What is the correct order of steps for the students to take?

The enthalpy change for the overall reaction  is 999 kJ.

To find the enthalpy change for the overall reaction [tex]PCl_{5}[/tex](g) → [tex]PCl_{3}[/tex](g) + [tex]Cl_{2}[/tex](g), we need to combine the given intermediate equations.

The first equation is: [tex]P_{4}[/tex](s) + 6 [tex]Cl_{2}[/tex](g) → 4 [tex]PCl_{3}[/tex](g), with an enthalpy change of Δ[tex]H_{1}[/tex] = -2,439 kJ.

The second equation is: 4 [tex]PCl_{6}[/tex](g) → [tex]P_{4}[/tex](s) + 10 [tex]Cl_{2}[/tex](g), with an enthalpy change of Δ[tex]H_{2}[/tex] = 3,438 kJ.

By reversing the first equation and multiplying the second equation by 4, we can cancel out [tex]P_{4}[/tex] (s) and [tex]Cl_{2}[/tex] (g) to obtain the overall reaction: [tex]PCl_{5}[/tex](g) → [tex]PCl_{3}[/tex](g) + [tex]Cl_{2}[/tex](g).

Since enthalpy change is a state function, we can sum up the enthalpy changes of the intermediate reactions to calculate the enthalpy change for the overall reaction:

Δ[tex]H_{overall}[/tex] = -2,439 kJ + 3,438 kJ = 999 kJ

Answer:

m(94Be) = 9.012 182 24 amuN(protons) = 4N(neutrons) = 9 – 4 = 5m(protons) = (4 protons) (1.007 276 47 amu/proton) = 4.029 105 88 amum(neutrons) = (5 neutrons) (1.008 664 90 amu/neutron) = 5.043 324 50 amum(protons) + m(neutrons) = 4.029 105 88 amu + 5.043 324 50 amu = 9.072 430 38 amuMass defect m = 9.072 430 38 amu – 9.012 182 24 amu = 0.060 248 14 amum = (0.060 248 14 amu/nucleus) (1.6605 10-27kg/amu) = 1.0004 10-28 kg/nucleusE =mc2= (1.0004 10-28 kg/nucleus) (3.00 108m/s)2= 9.0038 10-12J/nucleusN(nucleons)= N(protons)+N(neutrons) = 9E =(9.0038 10-12J/nucleus) (1 nucleus/9nucleons) =1.0004 10-12J/nucleon2.

The mass defect is 0.059 948 14 amu and the Binding energy/nucleon of the nuclide is  9.66 × 10⁻¹² J/nucleon.

It is expressed as

[tex]\Delta M = (Zm_{P} + Nm_{n}) - M_{A}[/tex]

where

[tex]\Delta M[/tex] = Mass defect

[tex]M_{A}[/tex] = Mass of nucleus

[tex]m_{P}[/tex] = mass of proton

[tex]m_{n}[/tex] = mass of electron

Z = Number of proton

N = Number of neutrons

Now put the values in above formula we get

[tex]\Delta M = (Zm_{P} + Nm_{n}) - M_{A}[/tex]

[tex]\Delta M = 4(m_{p}) + 5 (m_{n}) - M_{A}[/tex]

       = 4 (1.007 276 47 amu) + 5 (1.008 664 90 amu) - 9.012 182 24 amu

       = 4.029 105 88 amu + 5.043 324 50 amu - 9.012 182 24 amu

       = 9.072 130 38 amu - 9.012 182 24 amu

       = 0.059 948 14 amu

It is expressed as

ΔE = Δmc²

where

ΔE = Binding energy

ΔM = change in mass

c = speed of light

Now put the values in above formula we get

ΔE = Δmc²

     = (0.59 984 14 amu) (1.6605 × 10⁻²⁷ kg/amu)  (3 × 10⁸) (m/s)²

Nucleons = 8.96 × 10⁻¹¹

Binding energy/nucleon = 9.66 × 10⁻¹² J/nucleon

Thus from the above conclusion we can say that The mass defect is 0.059 948 14 amu and the Binding energy/nucleon of the nuclide is  9.66 × 10⁻¹² J/nucleon.

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The person must be a lawful, permanent resident for five years.

Answer: A

The naturalization criterion that is a requirement for becoming a US citizen is being a lawful, permanent resident for five years. This is part of the naturalization process which includes being at least 18, having good moral character, and proficiency in English.

The requirement for naturalization as a US citizen is: A. The person must be a lawful, permanent resident for five years. This criterion is part of a multi-step naturalization process that most foreign citizens must undergo to become citizens of the United States. An applicant must be at least 18 years of age, be a lawful permanent resident (green card holder), have resided in the United States as a lawful permanent resident for at least five years, have been physically present in the United States for at least 30 months, be a person of good moral character, and be able to speak, read, write and understand the English language. These requirements have evolved over time, with current laws simplifying the process for non-citizens serving in the military and increasing the importance of English language proficiency in the application process.

Answer:warm

Explanation: because it is in the southern hemisphere so in the winter while the northern hemisphere is in a cold winter the southern hemisphere is in a warm winter due to it being in the southern hemisphere where temperatures are really warm in the southern hemisphere.

Answer:the answer is warm

Explanation:

Molarity is defined as the number of moles of solutions divided by the volume of the solution in liters

Answer:

Molarity is defined as the number of moles of solutions divided by the volume of the solution in liters

Explanation:

Answer: Is there a list of birds, if not, it could be a seagull. They are arounf the water a lot and have sharp beaks which could possibily allow them to eat the same way as the eagle.

Birds that most likely catch and eat their food the way an eagle does include hawks and the African fish eagle. These birds, like the eagle, are raptors and utilize similar hunting and feeding techniques.

The question asks which bird most likely catches and eats its food in the same way as an eagle does. As the text mentions, eagles are examples of raptors, which are birds of prey. They use their clawed feet, also known as talons, to capture and kill their prey, which includes fish.

Similar to eagles, other birds that are known to catch and eat fish include the African fish eagle and hawk. All of these birds are adapted to hunting and consuming their prey similarly. Their sharp, hooked beak is perfect for tearing apart their prey and their strong legs and talons are well-equipped for grabbing and securing their catch.

Therefore, an African fish eagle or a hawk would most likely catch and eat its food the way an eagle does, flying with the fish to a safe location, such as a tree branch, before tearing it into small pieces to eat.

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Answer:

Carbon forms the key component for all known life on Earth.

Explanation:

Complex molecules are made up of carbon bonded with other elements, especially oxygen and hydrogen and frequently also with nitrogen, phosphorus and sulfur. Carbon is abundant on Earth. It is also lightweight and relatively small in size, making it easier for enzymes to manipulate carbon molecules.

the anwer is sulfer since its the only one that bonds with an oxygen atom

Sulfur atom has twice as many protons in it as an oxygen atom. The smallest unit of matter that may be divided without producing electrically charged particles is the atom.

The smallest unit of matter that may be divided without producing electrically charged particles is the atom. It is also the smallest piece of substance with chemical element-like characteristics. As a result, the atom serves as the fundamental unit of chemistry.

Space makes up the majority of an atom. The rest is made up of a cloud of electrons that are negatively charged surrounding a positive charge nucleus made up of protons and neutrons. Compared to electrons, which have been the lightest positive ions in nature, the nucleus appears small but dense. Electric forces, which link electrons to a nucleus of atoms, cause them to be drawn to any positive charge. Sulfur atom has twice as many protons in it as an oxygen atom.

Therefore, Sulfur atom has twice as many protons in it as an oxygen atom.

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Answer:Climate is defined as the average state of everyday's weather condition over a period of 30 years.[1][2] It is measured by assessing the patterns of variation in temperature, humidity, atmospheric pressure, wind, precipitation, atmospheric particle count and other meteorological variables in a given region over long periods of time. Climate differs from weather, in that weather only describes the short-term conditions of these variables in a given region.

Explanation:

repel each other because they have like charges

Answer:

the type of nuclear reaction cased is fission

Explanation:

Answer:

= 2.659 g NaCl

Explanation:

Molarity of a substance is given by the formula;

Molarity = moles/Volume in liters

Thus;

Number of moles = Molarity ×  volume in liters

                              = 1.3 M × 0.035 L

                              = 0.0455 Moles

But, the molar mass of NaCl is 58.44 g/mol

The mass of NaCl is therefore;

     = 0.0455 g × 58.44 g/mol

     = 2.659 g NaCl

The mass of NaCl in a 35-mL sample of a 1.3 M NaCl solution is approximately 2.7 g.

To calculate the mass of NaCl in a 35-mL sample of a 1.3 M NaCl solution, you need to start with the definition of molarity, which is moles of solute per liter of solution. First, convert the volume of the solution from milliliters to liters by dividing by 1000. Therefore, 35 ml equals 0.035 L.

Knowing that molarity(M) = mole/liters, we can use the given molarity to find out that there are 0.0455 moles of NaCl in our solution since (1.3 mol/L) × (0.035 L) = 0.0455 Mol.

Finally, use the molar mass of NaCl (58.44 g/mol) to convert this molar quantity into grams. That is (0.0455 Mol) × (58.44g/mol) = 2.66 g. So, the mass of NaCl in the solution is approximately 2.7 g.

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An explosive occurs when Gases expands. Therefore, option A is correct.

The term an explosion is defined as the rapid increase in volume and release of energy extremely.

An incendiary device or a chemical reaction that results in the rapid expansion of gas causes an explosion.

A very loud sound or a succession of noises and sensations, fire, heat, smoke, falling glass, or debris can all be indicators of an explosion.

Three general energy deposition techniques can lead to high explosive reactions, impact ignition by frictional and/or shear heating, bulk thermal heating and shock compression.

When there is a gas leak and a spark or flame are present, a gas explosion happens. Because they are frequently used for heating, gases including natural gas, methane, propane, and butane are the most frequent types of gases to cause explosions.

Thus, option A is correct.

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Explanation:

It is known that atoms that have same number of valence electrons will show similar chemical properties.

So, when we move from left to right across a period there occurs increase in number of valence electrons of each element. But when we move down a group then number of valence electrons remain the same.

Hence, elements of same group will show similar chemical properties.

Therefore, we can conclude that elements marked as 2 and 3 will have similar chemical properties.

Answer : The correct location on the periodic table of two elements have similar characteristics is, two elements present in the second column of the left side

Explanation :

The elements have similar characteristics when they are belong to the same family or group this means that when they are placed in the same column of the periodic table.

The elements of similar characteristics have same number of valence electrons.

In the given periodic table of the elements, the two elements present in the second column of the left side have similar characteristics because these two elements belong to the same family or group. While the other elements have different characteristics.

Answer:

463.0 g.

Explanation:

n = mass/molar mass.

where, n is the mass of copper(ii) fluoride​ (m = 4.56 mol),

mass of copper(ii) fluoride​ = ??? g.

molar mass of copper(ii) fluoride​ = 101.543 g/mol.

∴ mass of copper(ii) fluoride​ = (n)(molar mass) = (4.56 mol)(101.543 g/mol) = 463.0 g.

Answer:

A. to determine the efficiency of the reaction

Explanation:

Final answer:

The percent yield is calculated to assess the efficiency of a chemical reaction by comparing the actual yield to the theoretical yield. The correct option is (A).

Explanation:

Finding the percent yield of a reaction is necessary to determine the efficiency of the reaction, which is option A.

The percent yield is calculated by dividing the actual yield, the amount of product actually obtained from the reaction, by the theoretical yield, the maximum amount of product predicted by stoichiometry from the given amounts of reactants, and then multiplying by 100 to express it as a percentage.

The percent yield assesses how much product is obtained compared to what could have been obtained under ideal conditions. It reflects reaction efficiency, accounting for losses due to factors like incomplete reactions, side reactions, and difficulties in product recovery.

Answer:

1.5 moles of H₂SO₄ needs 3.0 moles pf KOH to be neutralized.​

Explanation:

KOH → K⁺ + OH⁻.

H₂SO₄ → 2H⁺ + SO₄²⁻.

So, every 1.0 mole of KOH produces 1.0 mol of OH⁻.

While, every 1.0 mole of H₂SO₄ produces 1.0 mol of H⁺.

Thus, every mol of H₂SO₄ needs 2.0 moles of KOH to be neutralized.

So, 1.5 moles of H₂SO₄ needs (2 x 1.5 mol) = 3.0 moles pf KOH to be neutralized.​

Answer:

Al₂(SO₄)₃ is the excess reactant.

Explanation:

Barium (Ba) react with Aluminium sulphate [Al₂(SO₄)₃] according to the following balanced equation:

It is clear that 3 mol of Ba react with 1 mol of Al₂(SO₄)₃ to give 3 moles of BaSO₄

The limiting reactant is the reactant that produces the least amount of BaSO ₄.

The molar masses of each substance involved.

Ba : 137.3 g/mol

Al₂(SO₄)₃: 342.1 g/mol

BaSO ₄:  233.3 g/mol

Then we calculate no of moles of each reactant from the given mass.

As following:

no. of moles of Ba = (mass /molar mass) = (1 g / 137.3 g/mol) = 0.0073 mol

no. of moles of Al₂(SO₄)₃ = (mass /molar mass)

                                         = (1.8 g / 342.1 g/mol) = 0.0053 mol

Then we calculate mol of product produced from each reactant

For BaSO₄

no of moles of BaSO₄ from Ba = (0.0073 * 3) / 3 = 0.0073 mol

then converting moles of BaSO₄ into mass

mass of BaSO₄ =  no of moles  * molar mass = 0.0073 * 233.3 = 1.7 g

For Al₂(SO₄)₃

no of moles of BaSO₄ from Al₂(SO₄)₃ = (0.0053 * 3) / 1 = 0.0159 mol

then converting moles of BaSO₄ into mass

mass of BaSO₄ =  no of moles  * molar mass = 0.0159 * 233.3 = 3.7 g

∴1 g of Ba  produces the least amount of barium sulfate, so it is the limiting reactant and Al₂(SO₄)₃ is the excess reactant.

The muddy water and dead fish can be due to soil erosion or sediment runoff, changes in photosynthesis due to excess organic material causing eutrophication, or changes in habitat conditions due to clear-cutting of forests.

The muddiness of the stream and the presence of dead fish could be signs of a phenomenon called soil erosion or sediment runoff. This is where heavy rain washes soil, which can contain toxins or pollutants, into a water source such as a stream. The influx of silt can make the water muddy and unhealthy for aquatic life, leading to the death of fish. Changes or disruptions in the ecosystem such as clear-cutting of forests increase the risk of this erosion since trees and vegetation help to hold the soil in place and buffer waterways.

Another possibility is the change in the stream's photosynthesis processes due to the debris and excess organic materials like leaves being washed into the stream. The increase in organic material can lead to a process called eutrophication, where the decomposition of organic material uses up oxygen in the water, thus suffocating fish and other aquatic species.

The death of fish might also be due to changes in their habitat. Clearing of trees could have changed the temperature of the water as shadows from the tree cover, which kept temperatures lower, no longer exist. Aquatic life such as leeches, trout and other species that have adapted to the previous temperature conditions of the fast-moving water may not survive in the warmer, slower moving water.

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Increased sedimentation from soil erosion due to clear-cutting and heavy rainstorms can lead to murky water, which suffocates fish and disrupts the aquatic food web by reducing visibility needed for predators to find food.

You are in a clear-cut section of forest and you notice a nearby stream is very muddy with many dead fish. This could be due to sedimentation resulting from the recent heavy rainstorm. The clear-cutting of trees can exacerbate soil erosion, leading to increased sediment in the water, which can suffocate fish by clogging their gills or destroying their habitat. This also disrupts the ecosystem, as sediment-laden water can make it difficult for predators such as waterfowl, frogs, and fishes to find food, which often depend on clearer water to hunt using visual cues or chemical cues.

The mudflows and flash flooding caused by the monsoon, further compounded by deforestation, often introduce a large amount of sediment and organic material into waterways, degrading the aquatic environment and affecting the entire aquatic food web.

Answer:

I don't know much about that.. So i downloaded and posted above image..

Hope this helps you...

Final answer:

A primary standard solution has a known concentration due to its high purity and stability, used for precise analytical work. Secondary standards, such as NaOH solutions, must be standardized against a primary standard to determine their concentration and are typically easier to handle but require more frequent calibration.

Explanation:

The difference between primary and secondary standard solutions is based on their properties and uses in analytical chemistry. A primary standard is a reagent that has a known purity, a known stoichiometry, and is stable over time.

An example of a primary standard is a precisely weighed sample of K₂Cr₂O₇ which, when dissolved in a specific volume of solvent, provides a solution with a known molarity.

On the other hand, a secondary standard does not inherently have a known concentration and thus requires standardization with a primary standard before use. NaOH is a typical secondary standard, which needs to be titrated against a primary standard, such as potassium hydrogen phthalate, to determine its concentration accurately.

Using primary standards ensures high accuracy in quantitative analysis, whereas secondary standards are more practical and less costly but must be calibrated regularly to assure accurate results. This distinction is crucial when preparing solutions for tasks such as titrations or calibrating analytical equipment in a laboratory.

Chemical potential energy: chemical potential of a species is energy that can be absorbed or released due to a change of the particle number of the given species, in a chemical reaction or phase transition

Gasoline used as kinetic energy: the various chemicals that make up gasoline contain a large amount of chemical potential energy that is released when the gasoline is burned in a controlled way in the engine of the car. The release of that energy does two things. Some of the potential energy is transformed into work, which is used to move the car

Dynamite used as kinetic energy: the dynamite being used was most likely made of nitroglycerin. Once the dynamite explodes from a percussion force (then breaking of weak bonds to releasing the raw atom) the energy is then converted to thermal, kinetic, and sound energy.

Chemical potential energy, stored in molecules, is released during chemical reactions. Both gasoline and dynamite store this energy that, when ignited, is converted into kinetic energy. Gasoline propels cars, whilst dynamite causes explosions.

Chemical potential energy is a form of energy stored in molecules that is released during a chemical reaction. For example, gasoline and dynamite both store chemical potential energy that can be converted into kinetic energy.

Consider gasoline put into a car's engine. It mixes with air and is ignited in the engine's combustion chamber, causing a chemical reaction that releases the gasoline's potential energy. This energy is transformed into kinetic energy, propelling the car forward.

Similarly, dynamite contains chemical potential energy. When ignited, a chemical reaction occurs, releasing this energy. This energy is quickly converted to kinetic energy, causing the explosive force that dynamite is known for.

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Answer:

When excited electrons fall to lower energy levels, they can release energy in the form of light. metal ions in the salts used in the flame tests.

Answer:

3.0 mol.

Explanation:

Molaity (m) is defined as the no. of moles of solute per kg of solvent.

m = (no. of moles of solute Ca(NO₃)₂)/(kg of solvent).

∴ no. of moles of solute Ca(NO₃)₂ = (m)(kg of solvent) = (3.0 m)(1.0 kg) = 3.0 mol.

Answer:

Mg

Explanation:

The periodic trend of ionization energy is going from left to right of the periodic table, ionization energy increases. in the periodic table, both magnesium (Mg) and Sodium (Na) fall under the same period.

Na is the found in the left-most end of the period and Mg comes after it. This means that Mg has the higher ionization energy.

Explanation:

Ionization energy is defined as the energy required to remove most loosely bound electron from a gaseous atom or ion.

Larger is the size of atom less energy will be necessary to remove the valence electron because force of attraction will be less between the nucleus and outermost electron.

Hence, it is easy to remove the outermost electron.

Whereas smaller is the size of atom great amount of energy will be required by it to remove the loosely bound electron.

So, when we move down a group there will be increase in size of atoms. Hence, ionization energy decreases.

On the other hand, when we move across a period then there occurs decrease in size of atoms. Hence, ionization energy increases.

As, magnesium is smaller is size than sodium and both of then are same period elements.

Thus, we can conclude that magnesium (Mg) atom has the higher ionization energy.

Chemical formulas are used to describe the types of atoms and their numbers in an element or compound. The atoms of each element are represented by 1 or 2 different letters. When more that one atom of a specific element is found in a molecule, a subscript is used to indicate this in the chemical formula.

Subscripts in chemical formulas represent the number of atoms of each element in a molecule. They are used in molecular formulas to indicate the precise quantity of each atom present, and they differ from coefficients in chemical equations, which represent individual, unbonded atoms.

The purpose of subscripts in chemical formulas is to indicate the number of atoms of each type in the molecule. For instance, in the molecular formula H₂, the subscript '2' shows that there are two atoms of hydrogen in the molecule. It's crucial to differentiate this from coefficients in a chemical equation, where for example, 2H symbolizes two separate hydrogen atoms, not bonded as one unit.

A molecular formula, like H₂, uses chemical symbols and subscripts to represent the exact number of each kind of atom in the molecule, while an empirical formula expresses the simplest, whole-number ratio of atoms in a compound. A structural formula illustrates the bonding arrangement of the atoms. For instance, C₆H₆ shows that a molecule of benzene contains six carbon atoms and six hydrogen atoms.

It's worth noting that isotopes, which are atoms of the same element with different numbers of neutrons, do not affect the usage of subscripts in chemical formulas. The atomic mass of an element includes the weighted average of all its isotopes' masses.

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Ocean acidification is the process of ocean waters becoming more acidic due to the dissolution of carbon dioxide in the ocean. This decrease in pH negatively affects marine species and the availability of calcium carbonate. If CO2 concentrations continue to rise, coral reefs may become rare by 2050.

Ocean acidification is the process of ocean waters decreasing in pH. Oceans become more acidic as carbon dioxide (CO2) emissions in the atmosphere dissolve in the ocean. This change is measured on the pH scale, with lower values being more acidic. The pH level of the oceans has decreased by approximately 0.1 pH units since pre-industrial times, which is equivalent to a 25% increase in acidity. The pH level of the oceans is projected to decrease even more by the end of the century as CO2 concentrations are expected to increase for the foreseeable future. Ocean acidification adversely affects many marine species, including plankton, mollusks, shellfish, and corals. As ocean acidification increases, the availability of calcium carbonate will decline. Calcium carbonate is a key building block for the shells and skeletons of many marine organisms. If atmospheric CO2 concentrations double, coral calcification rates are projected to decline by more than 30%. If CO2 concentrations continue to rise at their current rate, corals could become rare on tropical and subtropical reefs by 2050.

Final answer:

Ocean acidification, caused by the absorption of atmospheric CO2 into ocean waters forming carbonic acid, is the biological process leading to decreased pH in water surrounding organisms, threatening marine biodiversity and ecosystems.

Explanation:

The biological process that causes the pH of water surrounding an organism to decrease is known as ocean acidification. This process occurs when carbon dioxide (CO2) emitted into the atmosphere dissolves in ocean waters, forming carbonic acid which releases hydrogen ions (H*), thereby lowering the pH and increasing the acidity of the ocean. The ongoing rise in atmospheric CO2 due to activities such as burning fossil fuels and deforestation is accelerating this effect, leading to a significantly more acidic environment that can have detrimental effects on marine life, particularly organisms that rely on calcium carbonate for their shells and skeletons.

Ocean acidification is already having profound impacts on marine ecosystems, notably by reducing the availability of calcium carbonate which is vital for many marine species, including plankton, mollusks, shellfish, and corals. As CO2 levels continue to rise, the pH of the ocean is expected to drop further, endangering the health of coral reefs and the broader marine biodiversity.

Answer:

0.268 L

Explanation:

concentration is the number of moles of solute in 1 L of solution

number of moles of KCl - 5.0 g / 74.5 g/mol = 0.067 mol

the concentration of the solution to be prepared - 0.25 mol/L

concentration = number of moles of KCl / volume of solution

substituting the values in the equation

0.25 mol/L = 0.067 mol / V

V = 0.268 L

solution should be diluted to 268 mL to make a 0.25 M solution

Final answer:

To prepare a 0.25 M KCl solution, 5.0 g of KCl should be diluted to approximately 268 mL.

Explanation:

To find out to what volume we should dilute 5.0 g of KCl to prepare a 0.25 M solution, we first need to calculate the number of moles of KCl. The molar mass of KCl is approximately 74.55 g/mol. Therefore, the moles of KCl in 5.0 g can be calculated by dividing the mass of KCl by its molar mass:

Moles of KCl = mass / molar mass = 5.0 g / 74.55 g/mol ≈ 0.067 moles

Since Molarity (M) is defined as moles of solute per liter of solution, we can rearrange the formula to solve for volume (V).

M = moles of solute / volume of solution in liters

V = moles of solute / M = 0.067 moles / 0.25 M ≈ 0.268 liters or 268 mL

Therefore, to prepare a 0.25 M solution of KCl, we need to dilute 5.0 g of KCl to approximately 268 mL.

Answer:

The environment changes causing the animals to adapt.

Answer:

C. Ca.

Explanation:

The atom loses or gains electrons forming anion or cation to reach stability (fill the outermost shell of the electron levels).

When atom gains electrons forms anions with negative charge.

While, when atom loses electrons forms cations with positive charge.

A. O:

O atom has 8 electrons in its nucleus and gains 2 electrons to reach stability (10 electrons, configuration of Ne).

So, it forms O²⁻.

B. AI:

Al atom has 13 electrons in its nucleus and loses 3 electrons to reach stability (10 electrons, configuration of Ne).

So, it forms Al³⁺.

C. Ca:

Ca atom has 12 electrons in its nucleus and loses 2 electrons to reach stability (10 electrons, configuration of Ne).

So, it forms Ca²⁺.

D. Na:

Na atom has 11 electrons in its nucleus and loses 1 electron to reach stability (10 electrons, configuration of Ne).

So, it forms Na⁺.

Answer:

C. Maria

Explanation:

The ocean floor is made of basaltic rocks that have upwelled from the mantle.

The surface of the moon is typified by this rock type too. Several Volcanoes on the surface of the moon are basaltic in composition.

Answer:

Human ears can hear sound waves that vibrate in the range from about 20 times a second (a deep rumbling noise) to about 20,000 times a second (a high-pitched whistling). (Children can generally hear higher-pitched sounds than their parents, because our ability to hear high frequencies gets worse as we get older.) Speaking more scientifically, we could say that the sounds we can perceive have a frequency ranging from 20–20,000 hertz (Hz). A hertz is a measurement of how often something vibrates and 1 Hz is equal to one vibration each second. The human voice makes sounds ranging from a few hundred hertz to a few thousand hertz.

Suppose you could somehow hit a drum-skin so often that it vibrated more than 20,000 times per second. You might be able to see the skin vibrating (just), but you certainly couldn't hear it. No matter how hard you hit the drum, you wouldn't hear a sound. The drum would still be transmitting sound waves, but your ears wouldn't be able to recognize them. Bats, dogs, dolphins, and moths might well hear them, however. Sounds this like, with frequencies beyond the range of human hearing, are examples of ultrasound.

Ultrasound is sound or other vibrations having an ultrasonic frequency, particularly as used in medical imaging. Also, Infrasound is sound waves with frequencies below the lower limit of human audibility