Ethanol (c2h5oh) melts at -114°c. the enthalpy of fusion is 5.02 kj/mol. the specific heats of solid and liquid ethanol are 0.97 j/gk and 2.3 j/gk, respectively. how much heat (kj) is needed to convert 25.0 g of solid ethanol at -135°c to liquid ethanol at -50°c?

Explanation:

Wind turbines generate electricity by following simple principle. Moving wind transfers energy to the to the blades of the wind mill which results in spinning of the blades. These blades are connected to internal shaft which also starts spinning. This spinning of shaft generates electricity which is further distributed to electrical substations to provide electricity to homes and businesses.

Step 1: Wind moves the blades of the turbine.

Step 2: Internal shaft spins

Step 3: Generator produces electricity

Step 4: Distribution lines carry electricity to substation

Answer:

Explanation:

1 . Wind moves the blades of the turbine .

2. Internal shaft spins .

3. Generator produces electricity .

4. Distribution lines carry electricity to substations .

1) amount of energy required to change 1 gram of material from the solid to the liquid state at its melting point - latent heat of fusion.

The temperature at which the phase transition occurs is the melting point or the freezing point.

2)  a measure of the kinetic energy of the particles of a substance - temperature.

Temperature is the intensity of heat present in a substance and a thermometer is a device that measures temperature or a temperature gradient.

3) the amount of energy required to change 1 gram of a substance 1°C - specific heat.

Heat capacity of a sample is expressed in units of thermal energy per degree temperature (J/K).

Heat capacity is often defined relative to a unit of mass (J/kg·K or J/g·K), prefixed with the term specific.

For example, specific heat capacity of water is 4.184 J/g·K (Cp(H₂O) = 4.184 J/g·K).

4) amount of energy required to change 1 gram of material from the liquid to the gaseous state at its boiling point - latent heat of vaporization.

For example, evaporization is phase change process in which the water changes from a liquid to a gas (water vapor). Solar radiation is the source of energy for evaporation.

5) the amount of heat energy required to raise the temperature of 1 gram of liquid water from 14.5°C to 15.5°C - calorie.

Calorie (cal), or small calorie, is the amount of energy needed to heat one gram of water by one degree Celsius.

One small calorie is approximately 4.2 joules.

A calorie is a unit of energy.

Bicarbonate buffer system in blood consists of carbonic acid and bicarbonate ion. H2CO3/HCO3-

When a base enters the body the acid part of the buffer reacts with the base.

Thats the carbonic acid (H2CO3) reacts with the base.    

Answer:

The correct answer is carbonic acid.

Explanation:

The acid-base homeostatic mechanism known as the bicarbonate buffer system involves the balance of bicarbonate ion, carbonic acid, and carbon dioxide in order to sustain pH in the duodenum and in the blood, along with other tissues for maintaining adequate metabolic activities. As with the buffer system, the pH is monitored by the existence of both the weak acid, that is, the carbonic acid, and its conjugate base, like bicarbonate ion, so that any extra base or acid presented to the system getting neutralized. In the bicarbonate buffer system, the carbonic acid reacts with a base to balance the system.

 The  balanced chemical  equation  when sodium and  oxygen react is  as below

4 Na + O₂  → 2 Na₂O

  Explanation

From equation above 4  moles of  sodium (Na) react  with 1  mole   of oxygen (O₂)  to produce sodium oxide ( Na₂O)

Since there  is equal  number  number of atoms   in  side  of reactants  and    in the side  of product  the  equation  is balanced.

For  example there is 4 atoms of Na in side of reactant and 4  in side  of product.

Rule 2: anions. The anion name is formed from the name of the element, but “ide” replaces the normal ending in the elements name. So Cl-‐ is the ion formed from chlorine and its name is chloride ion. N-‐3 is the ion formed from nitrogen and its name is nitride ion.

most common is Ammonium, hope I got this right!

14/6 C --> 0/-1 e + 14/7 N

Either an electron or the symbol  can be used to represent the beta particle.

When carbon-14 decays into nitrogen-14, a process known as beta decay takes place. One of the neutrons in the carbon atom turns into a proton during this process, which results in the decay of a 14C atom into a 14N atom.

By adding one more proton to the atom, this results in the formation of a nitrogen atom rather than a carbon atom.

Beta decay of carbon-14 results in the release of one electron. The final product is a nucleus with seven protons and seven neutrons. As bizarre as it may sound, this indicates that one of the neutrons

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Final answer:

The symbol representing a beta particle emitted during radioactive decay of carbon-14 is the Greek letter ß, also represented as e- or ß-. This particle is a high-speed electron ejected from the nucleus, resulting in the formation of a nitrogen-14 nucleus.

Explanation:

When radioactive carbon (C-14) decays, it produces nitrogen-14 (N-14) and emits a beta particle. The symbol that represents a beta particle is the Greek letter ß. However, a beta particle can also be represented as an electron with a -1 charge, which is symbolized by e- or ß- in nuclear equations.

The beta particle is essentially a high-speed electron that's ejected from the nucleus during radioactive decay, and this process turns a neutron into a proton within the nucleus, increasing the atomic number by one while the mass number remains unchanged. The beta particle's emission is critical in the decay process of carbon-14, which is widely used in radioactive dating techniques.

Only (d) appears to be correct.

NaCl and CaCl₂ are ionic compounds. Both are made up of charged particles known as ions.

Opposite charges attract each other. So is the case between cations and anions. The two kinds of ions attract each other to produce an ionic lattice. Forces holding them together are known as ionic bonds.

Cations and anions pair up in an ionic compound. Their charges cancel out such that the final compound is neutral. Charged species shall always have a superscript in their formulae that indicates their charge. For example, [tex]\text{Ca}^{2+}[/tex] has positive charges. As a result, it comes with a superscript of "2+". Neither NaCl nor CaCl₂ has a superscript. They are both neutral.

The molar lattice enthalpy of an ionic compound measures the energy released when one mole of it was formed from gaseous ions. This value depends on the size and charge of each ion.

Each mole of CaCl₂ carry four times as much charge as NaCl and three time as much ions. CaCl₂ is expected to have a much higher molar lattice enthalpy.

FYI, the molar lattice enthalpy of NaCl is about -787 kJ/mol (Chemguide). The value for CaCl₂ is -2255 kJ/mol (ACS).

The salts NaCl and CaCl2 are held by ionic bonds. They do not conduct electricity in their solid state, but do so once dissolved or melted. They contain positive and negative ions and do not have the same crystal lattice of energy.

The salts NaCl and CaCl2 are indeed held together by ionic bonds, which are electrostatic forces of attraction between oppositely charged ions. These compounds, like many ionic solids, do not conduct electricity in their solid state as the strength of ionic bonds prevents ions from moving freely. However, once they dissolve in water or melt, they become excellent conductors of electricity because the ions can move freely, becoming electrolytes capable of conducting electricity. This is why the statement 'NaCl and CaCl2 are good conductors of electricity' applies only when these compounds are dissolved or melted.

The ions in ionic compounds like NaCl and CaCl2 do carry positive (for metal ions) and negative charges (for non-metal ions). They do not, however, all carry positive charges as suggested in the second part of your question. Lastly, while it is true that all ionic compounds form a crystalline structure due to the orderly arrangement of their ions, this does not imply that all ionic compounds have the same crystal lattice of energy. The exact structure and energy can variate between different ionic compounds.

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Silver gets oxidized when electroplating silver (Ag) on iron (Fe).

Electroplating is basically the process of plating a metal onto the other by hydrolysis mostly to prevent corrosion of metal or for decorative purposes.

Silver gets oxidized when electroplating silver (Ag) on iron (Fe).

In the process of putting a sliver coating on iron, the iron is the cathode on which the silver ions get reduced.

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So to find the empirical formula you have to simplify. What is something you can take out of all three? The number three, so divide everything by three leaving you with (C2H6O). I hope this helped!

The correct answer is [tex]C_2H_6O[/tex].

It is the simplest ratio of atoms of elements in a compound.

The GCF is 3, so factor 3 of the molecular formula:-

[tex] 3 ( C_2H_6O) [/tex]

The result is the empirical formula [tex]C_2H_6O[/tex].

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Answer : The mass of of water present in the jar is, 298.79 g

Solution : Given,

Mass of barium nitrate = 27 g

The solubility of barium nitrate at [tex]20^oC[/tex] is 9.02 gram per 100 ml of water.

As, 9.02 gram of barium nitrate present in 100 ml of water

So, 27 gram of barium nitrate present in [tex]\frac{27g}{9.02g}\times 100ml=299.33ml[/tex] of water

The volume of water is 299.33 ml.

As we know that the density of water at [tex]20^oC[/tex] is 0.9982 g/ml

Now we have to calculate the mass of water.

[tex]\text{Mass of water}=\text{Density of water}\times \text{Volume of water}[/tex]

[tex]\text{Mass of water}=(0.9982g/ml)\times (299.33ml)=298.79g[/tex]

Therefore, the mass of of water present in the jar is, 298.79 g

 The net ionic equation  is

Ag⁺(aq)  +Cl⁻(aq) →  AgCl(s)

Explanation

AgNO₃ (aq)  + KCl (aq)→ AgCl(s) +KNO₃(aq)

from above  molecular equation break  all  soluble electrolyte  into ions

Ag⁺(aq) +NO₃⁻ (aq) + K⁺(aq) +Cl⁻(aq) →   AgCl (s) + K⁺(aq) + No₃⁻(aq)

cancel the spectator  ions  in both side  of  equation =K⁺  and NO₃⁻  ions

The net  ionic equation is therefore

= Ag⁺(aq)  + Cl⁻(aq) →    AgCl(s)

The net ionic equation for the reaction AgNO₃(aq) + KCl(aq) ---> AgCl(s) + KNO₃(aq) is Ag+(aq) + Cl-(aq) ---> AgCl(s), which is found by first writing the complete ionic equation and then canceling the spectator ions, which appear on both sides of the reaction.

The process of writing a balanced net ionic equation involves several steps. Firstly, the complete ionic equation needs to be written which looks like this: Ag⁺(aq) + NO₃⁻(aq) + K⁺(aq) + Cl⁻(aq) ---> AgCl(s) + K+(aq) + NO₃⁻(aq). After that, we find the spectator ions that appear on both sides of the reaction. In this case, they are K+(aq) and NO₃⁻(aq). We then cancel out these spectator ions to get the net ionic equation, which is: Ag+(aq) + Cl-(aq) ---> AgCl(s). Essentially, these equations show the salts splitting into their ions if they are soluble in water (indicated by (aq)), and then recombining to form the precipitate (s).

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.125mol Fe3O4.

To find this, you need to create a molar ratio.

Reference the image to see what this looks like.

Once you have the ratio set, cross the same and multiply across before dividing what's on the bottom.

Hope this helps!

A volatile liquid is one that evaporates or vaporizes quickly at room temperature. Not all volatile substances are liquids; some are solids. In everyday language, "volatile" means to erupt emotionally or suddenly become angry or violent. It can also mean someone whose emotions swing up and down quickly.

A volatile liquid in chemistry describes a substance that rapidly evaporates at room temperature due to its low boiling point. Common examples of volatile liquids include alcohol, gasoline, and perfume.

In chemistry, a volatile liquid is one that evaporates or vaporizes quickly at room temperature due to its low boiling point. Volatility describes a substance's tendency to transition from the liquid to the gaseous phase. Liquids like alcohol, gasoline, and perfume are known as volatile as they readily evaporate, often creating a smell or fragrance we can detect. Take, for example, a perfume bottle. If it is left open, the liquid perfume inside tends to evaporate fast - this is because it is a volatile liquid.

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Answer:

A

Explanation:

The amplitude of a wave is directly proportional to the energy it carries. Amplitude is the distance of displacement, by a particle of the wave, in the media in which it travels. The higher the energy in the wave the higher the amplitude and vice versa.  The frequency and wavelength of the wave (which are dependent on the type of wave) remain unchanged even with the change in amplitude.

Some of the waves energy is always being dissipated as heat which will reduce the waves amplitude.

Those waves which carry energy in it in any form is known as waves energy, e.g. ocean waves, wind waves, etc.

Waves will carry energy in it and show their energy can be noticed in the form of their movement. When waves carry low amount of energy then they do not show much movement as compare to the waves which carry high energy. So, we conclude that wave energy is directly proportional to the amplitude, i.e. more energy results in more displacement of particle from their mean position in the medium.

Hence, option (a) is correct i.e. when amplitude reduces, some of the waves energy is always being dissipated as heat.

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Answer:

Francium would likely have the lowest electronegativity value.

Explanation:

Aluminum oxide is a covalent compound.

FALSE

Aluminum oxide is an ionic compound, not a covalent compound, with the formula Al₂O₃.

False. Aluminum oxide is not a covalent compound; it is an ionic compound. Ionic compounds typically form between metals and nonmetals, where electrons are transferred from the metal to the nonmetal.

Aluminum oxide [tex](\(Al_2O_3\))[/tex] is formed by the reaction of aluminum, a metal, with oxygen, a nonmetal:

[tex]\[4Al + 3O_2 \rightarrow 2Al_2O_3\][/tex]

In this reaction, aluminum (Al) loses electrons to form [tex]\(Al^{3+}\)[/tex] ions, and oxygen [tex](O)[/tex] gains electrons to form [tex]\(O^{2-}\)[/tex] ions. The resulting compound, aluminum oxide, has a three-dimensional array of ions held together by ionic bonds. This is in contrast to covalent compounds, where electrons are shared between atoms.

In summary, aluminum oxide is an ionic compound due to the transfer of electrons between aluminum and oxygen atoms.

Answer is: The electrons moved from the second energy level to the fourth.

Atomic number (Z) of sodium is 11, it means that it has 11 protons and 11 electrons, so atom of sodium is neutral.

Electron configuration of sodium atom in a ground state:

₁₁Na 1s² 2s² 2p⁶ 3s¹ or 2-8-1-0.

In a ground state of sodium atom, fourth energy level is empty.

In a excited state electron from second energy level (2s² 2p⁶) moves to fourth energy level.

Final answer:

A sodium atom has an excited electron configuration of 2-7-1-1 because electrons have been elevated to higher energy levels from the ground state configuration of 1s²2s²2p⁶3s¹.

Explanation:

The electron configuration of 2-7-1-1 represents a sodium atom in an excited state because electrons have been promoted to higher energy levels than found in the ground state. Normally, sodium has an electron configuration of 1s²2s²2p⁶3s¹.

When energy is absorbed, such as from heat in a flame, an electron may jump from a lower level to a higher one, changing the configuration to an excited state, such as 2-7-1-1, with the last two ones representing electrons in the 3s and 3p orbitals, respectively.

This excited sodium atom can then release energy in the form of light when the electrons 'fall' back to their original energy levels, resulting in the characteristic bright yellow color observed during a flame test.

This is the only option that correctly describe characterisitics of noble gases.  

All noble gases have a unique atomic fingerprint.

All noble gases have valence shells with 8 electrons but Heilum has only 2 valence electrons.

And all noble gases do not easily react with other elements as they have their outermost shell completly filled so they are highly stable.

All noble gases emits different colored light when electrified.

Noble gases have valence shells with 8 electrons and a unique atomic fingerprint. They do not easily react with other elements and emit different colors of light when electrified.

Noble gases are a group of chemical elements that have certain characteristic properties. Two options that correctly describe the characteristics of noble gases are:

One misconception in the given options is that all noble gases easily react with other elements. In fact, noble gases are known for their low reactivity due to their stable electron configurations and full valence shells.

The option stating that all noble gases emit pink light when electrified is also incorrect. While noble gases do emit light when an electric current is passed through them, the color of the emitted light varies for each gas. For example, argon emits a violet glow, neon emits red-orange, and helium emits a yellowish-orange glow.

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- 8 meter/sec

( - ) sign denotes deceleration.

a= (Final velocity-initial velocity)/Time

 =(0-80)/10

 = -8 meter/sec

Answer:

1.  Reacts with oxygen

2. Loss electrons

3. Reduce the element that oxidizes it.

Explanation:

Oxidation is a phenomenon in which an element or compound reacts with oxygen, producing an oxide (in case of metals).

Although strictly speaking, oxidation refers to the chemical process that involves the loss of electrons by a molecule, atom or ion.

If this element participate in a redox reaction when oxidized it is reducing the element that oxidizes it.

6:12:6: - this simplifies to 1:2:1   (answer)

You get the simplest form by dividing each of the 3 numbers by 6.

yes that would be the right answer 6:12:6 that's what i found out

Final answer:

The correct statement about resonance is that the cyanide ion has only one dominant resonance structure. Resonance structures represent the average distribution of electrons without changing the connectivity of atoms, and the true structure of a molecule is a hybrid of all resonance forms. So the correct option is d.

Explanation:

The correct statement about resonance is (d) the cyanide ion has only one dominant resonance structure. Resonance refers to the concept where the actual distribution of electrons in a molecule or polyatomic ion cannot be represented by a single Lewis structure; instead, it is best represented by two or more resonance structures which are averages of each other. It is important to note that when drawing resonance structures, the connectivity of atoms should not change, meaning altering the way atoms are connected is not permissible. Nitrate ion (NO3-), as another example, has resonance forms with equivalent bond lengths due to resonance, contradicting the statement that it has one long N—O bond and two short N—O bonds. It is a misconception to think that a molecule resonates rapidly between different bonding patterns; rather, the true structure is a hybrid that does not change from one form to another but is the average of the resonance forms.

Answer :

(a) The number of grams of iron metal obtained, 698.616 g

(b) The number of grams of carbon dioxide used in the reaction, 826.32 g

Solution : Given,

Mass of hematite = 1 Kg = 1000 g

Molar mass of hematite = 159.69 g/mole

Molar mass of iron = 55.8 g/mole

Molar mass of carbon dioxide = 44 g/mole

(a) First we have to calculate the moles of hematite.

[tex]\text{Moles of hematite}=\frac{\text{Mass of hematite}}{\text{Molar mass of hematite}}=\frac{1000g}{159.69g/mole}=6.26moles[/tex]

Now we have to calculate the moles of iron.

The given balanced reaction is,

[tex]Fe_2O_3(s)+3CO(g)\rightarrow 2Fe(s)+3CO_2(g)[/tex]

From the balanced reaction, we conclude that

As, 1 mole of hematite react to give 2 moles of iron

So, 6.26 moles of hematite react to give [tex]2\times 6.26=12.52[/tex] moles of iron

Now we have to calculate the mass of iron.

[tex]\text{Mass of iron}=\text{Moles of iron}\times \text{Molar mass of iron}[/tex]

[tex]\text{Mass of iron}=(12.52moles)\times (55.8g/mole)=698.616g[/tex]

(b) Now we have to calculate the moles of carbon dioxide.

From the balanced reaction we conclude that

As, 1 mole of hematite react to give 3 moles of carbon dioxide

So, 6.26 moles of hematite react to give [tex]3\times 6.26=18.78[/tex] moles of carbon dioxide

Now we have to calculate the mass of carbon dioxide.

[tex]\text{Mass of }CO_2=\text{Moles of }CO_2\times \text{Molar mass of }CO_2[/tex]

[tex]\text{Mass of }CO_2=(18.78moles)\times (44g/mole)=826.32g[/tex]

Therefore, (a) The number of grams of iron metal obtained, 698.616 g

(b) The number of grams of carbon dioxide used in the reaction, 826.32 g

Answer:  

(a) 20.5 g O₂, 8.38 g H₂O; (b) 230 g  

Step-by-step explanation:  

(a) Masses of CO₂ and H₂O  

pV = nRT            Divide each side by RT  

n = (pV)/(RT)  

p = 30.0 torr      Convert to atmospheres  

p = 30.0 × 1/760 = 0.039 47 atm  

V = 300 L  

R = 0.082 06 L·atm·K⁻¹mol⁻¹  

T = (37.0 + 273.15) K = 310.15 K  

n = (0.039 47 × 300)/(0.082 06 × 310.15)  

n = 0.465 mol  

Mass of CO₂ = 0.465 × 44.01 = 20.5 g  

Mass of H₂O = 0.465 × 18.02 = 8.38 g

===============  

(b) Mass lost during sleep  

Mass lost in 1 h = 20.5 + 8.38 = 28.9 g  

Mass lost in 8 h = 8 × 28.9     = 230 g

228.16 g of body mass is lost in 8 hours of sleep.

From the question, we can obtain the number of moles of each gas as follows;

Partial pressure of each gas= 30 torr or 0.039 atm

Volume of the gases =  300 L

Temperature of the gases = 37.0°C + 273 = 310 K

R = 0.082 atmLmol-1K-1

From PV =nRT

n = PV/RT =  0.039 atm × 300 L/0.082 atmLmol-1K-1  × 310 K

n = 0.46 moles of each gas

Hence;

Mass of CO2 lost in 1 hour =  0.46 moles × 44 g/mol = 20.24 g

Mass of water vapor lost in 1 hour = 0.46 moles × 18 g/mol = 8.28 g

If 20.24 g of CO2 is lost in 1 hour of sleep, in 8 hours of sleep;

8 × 20.24 g = 161.92 g of CO2 is lost.

Similarly, if 8.28 g of water vapor is lost in 1 hour of sleep, in 8 hours of sleep; 8 × 8.28 g = 66.24 g of water vapor is lost

Since both the CO2 and water vapor come from metabolism, total body mass lost in 8 hours of sleep = 161.92 g + 66.24 g  = 228.16 g

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Answer:

CH₄ + 2O₂ ⟶ CO₂ + 2H₂O + 212 800 cal

Step-by-step explanation:

CH₄ + 2O₂ ⟶ CO₂ + 2H₂O + 212 800 cal  

The heat is on the right-hand side of the equation, so the reaction is releasing heat.

The reaction is exothermic.

A is wrong. Your sign of ΔH is wrong, because graphite is the more stable form of carbon. We must add energy to graphite to convert it to diamond, so the process is endothermic.

B and D are wrong, because a ΔH > 0 indicates an endothermic reaction.

Answer:

C (graphite) → C (diamond), ΔH = - 0.45 kcal

CH4 + 2O2 → CO2 + 2H2O + 212,800 cal

Explanation:

exothermic reactions are characterized by releasing heat to the surroundings; the enthalpy change is negative, and the system temperature increases.

NH3 (g) + 12.0 kcal → ½N2 (g) + 3/2 H2 (g): it is not exothermic.

C (graphite) → C (diamond), ΔH = - 0.45 kcal: the reaction is exothermic because ΔH is negative

C + 2S → CS2, ΔH = 27,550 cal: it is not exothermic because the enthalpy change is positive

CH4 + 2O2 → CO2 + 2H2O + 212,800 cal: it is exothermic because it releases heat.

2H2O → 2H2 + O2, ΔH = +58 kcal: it is not exothermic because ΔH is positive.

Final answer:

The pressure exerted by the object is 0.556 torr.

Explanation:

To calculate the pressure exerted by an object, we use the formula:

Pressure = Force / Area

In this case, the force exerted by the object is 500 N and the area it covers is 4.5 m x 1.5 m = 6.75 m². So the pressure exerted by the object can be calculated as:

Pressure = 500 N / 6.75 m² = 74.07 Pa

Since the question specifically asks for the pressure to be calculated in torr, we need to convert Pa to torr. 1 Pa = 0.00750062 torr, so:

Pressure in torr = 74.07 Pa * 0.00750062 torr/Pa = 0.556 torr

Answer: Dark matter may be Dark matter form the cause of the expansion of the universe  and  a new form of subatomic particle.

Explanation:

85% of the matter of the universe. scientists don't know exactly what makes up dark matter. It may be made of baryonic or non-baryonic particles or some new subatomic particles. No light emits from it thus it is named dark matter. Only its gravitational effect is observable which led to its discovery.The velocity of stars is different in different regions of galaxy.  It is also thought to be cause of expansion of universe.

Thus, the correct answer is: Dark matter may be the cause of the expansion of the universe  and a new form of subatomic particle.

Answer:

A new form of subatomic particle and cold matter that emits little radiation

Explanation:

"Dark matter may be cold regular matter or a new form of subatomic particle."

You can find the answer in the review in the last section of your assignment.

See the sketch attached for a Lewis cross-and-dot structure of PCl₅.

The central P atom ends up with ten valence electrons.

Unlike P, Cl does not form expanded octets. Each Cl atom in PCl₅ will share one electron with a P atom. Each will form one P-Cl covalent bond and end up with a typical octet of eight electrons. Six of the eight electrons come from three non-bonding pairs (a.k.a. "lone pairs").

P is found in IUPAC group 15 of a modern periodic table. A neutral P atom has five valence electrons. Each of them goes to a P-Cl bond in PCl₅. The central P atom will end up forming five P-Cl bonds. That will gives the atom a total of ten valence electrons. That is two electrons more than a typical octet- hence the name "expanded octet".

Phosphorus pentachloride (PCl5) exhibits the concept of the expanded octet as phosphorus forms five covalent bonds. The total number of valence electrons in PCl5 is 40, and all 40 valence electrons are counted toward the central phosphorus atom.

Phosphorus pentachloride (PCl5) is a molecule featuring expanded octet concept, as the central phosphorus atom forms five covalent bonds. To determine the total number of valence electrons in PCl5, we need to count the valence electrons of each atom and consider the charge of the molecule. Phosphorus has five valence electrons, while each chlorine has seven valence electrons. Therefore, the total number of valence electrons in PCl5 is 40.

When we draw the Lewis structure, we place the phosphorus atom in the center and arrange the chlorine atoms around it. Each chlorine forms a single bond with phosphorus, resulting in five P-Cl bonds. The remaining valence electrons are placed on the chlorine atoms as lone pairs to fulfill the octet rule. Since there are no additional atoms bonded to the central phosphorus atom, all 40 valence electrons are counted toward the central P atom.

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Answer:

A) Elements

Explanation:

A mixture is a composite of two or more components that are combined physical and not through any chemical means. While a suspension is a mixture of a liquid and solid particles. Therefore, in both cases the components can be separated by some physical means.

A compound is a composite of two or more atoms which can be decomposed into simpler systems through chemical processes.

However, element is a single atom which can be neither be simplified any further by physical or chemical means.