The molecular-orbital model for Ge shows it to be:_______.
A) a conductor, because all the lower energy band orbitals are filled and the gap between the lower and higher bands is large.
B) an insulator, because all the lower energy band orbitals are filled and the gap between the lower and higher bands is large.
C) a semiconductor, because the gap between the filled lower and empty higher energy bands is relatively small.
D) a semiconductor, because the gap between the filled lower and empty higher energy bands is large.
E) a conductor, because its lower energy band orbitals are only partially filled.
Answer:
Option C
Explanation:
Pure germanium is a bad conductors of electricity. It is so because its valence band is full and its outer electrons are attached through covalent bond is a diamond like framework. In metallic sense, it is neither a conductor nor an insulator but a semiconductor. It has a small band gap of 0.7eV.
Hence, option C is correct
What is The charge of PbI2
Answer:
Lead iodide (II) is an inorganic compound, lead salt and hydrogen acid, with the PbI2 formula.
in the photosynthesis the energy starts as ___ energy and ends up as___energy
light heat
chemical: chemical
heat light
light chemical
Answer: Light, Chemical
Explanation: This is the answer because "photosynthesis takes place in two stages: the light-dependent reactions and the Calvin cycle. In the light-dependent reactions, which take place at the thylakoid membrane, chlorophyll absorbs energy from sunlight and then converts it into chemical energy with the use of water." - source https://opentextbc.ca/
In the photosynthesis the energy starts as Light energy and ends up as Chemical Energy. Hence option (D) is correct
What is Photosynthesis ?The process by that inexperienced plants and a few different organisms use daylight to synthesize nutrients from carbonic acid gas and water. chemical action in plants usually involves the inexperienced pigment and generates element as a by-product.
Photosynthesis may be a method employed by plants and different organisms to convert lightweight energy into energy that, through internal respiration, will later be discharged to fuel the organism's activities.
photosynthesis takes place in 2 stages: the light-dependent reactions and also the Calvin cycle. within the light-dependent reactions, that manifest itself at the thylakoid membrane, pigment absorbs energy from daylight and so converts it into energy with the employment of water.
Therefore, In the photosynthesis the energy starts as Light energy and ends up as Chemical Energy. Hence option (D) is correct
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Other than solubility of sample in the solvent, what is the criteria for the solvent (other than cheap and nontoxic) used for preparing the sample that impacts the experiment and why would this criteria be important in the spotting phase if you have to make repeated applications of the sample?
Answer and Explanation:
In order for the spotting phase to be efficient and for the sample to register the repeated applications of the sample, it is necessary that in addition to the solubility and low toxicity, the solvent has a low boiling point, but that allows an efficient and rapid evaporation, whenever necessary, so that it is possible to release the sample on the TLC plate.
The solvent must be able to dissolve the compounds completely with minimal heating.
Even though the question is incomplete but I will try to help you as much as possible. Solvents are considered based .on their specific applications. Generally, a solvent should be non toxic and cheap.
Also, the solvent must be able to dissolve the compounds completely with minimal heating. This is important in deciding weather the solvent is suitable or not.
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Which of the following is evidence that a chemical
change is occurring?
a. Cherry drink mix is added to water and the resulting
solution is red.
b. A white powder is added to cool tap water in a beaker
and the beaker gets hot.
c. Water is added to coffee until the solution becomes
clear.
d. Water is added to sand and the sand looks darker
Answer:
c. water is added to coffe until the solution becomes clear
Answer:
c
Explanation:
Water is added to coffee until the solution becomes
clear.
3. A very large distillation column is separating p-xylene (more volatile) from o-xylene. The column has two feeds that are saturated liquids. Feed 1 flows into the column at a rate of 90 kmol/h and contains 42 mol% p-xylene. Feed 2 flows at a rate of 20 kmol/h and contains 9 mol% p-xylene. The bottoms product should be 97 mol% o-xylene, and the distillate product should be 99 mol% p-xylene. Compute the distillate (D) and the bottoms (B) products flow rates
Answer:
the distillate (D) and the bottoms (B) products flow rates are;
B = 72.1875 kmol/hr
D = 37.8125 kmol/hr
Explanation:
Given the data in the question;
as illustrated in the image below;
F1 stream, ( 90 kmol/hr ) contains 42 mol% p-xylene and Feed 2 ( 20 kmol/hr) contains 9mol% p-xylene, so;
more volatile → p-xylene
less volatile → o-xylene
now, Overall balance;
F1 + F2 = D + B
90 + 20 = D + B
D + B = 110 ------------- let this be equation 1
p-xylene. component balance;
0.42F1 + 0.09F2 = 0.99D + 0.03B
0.42(90) + 0.09(20) = 0.99D + 0.03B
37.8 + 1.8 = 0.99D + 0.03B
0.99D + 0.03B = 39.6 --------------- let this be equation 2
from equation 1 and 2
input (D = 110 - B) into equation 2
0.99(110 - B) + 0.03B = 39.6
108.9 - 0.99B + 0.03B = 39.6
108.9 - 39.6 = 0.99B - 0.03B
69.3 = 0.96B
B = 69.3 / 0.96
B = 72.1875
now, input B = 72.1875 into equation 1
D + B = 110
D + 72.1875 = 110
D = 110 - 72.1875
D = 37.8125
Therefore, the distillate (D) and the bottoms (B) products flow rates are;
B = 72.1875 kmol/hr
D = 37.8125 kmol/hr
Which of the following things would be the MOST irresistible for a dog?
A
a veterinarian
B
a fire hydrant
C broccoli vomit surprise
Answer:
B.a fire hydrant
hope it helps!
Answer:
a veterinarian
Explanation:
i think
In the morning, a paintball pressure tank is at 306 atm. The weather heats up over the
course of the day, and by 3 PM, the outside temperature is roasting at 38.5°C, and the
pressure inside the tank is 324 atm. What was the temperature (in degree Celsius) in the
morning?
Carbon dioxide was used by early plants so that they could
grow / photosynthesise.
More plants developed and used more carbon dioxide.
What one is it grow or photosynthesis?
Answer:
Plants use carbon dioxide for photosynthesis
Explanation:
They take it in, and chemically combined it with water to form glucose and oxygen
Which of these describes a Mole in Chemistry?
A. A counting term for substances
B. The Molar mass of substance in grams
C. 6.02 x 10^23
D. All of the above describe a mole
Answer:
I think it's B, good luck
A chemistry graduate student is studying the rate of this reaction:
NH4OH(aq)→NH3(aq)+H2O(aq)
She fills a reaction vessel with and measures its concentration as the reaction proceeds:
Time (minutes) NH4OH
0 0.200M
1.0 0.0895M
2.0 0.577M
3.0 0.0426M
4.0 0.0337M
Use this data to answer the following questions.
a. Write the rate law for this reaction.
b. Calculate the value of the rate constant.
Answer:
Rate = k[NH₄OH]²
k = 6.17
Explanation:
We have concentrations of NH₄OH along with the given times. To determine the rate law of the reaction we need to determine first the order of reaction. This reaction can be order zero, first or second order. The expressions for each are the following:
Zero order:
k = [A₀] - [A] / t
First order:
k = 1/t * ln([A₀]/[A])
Second order:
k = (1/t) * (1/[A₀] - 1/[A])
And from here, the next part is easier. We just need to determine hat order is, calculating the value of k at two different times. If the value of k is constant, then we can say that the reaction is of that order.
Let's suppose its order zero (t = 1 and t = 2, [A₀] = 0.200 M):
k1 = 0.2 - 0.0895 / 1 = 0.1105
k2 = 0.2 - 0.577 / 2 = -0.1885
From this results we can conclude it's not zero order.
Let's suppose its order 1:
k1 = ln(0.2/0.0895) / 1 = 0.8041
k2 = ln(0.2/0.577) / 2 = 0.1733
It's not first order either, so we can conclude that this reaction is of 2nd order and the rate law would be:
Rate = k[NH₄OH]²Now that we know it's a second order reaction, we can determine the value of k using its expression:
k = (1/t) (1/[A] - 1/[A₀])
k = ln(1/0.0895 - 1/0.2) (1/1)
k = 6.17
And to confirm this value, let's calculate k for t = 2 s
k = (1/2) (1/0.0577 - 1/0.2)
k = 6.17The value is constant, so this is the true value of k.
Hope this helps
What does a wider tree ring indicate as opposed to a thinner tree ring
Answer:
Thicker rings indicate a longer or faster growing season. This means that the temperature was high for a longer time and allowed the tree to grow more. Smaller rings show shorter or slower growing seasons which means either the temperature was low or the tree didn't have enough water to grow very much.
Explanation:
Hoped that helped!
A DNA sample and a plasmid with the ampR and lacZ(for the enzyme beta-galactosidase) genes are treated with Pstl with the goal of making recombinant DNA molecules. the lacZ gene is placed in the cloning region so that it is disrupted by DNA inserts. Put the remaining steps for this process in the right order. NOT ALL statements will be used! The first step has already been given to you.
step options: -all the fragments have the sticky ends 5'-CTGCAG-3'
-cells containing the recombinant plasmid are grown in a medium with
ampicillin and x-gal(a galactose derivative)
-blue colonies that survive on the culture medium contain the
recombinant plasmid
-all the fragments have identical sticky ends: 5'-TGCA-3'
-colonies containing the recombinant plasmid can be removed from the
culture medium and grown
-DNA ligase joins the sticky ends of the DNA sample and the plasmid
-white colonies that survive on the culture medium are identified as
having the recombinant plasmid
step 1) DNA is treated with restriction enzyme
step 2)
step 3)
step 4)
step 5)
step 6)
Answer:
Explanation:
The main aim of this experiment is to correctly identify the sequential steps needed for making recombinant DNA molecules.
The first step is given as:
DNA is treated with restriction enzyme
The remaining steps in order are:
[tex]\text{-all the fragments have identical sticky ends: 5'-TGCA-3'}[/tex]
[tex]\text{-DNA ligase joins the sticky ends of the DNA sample and the plasmid}[/tex]
[tex]\text{-cells containing the recombinant plasmid are grown in a medium with}[/tex]
[tex]\text{ampicillin and x-gal(a galactose derivative)}[/tex]
[tex]\text{-white colonies that survive on the culture medium are identified as}[/tex]
[tex]\text{having the recombinant plasmid}[/tex]
[tex]\text{-colonies containing the recombinant plasmid can be removed from the}[/tex]
[tex]\text{culture medium and grown}[/tex]
Question 8 of 25
What is alchemy?
O A. A scientific approach to research that uses observations and
measurements to test ideas
O B. An early form of chemistry that people used to try to turn metal
into gold
O c. A belief that chemistry forms the basis of all areas of science
O D. An ancient philosophy that taught that all matter was composed
of earth, fire, water, and air
SUBMIT
Alchemy is "an early form of chemistry that people used to try to turn metal into gold".
The development of a universal cure for illness, as well as the discovery of a way to indefinitely extend life, were the goals of mediaeval chemical research and speculative philosophy.
Boyle contributed to the evolution of chemistry from alchemy. He used the experimental approach from physics and applied it to chemistry. Boyle contributed to the comparison of these two fields of knowledge by demonstrating that chemistry is just as important to study as physics.
Therefore, the correct statement will be "An early form of chemistry that people used to try to turn metal into gold".
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Help please thank you!!!
Answer:
I think its J
Explanation:
sorry if im wrong
A chemist titrates 190.0 mL of a 0.8125 M ammonia (NH) solution with 0.3733 M HCl solution at 25 °C. Calculate the pH at equivalence. The pK, of
ammonia is 4.75.
Round your answer to 2 decimal places.
Note for advanced students: you may assume the total volume of the solution equals the initial volume plus the volume of HCl solution added.
pH ?
Answer:
Approximately [tex]4.92[/tex].
Explanation:
Initial volume of the solution: [tex]V = 190.0\; \rm mL = 0.1900\; \rm L[/tex].
Initial quantity of [tex]\rm NH_3[/tex]:
[tex]\begin{aligned} n({\rm NH_3}) &= c({\rm NH_3}) \cdot V({\rm NH_3}) \\ &= 0.3733\; \rm mol \cdot L^{-1} \times 0.1900\; \rm L \\ &\approx 0.154375\; \rm mol\end{aligned}[/tex].
Ammonia [tex]\rm NH_3[/tex] reacts with hydrochloric [tex]\rm HCl[/tex] acid at a one-to-one ratio:
[tex]\rm NH_3 + HCl \to NH_4 Cl[/tex].
Hence, approximately [tex]n({\rm HCl}) = 0.154375\; \rm mol[/tex] of [tex]\rm HCl\![/tex] molecules would be required to exactly react with the [tex]\rm NH_3\![/tex] in the original solution and hence reach the equivalence point of this titration.
Calculate the volume of that [tex]0.3733\; \rm mol \cdot L^{-1}[/tex] [tex]\rm HCl[/tex] solution required for reaching the equivalence point of this titration:
[tex]\begin{aligned}V({\rm HCl}) &= \frac{n({\rm HCl})}{c({\rm HCl})} \\ &\approx \frac{0.154375\; \rm mol}{0.3733\; \rm mol \cdot L^{-1}} \approx 0.413541\; \rm L\end{aligned}[/tex].
Hence, by the assumption stated in the question, the volume of the solution at the equivalence point would be approximately [tex]0.413541\; \rm L + 0.1900\; \rm L \approx 0.6035\; \rm L[/tex].
If no hydrolysis took place, [tex]0.154375\; \rm mol[/tex] of [tex]\rm NH_4 Cl[/tex] would be produced. Because [tex]\rm NH_4 Cl\![/tex] is a soluble salt, the solution would contain [tex]0.154375\; \rm mol\![/tex] of [tex]\rm {NH_4}^{+}[/tex] ions. The concentration of [tex]\rm {NH_4}^{+}\![/tex] would be approximately:
[tex]\begin{aligned}c({\rm {NH_4}^{+}}) &= \frac{n({\rm {NH_4}^{+}})}{V({\rm {NH_4}^{+}})}\\ &\approx \frac{0.154375\; \rm mol}{0.6035\; \rm L} \approx 0.255782\; \rm mol \cdot L^{-1}\end{aligned}[/tex].
However, because [tex]\rm NH_3 \cdot H_2O[/tex] is a weak base, its conjugate [tex]\rm {NH_4}^{+}[/tex] would be a weak base.
[tex]\begin{aligned}pK_{\rm a}({{\rm NH_4}}^{+}) &= pK_{\rm w} - pK_{\rm b}({\rm NH_3})\\ &\approx 13.99 - 4.75 = 9.25\end{aligned}[/tex].
Hence, the following reversible reaction would be take place in the solution at the equivalence point:
[tex]\rm {NH_4}^{+} \rightleftharpoons NH_3 + H^{+}[/tex].
Let [tex]x\; \rm mol \cdot L^{-1}[/tex] be the increase in the concentration of [tex]\rm H^{+}[/tex] in this solution because of this reversible reaction. (Notice that [tex]x \ge 0[/tex].) Construct the following [tex]\text{RICE}[/tex] table:
[tex]\begin{array}{c|ccccc} \textbf{R}& \rm {\rm NH_4}^{+} & \rightleftharpoons & {\rm NH_3}& + & {\rm H}^{+}\\ \textbf{I} & 0.255782 \; \rm M \\ \textbf{C} & -x \;\rm M & & + x\;\rm M & & + x\; \rm M \\ \textbf{E} & (0.255782 - x)\; \rm M & & x\; \rm M & & x\; \rm M\end{array}[/tex].
Thus, at equilibrium:
Concentration of the weak acid: [tex][{\rm {NH_4}^{+}}] \approx (0.255782 - x) \; \rm M[/tex].Concentration of the conjugate of the weak acid: [tex][{\rm NH_3}] = x\; \rm M[/tex].Concentration of [tex]\rm H^{+}[/tex]: [tex][{\rm {H}^{+}}] \approx x\; \rm M[/tex].[tex]\displaystyle \frac{[{\rm NH_3}] \cdot [{\rm H^{+}}]}{[{ \rm {NH_4}^{+}}]} = 10^{pK_\text{a}({\rm {NH_4}^{+}})}[/tex].
[tex]\displaystyle \frac{x^2}{0.255782 - x} \approx 10^{-9.25}[/tex]
Solve for [tex]x[/tex]. (Notice that the value of [tex]x\![/tex] is likely to be much smaller than [tex]0.255782[/tex]. Hence, the denominator on the left-hand side [tex](0.255782 - x) \approx 0.255782[/tex].)
[tex]x \approx 1.19929 \times 10^{-5}[/tex].
Hence, the concentration of [tex]\rm H^{+}[/tex] at the equivalence point of this titration would be approximately [tex]1.19929 \times 10^{-5}\; \rm M[/tex].
Hence, the [tex]pH[/tex] at the equivalence point of this titration would be:
[tex]\begin{aligned}pH &= -\log_{10}[{\rm {H}^{+}}] \\ &\approx -\log_{10} \left(1.19929 \times 10^{-5}\right) \approx 4.92\end{aligned}[/tex].
A chemical process involves adding various agents to a vat and then waiting for the agents to react to make a final compound. The vat holds up to 1000 gallons. Chemical agents are added to the vat at a rate of 4.5 gallons per minute. Once the agents have been added to the vat, the reaction takes 85 minutes no matter the actual number of gallons in the batch. After the batch is complete, the vat must be cleaned. Cleaning always takes 15 minutes. What is the setup time of this process
Answer:
the total setup time of this process is 100 minutes
Explanation:
Given the data in the question;
Vat holds up to 1000 gallons;
Rate of chemical agents being added to the vat = 4.5 gpm
Reaction time = 85 minute
cleaning ( waiting time ) 15 minute
the setup time of this process = ?
To calculate the setup time for this process, we simply say;
the setup time = Reaction time + cleaning ( waiting time )
so we substitute in our values
the setup time = 85 mins + 15 mins
the setup time = 100 minutes
Therefore, the total setup time of this process is 100 minutes
What is the correct order for the three steps of how a hormone would work
A. Response > Reception > Transduction.
B. Reception > Response > Transduction.
C. Reception > Transduction > Response.
D. Transduction Response > Signaling.
Answer:
answers is -d
Explanation:
,kggc’hnftfj’trudging.ugu,y
Calculate how many grams of BeCl2 are required to produce 0.52 grams of MnCl2
Answer:
65.0cp
Explanation:
Which gland in the human body is a part of two human body systems (Digestive &
Endocrine)?
A. Testes
B. Ovaries
C. Both
D. Pancreas
Answer: D pancreas
Explanation: testes are for male ovary are for female one human can have both
A sample of NH3(g) is placed in a rigid container. When the equilibrium below is established, the partial pressure of hydrogen gas is 0.978 atm. What is the partial pressure of N2(g) at equilibrium?
Answer:
PpN₂ = 0.326 atm
Explanation:
In this case, let's write the equilibrium reaction taking place here:
2NH₃(g) <------> 3H₂(g) + N₂(g)
Now, we know that when the reaction reach the equilibrium the partial pressure of H₂ is 0.978 atm, so, let's write an ICE chart and see what's happening here:
2NH₃(g) <------> 3H₂(g) + N₂(g)
i) y 0 0
c) -2x +3x x
e) y-2x 3x x
At the beggining we just have the sample of NH₃, we don't know how much but we don't need that data to get the partial pressure. In equilibrium, its produced hydrogen and nitrogen, and we know how much of hydrogen was produced, so, with that we can solve for the value of the partial pressure of NO by a simple math operation:
PpH₂ = 0.978 atm = 3x
PpN₂ = x
PpN₂ = PpH₂ / 3
PpN₂ = 0.978 / 3
PpN₂ = 0.326 atmHope this helps
Use the solubility generalizations on the information page to predict if one or more precipitates will form when aqueous solutions of zinc chloride (ZnCl2) and sodium carbonate (Na2CO3) are mixed. Write the formula of any precipitate that could form.
Answer: The formula for the precipitate formed is [tex]ZnCO_3[/tex]
Explanation:
A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.
A double displacement reaction in which one of the product is formed as a solid is called as precipitation reaction.
The balanced chemical equation when aqueous solutions of zinc chloride and sodium carbonate are mixed:
[tex]ZnCl_2(aq)+Na_2CO_3(aq)\rightarrow ZnCO_3(s)+2NaCl(aq)[/tex]
A rigid container has 44.5 grams of oxygen gas at room temperature and a pressure of 2.3 atm. How many grams of oxygen should the container have for the pressure to be 7.8 atm?
Answer:
The mass of oxygen the container must have is 150.85 g.
Explanation:
Given;
mass of the oxygen, m₁ = 44.5 g
initial pressure of the gas, P₁ = 2.3 atm
final pressure of the gas, P₂ = 7.8 atm
Atomic mass of oxygen gas, = O₂ = 16 x 2 = 32 g
initial number of moles of oxygen in the container, n₁ = 44.5/32 = 1.39
let the final number of moles of oxygen = n₂
Apply ideal gas equation;
PV = nRT
[tex]\frac{PV}{Rn} = T\\\\since \ temperature\ T \ is \ constant;\\\\\frac{P_1V}{Rn_1} = \frac{P_2V}{Rn_2}\\\\\frac{P_1}{n_1} = \frac{P_2}{n_2} \\\\n_2 = \frac{n_1P_2}{P_1} \\\\n_2 = \frac{1.39 \times 7.8}{2.3} \\\\n_2 = 4.714 \ moles[/tex]
The mass of the oxygen in grams is calculated as;
m₂ = 4.714 x 32g
m₂ = 150.85 g
Therefore, the mass of oxygen the container must have is 150.85 g.
How many grams are in 0.500 liters of SBr6?
Please show work if possible or say how to do it
Answer:
250 grams = 0.25 liter
Explanation:
Will give brainliest
A backpacker wants to carry enough fuel to heat 2.7 kg of water from 21 ∘C to 100.0 ∘C.
If the fuel he carries produces 36 kJ of heat per gram when it burns, how much fuel should he carry? (For the sake of simplicity, assume that the transfer of heat is 100 % efficient.)
Answer:
24.8g of fuel
Explanation:
while
[tex]C_{water}=4180j/kg*k[/tex]
[tex]m=\frac{2.7*4180*(100-21)}{36*1000}=24.8g[/tex]
1. How many grams does 10 moles of Carbon weigh?
Answer:120
Explanation: I think
Answer:
1321.177 grams.
Explanation:
each mole of carbon is 12.0107 grams.
can someone help me answer this question
Answer:
p= 1
e= 1
n= 0
predicted charge= +1
name of ion= Hydride
Molecules have Question 3 options: A) both potential and kinetic energy. B) only potential energy. C) only kinetic energy. D) neither kinetic nor potential energy.
Answer: A
Explanation:
Consider the reaction 2H2(g)+O2(g)→2H2O(l) 2 H 2 ( g ) + O 2 ( g ) → 2 H 2 O ( l ) What is the mass of water, H2O(l) H 2 O ( l ) , produced when 5.70 g g of O2(g) O 2 ( g ) reacts with excess H2(g) H 2 ( g ) ?hen 5.70 g g of O2(g) O 2 ( g ) reacts with excess H2(g) H 2 ( g ) ?
Answer:
mH₂O = 6.4116 g
Explanation:
Let's write the given reaction:
2H₂ + O₂ -------> 2H₂O
The problem states that 5.7 g of oxygen reacts with excess hydrogen, hence, the limiting reagent is the oxygen. With this mass of oxygen, we can determine the moles, and then, the moles of water with the mole ratio:
moles = mass / atomic weight AW of O₂ = 16 g/mol
Replacing we have:
moles O₂ = 5.70 / (16 * 2)
moles O₂ = 0.1781 moles
According to the balanced reaction, 1 mole of Oxygen produces 2 moles of water, so we have a mole ratio 1:2, therefore the moles of water would be twice the moles of oxygen:
moles H₂O = 0.1781 * 2 = 0.3562 moles
Finally the mass of water can be calculated solving for the mass from the expression of moles, and using molecular mass of water:
m = moles * MM MM H₂O = 18 g/mol
m = 0.3562 * 18
mH₂O = 6.4116 gHope this helps
17. Which of the following statement best explains what pollination is?
A. It is the union of sperm and egg cell.
B. It is the process where the pollen of one flower reaches the stigma of another flower.
C. It is the process wherein plants are developed from seeds.
D. It is the process by which seeds are sent by their parent plant into a faraway place to
become a new plant.
Answer:
ıt is the projesi where the polen of one flower reaches the sığmaz of another flower.
Answer:
B
Explanation:
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