A square chunk of plastic has a length of 5 cm,
width of 5 cm, and a height of 5 cm. It has a
g. What is its density?
mass of 200

The answer is D. When an electron falls into the valence band to fill a hole, it gives up energy in the form of light.

The diode in an LED bulb is a semiconductor device that allows electricity to flow in one direction only. It is made of two pieces of semiconductor material, one positive and one negative, that are joined together.

The diode in the process of electrolysis has two terminals, called the anode and the cathode. The anode is the positive terminal and the cathode is the negative terminal in the electrolysis. The anode is connected to the positive terminal of the power supply and the cathode is connected to the negative terminal of the power supply.

When the power is turned on, the diode allows electricity to flow from the anode to the cathode and lights up the LED bulb.

The light-emitting diode will emit light when an electron jumps from the conduction band to the valence band. This is because when the electron falls into the valence band, it will release energy in the form of light.

Therefore the correct option is d.

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The reaction is exothermic in nature and the value of q in kJ is -1.12x10^3 kJ

The reaction is 2H₂S(g) + 3O₂(g)→→→→→→2H₂O(g) + 2SO₂(g)

The amount of heat evolved in the reaction = 1.12 X 103 KJ

2 moles of hydrogen sulphide react.

In an is In an endothermic reaction, energy is consumed. an exothermic reaction, energy evolved Thus, the given reaction is exothermic.

Exothermic reactions are those reactions in which the energy is evolved or released by the reaction.

And endothermic reactions are those reactions in which heat or energy is absorbed in the reaction.

Since the reaction is evolving energy.

Hence the reaction is an exothermic reaction.

The value of q is defined as the amount of heat transferred to the system.

Since the heat is going away from the system.

Hence the value of q will be -ve.

And the magnitude of q will be exactly the same as the amount of heat evolved by the reaction.

Hence q = -1.12 X 103 KJ  (-ve sign shows that heat is being evolved i.e exothermic process)

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another name for a maggot is a worm

The amount of the concentrated solution and water needed would be 154.5 mL and 345.5 mL respectively.

The problem here can be solved using the simple dilution equation that is expressed as:

[tex]m_1v_1[/tex] = [tex]m_2v_2[/tex]

Where [tex]m_1[/tex] is the molarity of the undiluted solution, [tex]v_1[/tex] is the volume of the underlined solution needed, [tex]m_2[/tex] is the molarity of the solution to be prepared, and [tex]v_2[/tex] is the volume of the solution to be prepared.

In this case:

[tex]m_1[/tex] = 0.7280 M

[tex]v_1[/tex] = ?

[tex]m_2[/tex] = 0.2250

[tex]v_2[/tex] = 500.0 mL

Rearranging the equation to make [tex]v_1[/tex] the subject:

[tex]v_1[/tex] = [tex]m_2v_2/m_1[/tex]

Now, let's substitute the values:

[tex]v_1[/tex] = 0.2250 x 500.0/0.7280

    = 154.5 mL

This means the volume of the concentrated solution needed is 154.5 mL out of 257.4 mL available. Since our final volume is 500.0 mL, the 154.5 mL stock solution will be made up to 500 mL with water.

Thus, the amount of water required would be:

500.0 - 154.5

  = 345.5 mL

In other words, the volume of the concentrated solution needed is 154.5 while the volume of water needed is 345.5 mL.

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The complete question: If you have 257.4 mL of a 0.7280 M potassium carbonate solution and you need 500.0 mL of a 0.2250 M potassium carbonate solution, how much concentrated solution and how much distilled water do you need?

The volume of the flask for the preparation of 0.231M solution can be 200ml flask. The equation C1V1 = C2V2 is used for the dilution of the samples.

What is dilution?

Dilution is a process in which a solution is made less concentrated by adding some other constituent to it. To dilute a solution more solvent should be added than the solute. The number of ions of solute remains the same but the volume is increased so the concentration decreases.

For the dilution using,

C1V1 = C2V2

5.2M x 8ml = 0.231M x V2

V2 = 5.2M x 8ml / 0.231M

V2 = 180.08ml.

Therefore, 180.08ml of new solution is made through dilution for which me need 200ml flask or higher volume flasks.

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The answer to the task from above about the an atom of element periodic table is given below:

The chlorine atom is one of the halogens in the periodic table.

Right from time immemorial, the indepth knowledge and understanding of how atoms are arranged in the periodic table and react with with each speaks volume of the identities of the properties of elements.

Chlorine is regarded as an halogen simply because they are salt formers when it atoms react with alkali metals.

So therefore, it can be deduced that the periodic table is the heart of chemistry.

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Answer:

Your break would end at 4:18

Explanation:

Mole measures the number of elementary entities of a given substance that are present in a given sample. The mass of hydrogen is 20.2gram.

The SI unit of amount of substance in chemistry is mole. The mole is used to measure the quantity of amount of substance.

Given number of atoms= 6.02 x 10²⁴atoms

we know one mole of any element contains 6.022×10²³ atoms which is also called Avogadro number

mole =given number of atoms ÷ 6.022×10²³(Avogadro number)

Substituting the values

mole=6.02 x 10²⁴÷ 6.022×10²³

mole = 10 mole

Mole = mass ÷Molar mass

Molar mass = 2.02 g/mol

Substituting the given values

10= mass ÷ 2.02 g/mol

Mass = 20.2gram

Therefore, mass of hydrogen is 20.2gram.

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The pressure of 8.06 L of an ideal gas in a flexible container is decreased to one-third of its original pressure, and its absolute temperature is decreased by one-half and the final volume of gas is 12.09 L

The volume of gas in a flexible container is 8.06 L

The pressure is P1=X atm

Temperature is T1=YK

Let us calculate the volume V2 if Pressure P2=X/3 atm

Temperature T2=Y/2 K

Using the ideal gas equation, we get

P1V1/T1=P2V2/T2

V2=V1P1T2/T1P2

V2=8.06LX atm×Y/2K/YK.X/3 atm

V2=8.06x3/2

V2=12.09 L

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Answer:

A

B that is Cr,MN,Fe,Co. is the correct answer

C

D

The pressure that must be applied to increase the dentisy by 0.10% is 453.48 atm.

It's important to note that isothermal compressibility simply means the fractional differential change that can be seen in the volume as a result if the change in pressure.

It should be noted that the isothermal compressibility formula will be:

= 1/v (dv/dp)

where v = volume

p = pressure

dv = 0.10% = 0.001

This will be:

2.21 × 10^(-6) = 0.001/dp

dp = 0.001 / 2.21 × 10^(-6)

dp = 452.48 atm

New pressure = 1 atm + 452.48 atm

= 453.48 atm

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Complete question

The isothermal compressibility of lead at 293 K. Calculate the pressure that must be applied to increase the dentisy by 0.10%.

The new volume of a gas 40ml, if 50 mL at 81.0 kPa has its pressure increased to 101.3 kPa.

What is Boyle's Law?

Boyle's law is a gas law that states that the pressure exerted by a gas (with a given mass and constant temperature) is inversely proportional to its volume. In other words, as long as the temperature and amount of gas remain constant, the pressure and volume of a gas are inversely proportional to each other. Boyle's law was proposed in 1662 by the Anglo-Irish chemist Robert Boyle.

Any change in the volume occupied by a gas (at constant quantity and temperature) results in a change in the pressure exerted by it, according to Boyle's law.

In other words, the product of a gas's beginning pressure and volume is equal to the product of its end pressure and volume (at constant temperature and number of moles).

P1V1 = P2V2

Where,

P1 denotes the gas's initial pressure.

V1 denotes the gas's initial volume.

P2 denotes the gas's final pressure.

V2 denotes the gas's final volume.

The pressure-volume relationship provided by Boyle's law can be used to get this phrase. PV = k for a fixed amount of gas kept at a constant temperature. Therefore,

P1V1 = k (starting pressure * starting volume)

P2V2 = k (last pressure * last volume)

∴ P1V1 = P2V2

According to Boyle's Law

p1v1=p2v2

81x50= 101.3xv2

v2 = 140ml

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The final concentration of the diluted solution of NaF is equal to 1.24 M.

The concentration and the volume of the stock solution or dilute solution can be determined from the following equation:

M₁V₁ = M₂ V₂

where M₁ and V₁ are the concentration and volume of the stock or concentrated solution respectively and M₂ and V₂ are the concentration and volume of the diluted solution.

Given, a stock solution of NaF of concentration, M₁ = 2.4 M

The concentration of the diluted solution of NaF is M₂.

The volume of the concentrated solution of NaF, V₁ = 1.7 L

The volume of diluted solution of NaF, V₂  = 3.3 L

Substitute the value of the concentration and volume of NaF in equation (1):

(2.4)× (1.7) =  M₂ × (3.3)

M₂ = 1.24 M

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Answer:

4.4 x 10⁻¹⁹ J

Explanation:

To find the energy of the photon, you need to use the following equation:

E = hf

In this equation,

-----> E = energy (J)

-----> h = Planck's Constant (6.626 x 10⁻³⁴ J·s)

-----> f = frequency (Hz)

You can plug the given value and constant into the equation and solve for "E". The final answer should have 2 sig figs like the given value (6.7 x 10¹⁴ = 2 sig figs).

E = hf                                                               <----- Given equation

E = (6.626 x 10⁻³⁴ J·s)(6.7 x 10¹⁴ Hz)              <----- Insert values

E = 4.4 x 10⁻¹⁹ J                                              <----- Multiply

A weak base equilibrium as shown in the equation below.  the effect on Kb if  BH⁺ were added to the solution; the equilibrium constants  is remains unchanged.

The equation is given as :

B (aq) + H2O (l) ⇌ BH⁺ (aq) + OH⁻ (aq)

K = [ BH⁺ ] [ OH⁻] / [B]

the equilibrium constant  for the given reaction is remain unchanged. the equilibrium constant will only depends on the temperature of the reaction.

Thus, A weak base equilibrium as shown in the equation below.  the effect on Kb if  BH⁺ were added to the solution; the equilibrium constants  is remains unchanged.

B (aq) + H2O (l) ⇌ BH⁺ (aq) + OH⁻ (aq)

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The energy used to heat the iron from 25°C to 75°C will be 88J

Given,

m= 4 g

c, i.e, specific heat of Iron is 0.44 J°C⁻¹g⁻¹

The heat energy is given by  formula,

q=mcΔT

where q is the amount of heat and m is the substance's mass.

T represents the temperature change, and c is the material's specific heat capacity. The addition of heat affects various substances in varying degrees. Different materials' temperatures rise by different amounts when a given amount of heat is applied to them.

q =4× 0.44× ΔT

ΔT= T₂₋ T₁

ΔT= 75- 25

= 50°C

q= 4×0.44×50

=88 J

So, the energy used to heat the iron will be 88J.

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The volume of the lead II iodide required is 649 mL.

We know that the volume can be obtained by the use of the stoichiometry of the reaction. In this case, we have been given the balanced reaction equation as it appears in the question above. We now have to use it and find the volume as the question must have required.

Thus;

Number of moles of the lead II nitrate = 0.660 M * 319/1000 L

= 0.211 moles

Now we have to recall again that the number of moles is obtained as the product of the concentration and the volume of the solution.

Using the stoichiometry of the reaction;

1 mole of the  lead II nitrate reacts with 2 moles of the ammonium iodide

0.211 moles  of the  lead II nitrate reacts with 0.211 moles  * 2 moles/ 1 mole

= 0.422 moles

Now;

Volume of the solution = number of moles/ concentration

= 0.422 moles/0.650 M

= 0.649 L or 649 mL

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The solubility constant (Ksp) of lead (II) chloride if it has a molar concentration of 1.6 × 10-²M is 1.64 × 10-⁵.

Solubility is the amount of a substance that will dissolve in a given amount of a solvent, to give a saturated solution, under specified conditions.

PbCl₂(s) ⇌ Pb²⁺(aq) + 2Cl¯(aq)

The Ksp expression of lead chloride is as follows:

Ksp = [Pb²+] [Cl¯]²

There is a 1:1 molar ratio between PbCl₂ and Pb²⁺ but a 1:2 molar ratio between PbCl₂ and Cl.

Ksp = {1.6 × 10-²} {3.2 × 10-²}²

Ksp = 1.64 × 10-⁵

Therefore, 1.64 × 10-⁵ is the solubility constant of the lead (II) chloride.

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The number of grams of oxygen that can be prepared from 8.50g of pottasium chlorate is 3.33grams.

Stoichiometry is the study and calculation of quantitative (measurable) relationships of the reactants and products in chemical reactions (chemical equations).

According to this question, the decomposition of KClO₃ is generally used to prepare small amounts of O₂ in the laboratory.

2KClO₃ → 2KCl + 3O₂

Based on the above equation, 3 moles of oxygen is produced by the decomposition of 2 moles of pottasium chlorate.

8.50grams of KClO₃ is calculated in moles as follows: 8.50g ÷ 122.55 g/mol = 0.069mol of KClO₃.

This means that 0.069 × 1.5 = 0.104 moles of oxygen is produced.

mass of oxygen produced = 0.104 × 32 = 3.33grams.

Therefore, 3.33grams is the mass of oxygen formed.

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In the formation of the sodium chloride, there is the loss of one electron from the sodium atom to the chlorine atom.

An ionic bond is the kind of bond that is formed between a metal and a non metal. The metal is known to donate electrons to the non metal. In the actual sense, the compound that is formed is an ion pair because the metal is positively charged while the non metal is negatively charged.

In the case of the sodium chloride, we know that the both elements, sodium and chlorine are highly reactive. Hence the sodium atom would quickly loose electrons to the chlorine atom and then the sodium chloride compound is formed.

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The image shows the Bohr model of the chlorine atom.

We know that the Bohr model has to do with the model in which the electrons that are in the atoms are arranged in a definite order. The implication of this is that the electrons would be arranged in a certain specific energy level such that an electron can be moved from a lower to a higher energy level as we can see from the image that has been shown in the question that has been asked.

Having said that we have seventeen protons in the atom and the implication is that there are also seventeen electrons in the atom and this is going to correspond to the element chlorine atom which can be shown to be a member of the group seventeen of the periodic table of the elements.

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A gas evolved during a chemical reaction and has a volume of 651 mL at 38 °C and 869 torr.  the volume of this gas in mL at 110 °C and 3.87 atmospheres was 238 mL.

given that :

volume V1 = 651 mL

temperature T1 = 38 °C = 38 + 273 = 311 K

pressure P1  = 869 torr = 1.14 atm

pressure P2 = 3.87 atm

temperature T2 = 110 °C = 110 + 273 = 383 K

volume V2 ?

using ideal gas equation , we get :

P1 V1 / T1 = P2 V2 / T2

(1.14 × 651 ) / 311 = (3.87 × V2 ) / 383

2.38 = 0.010 V2

V2 = 238 mL

Thus, A gas evolved during a chemical reaction and has a volume of 651 mL at 38 °C and 869 torr.  the volume of this gas in mL at 110 °C and 3.87 atmospheres was 238 mL.

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Answer:

1.468 M

Explanation:

Answer:

See explanation

Explanation:

3. so the three metals are Cu, Zn, and Fe (i'm assuming based off of the other answers)

A metal (M1) more reactive than the one in solution (M2) will swap places, precipitating M2 out and M1 will dissolve in solution.
So as an example, Zinc is more reactive than Copper, so Zinc metal will displace Copper 2+ in solution, giving Copper metal and Zinc 2+ in solution

The metal ion in solution is Zn2+, which is a pretty reactive metal. We know that a metal has to be more reactive than Zn to turn Zn2+ into Zn. This means that any metal which produces a change when allowed into contact with Zn2+ would have to be very reactive.

The three metal wires are: Cu, Zn, and Fe

Cu is not more reactive than Zn, so no reaction will occur between Cu and Zn2+.

Fe is not more reactive than Zn, so no reaction between Fe and Zn2+

Zn is well... as reactive as Zn, so there will also be no reaction (because there is no incentive for change, no change happens)

Thus, number 3 will have an answer of "No reactions were observed, and no spontaneous chemical equations can be written" (Though zinc does react with water very slowly. Also, if the ZnCl2 was contaminated with acid, the Zinc wire may have formed some bubbles )

For number 4, it is the same logic. But it is also a little more complicated.
The metal in solution is Fe3+. The wires are Zn, Fe, and Cu
The annoying (or cool, depending on how you look at it) thing about Fe3+ is that it can be reduced to either Fe2+(aqueous), or all the way to Fe(solid).
depending on how much reactant is added and what exactly that other reactant is.

From this point on, instead of saying "Because Zn is more reactive than Fe..." I'll say "Because Zn turning into Zn2+ is more favourable than Fe turning into Fe3+" or something of the sort. Hopefully It doesn't become too confusing. Please ask questions in the comments

Zn turning into Zn2+ is much more favorable than Fe turning into Fe3+, so the Zn will react with Fe3+, turning it into Fe and giving Zn2+ (Charges are not balanced)

So Zn(s) + Fe{3+}(aq) -> Zn{2+}(aq) + Fe(s)

and balance it to get

3Zn(s) + 2Fe{3+}(aq) -> 3Zn{2+}(aq) + 2Fe(s)

Fe may seem like it would not react with Fe3+ since they both are iron. However Fe2+ exists, and since Fe2+ turning into Fe3+ is unfavourable (meaning that Fe3+ is a stronger oxidant) and Fe turning into Fe2+ is favourable, the following reaction happens:

Fe(s) + 2 Fe{3+}(aq) -> 3Fe{2+}(aq)

In this reaction, each iron metal atom gives two iron 3+ ions one electron, loosing 2 electrons itself in the process and turning into Fe2+. The two iron 3+ ions given one electron also turn into Fe2+ ions, resulting in 3 Fe2+ ions total

Copper is fairly unreactive, and while FeCl3 is technically reactive enough to react with copper, forming FeCl2 and CuCl, the CuCl layer prevents underneath copper from reacting further.

The weight percent of KCN and NaCN in the original sample are;

The weight percent of KCN and NaCN in the original sample is calculated as follows:

The mass of the original mixture of KCN and NaCN = 0.7256 g

The dissociation equation of the ionic compounds in an aqueous solution is given below:

KCN ⇄ K⁺ + CN⁻

NaCN ⇄ Na⁺ + CN⁻

Mass of precipitate of AgCN = 2.5874 g

Moles of AgCN in a 2.5874 g sample = mass / molar mass

molar mass of AgCN = 133.886 g/mol

Moles of AgCN in the sample = 2.5874 / 133.886

Moles of AgCN in the sample = 0.01932 moles

Moles of CN⁻ in the sample = 0.01932 moles

Mass of CN⁻ present in the sample = 0.01932 * 26

Mass of CN⁻ present in the sample = 0.50232 g

Moles of Na⁺ present = 0.01932 / 2 moles

Moles of Na⁺ present = 0.009663 moles

Mass of Na⁺ present = 0.00966 * 23

Mass of Na⁺ present = 0.2222 g

Moles of K⁺ present = 0.01932 / 2 moles

Moles of K⁺ present = 0.00966 moles

Mass of K⁺ present = 0.009663 * 39

Mass of K⁺ present = 0.3768 g

Mass of sample =  0.50232 g + 0.2222 g + 0.3768 g

Mass of sample = 1.10132 g

weight percent of KCN = (0.3768 + 0.50232/2)/1.10132 * 100%

weight percent of KCN = 57%

weight percent of NaCN = (100 - 57)%

weight percent of NaCN = 43%

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Since the A digital signal transmits energy in the form of waves, the conclusion that would be best based on this information is option C:  Digital transmission of information is a fast and reliable method.

Signals, both digital and analog, are transferred via electromagnetic waves. The sound you hear or the graphics you see on a screen are the result of changes in frequency and amplitude. The continuous waves that make up analog signals can be of any frequency and amplitude.

Note that Data transfer, also known as digital transfer or digital communication, is the movement of data between two locations. Digital messages from a data source, such as a computer or keyboard, may be the source of the transmitted data. A phone call or a video signal are examples of analog signals that could also be present.

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The value of hydroxide ion concentration, [OH⁻] in the table, given that [H₃O⁺] is 2.0×10⁻⁶ M, is 5.0×10⁻⁹ M

From the defininion of pH, we understood that the relationship between hydronium ion, H₃O⁺ and hydroxide ion, OH⁻ in a solution is given as:

[H₃O⁺] × [OH⁻] = 10¯¹⁴

With the above formula, we can determine the value of the hydroxide ion, OH⁻. Details below:

[H₃O⁺] × [OH⁻] = 10¯¹⁴

2.0×10⁻⁶ × [OH⁻] = 10¯¹⁴

Divide both side by 2.0×10⁻⁶

[OH⁻] = 10¯¹⁴ / 2.0×10⁻⁶

[OH⁻] = 5.0×10⁻⁹ M

Thus, we can conclude that the hydroxide ion concentration, [OH⁻] is 5.0×10⁻⁹ M

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+571.6 KJ and 1803.03 J/K are  the entropy (S) of system and the change of S of surrounding.

2H2O(l) --->2H2(g) + O2(g)

first step is to get dHrxn = dHf(Products) - dHf(reactants)

take dHf of reactants and products from standard thermodynamic table

dHf(H2O) = -285.8 KJ/mol

dHf(H2) =0 kj/mol

dHf(O2)= 0 kj/mol

dHrxn = 2dHf(H2) + dHf(O2) - 2dHf(H2O)

  = 2*0 + 0 - 2 [-285.8] kj =  +571.6 KJ

this is for 2 mole of H2O

for 1.88 mols H2O, dHrxn =  +571.6 KJ/2mol×1.88 mol = 537.304 kj

T =298 K

dS surrounding = - dHrxn/T = -537304 j/298 K = -1803.03 J/K

Entropy is the measurement of the amount of thermal energy per unit of temperature in a system that cannot be used for productive labor. Entropy is a measure of a system's molecular disorder or unpredictability since work is produced by organized molecular motion.

In an isolated system—one that does not exchange heat or work with its surroundings—spontaneous change for an irreversible process always moves in the direction of rising entropy, according to the Clausius form of the second law. For instance, the ice block and the stove are two components of a standalone system for which the overall entropy rises as the ice melts.

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Morphine is used medicinally as a pain reliever. If an aqueous solution of morphine has [H3O⁺] = 1.1 x 10-10 M, the pH of this solution is 9.6.

given that :

[H3O⁺] = 1.1 x 10-10 M

the pH of the solution is given as :

pH = - log ( [H3O⁺] )

pH = - log (  1.1 x 10-10 M )

pH = - (-9.6 )

pH = 9.6

the pH of the given solution is 9.6.

Thus, Morphine is used medicinally as a pain reliever. If an aqueous solution of morphine has [H3O+] = 1.1 x 10-10 M, the pH of this solution is 9.6.

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