Summarize the evidence indicating that over several hundreds of years or more there have been variations in the level of the solar activity.

A. The use of ice cores have helped track the activity of the Sun containing information over the centuries
B. Small features on the surface of the Sun provide evidence of past activity similar to craters on Earth
C. Counts of sunspots infer the overall magnetic field changes, which correlate with the level of the magnitude of the solar dynamo and hence solar activity. Astronomers have reliable data going back to 1750.
D. Scientists have reliable data on Earth’s temperature fluctuations beginning from 1880, which can be used to demonstrate solar activity.

The heat change required to melt 12.0 g of ice at 0°C is 4,002.6 joules.

To calculate the heat change in joules for melting 12.0 g of ice at 0°C, we need to use the specific heat of fusion of ice and the heat equation. The specific heat of the fusion of ice is 333.55 J/g.

The heat equation is:

Q = m × ΔH

where Q is the heat change, m is the mass of the substance, and ΔH is the specific heat of fusion.

Therefore, the heat change required to melt 12.0 g of ice at 0°C can be calculated as follows:

Q = 12.0 g × 333.55 J/g

Q = 4,002.6 J

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The first ionisation energy increases over time from left to right among the major group of elements. answer is option (a).

When an element loses its valence electron, its oxidation number increases (a process known as oxidation), and this energy loss is known as ionisation (Ei).

Earth alkaline metals, which are located immediately next to alkaline metals, have higher ionisation energies than alkaline metals because they have two valence electrons, while alkaline metals, which are located far left in the main group, have the lowest ionisation energies and are easiest to remove.

Because they contain a large number of valence electrons, nonmetals are far to the right in the main group and have the highest ionisation energy.

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The complete question is,

Among the elements of the main group, the first ionization energy increases

a. from left to right across a period.

b. from right to left across a period.

c. when the atomic radius increases.

d. down a group.

Taking into account the definition of dilution, the final concentration of the solution is 0.68 M.

Dilution is the process of reducing the concentration of solute in solution, which is accomplished by simply adding more solvent to the solution.

In a dilution the amount of solute does not change, but as more solvent is added, the concentration of the solute decreases, and the volume of the solution increases.

A dilution is mathematically expressed as:

Ci×Vi = Cf×Vf

where

In this case, you know:

Replacing in the definition of dilution:

4.2 M× 14 mL= Cf× 86 mL

Solving:

(4.2 M× 14 mL)÷ 86 mL= Cf

0.68 M= Cf

In summary, the final concentration is 0.68 M.

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Heat capacity of a substance or system is defined as the amount of heat required to raise its temperature through 1°C. It is denoted by C. Heat capacity is an extensive property. Here the energy change is 2508 J.

The specific heat capacity of a substance is defined as the amount of heat required to raise the temperature of 1 gram of the substance through 1°C.

The heat required to raise the temperature of a sample of mass 'm' and specific heat capacity 'c' is:

q = mc ΔT

q = 40 × 4.18 × 15 = 2508 J

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Difluoroethane (DFE) is a cheap, commonly obtainable volatile chemical that is safe for recreational inhalation.

Thus, It can be found in everyday household items including propellants, refrigerants, and compressed air dusters. When breathed, DFE is a central nervous system (CNS) depressant that causes a momentary feeling of euphoria.

Toxic effects are linked to prolonged or excessive usage, and rapid termination might cause withdrawal.3–5 We describe a DFE misuse case that was accompanied by skeletal fluorosis and withdrawal psychosis.

Difluoroethane is a colourless, odourless gas that is transported under its vapour pressure as a liquefied gas. Ingestion of the liquid can result in frostbite.

Thus, Difluoroethane (DFE) is a cheap, commonly obtainable volatile chemical that is safe for recreational inhalation.

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Answer:

A chemical equation is the symbolic representation of a chemical reaction in the form of symbols and formulae, wherein the reactant entities are given on the left-hand side and the product entities on the right-hand side.

Explanation:

Good luck!

Answer:

A chemical equation is the symbolic representation of a chemical reaction in the form of symbols and chemical formulas.

What is in a chemical equation?

A chemical equation (see an example below) consists of a list of reactants (the starting substances) on the left-hand side, an arrow symbol, and a list of products (substances formed in the chemical reaction) on the right-hand side.

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Sonce the stoichiometric coefficients for both carbon dioxide and carbon monoxide are the same, the moles of CO2 formed and the moles of CO used are the same, therefore if 10,8 mole of carbon dioxide are being produced, then you would need 10,8 moles of carbon monozide

The moles of Nitric Acid present (1.6244 mol) is more than twice the moles of Cu (0.969 mol). Therefore, Copper is the limiting reactant. Therefore, 17.45 g of water is formed. Since we can't have negative moles.

The number of moles of each reactant can be calculated by dividing the volume of each solution by its molarity. You can identify which reactant is the limiting one in the balanced chemical equation by dividing the number of moles of each reactant by its stoichiometric coefficient.

a) Calculating the moles of copper and nitric oxide and comparing their stoichiometric ratios will help us identify the limiting reactant.

From the given information, the moles of Cu is 0.969 mol.

The moles of Nitric Acid can be calculated using the formula:

moles of Nitric Acid = (molarity) x (volume in liters)

moles of Nitric Acid = (6.60 mol/L) x (246/1000 L)

moles of Nitric Acid = 1.6244 mol

The balanced equation shows that 1 mol of Cu reacts with 2 mol of Nitric Acid.

The moles of Nitric Acid present (1.6244 mol) is more than twice the moles of Copper (0.969 mol). Therefore, Copper is the limiting reactant.

b)We can see from the balanced equation that 1 mol of Copper reacts to create 1 mol of water. As a result, the amount of Water generated will be 0.969 mol, which is identical to the amount of Copper that was reacted.

mass of water = moles of water x molar mass of water, where the molar mass of water is 18.015 g/mol.

mass of water = 0.969 mol x 18.015 g/mol

mass of water = 17.45 g (rounded to two decimal places)

Therefore, 17.45 g of water is formed.

c) Copper is the limiting reactant, hence no Nitric Acid will be completely oxidised. We must first figure out how many moles of Nitric Acid are needed to react with all of the Copper in order to compute how much extra Nitric Acid is still there.

From the balanced equation, we know that 1 mol of Cu reacts with 2 mol of Nitric Acid. Therefore, the moles of Nitric Acid required to react with 0.969 mol of Copper will be:

moles of Nitric Acid = 2 x 0.969 mol

moles of Nitric Acid = 1.938 mol

The initial moles of Nitric Acid present is 1.6244 mol. Therefore, the moles of excess Nitric Acid remaining after the reaction is:

moles of excess Nitric Acid = initial moles of Nitric Acid - moles of Nitric Acid required

moles of excess Nitric Acid = 1.6244 mol - 1.938 mol

moles of excess Nitric Acid = -0.3136 mol

Since we can't have negative moles, we know that all of the Nitric Acidwill be consumed, and there is no excess Nitric Acid remaining.

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Copper is the limiting reactant, with n(Copper) = 0.969 mol being less than n(Nitric acid). It produces 17.44 grammes of water. As the outcome is negative, there is no excess Nitric acid. The reaction uses up all of the Nitric acid.

The method described in the following steps can balance a redox equation: (1) Split the equation into two equal halves. (2) Make each half-mass reaction's and charge equal. (3) Ensure that the quantity of electrons going to each half-reaction is the same. The half-reactions should be combined.

n(Nitric acid) = (246 mL) x (6.60 mol/L) = 1.6236 mol

Since n(Copper) = 0.969 mol is less than n(Nitric acid), Copper is the limiting reactant.

m(Water) = n(Water) x M(Water) = 0.969 mol x 18.015 g/mol = 17.44 g

Therefore, 17.44 grams of Water is formed.

n(Nitric acid) needed = n(Copper) x 2 = 1.938 mol

The excess amount of Nitric acid is:

n(Nitric acid) excess = n(Nitric acid) initial - n(Nitric acid) needed

= 1.6236 mol - 1.938 mol

= -0.3144 mol

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Explanation:

Use the Ideal Gas Law :

PV = n RT

STP = standard temp and pressure =   273.15 K  and  1  atm

n = number of moles

   CO2,  (using table of elements) ,

        has mole weight of  12.011 +2*15.999=~ 44 gm/mole

                 20 gm / 44gm/mole = .455 mole of CO2

    R = gas constant = .082057  L atm /(K mole)

Plug in the numbers and solve for  'V'

(1 atm ) V = .455  * .082057 * 273.15

V = 10.2 liters

Here is another way:

 ....knowing that a mole of gas occupies 22.4 L /mole at STP

        22.4 L / mole * .455 mole = ~10.2 liters

The Correct answer is D

Hydronium

hydroxide

To calculate the volume of water needed to create a 0.450 M solution of Al(NO3)3, we need to use the formula:

Molarity = moles of solute / volume of solution in liters

First, we need to determine the number of moles of Al(NO3)3 we have:

moles of Al(NO3)3 = mass / molar mass

molar mass of Al(NO3)3 = 1 x atomic mass of Al + 3 x atomic mass of N + 9 x atomic mass of O = 1 x 26.98 + 3 x 14.01 + 9 x 16.00 = 212.99 g/mol

moles of Al(NO3)3 = 41.6 g / 212.99 g/mol = 0.195 mol

Next, we can rearrange the formula above to solve for the volume of solution:

volume of solution = moles of solute / molarity

volume of solution = 0.195 mol / 0.450 M = 0.433 L

Therefore, we need to add 0.433 L (or 433 mL) of water to 41.6 g of Al(NO3)3 to create a 0.450 M solution.

The rate of the reaction for the following process if the rate of change for NOBr was measured as -0.5 M/s. is 0.25 M/s.

The rate of a reaction is typically expressed as the rate of change of the concentration of a reactant or product over time. For the given reaction:

[tex]2NOBr(g)[/tex] ↔[tex]2NO(g)[/tex] [tex]+[/tex] [tex]Br_{2}[/tex](g)

The rate of the reaction can be expressed as:

[tex]rate = -1/2 * d[NOBr]/dt[/tex]

where [tex]d[NOBr]/dt[/tex] is the change in the concentration of NOBr over time, and the negative sign indicates that the concentration of NOBr is decreasing over time.

If the rate of change for NOBr was measured as -0.5 M/s, we can substitute this value into the above equation to find the rate of the reaction:

rate = -1/2 * (-0.5 M/s)

= 0.25 M/s

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The first ionisation energy increases over time from left to right among the major group of elements. answer is option (a).

When an element loses its valence electron, its oxidation number increases (a process known as oxidation), and this energy loss is known as ionisation (Ei).

Earth alkaline metals, which are located immediately next to alkaline metals, have higher ionisation energies than alkaline metals because they have two valence electrons, while alkaline metals, which are located far left in the main group, have the lowest ionisation energies and are easiest to remove.

Because they contain a large number of valence electrons, nonmetals are far to the right in the main group and have the highest ionisation energy.

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The complete question is,

Among the elements of the main group, the first ionization energy increases

a. from left to right across a period.

b. from right to left across a period.

c. when the atomic radius increases.

d. down a group.

The amount of heat required is 246.165 Joules.



We can use the following method to figure out how much energy it will take to raise the temperature of benzene:

Q = mcΔT

Where Q = the amount of energy needed (in Joules).

m = the number of grams of benzene.

c = the amount of heat that benzene can hold (in J/g*K).

T = temperature change (in Kelvin)

But since the volume of benzene is given to us, we need to find the mass of Benzene by:

Density = mass/volume

mass = density x volume

mass = 0.876 g/cm3 x 50.00 mL = 43.8 g

Change in temperature = 28.75 - 25.52 = 3.23 K

Now, we can use the given numbers to fill in the formula for Q:

Q = mcΔT

Q = 43.8 g x 1.74 J/g*K x 3.23 K

Q = 246.165 J

So, it takes 238.92 Joules of heat energy to raise the temperature of 50 mL of benzene from 25.52°C to 28.75°C.

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Answer:

[tex]\Large \boxed{\boxed{\textsf{heat required = 246.2 J (4 s.f)}}}[/tex]

Explanation:

The heat energy required to raise the temperature of the reaction, i.e, the amount of heat energy released in the reaction (noting the rise in temperature, this is an exothermic reaction), can be calculated with the following calorimetry equation:

[tex]\Large \boxed{\textsf{$q=mc\Delta T$}} \sf \,, where:\\ \\\bullet q = quantity\,of\,heat\,released\,(measured\,in\,joules)\\ \bullet m = solvent\,of\,mass\,(measured\,in\,g\,or\,kg)\\\bullet c = specific\,heat\,capacity\,of\,solution\\\bullet \Delta T = change\,in\,temperature\,of\,solution[/tex]

To solve this, we know that:

[tex]\textsf{$\bullet$ m = 43.8 g (1 mL = 1 cm$^3$, using density = g/cm$^3$)}\\\textsf{$\bullet$ c = 1.74 J/g/K}\\\textsf{$\bullet \Delta T$ = 3.23 ($\Delta T$ is the same whether Kelvin or Celsius is used)}[/tex]

Inputting these values into the formula:

[tex]\large \textsf{$q = (43.8)(1.74)(3.23)$}\\ \\\large \textsf{$\therefore q=246.2$ J}\\ \\ \\\Large \boxed{\boxed{\textsf{$\therefore$ heat required = 246.2 J (4 s.f)}}}[/tex]

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Answer:

56,522 seconds = 942 minutes

Explanation:

n(Mg) = m/M(Mg) = 25 g / 24.31 g/mol = 1.03 mol of Mg

Q = n × 2 F = 1.03 mol × 2 × 96,485 C/mol = 197,820 C

t = Q / I = 197,820 C / 3.5 A = 56,522 s

Answer:

Explanation:

We can use the ideal gas law to solve for the temperature of the neon gas:

PV = nRT

where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature.

First, let's convert the volume from milliliters to liters:

V = 1520 mL = 1.52 L

Next, let's rearrange the ideal gas law to solve for T:

T = PV/nR

Now we can plug in the values and solve:

T = (325 mmHg)(1 atm/760 mmHg)(1.52 L)/(0.250 mol)(0.0821 L·atm/(mol·K))

T = 89.6 K

To convert to degrees Celsius, we subtract 273.15:

T = 89.6 K - 273.15 = -183.6 °C

Therefore, the temperature of the neon gas is 89.6 K or -183.6 °C.

When water ionizes, it means that some of the water molecules break apart into ions, which are electrically charged particles. If you could shrink down and see the true composition of water at the molecular level, means water molecules are in a constant state of motion and interaction with each other.

Water (H₂O) is a polar molecule, meaning it has a partial positive charge on one end (hydrogen) and a partial negative charge on the other end (oxygen). This polarity allows water molecules to interact with each other through hydrogen bonding, which gives water its unique properties, such as high boiling and melting points, high heat capacity, and strong surface tension.

When water ionizes, it means that some of the water molecules break apart into ions, which are electrically charged particles. In the case of water, it can ionize into hydrogen ions (H⁺) and hydroxide ions (OH⁻);

H₂O → H⁺ + OH⁻

This ionization occurs when water molecules dissociate or separate into these charged particles due to the transfer of a proton (H⁺) between water molecules.

If you could shrink down and see the true composition of water at the molecular level, you would observe that water molecules are in a constant state of motion and interaction with each other. Some water molecules would be dissociating into hydrogen ions (H⁺) and hydroxide ions (OH⁻), while others would be recombining to form water molecules again.

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Red light has a longer wavelength than violet light. Wavelength is the distance between two consecutive peaks or troughs of a wave, and it determines the color of light. The range of visible light wavelengths is between approximately 400 nanometers (nm) for violet light to 700 nm for red light. So, red light has a longer wavelength and lower frequency than violet light.

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The data obtained from the experiment shows a clear indication that a reaction has occurred between the H₂SO₄ and Ba(OH)₂ solutions. As the H₂SO₄ solution is added to the Ba(OH)₂ solution, the ammeter reading decreases indicating a decrease in conductivity.

The decrease in conductivity is due to the formation of an insoluble white precipitate, BaSO₄, as seen in observations. When no more H₂SO₄ is added, the ammeter reading stabilizes, indicating that the reaction has reached completion, as seen in observations e and f.

The formation of BaSO₄ precipitate indicates that the sulfate ion, SO₄²⁻, from H₂SO₄, has reacted with the barium ion, Ba²⁺, from Ba(OH)₂, forming an insoluble salt. This is a typical example of a precipitation reaction, where two aqueous solutions are mixed, resulting in the formation of an insoluble solid product.

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The question is inappropriate; The complete question is:

A chemistry student carried out an experiment with a conducting apparatus (ammeter) similar to the one below. This ammeter measures in milliamperes (mA). To 30 mL of the Ba(OH)2 solution, 10 mL portions of H2SO4 were added until a total of 50 mL of H2SO4 were used.

Explain the data. Is there any evidence that a reaction has occurred? How does this evidence indicate that the reaction has occurred between ions?

1.30 atmospheres is equivalent to 131723 pascal.

Atmospheres is a unit of measurement for pressure equal to 101325 Pa with symbol: atm.

Pascals, on the other hand, is the International System of Units (SI unit), the derived unit of pressure and stress, which is equivalent to one newton per square metre.

1 atmosphere = 101325 pascals

Therefore, 1.30 atm is equivalent to 1.3 × 101325 = 131723 Pa.

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To balance the given chemical equation using the oxidation state change method, we need to follow these steps:Step 1: Write the unbalanced equationKMnO4 + KCl + H2SO4 → K2SO4 + MnSO4 + Cl2
Step 2: Identify the elements that undergo oxidation and reductionIn this equation, the oxidation state of Mn changes from +7 to +2, which means it undergoes reduction, while the oxidation state of Cl changes from -1 to 0, which means it undergoes oxidation.

Step 3: Write the half-reactionsReduction half-reaction: MnO4^- → Mn^2+Oxidation half-reaction: Cl^- → Cl2Step 4: Balance the atoms and charges in each half-reactionReduction half-reaction: 8H+ + MnO4^- → Mn^2+ + 4H2OOxidation half-reaction: 2Cl^- → Cl2 + 2e^-Step 5: Balance the electrons in each half-reactionReduction half-reaction: 5e^- + 8H+ + MnO4^- → Mn^2+ + 4H2OOxidation half-reaction: 2Cl^- → Cl2 + 2e^-Step 6: Multiply each half-reaction by a factor to equalize the number of electrons transferredReduction half-reaction: 10e^- + 16H+ + 2MnO4^- → 2Mn^2+ + 8H2OOxidation half-reaction: 14Cl^- → 7Cl2 + 14e^-Step 7: Add the balanced half-reactions together10e^- + 16H+ + 2MnO4^- + 14Cl^- → 2Mn^2+ + 8H2O + 7Cl2Step 8: Cancel out the common terms on both sides of the equation2KMnO4 + 16KCl + 8H2SO4 → 2K2SO4 + 2MnSO4 + 7Cl2 + 8H2OTherefore, the balanced equation using the oxidation state change method is:2KMnO4 + 16KCl + 8H2SO4 → 2K2SO4 + 2MnSO4 + 7Cl2 + 8H2O.

The temperature of copper would rise by 263.8°C more than the temperature of water if we added the same amount of heat to equal masses of each substance.

Specific heat capacity is the amount of heat energy required to raise the temperature of one unit mass of a substance by one degree Celsius or Kelvin. To estimate the final temperature difference, we can use the specific heat capacity of each substance.

The specific heat capacity of copper is 0.385 J/g°C, while the specific heat capacity of water is 4.184 J/g°C. This means that water requires over ten times as much heat energy as copper to raise its temperature by one degree Celsius.

If we add an equal quantity of heat (in joules) to equal masses of copper and water, we can expect the temperature of copper to rise much more than the temperature of water. In fact, we can calculate the temperature difference using the following formula:

Q = mCΔT

where Q is the amount of heat added, m is the mass of the substance, C is its specific heat capacity, and ΔT is the change in temperature.

If we assume that we add the same amount of heat to equal masses of copper and water (let's say 100 grams each), then we can set up two equations using the specific heat capacities of each substance:

Q = 100 * 0.385 * ΔT (for copper)

Q = 100 * 4.184 * ΔT (for water)

Since Q is the same in both equations (we added the same amount of heat to each substance), we can set the two equations equal to each other and solve for ΔT:

100 * 0.385 * ΔT = 100 * 4.184 * ΔT

0.385 * ΔT = 4.184 * ΔT

3.799 * ΔT = Q (where Q is the amount of heat added)

ΔT = Q / 3.799

So, if we added 1000 joules of heat to 100 grams each of copper and water, we can expect the temperature difference between the two substances to be:

ΔT = 1000 / 3.799 = 263.8°C

This means that the temperature of copper would rise by 263.8°C more than the temperature of water if we added the same amount of heat to equal masses of each substance. However, it's important to note that this is a theoretical estimate, and in reality, there would be some loss of heat to the surroundings, which would affect the final temperature difference.

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Answer:

cual es el propósito de este experimento

Answer: 2136 molecules of CO2 at STP will occupy a volume of 8.91 × 10^-24 L

Explanation:

STP (standard temperature and pressure), 1 mole of any gas occupies 22.4 L of volume. Also, 1 mole of any gas contains 6.022 × 10^23 molecules.

1 mole of CO2 contains = 6.022 × 10^23 molecules

Therefore, 2136 molecules of CO2 will be present in a volume of:

= (1 mole CO2 / 6.022 × 10^23 molecules CO2) × (22.4 L / 1 mole CO2) × (2136 molecules CO2 / 1)

= 8.91 × 10^-24 L

Based on the information given, the mole should be considered a base unit in the SI system because it serves as a universally accepted measure of the amount or quantity of substances.

The mole is an amount unit similar to familiar units like pair, dozen, gross, etc. It provides a specific measure of the number of atoms or molecules in a bulk sample of matter.

A mole is defined as the amount of substance containing the same number of atoms, molecules, ions, etc. as the number of atoms in a sample of pure 12C weighing exactly 12 g.

SI units refer to units of measurement that are universally accepted for measuring the properties of quantities of objects.

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Answer:

The correct answer is C: 3484 ml

1- FIND MOLES OF magnesium METAL

Moles of Magnesium Metal = 0.6 g/24.31 g/mol = 0.0246 mol

Magnesium is a silvery-white alkaline earth metal that is a very abundant element in the Earth's crust. It is the eighth most abundant element in the universe.

2- FIND CHANGE IN T CALORIMETER

The change in temperature of the calorimeter is not given, so it cannot be calculated.

3- Find q calorimeter

The heat absorbed or released by the calorimeter is qcalorimeter = mCΔT, where m is the mass of the calorimeter, C is the specific heat capacity of the calorimeter, and ΔT is the change in temperature of the calorimeter. Since the mass and change in temperature of the calorimeter are not given, qcalorimeter cannot be calculated.

4- Find q reaction

The heat absorbed or released by the reaction is qreaction = nCΔT, where n is the number of moles of the reactant, C is the specific heat capacity of the reaction, and ΔT is the change in temperature of the reaction. Since the number of moles of the reactant and change in temperature of the reaction are not given, qreaction cannot be calculated.

5- Find the change in heat reaction per mole of Mg consumed

The change in heat per mole of Mg consumed is qMg = qreaction/n, where qreaction is the heat absorbed or released by the reaction and n is the number of moles of Mg. Since qreaction and n are not given, qMg cannot be calculated.

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