Select the correct answer. what is the chemical formula of magnesium bromide? a. mgbr2 b. mgbr c. mg2br2 d. mg2br

The mass number of an atom that has 53 protons, 78 neutrons, and 54 electrons would be 131.

A mass number can be described as the sum total of the number of protons and neutrons that are contained within the nucleus of an atom.

If we want to calculate the mass number of an atom, we need to add the number of neutrons present inside the atoms with the number of protons present inside the atom.

As mentioned in the question, the number of protons inside the said atom is 53 whereas the number of neutrons is 78. Hence,

53+78= 131

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The minimum mass of octane that could be left over is 0.468 grams.

Step 1: Data given

Mass of octane = 3.4 grams

Mass of oxygen = 20.5 grams

Molar mass octane = 114.23 g/mol

Molar mass oxygen = 32.0 g/mol

Step 2: The balanced equation

2C₈H₁₈ + 25O₂ → 16CO₂ + 18H₂O

Step 3: Calculate the number of moles

Moles = mass / molar mass

Moles octane = 3.4 grams / 114.23 g/mol

Moles octane = 0.0297 moles

Moles O₂ = 20.5 grams / 32.0 g/mol

Moles O₂ = 0.640 moles

Step 4: Calculate the limiting reactant

For 2 moles octane we need 25 moles O₂ to produce 16 moles CO₂ and 18 moles H₂O

O₂ is the limiting reactant. It will completely be consumed (0.640 moles). There will react 0.0320/ 12.5 = 0.0256 moles.

There will remain 0.0297 - 0.0256  = 0.0041 moles octane.

Step 5: Calculate mass octane remaining

Mass octane = moles * molar mass

Mass octane = 0.0041 moles * 114.23 g/mol

Mass octane = 0.468 grams

The minimum mass of octane that could be left over is 0.468 grams.

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(a) The work done when the gas expands isothermally against a constant external pressure is 87.992 kJ

(b) The work that would be done if the same expansion occurred reversibly is 167.4 J

Given that the mass of methane m is = 4.5 gram = 0.0045 kg

Volume occupies [tex]V_{1}[/tex] = [tex]12.7dm^{3}[/tex]

And volume is increased by [tex]3.3dm^{3}[/tex]

So, the increased volume [tex]V_{2}[/tex] is

12.7 + 3.3 = 16 litres

Given temperature T is 310K

Pressure is given as 210 Torr = 26664.5 Pa

(a) Now, at the given pressure the work done is given by

W = P( [tex]V_{2}[/tex] - [tex]V_{1}[/tex])

W = 26664.5 (16 - 12.7)

W = 87992.85 J

W = 87.992 kJ

(b) At reversible process work done is given by

W = nRT㏑[tex]\frac{V2}{V1}[/tex]

We have the given mass = 4.5 gram

Molar mass of methane = 16

So number of moles is

n = Mass in gram / Molar Mass

n = 4.5 / 16

n = 0.28125

So, work done is

W = 0.28125 × 8.314 × nRT㏑[tex]\frac{16}{12.7}[/tex]

W = 167.4 J

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The shortest covalent bond is the H-F bond. Therefore, option (A) is correct.

The electronegativity decreases down the group and the Fluorine is the most electronegative atom in the periodic table. The size of the atoms also increases as we go down the group.

The bond length of the hydrogen halides will follow the order HF < HCl < HBr < HI. The radius of the Iodine atom is the largest and to form a molecule, the hydrogen atom will be farthest as compared to all hydrogen halides.

The molecule with Fluorine will have the shortest bond length because its atom has the smallest size, making them attach very closely. So the covalent bond of hydrogen fluoride will be the shortest.

The relationship between bond length and bond strength is inverse in nature. The bond length of HI is the greatest, it will have the least bond strength. So the order for bond strength of the hydrogen halides is  HF > HCl > HBr > HI.

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Answer: I think it’s C

Explanation:

I think it’s C because animal cells do not have a cell wall and the cell wall is unique to plant cells

Answer:

A -carbon and lithium.

Explanation:

Carbon and lithium are two elements form acidic oxides.

One or more oxygen atoms are joined with another element to form a chemical molecule known as an oxide (for instance, Li2O).

The term "oxide" refers to a binary compound containing oxygen and another element, such as CO2, SO2, CaO, CO, ZnO, BaO2, and water. Because oxygen is combined with just one other element in these substances, they are referred to as oxides. Oxides are divided into acidic, basic, amphoteric, and neutral categories based on their acid-base properties:

An oxide is referred to as acidic if it reacts with water to form an acid. A basic oxide is an oxide that produces a base in water. A substance that can chemically react as either an acid or a base is called an amphoteric solution.

Therefore, Carbon and lithium are two elements form acidic oxides.

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Answer:

The easiest way to find the number of neutrons, protons, or electrons is to look at the element's atomic number on the periodic table, that number is equal to the number of protons. Which is equal to the number of electrons unless there's an ion superscript listed after the element.

Explanation:

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0.00925 moles OR 9.25103 moles of OH remain unreacted in the solution after the neutralization process is finished.

In a neutralization reaction, an acid and a base mix chemically to yield salt and water as the final products. During a neutralization process, H+ and OH- ions interact to produce water.

The balanced chemical equation is

H₂SO₄ + 2KOH → K₂SO₄ + 2H₂O

Now determine the number of moles

For H₂SO₄

Volume = 23.61 mL = 0.02361L

Concentration = 0.120M

From the formula,

Number of moles = Concentration × Volume

∴ Number of moles of H₂SO₄ = 0.120 × 0.02361

Number of moles of H₂SO₄ = 0.0028332 moles

For KOH

Volume =mL = 48.16ml = 0.04816 L

Concentration = 0.309 M

∴ Number of moles of KOH = 0.309 × 0.04816

Number of moles of KOH = 0.01488144 moles

From the equation of reaction,

0.0028332 moles of H₂SO₄ will neutralize 2× 0.0028332moles KOH

2× 0.0028332 = 0.0056664 moles

This means only 0.0056664 moles of KOH reacted

The amount of unreacted OH moles will now be discussed.

Number of unreacted OH moles equals the total number of OH moles at the start of the reaction. Quantity of OH that reacted in moles

∴ Number of moles of unreacted OH⁻ = 0.01488144 moles - 0.0056664 moles

Number of moles of unreacted OH⁻ ≅ 0.00925 moles OR 9.25×10⁻³ moles

Hence, the number of moles of OH⁻ that are unreacted in the solution after the neutralization is complete is 0.00925 moles OR moles 9.25×10⁻³.

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In carrying out the first standardization in this experiment, a student used 0.5793 g of potassium hydrogen phthalate (khp) and 24.55 ml of a NaOH solution are needed to reach the equivalence point then the concentration of student NaOH solution is 0.02455 L

Standardization is the process in which determining the exact concentration of molarity of the solution and here given data is

Mass of potassium hydrogen phthalate (C₈H₅KO₄) = 0.5793 g

Molar mass of potassium hydrogen phthalate (C₈H₅KO₄) = 204.22g/mol

The number of mole of potassium hydrogen phthalate present then,

Number of moles = mass/molar mass

Number of moles = 0.5793 g/204.22g/mol = 0.002836 mole

Volume of NaOH present = 24.55 ml

1 ml =  0.001 L then, 24.55 ml = 24.55 ml×0.001 L = 0.02455 L

The concentration (in mol/l) of the student's naoh solution is 0.02455 L

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The final volume of the ideal gas in a flexible container will be 9.0 L.

Let:

Ideal-gas Equation establishes a relation between pressures, volumes, and temperatures of different conditions.

Using the Ideal-Gas Equation:

                              PV = nRT

Ideal-Gas Equation for initial conditions will be:

                              PV = nRT.....................................................(i)

Ideal-Gas Equation for final conditions will be:

                              (P/3)X = nR(T/2)........................................(ii)

On dividing equations (i) and (ii):

                             PV = nRT / (P/3)X = nR(T/2)

                             3V/X = 2

                             X = 3V/2

Putting the value of V = 6L:

                             X = 3(6L)/2 = 9L

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According to the given statement is 11.36 g/ml is the density of the object.

The proportion of an object's mass to its volume has been its density. The unit of density is frequently grams per cubic centimeter (g/cm3). Keep in mind that the volume is measured in cubic centimeters, not grams (the same volume as 1 millilitre). More particles will make a box denser than fewer particles in the same box.

Absolute density and relative density are the two main types of density. Relative density, also known as specific gravity, is the proportion of a product's density to the density of a reference material.

Mass  = 125  g

Initial Volume =55.0 mL

Final  Volume = 66.0 mL

Volume = 66.0mL - 55.0mL

Volume= 11.0 mL

ρ = m/v

ρ = 125/11

ρ = 11.36 g/ml.

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a.) 5.34102 Zn(cu)2 molecules are formed.

b.) The mass of Zn(cu)2 formed is 10.41 g at 117.44 g/mol

The entire numbers next to each component of the reaction should be noted because they will be necessary for the stoichiometric calculations that follow:

K[ag(CN)2] has a molar mass of 199 g/mol.

Zn(Cn)2 has a molar mass of 117.44 g/mol.

6.022 x 1023 molecules per mole is Avogadro's number.

a.)

35.27 g* (199 g/1 mol) x (1 mol Zn(Cn)2/ 2 mol K[Ag(CN)2]) x

(6.0221023 molecules/mol) = 5.341022 Zn(Cn)2 molecules.

b.)

35.27 g x (199 g/1 mol) x (1 mol Zn(Cn)2/ 2 mol K[Ag(CN)2]) x

Zn(Cn)2 equals 10.41 g at (117.44 g/mol).

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From ores like k[ag(CN)2], silver is frequently removed before being recovered by reaction and 5.34102 Zn(Cu)2 molecules are formed and the masses of Zn(Cu)2 formed is 10.41 g at 117.44 g/mol.

It is important to take notice of the whole numbers next to each reaction component because the following stoichiometric calculations will require them:

The molar mass of K[ag(CN)2] is 199 g/mol.

The molar mass of Zn(Cn)2 is 117.44 g/mol

Avogadro's number is 6.022 x 1023 molecules per mole.

a.) 35.27 g* (1 mol Zn(Cn)2/ 2 mol K[Ag(CN)2]) x (199 g/1 mol) x

5.341022 Zn(Cn)2 molecules =

6.0221023 molecules/mol.

b.) 35.27 g x (1 mol Zn(Cn)2/ 2 mol K[Ag(CN)2]) x (199 g/1 mol) x

10.41 g of Zn(Cn)2 are,

= 117.44 g/mol.

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Answer: so the answer will be 25 J

Explanation: The mass is 0.5 kg and the velocity is 10 meters per second. So: KE = (1/2)(0.5)(10)^2. Thus the kinetic energy of the ball is 25 J

There would be seven peaks if you could observe them all while considering no decomposition of the ion into smaller fragments.

Each sulfur isotope would give a peak so there are three possible combinations of the hydrogen isotopes:

H-H (m/z = 2), H-D (m/z = 3) and D-D (m/z = 4).

Thus, you will find 4 × 3 = 12 components for the molecular ion.

However, some of these peaks will overlap each other so the stable isotopes of sulfur have masses 32, 33, 34, and 36.

Thus, the expected peaks will be:

32S:m/z=34,35,36

33S:m/z=35,36,37

34S:m/z=36,37,38

36S:m/z=38,39,40

If every peak were visible, you would see seven peaks in total.

They would have m/z = 34, 35, 36, 37, 38, 39, 40.

Isotope peaks are ionic parts of the same chemical equation that are more often than not visible to different adjoining crests inferable to particles of distinctive isotopic compositions.

The number of isotope crests and the relative concentration of each crest depends on the chemical equation of the ionic part and the normal isotopic composition of its constituent components.

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This canyon is an example of how the surface of Earth changes slowly due to the slow and gradual process of erosion by water and wind.

The slow and gradual process of erosion by water and wind is responsible for the slow change in the surface of Earth demonstrated by the canyon.

The canyon demonstrates how the surface of Earth changes slowly due to the process of erosion by water and canyon, which gradually wear away the rock and reshape the landscape over millions of years.

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The release of O₂( oxygen gas) from the process of photosynthesis is made disks to be able to float.

Photosynthesis can be described as the process in which green plants manufacture their food in the presence of sunlight which is trapped by the chlorophyll of the leaves. They are also called primary producers and they use compounds such as water and carbon dioxide.

The spinach leaf disks intake carbon dioxide from a sodium bicarbonate solution and sink to the bottom of a beaker. When the beaker is exposed to light, the disks use carbon dioxide gas and water to produce oxygen gas and glucose. Oxygen gas released from the leaves due to photosynthesis forms tiny bubbles that make the leaves float.

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A compound differs from a mix in that a compound has a definite composition by the mass of the elements it contains. Option C.

A compound may be a substance formed by the chemical combination of two or more elements. a mix is a substance formed by physically mixing two or more substances. a mix is two or more substances that are not chemically combined, and a compound is 2 or more elements that are chemically combined.

This differs from compounds, which are composed of drugs in fixed proportions. Substances during a mixture do not chemically combine to form new substances as compounds do. A compound may be a substance formed by the combination of two other chemical elements. a mix is a substance formed from two or more substances that can be separated using physical methods.

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The final pressure of the balloon that was initially filled with a volume of 2.20L to 3.86L is 430.3mmHg.

The pressure of a gas can be calculated using the Boyle's law equation as follows:

P₁V₁ = P₂V₂

Where;

According to this question, the volume of a balloon filled with He at 755 mmHg is expanded from 2.20L to 3.86L at a constant temperature. The final pressure can be calculated as follows:

755 × 2.2 = P₂ × 3.86

1661 = 3.86P₂

P₂ = 430.3mmHg

Therefore, the final pressure of the balloon that was initially filled with a volume of 2.20L to 3.86L is 430.3mmHg.

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Hybridization of atomic orbitals produces orbital shapes and spatial orientations that correlate to those predicted in VSEPR theory is how they are reconciled and is denoted as option D.

This is a term in chemistry which refers to the process in which atomic orbitals mix to form a new atomic orbital. The orbital usually has a different shape and a similar energy during the mixing process.

It helps us to reconcile valence bond theory with vsepr theory by producing orbital shapes and spatial orientations that correlate to those predicted in VSEPR theory hence why option D was chosen.

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The mass of the iron oxide produced in the given chemical reaction is equal to 27.04 grams.

The limiting reagent in a chemical reaction can be described as that reactant that will decide the amount of the yield of the product. The reactant consumed first will confirm the completion of the reaction if the reactants are not taken in stoichiometry.

Given the chemical reaction of the formation of iron oxide:

4Fe   +    3O₂    →    2Fe₂O₃

Given the mass of the iron = 15.4 grams

The moles of the iron = 15.4/56 = 0.275 mol

The mass of the oxygen gas = 3.6 grams

The moles of the oxygen gas = 3.6 /32 = 0.1125 mol

From the chemical equation, 4 moles of the Fe react with oxygen = 3 mol

Then 0.275 mol of the Fe will react with oxygen = 3/4 × 0.275 = 0.206 mol

Therefore, oxygen is the limiting reagent here.

The 3 mols of oxygen produced iron oxide = 2 mol

0.1124 mol of oxygen will produce iron oxide = (2/3) × 0.1125 = 27.04 g

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1. The longer distance for each choice is:

2. The complete statements are as follows;

3. The basic unit of length in the metric system is the meter and is represented by a lowercase m.

4. The meter is defined as the distance traveled by light in absolute vacuum in 1⁄299,792,458 of a second.

5. The values that complete each statement is given below:

6. The larger value for each option is:

7. The number of millimeters in 1 centimeter is 10 mm

8. Using the ruler and line, the answers are:

The unit for measuring distance in the metric system is the meter. Smaller and larger values of the meter are also used such as millimeters, centimeters, kilometers, etc.

Other units for measuring distance include yards, miles, and inches.

The various units for measuring distance can also be interconverted using their conversion factors.

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This conclusion is wrong; because the covalent molecules do not conduct electricity.

A covalent bond is created when one or more pairs of electrons are exchanged between two atoms. The two atomic nuclei are drawing these electrons in unison. A covalent bond is created when there is not enough room between the electronegativities of two atoms for an electron transfer to occur and produce ions.

The atoms associate in a covalent bond by exchanging electrons. Typically, nonmetals form covalent connections with one another. For instance, each hydrogen (H) and oxygen (O) share two electrons to form the molecule of two hydrogen atoms singly linked to one oxygen atom that is known as water (H₂O).

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The mole fraction of water decreases because, at this starting mole fraction, solid water forms before solid acetic acid.

What is mole fraction ?

Mole fraction represents the number of molecules of a particular component in a mixture divided by the total number of moles in the given mixture. It’s a way of expressing the concentration of a solution.

The amount fraction is another name for the mole fraction.  It is the same as number fraction, which is calculated by dividing the number of molecules in a constituent (Ni) by the sum of all molecules. Instead of using a Roman x, the lowercase Greek letter chi is occasionally used to represent the mole fraction. The IUPAC recommends the letter y for gas mixtures.

Because it does not include the name of the unit mole, the National Institute of Standards and Technology of the United States prefers the phrase amount-of-substance fraction to mole fraction.

Molar concentration is a proportion of moles to volume, whereas mole fraction is a ratio of moles to moles.

The mole fraction of water decreases because, at this starting mole fraction, solid water forms before solid acetic acid.

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The heat of reaction is  1.8 KJ. A calorimeter is a device used in calorimetry, a procedure for calculating heat capacity and measuring the heat of chemical processes or other physical changes.

Volume of water = 67.9 mL

Since the density of water is 1.00 g/mL

Density = mass/volume

Mass of water = Density × volume

Mass of water =  1 g/mL × 67.9 mL

Mass of water = 67.9g or 0.0679 Kg

Temperature change =  6.5 oC

Specific heat capacity of water= 4.184 J/Kg

From;

H = mcθ

m = mass of water

c = heat capacity of water

θ = temperature rise

Substituting values;

H = 0.0679 Kg × 4.184 J/Kg × 6.5 oC

H = 1.8 KJ

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Answer:

Its 1s22s22p63s23p1 ik it looks a lil goofy but i think its right

Explanation:

The pH value of the resulting solution is 11.9.

To calculate the pH value of the solution we need to calculate the molarity (c) of the solution, using the number of moles of HCl (n) and the volume of the solution (V = 662 mL = 0.662 L).

c = n/V

To obtain the number of moles of HCl, we are going to use the mass of HCl (m = 18.4 g) and its molar mass (M = 36.5 g/mol):

n = m/M

n = 18.4 g / 36.5 g/mol

n = 0.504 mol

Now we can calculate the molarity:

c = 0.504 mol / 0.662 L

c = 0.761 M

Because HCl is a monoprotic acid, the molarity of the solution is equal to the concentration of H⁺ ions ([H⁺] = 0.761 M), which is important for calculating pH:

pH = -log[H⁺]

pH = -log(0.761)

pH = 11.9

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Using the half-life of Am-241, its molar mass and the mass of the sample, we can calculate that it will release 3.57 * 10¹¹ α-particles each second.

If the half-life of Am-241 is 432 years, that means that in 432 years, we will have half of the starting amount, which is:

3.89 g / 2 = 1.945 g

Using the molar mass of Am-241 (241 g/mol), we can calculate the number of moles (n) in 1.945 g:

n = m/M = 1.945 g / 241 g/mol = 8.07 * 10⁻³ mol

Because each mol contains 6.022 * 10²³ particles, over 432 years we will release:

8.07 * 10⁻³ * 6.022 * 10²³ = 4.86 * 10² α-particles

Now we can calculate the number of seconds in 432 years:

432 years * 365.25 days * 24 hours * 60 minutes * 60 seconds = 1.36 * 10¹⁰ seconds

So, each second the sample of Am-241 will release:

4.86 * 10²¹ / 1.36 * 10¹⁰ = 3.57 * 10¹¹ α-particles

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Answer:

Atomic emission spectra are produced when excited electrons return to the ground state. When electrons return to a lower energy level, they emit energy in the form of light.

Explanation: