A 100.0g sample of eighteen karat gold contains 75g of gold and 25.0g of other metals. What is the percent of gold in the sample

People refuse to answer questions from authorized Stats SA officials because they don't want to reveal confidential information.

An official Stats is an official who has the function of asking citizens for different information in order to establish general statistics for all citizens.

Some people refuse to answer questions out of mistrust, because they don't want to share personal information.

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Only reactions B and C would be spontaneous at 298 K.

Spontaneous reactions are reactions that occur naturally and do not require external energy input to proceed. This can be determined by calculating the Gibbs free energy of the reaction at a given temperature and pressure. Gibbs free energy can be calculated using the equation ΔG = ΔH - TΔS, where ΔH is the enthalpy change of the reaction, ΔS is the entropy change of the reaction, T is the temperature in Kelvin, and ΔG is the change in free energy of the reaction.
A spontaneous reaction will have a negative ΔG, meaning that the reaction is exergonic and releases energy. Therefore, the products of the reaction are more stable than the reactants. If ΔG is positive, the reaction is endergonic and requires energy input to proceed.
In order to determine which of the following reactions would be spontaneous at 298 K, we must calculate the ΔG of each reaction and determine if it is positive or negative. The reactions are:
A. 2H2O(l) → 2H2(g) + O2(g) ΔH = 484 kJ/mol, ΔS = 69.9 J/K mol
B. CO2(g) + H2(g) → CO(g) + H2O(g) ΔH = 41 kJ/mol, ΔS = -102.6 J/K mol
C. Fe2O3(s) + 2Al(s) → Al2O3(s) + 2Fe(l) ΔH = -850 kJ/mol, ΔS = -243 J/K mol
To calculate ΔG at 298 K, we will use the equation ΔG = ΔH - TΔS. The temperature in Kelvin is 298 K, or 25°C.
A. ΔG = (484,000 J/mol) - (298 K) x (69.9 J/K mol) = +4165 J/mol (positive, non-spontaneous)
B. ΔG = (41,000 J/mol) - (298 K) x (-102.6 J/K mol) = -2874 J/mol (negative, spontaneous)
C. ΔG = (-850,000 J/mol) - (298 K) x (-243 J/K mol) = -42600 J/mol (negative, spontaneous)

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This atom has a mass number of 195. Hence, there are 78 protons in an atom, which is the atomic number.

Atoms that belong to the same element with the same isotopes Z but a distinct mass number A are known as isotopes. Carbon-12, Carbon-13, while Carbon-14 are three isotopes of the element carbon, each with a mass of 12, 13, and 14.

Atoms that belong to the same element with an identical electron density Z but a distinct mass number A are known as isotopes. For instance, carbon-12, carbon-13, or carbon-14 are three isotopes of the crystal structures, with corresponding weights of 12, 13, and 14.

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The products of the alpha decay of radium-226 and the beta decay of carbon-14 are radon-222 and nitrogen-14, respectively.

The alpha decay of radium-226 results in the emission of an alpha particle, which is a helium nucleus consisting of two protons and two neutrons.

Therefore, the product of the alpha decay of radium-226 is radon-222:

Ra-226 → Rn-222 + alpha particle

On the other hand, In the case of carbon-14, beta minus decay occurs, in which a neutron is converted into a proton, and an electron and an antineutrino are emitted.

So carbon-14 becomes nitrogen-14:

C-14 → N-14 + beta particle

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--The complete Question is, What is the product of the alpha decay of radium-226 and the beta decay of carbon-14?--

The proximity of unsaturated groups (C=C, C=O, aromatic) and electronegative atoms (O, N, halogen) has an impact on the proton NMR chemical shift. Electronegative groups shift to the left (down field; ppm rise).

The chemical shift in nuclear magnetic resonance (NMR) spectroscopy refers to the atomic nucleus' resonant frequency in relation to a standard in a magnetic field. The location and quantity of chemical changes frequently serve as diagnostic indicators of molecular structure.

You take into account the chemically non-equivalent proton(s) one at a time while making chemical shift predictions. Find the origin of each proton or proton pair that is not chemically comparable. Whether the proton(s) is/are linked to a methyl, methene, or methine determines the beginning point.

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Answer:

\(m_{Zn(OH)_2}=38.4g\)

Explanation:

Hello!

In this case, for the undergoing chemical reaction:

\(ZnO(s)+H_2O(l)\rightarrow Zn(OH)_2\)

We evaluate the yielded moles of zinc hydroxide by each reactant as shown below:

\(n_{Zn(OH)_2}^{by ZnO}=35.4gZnO*\frac{1molZnO}{81.38gZnO}*\frac{1molZn(OH)_2}{1molZnO} =0.435molZn(OH)_2\\\\n_{Zn(OH)_2}^{by H_2O}=6.96gH_2O*\frac{1molH_2O}{18.02gH_2O}*\frac{1molZn(OH)_2}{1molH_2O} =0.386molZn(OH)_2\)

In such a way, since the water yields a smaller amount of zinc hydroxide we conclude it is the limiting reactant so the maximum mass is computed below:

\(m_{Zn(OH)_2}=0.386molZn(OH)_2*\frac{99.424 gZn(OH)_2}{1molZn(OH)_2} \\\\m_{Zn(OH)_2}=38.4g\)

Because the water limits the yielded amount of zinc hydroxide.

Best regards!

The concentration of CO2 in club soda is approximately 1.1964 g/L.

To find the concentration of CO2 in club soda, we need to use the stoichiometry of the reaction and the volume and concentration of the NaOH solution used.

The balanced equation for the reaction is:

CO2(aq) + 2NaOH(aq) → Na2CO3(aq)

From the stoichiometry of the equation, we can see that 1 mole of CO2 reacts with 2 moles of NaOH. Therefore, the moles of CO2 can be calculated using the volume and concentration of NaOH solution used.

Given that 32.14 mL of 0.04202 M NaOH solution was used, we can calculate the moles of NaOH:

moles of NaOH = volume (L) × concentration (M)

moles of NaOH = 32.14 mL × 0.04202 mol/L

moles of NaOH = 0.001351 mol

According to the stoichiometry of the equation, 1 mole of CO2 reacts with 2 moles of NaOH. Therefore, the moles of CO2 can be calculated as:

moles of CO2 = (moles of NaOH) / 2

moles of CO2 = 0.001351 mol / 2

moles of CO2 = 0.0006755 mol

Now, we need to convert the moles of CO2 to grams. The molar mass of CO2 is approximately 44.01 g/mol.

mass of CO2 = moles of CO2 × molar mass of CO2

mass of CO2 = 0.0006755 mol × 44.01 g/mol

mass of CO2 = 0.02979 g

Finally, we need to express the concentration of CO2 in club soda in g/L. We are given that the sample of club soda used is 25.00 mL.

concentration of CO2 = (mass of CO2) / (volume of club soda in L)

concentration of CO2 = 0.02979 g / (25.00 mL × 0.001 L/mL)

concentration of CO2 = 1.1964 g/L

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Answer:

0.0730

Explanation:

decimal 0s don't count except for ones at the end

Answer:

\(\rho =1.96\frac{g}{L}\)

Explanation:

Hello there!

In this case, since this imaginary gas can be modelled as an ideal gas, we can write:

\(PV=nRT\)

Which can be written in terms of density and molar mass as shown below:

\(\frac{P}{RT} =\frac{n}{V} \\\\\frac{P}{RT} =\frac{m}{MM*V}\\\\\frac{P*MM}{RT} =\frac{m}{V}=\rho\)

Thus, by computing the pressure in atmospheres, the resulting density would be:

\(\rho = \frac{165/760 atm * 314.2 g/mol}{0.08206\frac{atm*L}{mol*K}*425K} \\\\\rho =1.96\frac{g}{L}\)

Best regards!

Answer:

Dissolving NH4F in water will form a weak acidic solution.

Explanation:

That it is a weak acid solution means that it has a pH below 7 but close to the value, that is, it does not contain as many acids as those substances that are around a pH of 1 to 4, generally weak acids have a pH approximately 5 to 6

The solution of solid ammonium fluoride in pure water has been slightly acidic in nature.

Ammonium fluoride has been an ionic compound formed by the interaction of cationic ammonia and anionic fluoride ions. The dissolution of ionic compounds will result in the compound in its dissociated ionic state.

The dissociation results in the formation of ammonium cation. The ammonium has been a strong acid.

The resulted anion has been fluoride. It has been a strong base, but slightly weaker than ammonia.

Thus the resultant solution will result in slightly acidic nature.

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In evolution, isolation means one group is separated and isolated from a population to study the adaption of evolutionary changes over a period of time.

A natural phenomenon called evolution describes how inheritable traits of a species alter through time.

Natural selection, mutation, genetic drift, and migration are the key drivers. Geographical or reproductive isolation stop the exchange of genetic material across populations. As a consequence of adaptation to a particular environment or niche throughout time, populations of many species changed (natural selection).

When there is a barrier that the creatures can't overcome, they become isolated, which implies they are separated from other members of their species. The isolation of organisms is a consequence of environmental change. When mountain ranges or deserts emerge or when continents separate, isolation may develop gradually.

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Answer:

6 mol H₂O

General Formulas and Concepts:

Chemistry

Explanation:

Step 1: Define

RxN:     2H₂ + O₂ → 2H₂O

Given:   3 moles O₂

Step 2: Stoichiometry

\(3 \ mol \ O_2(\frac{2 \ mol \ H_2O}{1 \ mol \ O_2} )\) = 6 mol H₂O

Step 3: Check

We are given 1 sig fig.

Our final answer has 1 sig fig, so no need to round.

Answer:

B.

Explanation:

Assume the structures are like those in the Figure.

Structure B. looks like a branched chain. However, it has a continuous chain of six carbon atoms. It is a proper representation of a "straight" chain isomer of hexane.

A. is wrong. It has a branched chain.

C. is wrong. The chain has seven carbon atoms. This is heptane.

6.02 x \(10^{20\) formula units of MgCl₂ is equal to 0.1 moles of MgCl₂.

To convert formula units of MgCl₂ to moles of MgCl₂, we need to use Avogadro's number, which relates the number of formula units to the number of moles.

Avogadro's number (NA) is approximately 6.022 x 10^23 formula units per mole.

Given that we have 6.02 x 10^20 formula units of MgCl₂, we can set up a conversion factor to convert to moles:

(6.02 x 10^20 formula units MgCl₂) * (1 mol MgCl₂ / (6.022 x 10^23 formula units MgCl₂))

The formula units of MgCl₂ cancel out, and we are left with moles of MgCl₂:

(6.02 x 10^20) * (1 mol / 6.022 x 10^23) = 0.1 mol

Therefore, 6.02 x 10^20 formula units of MgCl₂ is equal to 0.1 moles of MgCl₂.

It's important to note that this conversion assumes that each formula unit of MgCl₂ represents one mole of MgCl₂. This is based on the stoichiometry of the compound, where there is one mole of MgCl₂ for every one formula unit.

Additionally, this conversion is valid for any substance, not just MgCl₂, as long as you know the value of Avogadro's number and the number of formula units or particles you have.

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The correct answer is: Atoms are the building blocks that make up elements. At the center of each atom is a nucleus composed of small particles called protons and neutrons. Nuclei is the plural of nucleus; option C.

The atomic number of an element is the number of protons present in the nucleus of the atom of the element.

The nucleus is the center of the atom and is the heaviest part of the atom.

Another sub-atomic particle fund in the nucleus is the neutron.

Elements are named according to the number of protons in the nuclei.. This is because the number of protons in the nucleus of any given atom whereas the neutron number may vary, Also, electrons are easily removed from atoms of elements.

In conclusion, the number of protos in atom is used to name the atom.

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Answer:

How do amoeba respire.

Define Diffusion.

Answer:

Number of neutrons

Explanation:

All have one single proton.  Hydrogen has no neutrons.  Hydrogen 2 or deuterium has 1 neutron.  Hydrogen 3 or tritium has 2 neutrons.

Answer:

polar bonds- H2O, CO2, CH3CL,

The molecules that have polar bonds are CH₃Cl, and H₂O.

A polar bond is a type of covalent bond where the electron is unequally distributed.

This unequal distribution is due to the electronegativity difference of the attached atoms in the molecule.

A lewis structure of the molecule is studied to determine whether the compounds are polar and non-polar.

The molecule CCl₄: has one carbon atom at the center and the chlorine surrounds the carbon from all four sides, so even if there is a difference in the electronegativity the net dipole movement gets balanced from all four sides, so it is not a polar bond.

The molecule CH₃Cl

Similar to the CCl₄, hydrogen, and chlorine is surrounding the carbon, the three sides are hydrogen and one side is chlorine, so there is a net dipole movement and so it is a polar bond.

The molecule H₂O: The dipole movement of Hydrogen and oxygen are both in opposite directions and of different magnitude hence it will have a net dipole movement and so it is polar.

The molecule CO₂ and O₂ have net dipole movements as zero so are not polar compounds.

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GAS A, Graham's law states that the rate of effusion of a gas is inversely proportional to the square root of its molar mass or that the rate of effusion of two gases = square root of the inverse of their molar masses.

PV = nRT, where P is pressure (in atm), V is the volume (in L), n is the number of moles of gas, R is the universal gas constant (0.08206 Latm/molK), and T is temperature, is the formula used to calculate the molar mass (in K).

By dividing the mass of one mole of ammonia by the aforementioned volume, the density can now be computed. This density is somewhat lower than the ammonia density at the STP, which is equivalent to (170.4g/mol)(22.4L/mol)=0.761g/L.

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The balanced equation for the dissolving of aluminum chloride into an aqueous solution with the dissociation of the ions is; AlCl3(s) → Al^3+ (aq) + 3 Cl^-(aq).

An equation is a representation of the change that occurs inside a reaction vessel. Usually, we use this tool to show on paper, a process that we can not see with or eyes.

The equation that shows the balanced equation for the dissolving of aluminum chloride into an aqueous solution with the dissociation of the ions is; AlCl3(s) → Al^3+ (aq) + 3 Cl^-(aq).

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The SI unit that refers to the number of particles contained in a substance is the mole (mol).

Answer:

I think its epicenter

Explanation:

The epicenter is the point on the earth's surface vertically above the hypocenter, point in the crust where a seismic rupture begins.

Answer:

Explanation:

c) fusion combines into one product plus energy

Answer: I believe the correct answer would be A.

Answer:

GHG emissions are often measured in carbon dioxide (CO2) equivalent. To convert emissions of a gas into CO2 equivalent, its emissions are multiplied by the gas's Global Warming Potential (GWP).

There are several physical methods that can be used to monitor the rate of a chemical reaction are; Spectrophotometry, Conductometry, and Turbidity measurement

Spectrophotometry involves measuring the changes in the intensity of light absorbed or transmitted by a solution during a chemical reaction. Spectrophotometers are used to measure the amount of light absorbed or transmitted by a sample at different wavelengths.

Conductometry  involves measuring the changes in electrical conductivity of a solution during a chemical reaction. Conductivity meters are used to measure the electrical conductivity of a solution, which can change as the concentration of ions in the solution changes during a chemical reaction.

Turbidity measurement involves measuring the changes in the clarity or turbidity of a solution during a chemical reaction. Turbidimeters or nephelometers can be used to measure the amount of light scattered by a sample, which can change as particles form or dissolve during a reaction.

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--The given question is incomplete, the complete question is

"What are the physical methods of monitoring the rate of a chemical reaction?"--

Answer: Covalent Bond

Explanation: A hydrogen molecule forms from two hydrogen atoms, each with one electron in a 1 s orbital. The two hydrogen atoms are attracted to the same pair of electrons in the covalent bond. The bond is represented either as a pair of “dots” or as a solid line.

The evidence of chemical reactions can be given as:

Blue colour solution=iron and copper(II) sulfate  

no reaction=copper and hydrochloric acid

Brown colour solution=zinc and iron(III) nitrate

Brown colour solution=zinc and magnesium sulfate

hydrogen gas liberate= zinc and hydrochloric acid

hydrogen gas liberate=iron and hydrochloric acid

Chemical reaction is the process by which a number of chemicals (the reactants) change into a number of unique compounds (the products). Materials are composed of chemical components or chemical elements. The atoms which make comprised the reactants of a chemical reaction are rearranged to create different products.

Blue colour solution=iron and copper(II) sulfate  

no reaction=copper and hydrochloric acid

Brown colour solution=zinc and iron(III) nitrate

Brown colour solution=zinc and magnesium sulfate

hydrogen gas liberate= zinc and hydrochloric acid

hydrogen gas liberate=iron and hydrochloric acid

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The non-metal elements in Group 7 – known as the halogens – get less reactive as you go down the group

Answer & Explanation:

The reactivity of elements in Group VII, also known as Group 17, decreases with increasing atomic radius. This is because halogens have high electronegativities and a proclivity to gain electrons in noble gas configurations. Myths are traditional stories or beliefs that explain cultural or societal beliefs, customs, or natural phenomena. They can be passed down through generations and can be based on true or fictitious events. Mythology, on the other hand, is the collection of myths associated with a specific culture or religion. Mythology can be amplified through retelling, incorporation into religious practices; association with significant events or figures, and adaptation into other media forms such as literature, film, or art.