Question 28
(1 mark)
Two other minerals can be seen in the photo:

galena, a dark grey mineral with the formula PbS

iron pyrite, a gold-coloured mineral with the formula FeS2

Compare their chemical formulas, by writing down one similarity and one difference between these two minerals.

Note: Pb = lead, Fe = iron, S = sulfur.




Question 29
(1 mark)
Wanting to create the beautiful golden colour of iron pyrite, FeS2, in the lab, a student mixes together black powdered iron (Fe) and yellow powdered sulfur (S). The result is a dull, yellowish grey powder. Propose why this attempt failed?




Question 30
(1 mark)
The student can vary the proportions of iron and sulfur by adding more of each powder to the mixture. Clarify why the same thing isn't true for the compound iron pyrite.

The rate of appearance of NOBr at the given time is 9.80 × [tex]10^-^4[/tex] M/s which is the second option as the question asks to determine the rate of appearance of NOBr, which is a product of the given chemical reaction, at the given time when the rate of disappearance of Br₂ is known. 

For every 1 mole of Br₂ that disappears, 2 moles of NOBr appear. Thus, we can set up a proportion:

(2 mol NOBr / 1 mol Br₂) = (rate of appearance of NOBr / rate of disappearance of Br₂)

Substituting the given values,

(2 mol NOBr / 1 mol Br₂) = (rate of appearance of NOBr / 4.90 x  [tex]10^-^4[/tex] M/s)

Solving for the rate of appearance of NOBr,

rate of appearance of NOBr = (2 mol NOBr / 1 mol Br₂) x (4.90 x  [tex]10^-^4[/tex] M/s) = 9.80 ×  [tex]10^-^4[/tex]M/s

The rate of appearance of NOBr at the given time is 9.80 × [tex]10^-^4[/tex] M/s.

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The triacylglycerol depicted may be converted to a saturated fat by adding two hydrogen atoms (H2) to each carbon-carbon double bond. Six hydrogen atoms (H2) are required to convert the three carbon-carbon double bonds in triacylglycerol into saturated fat.

This is so that the triacylglycerol may be converted to a saturated fat by using hydrogen molecules (H2) to saturate the double bonds.

Triacylglycerol's physical characteristics, such as its melting point, will similarly be altered by the addition of hydrogen molecules (H2), making it more solid at normal temperature.

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Answer:

Explanation:

In the given reaction, carbon has a greater oxidation number in carbon dioxide (CO₂) than in carbon monoxide (CO). In CO₂, the oxidation number of carbon is +4, while in CO it is +2.

The final temperature of the copper and water after they come to thermal equilibrium is 109.8°C.

Temperature is a measure of the amount of thermal energy present in a substance or object. It is measured in degrees on a scale such as Fahrenheit, Celsius, or Kelvin. Temperature is important in determining the physical and chemical properties of a substance, such as its melting point, boiling point, and specific gravity. Temperature also affects the rate of a chemical reaction and the speed of diffusion.

The change in temperature of the copper can be calculated using the equation
ΔT = (Q/mc), where Q is the heat transferred, m is the mass of the copper, and c is the specific heat of copper.
Q = mcΔT = (192 g)(0.385 J/g °C)(100°C) = 74080 J
The heat transferred from the copper must equal the heat transferred to the water. Therefore,
(74080 J) = (0.85 L)(4.184 J/g°C)(ΔT)
ΔT = (74080 J)/[(0.85 L)(4.184 J/g°C)] = 109.8°C
The final temperature of the copper and water after they come to thermal equilibrium is 109.8°C.

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A crucial trace mineral is chromium. Trivalent chromium, which is safe for people, and hexavalent chromium, which is toxic, are the two types.

Thus, Foods and dietary supplements both contain trivalent chromium. It might assist maintain normal blood sugar levels by enhancing the body's utilization of mineral.

Chromium is used by people to treat deficiencies. Additionally, it is used to treat bipolar disorder, diabetes, high cholesterol, and a variety of other conditions, but the majority of these uses are not well-supported by science.

Chromium by mouth doesn't help control blood sugar levels in people with prediabetes. Schizophrenia. Taking chromium by mouth doesn't affect weight or mental health in people with schizophrenia.

Thus, A crucial trace mineral is chromium. Trivalent chromium, which is safe for people, and hexavalent chromium, which is toxic, are the two types.

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A potential problem associated with travel to another planet is : the extended time for humans to be in space.

It is highly likely that humans will travel to another planet, and Mars is currently considered the most viable option for human exploration. However, there are many potential problems associated with this endeavor, and one of the major issues is the extended time that humans would need to spend in space.

Traveling to Mars would take several months, and once there, astronauts would need to spend significant amount of time on planet before returning to Earth. This means that they would be exposed to high levels of radiation and would need to find ways to survive in harsh and unforgiving environment.

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The molecular formula of the strychnine, given that it is composed of 75.45% carbon, 6.59% hydrogen, 8.38% nitrogen, and the balance oxygen is C₂₁H₂₂N₂O₂

First, we shall obtain the empirical formula of compound. Details below:

Divide by their molar mass

C = 75.45 / 12 = 6.2875

H = 6.59 / 1 = 6.59

N = 8.38 / 14 = 0.5986

O = 9.58 / 16 = 0.59875

Divide by the smallest

C = 6.2875 / 0.5986 = 10.5

H = 6.59 / 0.5986 = 11

N = 0.5986 / 0.5986 = 1

O = 0.59875 / 0.5986 = 1

Multiply through by 2 to express in whole number

C = 10.5 × 2 = 21

H = 11 × 2 = 22

N = 1 × 2 = 2

O = 1 × 2 = 2

Thus, we can conclude that the empirical formula is C₂₁H₂₂N₂O₂

Now, we shall determine the molecular formula of strychnine. Details below

Molecular formula = empirical × n = mass number

[C₂₁H₂₂N₂O₂]n = 140.22

[(12×21) + (1×22) + (14×2) + (16×2)]n = 334

334n = 334

Divide both sides by 334

n = 334 / 334

n = 1

Molecular formula = [C₂₁H₂₂N₂O₂]n

Molecular formula = [C₂₁H₂₂N₂O₂]1

Molecular formula = C₂₁H₂₂N₂O₂

Thus, we can conclude that the molecular formula of strychnine is C₂₁H₂₂N₂O₂

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Answer:

Unsaturated

Explanation:

A solution is unsaturated when it contains less than the maximum amount of solute that is capable of being dissolved.

To calculate the concentration resulting from the dilution of 500.0 mL of 4.267 M to a volume of 1.85 L, we can use the equation:
M1V1 = M2V2
where M1 is the initial concentration, V1 is the initial volume, M2 is the final concentration, and V2 is the final volume.

Plugging in the given values, we get:
4.267 M)(500.0 mL) = M2(1.85 L)
Simplifying this equation, we get:
M2 = (4.267 M)(500.0 mL) / (1.85 L)
M2 = 1.153 M
Therefore, the concentration resulting from the dilution is 1.153 M.
To calculate the concentration after dilution, you can use the dilution formula: C1V1 = C2V2, where C1 and V1 are the initial concentration and volume, and C2 and V2 are the final concentration and volume.
Given:
C1 = 4.267 M
V1 = 500.0 mL = 0.5 L (converted to liters)
V2 = 1.85 L
Now, find C2:

C2 = (C1 * V1) / V2
C2 = (4.267 M * 0.5 L) / 1.85 L
C2 ≈ 1.153 M
The concentration after dilution is approximately 1.153 M.

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To find the concentration resulting from the dilution, we can use the equation:
M1V1 = M2V2
where M1 is the initial concentration, V1 is the initial volume, M2 is the final concentration, and V2 is the final volume.

Plugging in the given values, we get:
(4.267 M)(500.0 mL) = M2(1.85 L)
Simplifying and converting units, we get:
M2 = (4.267 M)(500.0 mL) / (1.85 L)
M2 = 1.16 M
Therefore, the concentration resulting from the dilution is 1.16 M.
To find the concentration after dilution, you can use the dilution formula:
C1V1 = C2V2
where C1 is the initial concentration, V1 is the initial volume, C2 is the final concentration, and V2 is the final volume.
Given:
C1 = 4.267 M
V1 = 500.0 mL (0.5 L)
V2 = 1.85 L
Rearrange the formula to solve for C2:
C2 = (C1V1) / V2
Now, plug in the given values:
C2 = (4.267 M * 0.5 L) / 1.85 L
C2 ≈ 1.154 M
So, the resulting concentration after dilution is approximately 1.154 M.

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First, we need to calculate the heat gained by the cold water and the heat lost by the hot water:

Qcold = mcΔT = (30 g)(4.184 J/g-°C)(1.93°C) = 242.06 J

Qhot = mcΔT = (70 g)(4.184 J/g-°C)(-1.93°C) = -546.53 J

Since energy is conserved, we can assume that the heat gained by the cold water and calorimeter is equal to the heat lost by the hot water:

Qcold + Qcalorimeter = Qhot

Qcalorimeter = Qhot - Qcold

Qcalorimeter = -546.53 J - 242.06 J = -788.59 J

Therefore, the heat capacity of the calorimeter can be calculated as:

Ccalorimeter = Qcalorimeter / ΔT

Ccalorimeter = (-788.59 J) / (1.93°C)

Ccalorimeter ≈ -408.4 J/°C

Note that the negative sign indicates that the calorimeter loses heat when the system gains heat, which is expected since the calorimeter is absorbing some of the heat from the hot water.

If heat is going into a system, it means that energy must have come out from the surroundings.

Heat is a form of energy transfer from a hotter object to a cooler one, and the direction of heat flow is always from the hotter object to the cooler one.

Therefore, if heat is entering a system, it must be gaining energy from its surroundings, which are at a lower temperature and therefore have less thermal energy.

Conversely, if heat is leaving a system, it means that energy is being transferred from the system to its surroundings, which are at a higher temperature and therefore have more thermal energy.

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The initial sample had 0.010925 mol of Copper(II) oxide, or one mole.

The kinetic-molecular theory, which describes the states of matter, is based on the presumption that matter is composed of minuscule particles that are constantly in motion. This theory explains the observable properties and behaviours of solids, liquids, and gases. The container's walls and the quickly moving particles' collisions with one another are constant.

Copper(II) oxide + Sulfuric acid → Cupric sulfate + Water

One mole of Copper(II) oxide interacts with one mole of Sulfuric acid, as shown by the equation. The amount of Sulfuric acid that reacted with the Copper(II) oxide in the sample is therefore equal to the amount of Copper(II) oxide in the sample.

We must first determine how many moles of Sulfuric acid interacted with the sample:

moles Sulfuric acid = concentration × volume

moles Sulfuric acid = 0.437 mol/L × 0.025 L

moles Sulfuric acid = 0.010925 mol

Since the acid is in excess, the moles of Sulfuric acid remaining after treatment of the sample is:

moles Sulfuric acid remaining = moles Sulfuric acid added – moles Sulfuric acid reacted

moles Sulfuric acid remaining = 0.437 mol/L × 0.0354 L – 0.010925 mol

moles Sulfuric acid remaining = 0.007571 mol

To determine the number of moles of Copper(II) oxide in the original sample, we can use the following equation:

moles Copper(II) oxide = moles Sulfuric acid reacted = 0.010925 mol

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Answer:

Data collection is the act of obtaining information from diverse sources, and data analytics is the process of processing that information to derive practical insights.

Explanation:

The mass of the platinum ring is 76.0 grams.

We need to know the molar mass of platinum and the number of platinum atoms in the ring.

The molar mass of platinum (Pt) is 195.08 g/mol.

The number of platinum atoms in the ring is 2.35×10^23.

Now we can use the following formula to calculate the mass of the ring:

mass = (number of atoms) x (atomic mass) / Avogadro's number

where Avogadro's number is 6.022 x 10^23 mol^-1.

Substituting the values:

mass = (2.35×10^23 atoms) x (195.08 g/mol) / (6.022 x 10^23 mol^-1)

mass = 76.0 g

Therefore, the mass of the platinum ring is 76.0 grams.

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Answer:

9. B

10. Loses

Explanation:

9. Conduction is The procedure by which thermal energy or electricity is directly transported through a substance without the material moving when there is a variance in temperature between adjacent parts. Only choice B shows this process.

10. In exothermic reactions, energy/heat is lost. Exothermic reactions are characterized by a negative delta H, such as the delta H for the reaction show.

The mathematical variable is not a standard term in experimental design and is not typically used to describe variables in scientific experiments.

The variable that is unknown until the experiment is performed is typically the responding variable.

The responding variable is the variable that is observed and measured during the experiment, and its value changes in response to the manipulated variable. In contrast, the manipulated variable is the variable that is intentionally changed by the researcher to observe its effect on the responding variable.

The controlled variable is the variable that is kept constant throughout the experiment to ensure that any changes in the responding variable are due to the manipulated variable and not due to other factors. The mathematical variable is not a standard term in experimental design and is not typically used to describe variables in scientific experiments.

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When the second cation first starts to precipitate, 80.8% of Ca²⁺ will still be in solution.

A cation is an ion with a positive charge. It is formed when an atom loses one or more of its electrons, resulting in a net positive charge. Cations are attracted to anions (ions with a negative charge) due to their opposite charges. Cations are found in many different substances, including acids, bases, and salts.

Ca₃(PO₄)₂ will be the first species that separates out of solution when solid Na₃PO₄ is introduced to the mixture. This is due to Ca3(PO4)2 having a substantially lower solubility than Ag₃PO₄ and Na₃PO₄.

The proportion of the first cation (Ca²⁺ ) still in solution when the second cation (Ag⁺) is just beginning to precipitate will depend on the starting concentrations of the two cations. In this instance, the starting concentrations of Ca²⁺  and Ag⁺ are 0.0400 M and 0.0990 M, respectively. Therefore, 80.8% of Ca²⁺  will still be in solution when its second cation first begins to precipitate.

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Step-by-step Explanation:

8.51 moles is to 5.12 L  as  'x'  moles is to (13.3-5.12) L

8.51 moles / 5.12 L    =   x / ( 13.3-5.12)

x = 13.6 moles

The amount of zinc chloride that would be formed if 77.1 grams of zinc reacts is approximately 160.77 grams

To determine how many grams of zinc chloride ([tex]ZnCl_2[/tex]) would be formed if 77.1 grams of zinc (Zn) reacts, we'll use stoichiometry.

First, we need the molar masses of the substances involved:

Zn: 65.38 g/mol
[tex]ZnCl_2[/tex] : 136.29 g/mol
Now, we'll convert grams of Zn to moles:
77.1 g Zn × (1 mol Zn / 65.38 g Zn) = 1.179 moles Zn
According to the balanced chemical equation, 1 mole of Zn reacts to form 1 mole of [tex]ZnCl_2[/tex]:
1.179 moles Zn × (1 mol ZnCl₂ / 1 mol Zn) = 1.179 moles ZnCl₂

Finally, convert moles of ZnCl₂ to grams:
1.179 moles ZnCl₂ × (136.29 g ZnCl₂ / 1 mol ZnCl₂) ≈ 160.77 g ZnCl₂
So, approximately 160.77 grams of zinc chloride would be formed if 77.1 grams of zinc reacts.

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Before the chairs touch, the temperature of the bottom chair is lower than the temperature of the top chair, this is because the molecules in the bottom chair are in contact with a cooler surface.

After the chairs have been touching for a while, the heat will begin to transfer from the top chair to the bottom chair through a process called conduction. This will continue until the temperature of the two chairs equalizes, at which point there will be no more net heat transfer between them.

The final temperature of both chairs will be somewhere between the initial temperatures of the two chairs, and will depend on factors such as the thermal conductivity of the material, the size of the chairs, and the duration of the contact.

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The oxidation number of the unknown chlorine in the compound is + 5

The oxidation number of an element in a compound is determined by a set of rules based on its position in the periodic table, as well as the charges of other atoms in the compound

We know that the oxidation number of the chlorine which we want to obtain would be designated as x and the total of the oxidation numbers of the elements in the compound is zero.

Thus we have that;

1 + x + 3(-2) = 0

1 + x - 6 = 0

-5 + x = 0

x = 5

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The volume of the carbon dioxide is produced at the 31.0 °C and the 0.995 atm is 119,786 L.

The number of moles of octane = 538 mol

The moles of carbon dioxide = 4888 mol

The temperature of the gas = 31.0 °C

The pressure of the gas = 0.995 atm

The volume of the gas = ?

The ideal gas equation is :

P V = n R T

Where,

The p is the pressure = 0.995 atm

The V is the volume = ?

The n is moles of gas = 4888 mol

The R is gas constant = 0.823 atm L / mol K

The T is temperature = 31 + 273 = 304 K

V = n R T / P

V = ( 4888 mol × 0.0823 × 304 ) / 0.995

V = 119,786 L

The volume is 119,786 L.

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The mass of carbon dioxide formed when 24 kg of carbon is burnt completely in oxygen is 88 kg, and the heat released is 811.2 MJ.

What is Molar Mass?

Molar mass is the mass of one mole of a substance and is expressed in grams per mole (g/mol). It is calculated by adding up the atomic masses of all the atoms in a molecule or formula unit of a compound. The molar mass is used in stoichiometry calculations to convert between mass and moles of a substance.

The balanced equation for the combustion of carbon is:

C + O₂ → CO₂

From the equation, we can see that one mole of carbon reacts with one mole of oxygen to produce one mole of carbon dioxide. The molar mass of carbon dioxide is 12 + (2 × 16) = 44 g/mol.

First, let's find the number of moles of carbon in 24 kg:

n(C) = m/M = 24000 g / 12 g/mol = 2000 mol

Therefore, 2000 mol of CO₂ will be produced.

The mass of CO₂ produced can be calculated as:

m(CO₂) = n(CO₂) × M(CO₂) = 2000 mol × 44 g/mol = 88,000 g = 88 kg

Now, let's calculate the heat released during combustion:

Heat released = 33.8 MJ/kg × 24 kg = 811.2 MJ

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The mass of Na₃PO₄ formed during the reaction is 328 g.

The balanced chemical equation for the reaction is:

[tex]3NaOH + Na_3PO_4 - > 3Na_2PO_4 + H_2O[/tex]

From the equation, we can see that 3 moles of NaOH produce 1 mole of Na₃PO₄.

Given that 2.0 moles of Na₃PO₄ is produced, we can set up a proportion to find the amount of NaOH required:

3 mol NaOH / 1 mol Na₃PO₄ = x mol NaOH / 2.0 mol Na3PO4

Solving for x, we get:

x = (3 mol NaOH / 1 mol Na₃PO₄) × (2.0 mol Na₃PO₄ / 1) = 6.0 mol NaOH

So, 6.0 moles of NaOH are required to produce 2.0 moles of Na₃PO₄.

To find the mass of Na₃PO₄ produced, we can use its molar mass:

mass = moles × molar mass = 2.0 mol × 164 g/mol = 328 g

Therefore, the mass of Na₃PO₄ formed during the reaction is 328 g.

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All of the equation-related claims are not entirely true. The appropriate chemical formula should be:

Fe(OH)3 + 3NH4Cl = FeCl3 + 3NH4OH

Because the total mass of the reactants and products are equal, as well as the number of each type of atom in each of the reactants and products, mass is conserved in this balanced equation. Depending on the stoichiometric coefficients in the balanced equation, there may or may not be an equal amount of molecules in the reactants and products.

Iron(III) hydroxide (Fe(OH)3) and ammonium chloride (NH4Cl) are the products of the chemical reaction between iron(III) chloride (FeCl3) and ammonium hydroxide (NH4OH).

The coefficients (the numbers in front of the chemical formulae) must be changed to make sure that the number of each type of atom is the same on both sides of the equation in order to ensure that the equation is balanced. The coefficients in this instance are:

Fe(OH)3 + 3NH4Cl = FeCl3 + 3NH4OH

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The average speed of a gas molecule is proportional to the square root of its temperature and inversely proportional to the square root of its molar mass. Therefore, we can use the following equation to find the average speed of a CO2 molecule at the same temperature:

v2/v1 = sqrt(M1/M2)

where v1 and v2 are the average speeds of the oxygen and CO2 molecules, respectively, M1 and M2 are the molar masses of oxygen and CO2, respectively.

The molar mass of oxygen (O2) is 32 g/mol, and the molar mass of CO2 is 44 g/mol.

We are given that the average speed of an oxygen molecule is 4.37 × 10^4 cm/s at 25°C. We can convert the temperature to Kelvin by adding 273.15 to get:

T = 25°C + 273.15 = 298.15 K

Now we can solve for v2:

v2 = v1 * sqrt(M1/M2)

v2 = 4.37 × 10^4 cm/s * sqrt(32 g/mol / 44 g/mol)

v2 = 3.67 × 10^4 cm/s

Therefore, the average speed of a CO2 molecule at the same temperature is 3.67 × 10^4 cm/s.

The volume of the balloon once they have cooled to the outside temperature of -34.0 c is 1.53 L.

Charles' law predicts the relationship between the volumes and the temperatures of a sample of an ideal gas at different conditions. For this equation to hold true, the number of molecules and the pressure must remain constant despite changes in the environment.

Determine the volume of the balloon outside, V2. We do this by applying Charles' law, such that we relate the volume, V, and the temperature, T, of a sample of gas as

V₁ /T₁ = V₂/ T₂

at two conditions. We are given the following values for the variables:

• V₁ = 1.90 L

T₁ = 22.0+ 273.15 = 295.15 K

T₂= 34.0+273.15= 239.15 K

We proceed with the solution.

V₁/T₁ = V₂/T₂

V₁ /T₁ × T₂ = V₂

1.90 L/295.15 K x 239.15 K = V₂

1.53 L =V₂

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The complete question is

Balloons for a New Year's Eve party in Fargo, ND, are filled to a volume of 1.90 L at a temperature of 22.0 degrees Celsius and then hung outside where the temperature is -34.0 degrees Celsius. What is the volume of the balloons after they have cooled to the outside temperature? Assume that atmospheric pressure inside and outside the house is the same.

Answer:

A. setting standards and governing the cleanliness of water used by Americans

Explanation:

The responsibilities of the Environmental Protection Agency (EPA) is to make sure that:

The S-P difference (sec) is the time gap between the arrival of the S-wave and the arrival of the P-wave at a seismic station. The S-P discrepancy is depicted in the figure as 20 seconds.

The amplitude (mm) of a seismic wave is the largest displacement from its resting point. The amplitude of the waves is not depicted in the image and cannot be calculated based on the information provided.

Distance (km): Using the S-P time difference and the known velocity of seismic waves, the distance from the seismic station to the earthquake epicenter may be determined. Seismic wave velocity is determined by the type of wave and the features of the Earth's interior. The velocity of P-waves in the Earth's crust, for example, is around 6 km/s. We may compute the distance to the epicenter using this value and the S-P difference of 20 seconds as follows:

Distance = Speed x Time = 6 km/h x 20 seconds = 120 kilometres

As a result, the distance between the seismic station and the earthquake epicenter is about 120 km.

The magnitude of an earthquake (M) is a measurement of the energy generated by the earthquake based on the amplitude of the seismic waves and the distance to the epicenter. Magnitude is commonly measured on a logarithmic scale, with each whole number reflecting a factor of ten increase in energy release.

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