Answer:
Astatine is a halogen with several isotopes that all have short half-lives.
Which of the following combinations of mass number and neutrons are possible as isotopes of astatine? Choose one or more:
i) A = 211, n = 127
ii) A = 210, n = 125
iii) A = 220, n = 134
iv) A = 207, n = 122
v) A = 209, n = 124
Explanation:
The mass number is the sum of the number of protons and the number of neutrons in an atom.[tex]A=no.of protons+no.of neutrons\\=>no.of neutrons=A-no.of protons\\[/tex]
Atomic number of At(astatine ) =85
That means it has --- 85protons.
Its mass number A=210
Hence, the number of neutrons in At are:
[tex]n=A-Z\\=>n=210-85\\=>n=125[/tex]
Second option:
ii) A=210 , n=125 is the answer.
Determine whether each melting point observation corresponds to a pure sample of a single compound or to an impure sample with multiple compounds.
a. Wide melting point range __________
b. Experimental melting point is close to literature value _________
c. Experimental melting point is below literature value _________
d. Narrow melting point range __________
Answer:
Wide melting point range - impure sample with multiple compounds
Experimental melting point is close to literature value - pure sample of a single compound
Experimental melting point is below literature value - impure sample with multiple compounds
Narrow melting point range - pure sample of a single compound
Explanation:
The melting point of substances are easily obtainable from literature such as the CRC Handbook of Physics and Chemistry.
A single pure substance is always observed to melt within a narrow temperature range. This melting temperature is always very close to the melting point recorded in literature for the pure compound.
However, an impure sample with multiple compounds will melt over a wide temperature range. We also have to recall that impurities lower the melting point of a pure substance. Hence, the experimental melting point of an impure sample with multiple compounds is always below the literature value.
Consider an atom that has an electron in an excited state. The electron falls to a lower energy level. What effect does that have on the electron?
A.The electron releases energy in the form of light.
B.The electron absorbs energy in the form of light.
C.The electron retains its energy without any change.
D.The electron transfers its energy to other electrons.
Answer:
c it does not change the energy state
Explanation:
Rank each of the following gases in order of increasing Urms assuming equivalent amounts and all gases are at the same temperature and pressure where 1 is the lowest Urms Gas 1: H2S Gas 2: He Gas 3: NF3 Gas 4: H20
Answer:
NF3< H2S< H2O< He
Explanation:
The average speed of a gas depends on the relative molecular mass of the gas. Lighter gases have a greater average speed and move faster than heavier gases.
Hence, we need to arrange these gases listed in the question in order of decreasing molecular mass in order to obtain the order of increasing Urms assuming equivalent amounts and all gases are at the same temperature and pressure.
Hence; NF3< H2S< H2O< He
What is the purpose of the scientific method?
Answer:
C. To remove any source of bias in an experience
Draw the product formed when diene and dienophile react in a Diels–Alder reaction.
Answer:
Explanation:
Diels-Alder reactions are cyclo-additional reactions between conjugated dienes and a dienophile (a substituted alkene compound for example acrylic acid) to produce a ring structure of cyclohexene compounds.
From the image attached below, we will see the reaction between 2,3-dimethylbuta-1,3-diene which is a conjugated diene with acrylic acid to produce a Diel-Alder adduct as the product. From the reaction, a single new π-bond and two σ-bonds are produced.
PLZZZ HELPPPPPPPPPPPPPPPP
For this task, you will consider the information you have researched so far, conduct further research, create a thesis, and write a one-page research paper based on your research and thesis. Your research and thesis should address the following prompt: How should Florida address its growing energy demands, and what energy sources should the state focus on in the future? Consider the energy options available in Florida, the pros and cons of various energy sources, as well as concepts such as energy conservation.
In the next steps, you will conduct further research, form a thesis, and write a one-page research paper based on your findings and opinions.
a. Select a topic. Before creating your report, understand the purpose, process, and goals of a research assignment.
The first step in writing a research paper is to select a topic; in this assignment your topic should focus on issues related to energy production and consumption in Florida.
Begin brainstorming ideas by thinking about your prior knowledge of the topic.
Try engaging in preliminary research to help select a relevant, interesting topic.
b. Choose a thesis statement. Begin thinking about the stance or viewpoint that your writing will take. Once you have a general idea of your opinion, develop a thesis statement, or the main idea of an essay that includes the topic and the viewpoint.
Make sure that the thesis is relevant to the topic and assignment.
Keep in mind that as you continue researching and begin writing, your thesis may change slightly from your original idea.
Check with your teacher to make sure that the topic you chose is appropriate and feasible.
c. Gather sources. Next, begin gathering and organizing additional sources to build your argument. It is important to understand the purpose of your research. Evaluate each source, and consider these questions:
Who authored the document?
What is the purpose of the document?
When was the document written?
How will this document help your argument?
d. Develop your position. Now that you have analyzed sources to use as evidence, revisit the essay topic. Then develop your report with these factors in mind:
Create an outline to help organize the structure of your report.
Your thesis should be well-supported by your research.
Match the evidence in your sources to the points in your report.
Articulate any solutions you may think are relevant to deal with the energy issues in Florida.
e. Write your first draft. Write a one-page research paper on your selected topic. As you write your paper, use quotations from and summaries of your sources to support your argument.
To avoid plagiarism, make sure to cite your sources properly with in-text citations and a works cited page.
f. Proofread and Revise. When you are finished writing your first draft, reread your essay to check for all of the points above, and then proofread and revise to be sure your work doesn’t contain errors in grammar, spelling, logic, or cohesion. Finally, develop a final draft that is polished and ready to be turned in. Nice work!
Answer:
What kind of chemical reaction occurs when fossil fuels and biomass are burned? What is produced in addition to energy?
What is acid rain? Which fossil fuel causes acid rain? What are the chemical reactions that produce the acid?
Difference Between Biomass and Fossil Fuels
In terms of environmental impact, what’s the difference between natural gas, coal, and biomass? Consider both carbon dioxide (CO2) emissions and acid rain.
What’s the difference between nonrenewable and renewable energy sources? Is biomass a renewable energy source?
What’s a new discovery that makes it easier to use biomass as an energy source?
Comparing Biomass with Other Renewable Energy Sources
What are the pros and cons of several renewable energy sources? Renewable energy sources include biomass, wind power, hydropower, solar power, and geothermal power.
Making Recommendations for Energy Choices
Which renewable energy sources should be developed in your area, and why? Consider abundance of the energy source, ease of setup in your area, and cost.
Review the seven questions. Write a few sentences summarizing what you already know about these topics.
Explanation:
Ion R2+ có phân lớp ngoài cùng là 3p6
a.Viết cấu hình electron của R và R2+ dưới dạng chữ và ô obitan.
b.Xác định Z, chu kỳ, nhóm, phân nhóm và tên nguyên tố R.
c.Viết công thức oxit cao nhất của R
d.Nêu bộ trị số có thể có của 4 số lượng tử đối với R
How many aluminum atoms are in 2.88 g of aluminum?
Express your answer to three significant figures.
Answer:
Explanation:
1 Mole of Aluminum with mass 26.98g contains 6.02*10^23 atoms.
In 2.88g of Aluminum, there are 2.88/26.98*6.02*10^23 = 6.426*10^22 atoms.
Answer:
Explanation:
no of Al atoms = 2.88/26.98*6.02*10^23
= 6.426*10^22
= 6.43*10^22
22)
)
Limestone can form as a result of
A)
metamorphosis of conglomerate rock
B)
cooling of molten rock under the oceans
C)
precipitation from evaporating water
D)
radioactive decay of dolostone
Answer:
tge answer is a
Explanation:
I'm smart like that
Identify the Lewis acid and Lewis base from among the reactants in each of the following equations.
Part A
Ag+(aq)+2NH3(aq)⇌Ag(NH3)2+(aq)
a. Ag+ is the Lewis acid and NH3 is the Lewis base.
b. Ag+ is the Lewis base and NH3 is the Lewis acid.
Part B
AlBr3+NH3⇌H3NAlBr3
a. AlBr3 is the Lewis base and NH3 is the Lewis acid.
b. AlBr3 is the Lewis acid and NH3 is the Lewis base.
Part C
Cl−(aq)+AlCl3(aq)⇌AlCl4−(aq)
a. AlCl3 is the Lewis acid and Cl− is the Lewis base.
b. AlCl3 is the Lewis base and Cl− is the Lewis acid.
Answer:
Part A
Ag+ is the Lewis acid and NH3 is the Lewis base.
Part B
AlBr3 is the Lewis acid and NH3 is the Lewis base.
Part C
AlCl3 is the Lewis acid and Cl− is the Lewis base.
Explanation:
A Lewis acid is any specie that accepts a lone pair of electrons. Ag^+, AlBr3 and AlCl3 all accepted lone pairs of electrons according to the three chemical reaction equations shown. Hence, they are Lewis acids.
A Lewis base donates a lone pair of electrons. They include neutral molecules having lone pair of electrons such as NH3 or negative ions such as Cl- .
Can someone help me answer this please
Answer:
A) 1.3 × 10⁻⁵ mol/L
Explanation:
Step 1: Write the balanced equation for the solution of AgCl
AgCl(s) ⇄ Ag⁺(aq) + Cl⁻(aq)
Step 2: Make an ICE Chart
AgCl(s) ⇄ Ag⁺(aq) + Cl⁻(aq)
I 0 0
C +S +S
E S S
If we replace the solubility (S) in the Ksp expression, we get,
Ksp = [Ag⁺] [Cl⁻] = S × S = S²
S = √Ksp = √1.8 × 10⁻¹⁰ = 1.3 × 10⁻⁵ mol/L
3 The questions refer to the substances in the table.
Melting point/°C
Boiling point/°C
A
-259
-253
B
0
100
C
3700 (sublimes)
D
-116
34.5
E
801
1413
a Write down the physical states of each compound at
i 30°C.
ii -100°C
iii 80°C
Explanation:
3 The questions refer to the substances in the table.
Melting point/°C
Boiling point/°C
A
-259
-253
Which of the following is a protein source of plant origin
Answer:
soy....plant protein also is found in vegtables and grain products.
The protein that is derived from the plant is soyabean. Protein-rich foods have a rich source of amino acids. Amino acids are required by the body for different cellular activities.
What are proteins?
Proteins are present in plant-based foods and animal-based foods. In nature, the plant-based foods that are rich in proteins are soybeans, beans etc. Animal products such as dairy products, milk, and cheese are rich sources of proteins.
Animal-based foods such as eggs, meat, and fish have a good amount of protein. The proteins are made up of amino acids. Peptide bonds connect each amino acid to the next.
Proteins are necessary for the body, as cells need amino acids for both structural and functional support. Not all cells of the body synthesise all amino acids. Some essential amino acids are required by the body and can be taken from external sources such as plants.
Hence, the plant-based protein is soyabean.
To learn more about the protein, here
https://brainly.com/question/17095120
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The question is incomplete; the complete question may be the following:
1) Which of the following is a protein source of plant origin?
A)egg
B) Soyabean
C)cheese
D)Milk
How do we fix climate change?
The biggest problem of course is conspiracy theorys. Some say it is just a hoxe when really their chidrin or grandchidrin will sufer greatly from it. How do we educate ourselfs better?
Answer:
Hi so your answer is that to helping fix the climate change you have to : speak up , power your home with renewable engery , reduce water waste , dont waste food , and finally invest energy .
Explanation:
Really hope i helped , have a nice day :)
Answer:
we can reduce air pollution,which is one of the main cause of climate change.Climate change is not a hoxe if it is not attending the upcoming generations will suffer greatly.
Soap
a. Assume that Crisco is a single triacylglyceride (it is actually a mixture of triacylglycerides) in which all acyl groups are palmitate (palmitic acid = CH,3(CH2)14CO2H). Draw the structure of this triacylglyceride.
b. Show the products that are generated when Crisco and sodium hydroxide react. Use the same assumption as in question a. b. Show the products that are generated when Crisco and sodium hydroxide react. Use the same assumption as in question a.
c. What is the purpose of adding ethanol in the preparation of soap?
Answer:
Explanation:
From the given information:
The structure of the triacylglyceride can be seen in the first image attached below and the products produced as the result of the reaction between Crisco and sodium hydroxide (NaOH) are Glycerol and 3-Palmitic acid as shown in the second image below.
Lastly, the purpose of the addition of ethanol is because water and oils are not miscible. Thus, ethanol has the potential to mix and dissolve in water as well as in oil on a selective partial level. This method aids in the formation of water, soap, salt, and fatty acids from the interaction between fatty acid and sodium hydroxide. As a result, ethanol improves the interaction between the water and the oil. It is less polar to water and aids in the dissolution of nonpolar fats such that sodium hydroxide may react with ethanol.
complete and balanced the following equations by predicting the products of each reaction pair.
NA + LiCI -> _ + _
Explanation:
this is a single Replacement Reaction, so Na and Cl will form a bond.
Why can characteristics properties be used to identify unknown substances
Characteristic properties are used because the sample size and the shape of the substance does not matter.
which of the following molecules would you expect to have a dipole moment of zero? a,CH2 Ch3
bH2C=0
cCH2cl
dNH3
Answer: The molecule [tex]CH_{3}-CH_{3}[/tex] is expected to have a dipole moment of zero.
Explanation:
The product of magnitude of the charge calculated in electrostatic units is called dipole moment.
Formula for dipole moment is as follows.
Dipole moment = Charge (in esu) [tex]\times[/tex] distance (in cm)
Non-polar molecules have zero dipole moment.
For example, [tex]CH_{3}-CH_{3}[/tex] is a non-polar molecule so its dipole moment is zero.
[tex]H_{2}C=O[/tex] is a polar molecule so it will have dipole moment.
[tex]CH_{2}Cl_{2}[/tex] is a polar molecule so it will have dipole moment.
[tex]NH_{3}[/tex] has nitrogen atom as more electronegative than hydrogen atom. So, net dipole moment will be in the direction of nitrogen atom.
Thus, we can conclude that the molecule [tex]CH_{3}-CH_{3}[/tex] is expected to have a dipole moment of zero.
What is the volume in (a) liters and (b) cubic yards of a room that is 10. meters wide by 15 meters long and 8.0 ft high?
Answer:
V = 364500 L, 476.748 yard³
Explanation:
Given that,
The dimensions of a room are 10 meters wide by 15 meters long and 8.0 ft high.
l = 10 m, b = 15 m, h = 8 ft = 2.43 m
The volume of the room is :
V = lbh
So,
V = 10×15×2.43
V = 364.5 m³
As 1 m³ = 1000 L
364.5 m³ = 364500 L
Also, 1 m³ = 1.30795 yard³
364.5 m³ = 476.748 yard³
Hence, this is the required solution.
Which of the following aqueous solutions are good buffer systems?
a. 0.34 M calcium iodide + 0.22 M sodium iodide.
b. 0.27 M ammonia + 0.38 M ammonium nitrate.
c. 0.27 M nitric acid + 0.18 M sodium nitrate.
d. 0.18 M hydrofluoric acid + 0.14 M hydroiodic acid.
e. 0.14 M calcium hydroxide + 0.28 M calcium chloride.
Answer:
b. 0.27 M ammonia + 0.38 M ammonium nitrate.
Explanation:
Hello there!
In this case, according to the given information, it turns out possible for us to bear to mind the fact that buffest must be prepared by using either of the following pairs:
weak acid/conjugate base
weak base/conjugate acid
So that the pH might be set constant. In such a way, since a. shows two salts, c. a strong acid with a neutral base, d, shows two acids and e. a strong base with a neutral base, we infer the correct buffer is b. 0.27 M ammonia + 0.38 M ammonium nitrate because it has a weak base (ammonia) and its conjugate acid, ammonium.
Regards!
What is the IUPAC name for this organic molecule?
Answer:
2–methylbutane
Explanation:
To name the compound given above, the following must be obtained:
1. Determine the longest continuous carbon chain. This gives the parent name of the compound.
2. Determine the substituent group attached.
3. Determine the position of the substituent group by giving it the lowest possible count..
4. Combine the above to obtain the name of the compound.
With the above information, we can name the compound as follow:
1. The longest continuous carbon chain of the compound is 4. Thus, the parent name is butane.
2. The substituent group attached to the compound is methyl (–CH₃).
3. The methyl (–CH₃) group is located at carbon 2 (i.e counting from the left side).
4. The name of the compound is:
2–methylbutane
When aqueous solutions of potassium cyanide and hydrobromic acid are mixed, an aqueous solution of potassium bromide and hydrocyanic acid results. Write the net ionic equation for the reaction.
Answer:
hey there
Explanation:
CN- (aq) + H+ (aq) → HCN(I)
The reactants are aqueous solutions:
NaCN(aq) and HBr(aq)
When you mix these compounds you make pure HCN (I)
The molecular equation is:
NaCN(aq) + HBr(aq) → NaBr(aq) + HCN(I)
When you dissociate the reactants, you have: Nat(aq) +CN¯(aq) + H*(aq) + Br−(aq) → Nat(aq) + ->
Br (aq) + HCN(I)
Sodium bromide, it is a salt, that can also be
dissociated in the solution
To make, the net ionic equation you remove the repeated ions
CN- (aq) + H+ (aq) → HCN(I)
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cho 6,72 gam Fe tan hết trong dung dịch H2SO4 đặc nóng dư thu được V lít khí SO2. Giá trị của V là
4,032
BT electron
nSO2= 3nFe/
Select the correct answer.
What is the solution to the problem expressed to the correct number of significant figures?
(102,900 ÷ 12) + (170 × 1.27) = ?
Which diagram shows the correct direction of electron flow in an electrolytic cell?
1)
2)
3)
4)
Sorry I couldn't put the diagram in, Thanks.
Answer:
A
Explanation:
The most stable conformation of the following compound has
A. An axial methyl group and an axial ethyl group.
B. An axial methyl group and an equatorial ethyl group.
C. An axial tert-butyl group.
D. An equatorial methyl group and an equatorial ethyl group.
E. An equatorial methyl group and an axial ethyl group.
Answer:
The most stable conformation of the following compound has
A. An axial methyl group and an axial ethyl group.
B. An axial methyl group and an equatorial ethyl group.
C. An axial tert-butyl group.
D. An equatorial methyl group and an equatorial ethyl group.
E. An equatorial methyl group and an axial ethyl group.
Explanation:
The most stable conformation in the cyclohexane ring is the one in which both the substituents are in the equatorial position.
Among the given options,
option D An equatorial methyl group and an equatorial ethyl group.
When the substituents in the cyclohexane ring are in equatorial positions then, the steric repulsions will be reduced.
Answer is option D.
which is the correct orbital diagram for carbon
Answer:
Below
Explanation:
Got it right
Check the periodic table, then click electrons
What is the pH of a solution with a 7.8 × 10−13 M hydronium ion concentration?
A) 1.9
B) 2.8
C) 11
D) 12
Answer:
12Explanation:
The pH of a solution can be found by using the formula
[tex]pH = - log [ { H_3O}^{+}][/tex]
From the question we have
[tex]ph = - log(7.8 \times {10}^{ - 13} ) \\ = 12.1079...[/tex]
We have the final answer as
12Hope this helps you
The pH of this solution with a 7.8 × 10⁻¹³ M concentration of hydronium ion is equal to: D. 12.
Given the following data:
Concentration of hydronium ion = 7.8 × 10⁻¹³ M.
What is pH?pH is literally the power of hydrogen ions and it can be defined as a measure of the molar concentration of hydrogen ions in a given solution.
How to calculate the pH of a solution?We would determine the pH of this solution by using this formula;
pH = -log[H⁺]
pH = -log(7.8 × 10⁻¹³).
pH = -(-12.1)
pH = 12.1 ≈ 12.
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CAN SOMEONE HELP ME PLZ AND THANKS WILL MARK U AS BRAINLIEST
Explanation:
2. [tex]2C_2H_6 + 7O_2 \rightarrow 4CO_2 + 6H_2O[/tex]
First, we need to find the number of moles of [tex]CO_2[/tex] at 300K and 1.5 atm using the ideal gas law:
[tex]n= \dfrac{PV}{RT}= \dfrac{(1.5\:\text {atm})(33\:L)}{(0.082\:\text{L-atm/mol-K})(300K)}[/tex]
[tex]=2.0\:\text{mol}\:CO_2[/tex]
Now use the molar ratios to find the number of moles of ethane to produce this much [tex]CO_2[/tex].
[tex]2.0\:\text{mol}\:CO_2 \times \left(\dfrac{2\:\text{mol}\:C_2H_6}{4\:\text{mol}\:CO_2}\right)[/tex]
[tex]=1.0\:\text{mol}\:C_2H_6[/tex]
Finally, convert this amount to grams using its molar mass:
[tex]1.0\:\text {mol}\:C_2H_6 \times \left(\dfrac{30.07\:\text g\:C_2H_6}{1\:\text{mol}\:C_2H_6} \right)[/tex]
[tex]=30.1\:g\:C_2H_6[/tex]
3. [tex]3Zn + 2H_3PO_4 \rightarrow 3H_2 + Zn_3(PO_4)_2[/tex]
Convert 75 g Zn into moles:
[tex]75\:\text g\:Zn \times \left(\dfrac{65.38\:\text g\:Zn}{1\:\text{mol}\:Zn}\right)=1.1\:\text{mol}\:Zn[/tex]
Then use the molar ratios to find the amount of H2 produced.
[tex]1.1\:\text{mol}\:Zn \times \left(\dfrac{3\:\text{mol}\:H_2}{3\:\text{mol}\:Zn}\right)=1.1\:\text{mol}\:H_2[/tex]
Now use the ideal gas law [tex]PV=nRT[/tex] to find the volume of H2 produced at 23°C and 4 atm:
[tex]V= \dfrac{nRT}{P}= \dfrac{(1.1\:\text{mol}\:H_2)(0.082\:\text{L-atm/mol-K})(296K)}{4\:\text{atm}}[/tex]
[tex]=8.9\:\text L\:H_2[/tex]