Acetic acid has a Ka of 1.8×10−5. Three acetic acid/acetate buffer solutions, A, B, and C, were made using varying concentrations:______[acetic acid] ten times greater than [acetate],[acetate] ten times greater than [acetic acid], and[acetate]=[acetic acid].Match each buffer to the expected pH.pH = 3.74 ; pH = 4.74 ; pH = 5.74

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:

The answer to your question is 43.9 g of NaCl

Explanation:

Data

Grams of NaCl = ?

Volume = 0.75 L

Molarity = 1 M

Number of moles = ?

Formula

[tex]Molarity = \frac{number of moles}{volume}[/tex]

Solve for number of moles

Number of moles = Molarity x volume

Substitution

Number of moles = 1 x 0.75

                             = 0.75

Molecular weight of NaCl = 23 + 35.5 = 58.5

Calculate the grams of NaCl using proportions

                           58.5 g of NaCl ---------------- 1 mol

                              x                     ---------------- 0.75 moles

                              x = (0.75 x 58.5) / 1

                              x = 43.9 g of NaCl

Final answer:

The student's 0.75 L solution of 1 M NaCl contains 43.83 grams of NaCl. This is found by multiplying the volume by the molarity and then by the molar mass of NaCl.

Explanation:

To calculate the number of grams of NaCl in a 0.75 L solution with a concentration of 1 M, we need the formula:

mass (g) = volume (L) × molarity (M) × molar mass (g/mol)

The molar mass of NaCl is approximately 58.44 g/mol. Given that the solution's molarity is 1 M, and the volume is 0.75 L, we can calculate the mass of NaCl as follows:

mass (g) = 0.75 L × 1 mol/L × 58.44 g/mol

mass (g) = 43.83 grams of NaCl

Therefore, a 0.75 L solution of 1 M NaCl contains 43.83 grams of NaCl.

Answer: Group 6

Explanation:

There are eight (8) groups in the periodic table. Elements in Group 6 include OXYGEN, SULPHUR etc.

These elements have an outermost shell with 6 electrons; thus, they are always ready to RECEIVE two electrons from possible donors to form a completely filled outermost shell.

For example

Oxygen has atomic number of 8, its configuration is 2, 6

Sulphur, has atomic number of 16, its configuration is 2, 8, 6

Each require TWO electrons to attain stable octet structure, so, will accept two electrons and become an ANION with -2 charge

O2 + 2e- ---> 2O-

S2 + 2e- ---> 2S-

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:

D

Explanation:

The equation for the dissociation of acetic acid is shown in the image attached. Removing the proton drives the equilibrium position towards the right, that is dissociation of more acetic acid to maintain equilibrium according to Let Chateliers principle.

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.

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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Answer:

The correct answer is " is halved and has its sign changed".

Explanation:

I had to find the chemical equation that the statement refers to.

When the enthalpy of this overall chemical equation is calculated, the enthalpy of the second intermediate equation is halved and its sign changes. This is because in the global equation only one CaO molecule is used, while in the semi-reaction the enthalpy change for two CaO molecules is given, so the enthalpy change must be divided by 2. Also, the sign changes because in the globular equation the inverse reaction of the one shown in the semi-reaction is produced, in this way we have that the CaO is on the side of the reagents and in the semi-reaction it is on the side of the products.

Have a nice day!

A. is halved and has its sign changed

got it correct on test :)

Answer:

Negative; positive

Explanation:

Whenever we have an ionic substance, by convention, we firstly write a symbol of a metal we have. Metals tend to lose their electrons to make ionic compounds and become positively charged species, also known as cations.

Similarly, the metal cation in an ionic substance is followed by a nonmetal. Nonmetal atoms tend to gain the electrons lost by the metals in order to become negatively charged species, also known as anions.

That said, at the front of the compound we have a cation with the positive charge and at the back of the compound we have an anion with the negative charge.

Answer:

Theory

Explanation:

A proved hypothesis usually becomes known as a theory.

Let's take an example. Remember the experiment for the Newton's law of universal gravitation. In an experiment like this, we should have a reference point, a hypothesis. The thought process would be, for example, to intuitively propose that the force of gravity depends on the masses of the two objects and the distance between them.

As a second step, sufficiently high number of experiments should be performed to prove this relationship with different masses and different distances to see how force correlates with the given variables.

Having noticed that the two masses are directly proportional to force and that force is inversely proportional to the square of a distance between the two objects, a proportionality constant is also found, so then we have an equation which would help us solve for the force of gravity between any two objects knowing their masses and the distance between them.

Overtime, after this hypothesis is proved analyzing substantial data, it becomes an accepted theory that can be used and applied.

A hypothesis that is extensively supported by numerous experiments and evidence can become a scientific theory, which is a well-substantiated explanation for a set of observations.

A hypothesis is a tentative explanation for scientific observations that seeks to put the system being studied into a testable form. When a hypothesis is supported through many experiments over an extended period, it can evolve into a well-substantiated explanation known as a scientific theory.

Scientific theories are broad explanations for events that are widely accepted as true because they have been thoroughly tested and are supported by a significant amount of evidence. For a hypothesis to become a scientific theory, it must consistently produce experimental results that agree with predictions, and it must withstand rigorous scrutiny. The process of experimental verification and any necessary modification of a hypothesis as part of its development into a theory is an essential aspect of the scientific method.

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:

D

Explanation:

A covalent bond is said to be formed when two electrons are shared between two bonding atoms as in the formation of the water molecule.

Covalent bonds form between hydrogen and oxygen atoms in a water molecule due to the sharing of electrons between these atoms. This is a characteristic behavior of covalent bonds, as opposed to ionic bonds that involve a transfer of electrons.

Covalent bonds form between hydrogen and oxygen atoms in a water molecule as a result of the sharing of electrons between atoms (option d). Unlike ionic bonds, which involve the transfer of electrons from one atom to another, covalent bonds occur when two atoms share one or more pairs of their valence electrons. In the case of water, each hydrogen atom shares an electron with the oxygen atom, forming two covalent bonds and resulting in the formation of a water molecule.

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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.

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: 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 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:

Magnet with a positive and a negative pole

Explanation:

A great analogy to demonstrate what a polar molecule looks like is to imagine a magnet. A magnet has one positively charged end and one negatively charged end, two poles, that is.

Imagine that we have a magnet of a shape of a prism (water molecule has a bent shape). The two base vertices of the face of the triangle are positively charged, that's because hydrogen is less electronegative than oxygen and, hence, the two hydrogen atoms are partially positively charged in a water molecule.

Oxygen is more electronegative than hydrogen meaning it has a greater electron-withdrawing force, so electrons are closer to oxygen within the O-H bonds. Oxygen, as a result, becomes partially negatively charged, so it's our negative pole of the magnet.

Final answer:

Water is a polar molecule with a partial negative charge on the oxygen atom and partial positive charges on the hydrogen atoms. An analogy that can be used to compare this is a magnet, where opposite poles attract each other. This polarity in water molecules allows for the formation of hydrogen bonds.

Explanation:

Water is a polar molecule due to the unequal sharing of electrons between the oxygen and hydrogen atoms. The oxygen atom attracts the shared electrons more strongly, resulting in a partial negative charge on the oxygen atom and partial positive charges on the hydrogen atoms. This creates a dipole in the molecule, with the oxygen end being slightly negative and the hydrogen end being slightly positive.

One analogy that can be used to compare this is a magnet. In a magnet, the north pole attracts the south pole, and vice versa. Similarly, the partial negative oxygen end of water attracts the partial positive hydrogen ends of nearby water molecules, forming hydrogen bonds. These hydrogen bonds are stronger than conventional dipole-dipole forces and contribute to some of the unique properties of water, such as its high boiling point and ability to dissolve many substances.

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:

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 answer is 79.875

Explanation:

355/22.5*100

The amount of alcohol in the bottle of mouthwash is equal to 79.88 ml.

The volume percent is the concentration of a solution which is determined by the volume of a solute divided by the volume of a solution and multiplied by 100.

Volume Percentage = (Volume of Solute/Volume of Solution) × 100

Because a solution is made of both a solute and a solvent, the volume of a solution is equal to the sum of the volumes of the solute as well as the volume of the solvent present in it. All of the volumes must be expressed in milliliters.

Given, the percentage of alcohol in the mouthwash = 22.5 %

If we consider that the volume of the bottle of mouthwash is 100ml.

Then the amount of alcohol present in it = 22.5 ml

If 100ml of a bottle of mouthwash contains alcohol = 22.5 ml

Then the 355 ml of a bottle of mouthwash will contain alcohol is

= (22.5/100) × 355

= 79.88 ml

Therefore, 79.88 ml of alcohol present in 355 ml of mouthwash.

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Answer: option A) adequacy

Explanation:

Definitely, ACK has an healthy diet missing ADEQUACY of energy provision. This is seen in the shortfall of 1200 kilocalories of energy (2800 - 1600 = 1200).

Note that Ack feed on varieties of food, thus he gets balanced diet, and a variety diet. However, he is short of 1200 kilocalories, thus making him miss ADEQUACY

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: norfenefrine [tex](C_8H_{11}NO_2)[/tex]

Explanation:

Depression in freezing point is given by:

[tex]\Delta T_f=i\times K_f\times m[/tex]

[tex]\Delta T_f=T_f^0-T_f=(-114.6-(-115.5)^0C=0.9^0C[/tex] = Depression in freezing point

i= vant hoff factor = 1 (for non electrolyte)

[tex]K_f[/tex] = freezing point constant = [tex]1.99^0C/m[/tex]

m= molality

[tex]\Delta T_f=i\times K_f\times \frac{\text{mass of solute}}{\text{molar mass of solute}}\times \text{weight of solvent in kg}}[/tex]

Weight of solvent (ethanol)= [tex]density\times volume=0.789g/cm^3\times 1.50cm^3=1.18g=1.18\times 10^{-3}kg[/tex]

Molar mass of unknown non electrolyte = M g/mol

Mass of unknown non electrolyte added = 82 mg = 0.082 g (1g=1000mg)

[tex]0.9=1\times 1.99\times \frac{0.082g}{M g/mol\times 1.18\times 10^{-3}}kg}[/tex]

[tex]M=154g/mol[/tex]

The molecular mass of norfenefrine [tex](C_8H_{11}NO_2)[/tex] is near to 154 and thus the identity of the white powder is norfenefrine .

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: 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.

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:

C. Atoms lose energy as a gas changes to a solid

Explanation:

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:

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.

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.

Learn more about wavelength here:

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