How many unpaired electrons are contained in each element: (a) chlorine, (b) selenium, (c) cesium, and (d) phosphorus?

Answer:

1. It can only change into a gas once it reaches its boiling point. A liquid can only change once it reaches its freezing point.

2. A gas can turn into a liquid/solid when the temperature drops.

Explanation:

The answers are pretty much self explanatory

Answer:

Ammonia does not have a trigonal shape.

Explanation:

According to VSEPR theory:

Molecules with 3 sigma bonds and no lone pair possess trigonal planar shape irrespective of the number of pi bonds.

Hence except ammonia all other molecules given possess trigonal planar shape.

Answer:

Theoretical number of moles

Explanation:

The coefficient used in balancing a chemical reaction helps to show theoretically the number of moles of reactants used or products formed. It tends to give a representation of the ratio of the number of moles of reactants and products.

What we are saying in essence is that it helps to picture the number of moles of the reactants coming into the chemical reaction or the number of moles of products formed as the reaction proceeds to completion

In a chemical equation, a coefficient is the number placed in front of substances' chemical formulas. It dictates the relative quantities of each substance involved in a chemical reaction.

In a chemical equation, a coefficient represents the relative number of molecules or atoms involved in a reaction. The coefficient is the number placed immediately to the left of the chemical formula of a reactant or product. It determines the amount of each substance that is consumed or produced in the chemical reaction. For instance, in the reaction 2H2 + O2 -> 2H2O, the coefficients (2 for H2, 1 for O2, and 2 for H2O) indicate that two molecules of hydrogen gas react with one molecule of oxygen gas to produce two molecules of water. A coefficient of 1 is usually omitted from the equation.

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Answer : The correct option is, (A) Hydrogen atoms are added to fats to make them more saturated.

Explanation :

Hydrogenation : Hydrogenation means to treat with hydrogen that means it is a chemical reaction between the molecular hydrogen and the another compound or an element in the presence of catalyst like, nickel, palladium etc.

When an organic compound is hydrogenated then it becomes more saturated with the hydrogen atoms.

The largest scale application of hydrogenation is the processing of vegetable oils. Typically, vegetable oils are derived from polyunsaturated fatty acids. Their partial hydrogenation reduces most but not all of these carbon-carbon double bonds.

Liquid fats : They have the highest degree of unsaturation. Vegetable and marine oils are liquid fats.

Solid fats : They are highly saturated. Vegetable and animal fats are solid fats.

Hence, the correct option is, (A) Hydrogen atoms are added to fats to make them more saturated.

Answer:

1. Process by which water vapor changes into liquid water - condensation

2. Process by which liquid water changes into water vapor - evaporation

3. Moisture falling from the clouds as snow, rain, or hail - precipitation

4. The process by which plants give off water vapor - transpiration

5. Moisture collecting on cool surfaces - dew

Explanation:

Process by which water vapor changes into liquid water  is condensation. Process by which liquid water changes into water vapor is evaporation Moisture falling from the clouds as snow, rain, or hail is precipitation.The process by which plants give off water vapor is transpiration. Moisture collecting on cool surfaces is dew  .

Precipitation is defined as any liquid or frozen water which forms in the atmosphere and then gets received on Earth.It is one of the most important steps of the water cycle.

Precipitation takes place in form of clouds when water vapor gets accumulated in clouds and they get bigger and heavy, when the clouds become heavy enough they fall to the land in the form of rain,if a cloud is present at higher altitudes , the water present in the clouds freezes and fall to the ground in form of snow,hail.

Precipitation occurs always in case of fresh water because the sea salt does not evaporate with the water.The different types of precipitation are rain, drizzle,snow,snow hail,etc.

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Answer:

Propane and methane

Explanation:

The organic compounds are the one that has Carbon (C) as its principal component. Most organic compounds are made up of carbon, hydrogen and oxygen atoms, often combined with others such as nitrogen, phosphorus or sulfur .

Answer:

B

Explanation:

The cohesive and adhesive forces are terms that are used to explain the phenomena that lead up to the formation of a meniscus when a liquid is poured into a capillary tube.

The cohesive forces are those forces that exist between the molecules of the liquid. They are essentially the intramolecular forces that exist in between the molecules of the liquid.

The adhesive forces are the intermolecular forces that occur between molecules of the liquid and the molecules of the material used to make the container.

Let’s use the pouring of a non polar liquid such as mercury into a capillary tube. It would be noted that the shape of the surface of the mercury shows a convex meniscus. This is because the cohesive forces between mercury molecules is greater than the adhesive forces between glass and mercury molecules.

Hence, what we’re driving at is that the shape the meniscus of the surface of the liquid takes depend on the balance between the cohesive and the adhesive forces.

Answer:

The correct answer is option D.

Explanation:

All the cations given belong to the group-1 cation and will give precipitate of their respective chlorides when HCl is added to their aqueous solution.

[tex]Ag^+(aq)+HCl(aq)\rightarrow AgCl(s)+H^+(aq)[/tex]

[tex]Cu^{2+}+(aq)+2HCl(aq)\rightarrow CuCl_2(s)+2H^+(aq)[/tex]

[tex]Hg_{2}^{2+}+(aq)+2HCl(aq)\rightarrow Hg_2Cl_2(s)+2H^+(aq)[/tex]

[tex]Pb^{2+}+(aq)+2HCl(aq)\rightarrow PbCl_2(s)+2H^+(aq)[/tex]

All the precipitates are insoluble in cold water but out of all these only lead(II) chloride is soluble in warm water.

The ion present in a solution that forms a white precipitate upon the addition of dilute HCl and dissolves when warmed is Pb2+ because PbCl2 is more soluble in hot water. So the correct option is D.

When determining which ion is present in a solution that produces a white precipitate upon the addition of dilute HCl and then dissolves upon warming, we need to consider the solubility properties of the possible ions' chlorides. Ag+, Pb2+, and Hg2_2+ are all known to form insoluble chlorides. However, the key information here is that the white precipitate dissolves when warmed. This is characteristic of PbCl2, which is more soluble in hot water than the chlorides of silver or mercury. Therefore, the ion that produces a white precipitate is Pb2+, and the precipitate is lead(II) chloride, also referred to as PbCl2.

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Answer : The correct option is, Iron(III) phosphate, [tex]FePO_4[/tex].

Explanation :

Ionic compound : It is defined as the compound which is formed when electron gets transferred from one atom to another atom.

All the polyatomic ions always form an ionic compound.

Polyatomic ions : It is a charged species that composed of two or more atoms and these charged species are bonded by the covalent bond.

(1) The chemical formula for Ammonium sulfite.

The given compound ammonium sulfate is an ionic compound. It is made up of two different ions which are ammonium ion [tex](NH_4^+)[/tex] and sulfite ion [tex](SO_3^{2-})[/tex] by the criss-cross method. Thus, the correct chemical formula for ammonium sulfite is [tex](NH_4)_2SO_3[/tex].

(2) The chemical formula for Iron(III) phosphate.

The given compound iron(III) phosphate is an ionic compound. It is made up of two different ions which are iron ion [tex](Fe^{3+})[/tex] and phosphate ion [tex](PO_4^{3-})[/tex] by the criss-cross method. Thus, the correct chemical formula for iron(III) phosphate is [tex]FePO_4[/tex].

(3) The chemical formula for Lithium carbonate.

The given compound lithium carbonate is an ionic compound. It is made up of two different ions which are lithium ion [tex](Li^+)[/tex] and carbonate ion [tex](CO_3^{2-})[/tex] by the criss-cross method. Thus, the correct chemical formula for lithium carbonate is [tex]Li_2CO_3[/tex].

(4) The chemical formula for Magnesium dichromate.

The given compound magnesium dichromate is an ionic compound. It is made up of two different ions which are magnesium ion [tex](Mg^{2+})[/tex] and dichromate ion [tex](Cr_2O_7^{2-})[/tex] by the criss-cross method. Thus, the correct chemical formula for magnesium dichromate is [tex]MgCr_2O_7[/tex].

From this we conclude that, the correct set of chemical name and chemical formula for the same compound is Iron(III) phosphate.

Hence, the correct option is, Iron(III) phosphate, [tex]FePO_4[/tex].

Answer: B. iron(III) phosphate, FePO4

Explanation:

Answer:

5.74 g

Explanation:

Using conservation of mass:

mass of the reactant = mass of the product if the system is closed

but in this case the bubbles must have been allow to leave the solution and the resulting mass after the reaction equals 64.96 g  

to find the mass of Co2 released

we subtract mass of the remaining product from the mass of the reactant

mass of reactant =14 g + 56.70 = 70.7 g

mass of carbon dioxide = 70.7 - 64.96 ( mass of the remaining product after the bubble) = 5.74 g

Answer:

D

Explanation:

∆H° = ∆Hf ° (products) – ∆Hf ° (reactants)

Answer:

The volume of base was required for the titration is 13,53mL

Explanation:

In a titration of an acid (HX) with a base (YOH), the reaction of neutralization is:

HX + YOH → YX + H₂O

In the burette you are adding base until all HX reacts. The addition of base is in volume.

If in the beginnig, the volume that you read of base is 2,94mL and at the endpoint you read a volume of 16,47mL. The volume you spent in the titration that is the same volume of base you required for the titration is:

16,47mL - 2,94mL = 13,53mL

I hope it helps!

To find out the volume of base required for the titration, subtract the initial volume from the final volume. In this case, the calculation would be 16.47 mL - 2.94 mL, which equals 13.53 mL of base.

To calculate the volume of the base required for the titration, simply subtract the initial volume of the titrant from the final volume. In this case, we subtract the initial reading of the base titrant volume(2.94 mL) from the final reading after reaching the endpoint (16.47 mL).

So, the calculation would be: 16.47 mL - 2.94 mL = 13.53 mL

Therefore, 13.53 mL of base was required for the titration. This is the volume that was consumed to neutralize the acid to the endpoint.

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Answer:

Mineral

Explanation:

Mineral:-

Hence, the answer to the problem is:- mineral.

Final answer:

A mineral is defined as a naturally occurring, inorganic solid with a unique chemical formula and an ordered crystalline structure.

Explanation:

The subject of the question is referring to a mineral, which is a naturally occurring, inorganic, solid substance with a crystal structure and a specific chemical composition.

Minerals are formed through natural processes and are identified by their physical properties such as crystalline structure, hardness, density, and color.

It is important to note that to be classified as a mineral, a substance must be naturally occurring and not man-made, meaning minerals are not composed of complex carbon molecules that are characteristic of life.

Thus, while water is not considered a mineral, ice can be considered a mineral as long as it occurs naturally.

Answer: Option (a) is the correct answer.

Explanation:

Ionic salts are defined as the salts which tend to contain ionic bonds as there occurs transfer of electrons between its combining atoms.

So, when an ionic salt melts or it is dissolved in water then it will dissociate into its respective ions and as electricity is the flow of electrons or ions. Hence, this salt is then able to conduct electricity.

As covalent compounds are insoluble in water so, they do no dissociate into ions. Hence, they do not conduct electricity.

Similarly, metallic and network solids do not dissociate into ions either when melted or dissolved in water. Therefore, they also do not conduct electricity.

Thus, we can conclude that when a white crystalline salt conducts electricity when it is melted and when it dissolves in water then this bond is of ionic type.

The quantization of energy at atomic level has been described below.

        Quantization of energy is a postulate developed by Max Planck where he stated that energy was quantized and that it could either be emitted or absorbed but that will happen in just integral multiples of a small unit of energy which he referred to as quantum.

        Now, applying that concept of quantization of energy to atomic level, It simply means that by promoting electrons to higher-energy orbitals, there will be particular discrete energy levels which an atom can achieve.

       Now, what the above paragraph implies is that for every possible orbital from which an electron can be promoted, it would definitely possess a certain energy level. Thus, when an amount of electron falls from a high-energy orbital to a lower-energy orbital, it means that a discrete amount of energy would be released which will be called a photon.

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Final answer:

At the atomic level, energy is quantized, meaning electrons can occupy only discrete energy levels, described by quantum numbers. Movement between these energy states occurs via the absorption or emission of a photon with the precise energy difference.

Explanation:

The concept of energy quantization at the atomic level refers to the observation that the energies of electrons within an atom are quantized, meaning that these electrons can only occupy certain fixed energy levels. These discrete energy states are described by quantum numbers, which are integer values that define the possible arrangements of electrons in an atom. Electrons can move between these energy states by absorbing or emitting a photon that matches the energy difference between levels.

One of the first indications of energy quantization came from the study of blackbody radiation, where Max Planck proposed that the energy levels of emitting atoms and molecules were quantized with allowed values of E = (n + 1)hf, with n being a non-negative integer (0, 1, 2, 3,...). Therefore, these quantized energy levels help to explain the unique emission and absorption spectra observed for different elements.

Answer:

555 ft per min

Explanation:

For the problem above, we can use the IAP chart and the ILS RWY 32 L approach. If we consider an electronic glide slope of 3 degrees, with the table of Rate-of-Descent in the IAP chart. Adjusting the angle of descent to 3 degrees and shifting the ground speed to approximately 105 knots, the estimated rate of descent is 555 ft per min.

To maintain the electronic glide slope at 105 knots ground speed, one would reference standard rates of descent for planning: about 600 fpm for general aviation and 450 fpm for a STOL aircraft with a 7-degree glideslope. These figures can vary depending on specific glide conditions such as aircraft configuration or wind, and precise planning may adjust these rates based on lift, air density, and safety margins.

To find the approximate rate of descent for maintaining the electronic glide slope at 105 knots ground speed, we must consider the standard glide ratio used for planning purposes in aviation. For general aviation, which often uses a power-off approach, a rate of descent of about 600 feet per minute (fpm) is typical, while Short Takeoff or Landing (STOL) aircraft with a steeper 7-degree glideslope might require around 450 fpm.

When determining the time of descent without wind and assuming a steady glide at a constant airspeed and angle, we can employ this information to estimate the time to descend from a certain altitude. For an altitude of 20,000 feet, the accuracy of the time of descent estimation can vary based on the increments and assumptions made in the calculations. When breaking down the glide into increments, smaller increments should provide more accurate results, but as seen in the given example, there's only a small 2% error or two minutes difference between the 'exact' solution and the approximation.

Raymer suggests adjustments to the calculations depending on the usage of thrust reversers or when including a safety margin for commercial aircraft under FAR part 25. These adjustments would affect the range and rate of descent calculations, so in a real-world scenario, they would need to be considered for precise planning.

For our purpose, if the glide is performed under no wind and at optimum conditions for lift over drag (L/D), we simply need the rate of descent to plan the glide slope. However, exact calculations do require the lifting capacity and air density at the altitudes used as increments, as suggested in the context.

The claim that, if true would support the claim that the NO3− ion has three resonance structures is that; "The NO3− ion is not a polar species."

The existence of resonance in a molecule implies that all the bond lengths and bond angles are equal. Looking at the resonance structures as shown in the image attached, we can see that the nitrate ion is a triatomic specie.

Triatomic molecules are symmetrical hence the N-O bond angles in the nitrate ion is 120°. Recall that symmetrical molecules are nonpolar. Hence if the resonance structures for nitrate ion are true then the nitrate ion will be nonpolar.

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"The correct statement that would support the claim that the NO3^- ion has three resonance structures is: C. One of the bonds in NO3^- is shorter than the other two.

The NO3^- ion, known as the nitrate ion, has a central nitrogen atom that is double-bonded to one oxygen atom and singly bonded to two other oxygen atoms. However, due to the equivalence of the three oxygen atoms in the molecule, the double bond is delocalized over the three nitrogen-oxygen bonds, giving rise to three resonance structures. These structures are identical in energy and contribute equally to the overall hybrid structure of the ion.

Resonance structures are a way of describing the delocalization of electrons within certain molecules or polyatomic ions. They are represented by different Lewis structures that differ only in the position of the electrons, not in the arrangement of the atoms. For the NO3^- ion, the three resonance structures are as follows:

1. A double bond between the nitrogen atom and one of the oxygen atoms, with the other two oxygen atoms each having a single bond and a negative charge.

2. A double bond between the nitrogen atom and another oxygen atom, with the first oxygen atom now having a single bond and a negative charge.

3. A double bond between the nitrogen atom and the third oxygen atom, with the second oxygen atom now having a single bond and a negative charge.

The statement The NO3^- ion is not a polar species (A) does not necessarily support the claim of three resonance structures. While it is true that NO3^- has three resonance structures, the polarity of a molecule is determined by the distribution of charge across the entire molecule, not just the presence of resonance structures. In the case of NO3^-, the ion is actually polar because the central nitrogen atom has a positive formal charge and the oxygen atoms have negative formal charges, leading to a separation of charge.

The statement One of the bonds in NO3^- is longer than the other two (B) is incorrect because in reality, due to resonance, all nitrogen-oxygen bonds in NO3^- are of equal length. Resonance tends to average out bond lengths, leading to bonds that are intermediate between single and double bond lengths.

The statement One of the bonds in NO3^- is shorter than the other two (C) is the correct choice because it implies that one of the bonds has more double bond character than the others, which is consistent with the idea of resonance. In the hybrid structure of NO3^-, the bonds are not completely equalized; the double bond is still slightly shorter than the two single bonds due to the greater electron density in the double bond. This is a subtle point that acknowledges the presence of resonance while also recognizing that the bonds are not perfectly identical in character.

Answer : The volume of the stock solution he need to make the dilute solution will be, 45 mL

Explanation :

According to dilution dilution law:

[tex]M_1V_1=M_2V_2[/tex]

where,

[tex]M_1[/tex] = molarity of concentrated solution

[tex]M_2[/tex] = molarity of dilute solution

[tex]V_1[/tex] = volume of concentrated solution

[tex]V_2[/tex] = volume of dilute solution

Given:

[tex]M_1[/tex] = [tex]6.0\times 10^{-3}M[/tex]

[tex]M_2[/tex] = [tex]6.0\times 10^{-4}M[/tex]

[tex]V_1[/tex] = ?

[tex]V_2[/tex] = 450 mL

Now put all the given values in the above formula, we get:

[tex](6.0\times 10^{-3}M)\times V_1=(6.0\times 10^{-4}M)\times 450mL[/tex]

[tex]V_1=45mL[/tex]

Therefore, the volume of the stock solution he need to make the dilute solution will be, 45 mL

The desired pH would have been 1.60. But due to the increased volume and thus, decreased concentration of the HCl solution, the actual pH is 1.70.

(a) Desired solution pH: The laboratory technician wanted to prepare a 200.0 mL of a 0.025 m HCl solution. HCl is a strong acid, meaning it completely ionizes in solution. The hydronium ion molarity is equal to the concentration of the HCl, so 0.025 M. The pH of this solution is calculated using the formula pH = -log(H3O+). Therefore, pH = -log(0.025) = 1.60.

(b) Actual solution pH: The technician accidentally used a 250.0 mL flask to make the solution, which actually made a less concentrated solution. The new molarity is (0.025 mol HCl / 0.250 L) = 0.020 M. This is the new concentration of the hydronium ions. pH = -log(0.020) = 1.70.

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Answer: The given substances are placed in order from most soluble in water to least soluble in water as follows.

         [tex]MgCl_{2}[/tex] > [tex]C_{4}H_{9}OH[/tex] > [tex]C_{3}H_{8}[/tex] > [tex]CH_{4}[/tex]

Explanation:

It is known that like dissolves like which means a polar compound will be soluble in a polar solvent. And, a non-polar compound will be soluble in non-polar solvent.

Ionic compounds are soluble in polar solvent like water. For example, [tex]MgCl_{2}[/tex] is an ionic compound and it is readily soluble in water.

2-butanol ([tex]C_{4}H_{9}OH[/tex]) is also a polar compound and it will also dissolve in water but to a lesser extent as compared to magnesium chloride.

Whereas both methane and propane are non-polar in nature. But as propane is larger in size as compared to methane so, it will be slightly more soluble in water as compared to methane.

Thus, we can conclude that the given substances are placed in order from most soluble in water to least soluble in water as follows.

     [tex]MgCl_{2}[/tex] > [tex]C_{4}H_{9}OH[/tex] > [tex]C_{3}H_{8}[/tex] > [tex]CH_{4}[/tex]

The substances, ranked from most to least soluble in water, are magnesium chloride (MgCl2), 2-butanol (C4H9OH), methane (CH4), and propane (C3H8). This is based on their ability to form hydrogen bonds with water.

The solubility of substances in water primarily depends on whether or not the substance can form hydrogen bonds with water. More the ability to form hydrogen bonds, greater the solubility in water.

So, magnesium chloride MgCl2, an ionic compound, will be the most soluble. It dissolves in water by breaking apart into individual ions which are then surrounded by water molecules. Next would be 2-butanol, C4H9OH, a polar molecule with an -OH group that can form hydrogen bonds with water. The last two, methane, CH4, and propane, C3H8, are nonpolar and thus less soluble in water. Methane is slightly more soluble than propane due to its smaller size.

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Answer:

The enthalpy change during the reaction is -67.78 kJ/mol.

Explanation:

Volume of solution = 50.0 mL + 50.0 mL = 100.0 mL

Density of the solution = 1.00g/mL

Mass of the solution , m= 100.0 mL × 1.00 g/mL = 100 g

First we have to calculate the heat gained by the solution .

[tex]q=mc\times (T_{final}-T_{initial})[/tex]

where,

q = heat gained = ?

c = specific heat of solution = [tex]4.184 J/^oC[/tex]

[tex]T_{final}[/tex] = final temperature = [tex]24.21^oC[/tex]

[tex]T_{initial}[/tex] = initial temperature = [tex]23.40^oC[/tex]

Now put all the given values in the above formula, we get:

[tex]q=100g\times 4.184 J/^oC\times (24.21-23.40)^oC[/tex]

[tex]q=338.904 J[/tex]

Now we have to calculate the enthalpy change during the reaction.

[tex]\Delta H=-\frac{q}{n}[/tex]

where,

[tex]\Delta H[/tex] = enthalpy change = ?

q = heat gained = 338.904 J

[tex]moles=Molarity\times Volume (L)[/tex]

Molarity of silver nitrate = 0.100 M

Volume of silver nitrate = 50.0 mL = 0.050 L

Moles of silver nitrate = n

[tex]n=0.100 M\times 0.050 L=0.005 mol[/tex]

[tex]\Delta H=-\frac{338.904 J}{n}=-\frac{338.904 J}{0.005 mole}=-67,780.8 J/mol=-67.78 kJ/mol[/tex]

(1 kJ= 1000 J)

Therefore, the enthalpy change during the reaction is -67.78 kJ/mol.

To calculate the enthalpy change of the reaction, the total mass of solution and the temperature increase are used with the specific heat to determine the heat involved, which is then standardized per mole of AgNO3, resulting in an enthalpy change of +67.837 kJ/mol of AgNO3.

When 50.0 mL of 0.100 M AgNO3 is mixed with 50.0 mL of 0.100 M HCl, the resulting temperature change in a calorimeter is used to calculate the enthalpy change (ΔH) for the reaction. The calorimetry formula is used: q = m x c x ΔT, where q is the heat absorbed or released, m is mass, c is the specific heat capacity, and ΔT is the change in temperature.

First, the total mass of the solution is calculated by combining the volumes of the two solutions (assumed to be equivalent to mass due to the given density of 1.00 g/mL):
50.0 mL + 50.0 mL = 100.0 mL = 100.0 g.

The total amount of heat (q) involved can be calculated: q = m x c x ΔT = 100.0 g x 4.184 J/g°C x (24.21°C - 23.40°C) = 339.184 J.

Since the reaction involves 0.100 mol of the 50.0 mL AgNO3 solution, we calculate the enthalpy change per mole of AgNO3: ΔH = q/n = 339.184 J / 0.0050 mol = 67836.8 J/mol = 67.837 kJ/mol.

The enthalpy change ΔH for the reaction of AgNO3 with HCl to form AgCl and HNO3 is therefore +67.837 kJ/mol of AgNO3.

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Answer:

Tar sands.

Explanation:

Tar sands also called as oil sands, it is defined as the mixture of mostly clay, water, tar sand, and a molasses like substances known as bitumen. Bitumen is composed of hydrocarbons in liquid oil in same molecules, and it is mainly used for produce gasoline, and other petroleum products.

Extracting bitumen is significantly more difficult, and costlier compared to other extracting refining liquid oil. Common extraction method of bitumen includes surface mining.

Answer:

Dry Ice is a pure substance.

Explanation:

Dry Ice is the solid form of Carbon Dioxide which is formed when gaseous Carbon Dioxide molecules sublime at very low temperatures (-109.5 Fahrenheit).

Dry ice is solid carbon dioxide and is considered a pure substance because it consists of only one kind of matter, with consistent composition and properties throughout the sample.

Dry ice, which is solid carbon dioxide (CO2), is considered a pure substance. A pure substance has a constant composition and properties that are consistent throughout the sample. This means it contains only one kind of matter. Dry ice sublimes, directly transitioning from a solid to a gas at atmospheric pressures and a temperature of -78°C, without passing through a liquid phase. This property makes it exceedingly useful as a cooling agent. Since dry ice consists solely of carbon dioxide without any other substance mixed in, it fits the definition of a pure substance more specifically, it is a compound because it is made up of more than one element chemically bonded together (carbon and oxygen in this case).

Mixtures, on the other hand, are a combination of two or more substances that can be separated into their individual components. Examples include air, sea water, and soil. Unlike mixtures, the composition of a pure substance like dry ice remains unchanged.

Answer:

A

Explanation:

The law of conservation of mass states that matter can never be created nor destroyed but can be converted from one form to another.

The law of conservation of energy posits that energy cannot be created nor destroyed but can be converted from one form to another.

These laws are the basic laws of existence. Although the laws have been adjusted, they still form the basic principle behind several scientific laws and are responsible for a whole lot of scientific advancements.

While the first law focuses on matter and the content of matter in a body, the second law basically focuses on energy. The second law serves to support the inter convertibility behind the several forms or types of energy.

For example, to do many useful work at home, it is found that energy is converted from its electric form to say heat in an electric iron to press our clothes.

Also, the first law is a fundamental principle useful in the balancing of our chemical equations.

Answer: orderly arrangement of particles

Explanation:

In a crystaline solid, the particles that compose the solid are arranged or packed in an orderly manner to form a three dimensional crystal lattice with a defined structure. Sodium chloride is a crystaline solid.

In an amorphous solid, the particles that compose the solid aren't arranged in an orderly manner hence the solid tends to be brittle, e.g glass

Answer:

The correct answer is the difference between the standard electric potential of the two half cells.

Explanation:

Cell potential of an electro chemical cell can be defined as the difference between the reduction potential of the negatively charged electrode or cathode and reduction potential of the positively charged electrode or cathode.

              E0 cell= Eo cathode - E0 anode

If the E0 cell of an ion is positive then that ion will have high tendency to gain electron thereby acting as an oxidant.On the hand if an ion has negative E0 then that ion will have high tendency to donate electron thereby acting as reducing agent.

Answer:

The symbols of the diphosphate ion is P₂O₇⁴⁻

Explanation:

The compound Ca₂P₂O₇ is known as Calcium pyrophosphate. for the compound to be formed, two ions are put together. The cation Ca²⁺ and the anion P₂O₇⁴⁻. The oxidation state of calcium is always +2. The anion has to have a charge of -4 to make the formula Ca₂P₂O₇.

 symbol                  Ca                  P₂O₇

oxidation state       +2                   -4

 valency                   2                     4

       Crossing the valency and finding the ratio of the valency after crossing

                                      = Ca₄ (P₂O₇)₂  

                                      = Ca₂P₂O₇          

The wavelength of a radio frequency can be calculated using the formula: wavelength = speed of light / frequency. The wavelength of an AM station broadcasting at 1290 kHz is approximately 232.56 meters.

This question pertains to radio wave transmission and involves knowledge of the speed of light, frequency, and wavelength. The wavelength (λ) of any wave is related to its frequency (f). The wavelength of a radio frequency can be calculated using the formula: wavelength = speed of light / frequency. The speed of light is approximately[tex]3 x 10^8[/tex]meters per second. To calculate the wavelength of an AM station broadcasting at 1290 kHz, we need to convert the frequency to hertz. 1 kHz = 1000 Hz, so 1290 kHz = 1,290,000 Hz. Plugging in the values, we get:

wavelength = [tex](3 x 10^8 m/s)[/tex] / (1,290,000 Hz) = 232.56 meters.

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To convert pressure from lb/in^2 to atmospheres, you divide the pressure in lb/in^2 by 14.7 (1 atm). Therefore, 36.0 lb/in^2 is approximately equivalent to 2.45 atmospheres.

The pressure of 36.0 lb/in^2, often used in car tires, can be converted into equivalents in atmospheres (atm) using known conversion factors. First, we know that 1 atmosphere is equivalent to 14.7 psi (pounds per square inch), which is a measure of pressure. Therefore, to convert the pressure of 36.0 lb/in^2 into atmospheres, you just divide the PSI by 14.7. So, 36.0 lb/in^2 divided by 14.7 (which represents 1 atm) equals approximately 2.45 atm. Thus, 36.0 lb/in^2 is equivalent to approximately 2.45 atmospheres.

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The work done by the system is first calculated to be 121.7J. Then, the change in internal energy (ΔE) is found by summing the heat emitted and the work done, leading to a final ΔE of -753.3J.

Given the volume expansion and the external pressure, we can first calculate the work done by the system, using the formula: Work = Pressure * Volume Change. In this case, the volume change is 1.45L - 0.255L = 1.195L. Because the units in this equation need to be in liters and atmospheres, we'll convert 1.195L to atm*L using the conversion 1L*atm = 101.3J. The work done by the system then becomes 1.02 atm * 1.195L * 101.3J/L*atm = 121.7J. The heat emitted by the system (-875J), subtracted by the work done by the system gives us the change in internal energy (ΔE). Therefore, ΔE = q + w = -875J + 121.7J = -753.3J.

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During combustion in the cylinder, the involved energy transfers result in a change in internal energy (ΔE) of the system equal to the sum of the heat lost and the work done by the system. The work (W) is calculated from the external pressure and volume change of the piston, while the heat (Q) is given as 875 J. The change in internal energy is -998.586 Joules.

The subject of the question pertains to the calculation of the change in internal energy (ΔE) of a system during the combustion of fuel in a cylinder equipped with a piston. Within this mechanical system, work is done by the expanding gas against an external pressure. Energy transfer takes place: first, energy is converted from potential to kinetic during the combustion process; second, as the piston moves, work is done on the environment; and finally, heat is lost from the system. To calculate ΔE, we should remember the first law of thermodynamics, which states that the change in internal energy of a system (ΔE) is equal to the heat flow into the system (Q) plus the work done by the system (W), or, ΔE = Q + W.

For this question, W is calculated from the external pressure and volume change. Use W = -PΔV (external pressure times the change in volume), keeping in mind that work done by the system is considered negative, as the system is losing energy. So, W = -(1.02 atm)(1.45 L - 0.255 L) = -1.22 atm*L. Converting to Joule, we have W = -1.22 atm*L * 101.3 J/(atm*L) = -123.586 J. For the heat lost by the system, it is given as Q = -875 J (negative because heat is being lost).

Therefore, ΔE = Q + W = -875 J + -123.586 J = -998.586 J.

So, the change in internal energy (ΔE) for the combustion of the fuel in the given system is -998.586 Joules.

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