PLEASE HURRY IM TIMED Which type of change cannot be reversed?
physical change
chemical change

Answer:

65.0 K

Explanation:

To find the temperature, you need to use the Ideal Gas Law:

PV = nRT

In this equation,

-----> P = pressure (pKa)

-----> V = volume (L)

-----> n = moles

-----> R = Ideal Gas Constant (8.31 L*kPa/mol*K)

-----> T = temperature (K)

You can plug the given values into the equation and simplify to find the temperature.

P = 202.65 pKa                          R = 8.31 L*kPa/mol*K

V = 2.0 L                                     T = ? K

n = 0.75 moles

PV = nRT

(202.65 pKa)(2.0 L) = (0.75 moles)(8.31 L*kPa/mol*K)T

405.3 = (6.2325)T

65.0 K = T

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From Practical perform shown below, It conclude that  If you increase the temperature of a reaction, then the reaction rate will increase because particles experience more collisions at higher temperatures.

The effects of temperature and a reactant’s particle size on reaction rate.

Step 1: Gather Materials250 mL graduated cylinder

   Thermometer

   Water

   Timer

   Four 250 mL beakers

   Seven 1,000 mg effervescent tablets

Step 2: Measure the Reaction Rate at ≈ 20°C (Room Temperature)

a) Using a graduated cylinder, fill a 250 mL beaker with 200 mL of water.

b) Measure the temperature of the water and record it in the correct row of Table A.

c) Reset the timer. Start the timer as you place a full tablet into the beaker.

d) Record the reaction time on the Data Sheet in the correct row of Table A.

e) Compute the reaction rate to the nearest mg/L/sec. Record it in the last column of Table A.

Step 3: Measure the Reaction Rate at ≈ 40°C Repeat Step 2, heating the water to approximately 40°C using a hot plate during sub-step a.

Step 4: Measure the Reaction Rate at ≈ 65°CRepeat Step 2, heating the water to approximately 65°C using a hot plate during sub-step a.

Step 5: Measure the Reaction Rate at ≈ 5°CRepeat Step 2, chilling the water to approximately 5°C inside an ice bath during sub-step a. (To create an ice bath, place 100 mL of ice and 100 mL of water in a 600 mL beaker of ice water and wait until the temperature reaches approximately 5°C. To save time, you may wish to set up the ice bath, using an additional 250 mL beaker, while working on Step 4.)Variation of Particle Size

Step 6: Measure the Reaction Rate for a Full Tablet

a) Using a graduated cylinder, fill a 250 mL beaker with 200 mL of water.

b) Reset the timer. Start the timer as you place the tablet in the beaker.

c) Record the reaction time on the Data Sheet in the appropriate row of Table B.

d) Compute the reaction rate to the nearest mg/L/sec. Record it in the last column of Table B.

Step 7: Measure the Reaction Rate for a Partially Broken Tablet Repeat Step 6, but this time break the tablet into eight small pieces on a piece of filter paper. Make sure to place all of the pieces into the beaker at the same time.

Step 8: Measure the Reaction Rate for a Crushed Tablet Repeat Step 6, but this time crush the tablet into tiny pieces on a piece of filter paper. Make sure to place all of the pieces into the beaker at the same time.

Explanation:

According to chemical equilibrium,if you increase the temperature of a reaction, then the reaction rate will increase because particles experience more collisions at higher temperatures.

Chemical equilibrium is defined as the condition which arises during the course of a reversible chemical reaction with no net change in amount of reactants and products.A reversible chemical reaction is the one wherein the products as soon as they are formed react together to produce back the reactants.

At equilibrium, the two opposing reactions which take place take place at equal rates and there is no net change in amount of the substances which are involved in the chemical reaction.At equilibrium, the reaction is considered to be complete . Conditions which are required for equilibrium are given by quantitative formulation.

Factors which affect chemical equilibrium are change in concentration , change in pressure and temperature and presence of catalyst.

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Answer:

58.8 liters

Explanation:

\(14 \times 4 \: \times 1.05 = 58.8 \: liters\)

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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The Kc of the system is 1.29 * 10^22.

We know that the equilibrium constant has to do with the kind of constant that we can be able  to use to the conversion of the reactants to the products in the course of the reaction.

We know that;

Kp= Kc (RT)^Δn

Kp = Equilibrium constant in terms of pressure

Kc = Equilibrium constant in terms of concentration

R = gas constant

T = temperature

Δn = change in the number of moles

Then;

Kc = Kp/ (RT)^Δn

Kc = 7.7x10^24 /(0.082 * 298)^2

Kc = 1.29 * 10^22

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The mole ratio of PbO2 to water is 1:2.

The mole ratio of PbO2 to water, PbO2:H2O, is 1:2 when the reaction stoichiometry is taken into consideration.

The appropriate reaction is:

2 PbSO4 + 2 H2O ⇒ Pb + PbO2 + 2 H2SO4

The following numbers of moles of each component are involved in the reaction according to reaction stoichiometry, which describes the relationship between the amounts of reagents and products in a chemical reaction:

1 mole Pb

1 mole of PbO2

H2SO4: 2 mol

2 moles of PbSO4

Water: 2 moles

Then, you can see that according to the reaction's stoichiometry, 1 mole of PbO2 produces 2 moles of water (H2O).

Therefore,the mole ratio of PbO2 to water is 1:2.

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Answer:

i think its D

Explanation:

In order to get maximum accuracy, student should take average of results from all four trials.

Accuracy  in terms of chemistry can be defined as to how close a measurement is to the true value.There are three types of accuracy:

1) Point accuracy-It means accuracy is present at that point of scale only.It does not give any information about the accuracy of the instrument.

2)Percentage of true value--It is the accuracy  which is determined by identifying accuracy of the instrument  and comparing it with the measured true value.

3)Percentage of scale range- It is the accuracy  which determines accuracy of the measurement.

Accuracy in case of instruments  is neglected up  to ±0.5 percent.Accuracy of measurements can be increased by taking multiple measurements and taking into account human errors.

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Answer:chemical formula of acetic acid is  or

so, molecular mass of acetic acid = 2 × atomic mass of C + 4 × atomic mass of H + 2 × atomic mass of O

= 2 × 12 + 4 × 1 + 2 × 16

= 24 + 4 + 32

= 60g/mol

given mass of acetic acid = 22g

so, no of moles of acetic acid = given mass/molecular mass

= 22/60 ≈ 0.367

so, number of moles of acetic acid is 0.367mol

number of molecules in 0.367 mol of acetic acid = 6.022 × 10²³ × 0.367

= 2.21 × 10²³

Explanation:

Spectra can be used as an evidence that nuclear fusion occurs in the star through the ability of the elements generated to absorb light at specific wavelength.

The internal part of the star is made up of hydrogen gas, with a little helium.

The helium atom is formed through the nuclear fusion reaction that occurs in the core of the star.

Nuclear fusion reaction involves the combination of two or more atoms which leads to the formation of a new atom with the emission of great energy. This reaction leads to formation of helium elements in the core of the stars.

To detect if nuclear fusion reaction is occurring in the stars, a spectrum is used.

Because each element emits or absorbs light only at specific wavelengths, the chemical composition of stars can be determined using a spectrum.

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Answer:

4f its the last orbital of the above

According to the Aufbau principle and electronic configuration, orbital  which is farthest from the nucleus is 4f.

Electronic configuration is defined as the distribution of electrons which are present in an atom or molecule in atomic or molecular orbitals.It describes how each electron moves independently in an orbital.

Knowledge of electronic configuration is necessary for understanding the structure of periodic table.It helps in understanding the chemical properties of elements.

Elements undergo chemical reactions in order to achieve stability. Main group elements obey the octet rule in their electronic configuration while the transition elements follow the 18 electron rule. Noble elements have valence shell complete in ground state and hence are said to be stable.

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The kinetic energy of a moving object increases with its mass.

The formula for calculating kinetic energy is KE = 0.5 * mass * velocity^2.

The kinetic energy of a moving object increases with the square of its velocity, meaning that as the velocity of an object increases, its kinetic energy increases at a much faster rate.

Kinetic energy is the energy possessed by a moving object due to its motion.

One example of an experiment could be rolling two balls down a ramp, one with a heavier mass and one with a lighter mass, and measuring their velocities and kinetic energies at the bottom of the ramp.

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Heat is added to ice at 0 °C. Explain why the temperature of the ice does not change. What does change?When heat is added to ice at 0°C, the temperature of the ice does not change. This happens because all the heat energy is used up in overcoming the intermolecular forces of attraction (hydrogen bonds) that exist between the water molecules in ice.

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The decomposition of aspirin (acetylsalicylic acid,\(C_{9} H_{8} O_{4}\)) can occur through the hydrolysis reaction, resulting in the formation of acetic acid (\(CH_{3} COOH\)) and salicylic acid (\(C_{7} H_{6}O_{3}\)).

The decomposition of aspirin (acetylsalicylic acid, \(C_{9} H_{8} O_{4}\)) can occur through the hydrolysis reaction, resulting in the formation of acetic acid (\(CH_{3} COOH\)) and salicylic acid (\(C_{7} H_{6}O_{3}\)). To determine the moles of each product formed, we need to consider the balanced chemical equation for the reaction:

\(C_{9} H_{8} O_{4} = > C_{7} H_{6}O_{3} +CH_{3} COOH\)

From the equation, we can see that for every 1 mole of aspirin, 1 mole of salicylic acid and 1 mole of acetic acid are produced.

Therefore, the moles of salicylic acid and acetic acid formed will be equal to the number of moles of aspirin that decomposes. If we know the amount of aspirin in moles, we can directly calculate the moles of each product based on stoichiometry.

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Answer:

when naming ionic compounds — those are only used in naming covalent molecular compounds. Do NOT use prefixes to indicate how many of each element is present; this information is implied in the name of the compound. since iron can form more than one charge. Ionic Compounds Containing a Metal and a Polyatomic Ion.

Material from meteorites are not the elements used to make models of interstellar medium. The correct option is A.

The matter and radiation that prevail in the space between star systems in a galaxy are referred to as the interstellar medium in astronomy. This matter consists of gas including ionic, atomic, and molecular, dust, and cosmic rays.

Meteorite material is not used to create models of the interstellar medium.

Thus, the correct option is A.

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Answer:

Condensation

Explanation:

An exothermic process is one in which heat is lost. Condensation is a change of state from gas to liquid. Thus is loses heat.

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The following statement is true concerning the results of the Human Genome Project:

The Human Genome Project has raised many complicated ethical issues.

What is Human Genome?

The human genome refers to the complete set of genetic information (DNA) present in human cells. It includes both the protein-coding and non-coding regions of DNA. The human genome is made up of about 3 billion base pairs and is organized into 23 pairs of chromosomes. The study of the human genome is an important field of genetics and has many implications for understanding human biology, evolution, and disease.

The Human Genome Project was a scientific research project that aimed to identify and map all the genes in the human genome, which contains all the genetic information needed for human development and function. The project was completed in 2003 and provided a wealth of information about the structure and function of the human genome, including the location and sequence of all human genes.

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3.9g Oxygen

Explanation:

The molecular mass of KClO₃=122.55g/mol

The molecular mass of KCl=74.55g/mol

245.1g KClO3 produces 192 g of oxygen gas.

Therefore,5g KClO₃ gives=192*5/245.1=3.9g oxygen

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Answer:

Gravitational potential energy transforms into kinetic energy

Explanation:

Gravitational potential energy is the energy stored in an object because of its position or height above the Earth's surface.

The kinetic energy of an object refers to the energy that it possesses due to its movement.

When a skydiver first jumps from a plane, gravitational potential energy transforms into kinetic energy.

Answer:

Gravitational potential energy transforms into kinetic energy.

Explanation:

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Not enough information man

Answer: Vertebrates move by the actions of muscles on bones. Tendons attach many skeletal muscles across joints, allowing muscle contraction to move the bones across the joint.

Explanation:

Answer: The muscular system works in conjunction with the skeleton to produce movement of the limbs and body.

In the balanced equation \(2C_{2} H_{6}\) + \(7 O_{2}\) --> \(4 CO_{2}\) + \(6H_{2}O\) if 21 g of \(C_{2} H_{6}\) reacts with 32 g O₂, C₂H6 is the limiting reactant.

To determine the limiting reactant, we need to compare the amount of each reactant to the stoichiometric ratio in the balanced equation.

Let's calculate the number of moles for each reactant using their molar masses:

For \(C_{2} H_{6}\) (ethane):

Molar mass of \(C_{2} H_{6}\) = 2(12.01 g/mol) + 6(1.01 g/mol) = 30.07 g/mol

Number of moles of C₂H6 = 21 g / 30.07 g/mol ≈ 0.698 mol

For O₂ (oxygen):

Molar mass of O₂ = 2(16.00 g/mol) = 32.00 g/mol

Number of moles of O₂ = 32 g / 32.00 g/mol = 1.00 mol

Next, we compare the moles of each reactant to the stoichiometric ratio in the balanced equation:

2 moles of \(C_{2} H_{6}\) react with 7 moles of O₂ to produce 4 moles of CO₂ and 6 moles of H₂O.

From the given amounts, we have:

0.698 mol \(C_{2} H_{6}\) and 1.00 mol O₂.

Using the stoichiometric ratio, we can calculate the expected amount of CO₂ and H₂O produced for each reactant:

For C₂H6:

Expected moles of CO₂ = 0.698 mol C₂H6 * (4 mol CO₂ / 2 mol C₂H6) = 1.396 mol CO₂

For O₂:

Expected moles of CO₂ = 1.00 mol O₂ * (4 mol CO₂ / 7 mol O₂) ≈ 0.571 mol CO₂

Comparing the expected moles, we see that the calculated amount of CO₂ is greater when used \(C_{2} H_{6}\) as the limiting reactant. Therefore, the limiting reactant in this reaction is \(C_{2} H_{6}\).

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Answer:

B. The order in which specific traits may have evolved

Explanation:

Answer:

4.569 mg

:)))))))))))))))

Answer:

4569000 mg

Explanation:

004569 g × 1000 = 4569000 mg

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The partial charges on each fluorine atom are negative. Option B) The central O atom is the correct answer. Option B

The partial charges in a molecule are determined by the electronegativity values of the atoms involved. Electronegativity is the ability of an atom to attract electrons towards itself in a chemical bond. In the case of \(F_2O\), fluorine (F) is more electronegative than oxygen.

Fluorine is the most electronegative element on the periodic table, meaning it has a high ability to attract electrons. Oxygen is also relatively electronegative but less so than fluorine. When fluorine atoms bond with oxygen, the shared electrons will be pulled more towards the fluorine atoms, creating a polar covalent bond.

In \(F_2O\), each fluorine atom will pull the shared electrons towards itself, resulting in a higher electron density around the fluorine atoms. This creates a region of partial negative charge around the fluorine atoms.

Conversely, the oxygen atom will have a region of lower electron density and, therefore, a partial positive charge. This is because the shared electrons spend more time around the fluorine atoms due to their higher electronegativity.

Option B

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The correct answer is D. All of the above. Deep sea creatures have evolved various adaptations to survive in the extreme conditions of the deep ocean, below the photic zone where light penetration is minimal.

Deep sea creatures have evolved various adaptations to survive in the extreme conditions of the deep ocean, below the photic zone where light penetration is minimal. These adaptations enable them to navigate, find food, and cope with the high pressure and low temperatures. The correct answer is D. All of the above. Some deep-sea creatures have developed large eyes (option A) to maximize light sensitivity. This allows them to detect bioluminescent organisms or faint traces of light in their dark environment. Others have adapted by developing long, sensitive feelers or appendages (option B) that help them navigate and sense their surroundings. In addition, many deep-sea creatures have slower metabolisms (option C) to conserve energy and cope with the limited food availability in the deep ocean. They can survive on scarce food resources and endure long periods of fasting. By combining these adaptations, deep-sea creatures have successfully colonized the depths of the ocean and thrived in an otherwise challenging and inhospitable environment.

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Answer:

A

Explanation:

Water freezing and thawing involves no chemical change.  It has a chemical formula of H2O whether it is ice or water.

The primary source and a secondary source discuss the same

experiment. Trust more on the primary source because of option B. The primary source, because is written by the scientist who did the work.

Primary sources are files, pics, or artifacts that provide firsthand testimony or direct evidence concerning a historical topic underneath research. number one resources are unique documents created or experienced contemporaneously with the event being researched.

Number one assets consist of works via individuals commenting on a concept or event. Secondary resources are often portions of writing that difficult on the authentic supply. primary research comprises original research about numerous vital subjects.

A primary source is a primary-hand or contemporary account of an occasion or subject matter. they're the maximum direct proof of a time or event because they were created via human beings or matters that have been there at the time or event. those sources have no longer been modified via interpretation and provide unique notions or new records.

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The presence of hydrogen atoms is what the chemical formulas for acids have in common in this scenario.

This is referred to as any hydrogen-containing substance that is capable of donating a proton (hydrogen ion) to another substance.

Chemical formula on the other hand is used to identify each constituent element by its chemical symbol and indicates the proportionate number of atoms of each element and acids usually have hydrogen atoms which js what theyn have in common.

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