of the mass of the atmosphere.

The stratosphere contains the ozone layer, at an altitude between 15km and 35km. This atmospheric layer absorbs most of the UV radiation that Earth receives from the Sun.

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Answer:

Asexual reproduction

Explanation:

Cells are able to re produce themselves without other cells needed. If cells need others to make more then how would that work and plus we wouldn't have the theory of cells existing.

Answer:

Gathering viscosity data on a material gives manufacturers the ability to predict how the material will behave in the real world.

Example:

If toothpaste does not have the correct viscosity, it can either be too difficult to pump out from the tube, or pump out too much.

Answer:

hydrophobic: tending to repel or fail to mix with water.

hydrophylic​: having a tendency to mix with, dissolve in, or be wetted by water.

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The ion with a +3 charge, 28 electrons, and an atomic mass of 71 is the aluminum ion (\(Al^{3+}\)).

Aluminum (Al) typically has an atomic number of 13, which means it has 13 protons and 13 electrons in its neutral state. However, in the given ion, \(Al^{3+}\), the ion has lost three electrons, resulting in a +3 charge. This means that the ion now has 13 protons and only 10 electrons remaining, giving it a net positive charge of +3.

The atomic mass of aluminum is 26.98 atomic mass units (amu). The given ion has an atomic mass of 71 amu, which suggests that the ion has gained additional particles. In this case, the ion has also gained three neutrons, resulting in a higher atomic mass.

The total number of particles (protons, neutrons, and electrons) in the ion can be calculated by adding the number of protons (13) and the number of neutrons (3), which equals 16. Since the ion has a net charge of +3, it only contains 10 electrons.

In summary, the ion with a +3 charge, 28 electrons, and an atomic mass of 71 is the aluminum ion (\(Al^{3+}\)), which has 13 protons, 10 electrons, and 3 neutrons.

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If you don't practice enough it's obviously going to be hard but if you practice enough it's going to be a piece of cake so don't think if it's going to be hard or not just think it's going to be worth the try at the very end

Answer:

So the percentage mass of Magnesium in ocean water is 0.13%.

Explanation:

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The universe is divided into two according to thermodynamic, one is system over which we are doing experiments and other is surrounding that is surrounding the system. Therefore, the correct option is option A.

Thermodynamics is the branch of physical science that deals with the relations between heat and other forms of energy (such as mechanical, electrical, or chemical energy). Thermo means heat and dynamics means flow of heat or energy  from one place to another place.

Heat always flow from the source which is at high temperature to the sink which is at low temperature. The heat always from high temperature to low temperature source to maintain a equilibrium.  There are total three laws that govern the thermodynamic. First, second and third laws of thermodynamic.

In the given experiment, heat flowed from the surrounding hot air to the cooler air and transferred heat to the pennies by convection.

Therefore, the correct option is option A.

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Solution :

a). In this experiments, we can determine the hardness of the water or \($Ca^{2+}$\) ion concentration in the sample.

b). The Possible errors are :

- During the weighing of calcium standard preparation, if the balance is not traced properly, it will cause an error.

- By dilution of standard from the stock will lead a dilution error of 0.1 mL for 100 mL.

- Misreading the liter values will give an error.

c). Depending upon the calcium content present in the soil, we conclude that the fertile percent of the soil as well as the mineral capacity of the soil.

Answer: 4 HCl (g) + O₂ (g) → 2 Cl₂ (g) + 2 H₂O (l)

Explanation:

4 moles of hydrogen chloride (note that it is in the gaseous phase, otherwise it would be hydrochloric acid) react with 1 mole of oxygen gas to form 2 moles of chlorine gas and 2 moles of liquid water.

To conform with  the law of conservation of mass, the equation must be balanced, this means that there must be the same number of each type of atom  on both sides of the arrow.

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The balanced chemical reaction is:

4 HCl (g) + O₂ (g) → 2 Cl₂ (g) + 2 H₂O (l)

In first place, chlorine is heated with oxygen to form dichlorine monoxide gas. Then, this can be expressed as:

HCl (g) + O₂ (g)  → Cl₂ (g) +  H₂O (l)

On the other side, the Law of Conservation of Matter is also called the law of conservation of mass or the Law of Lomonósov-Lavoisier. This law postulates that "The mass is not created or destroyed, only transformed."

Then, the number of atoms that are present in the reagents has to be equal to the number of atoms present in the products.

Finally, the balanced chemical reaction is:

4 HCl (g) + O₂ (g) → 2 Cl₂ (g) + 2 H₂O (l)

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