Complete question is;
What is the frequency of light emitted when the electron in a hydrogen atom undergoes a transition from energy level n=6 to level n=3?
Answer:
Frequency = 2.742 × 10^(14) s^(-1)
Explanation:
First of all, the energy of hydrogen electron from online values is;
E_n = -2.18 × 10^(-18) × (1/n²) J
n is the principal quantum number
We are told that hydrogen atom undergoes a transition from energy levels n = 3 to n = 6.
Thus, it means we have to find the difference between the electrons energy in the energy levels n = 3 to n = 6.
Thus;
E_n = E_6 - E_3
Thus;
E_n = [-2.18 × 10^(-18) × (1/6²)] - [-2.18 × 10^(-18) × (1/3²)]
E_n = (2.18 × 10^(-18)) × [-1/36 + 1/9]
E_n = 0.1817 × 10^(-18) J
From Planck expression, we can find the frequency. Thus;
E = hf
Where h is Planck's constant = 6.626 × 10^(-34) m²kg/s
Thus;
0.1817 × 10^(-18) = 6.626 × 10^(-34) × f
f = (0.1817 × 10^(-18))/(6.626 × 10^(-34))
f = 2.742 × 10^(14) s^(-1)
Rupert had three substances. A brown substance was a liquid at room
temperature. He hit each of the other two with a hammer. A blue crystal
cracked but did not break. A silver substance flattened but did not crack.
Which two statements could be true?
A. The brown substance is ionic
B. The silver substance is ionic
C. The brown substance is molecular
D. The blue substance is ionic
Answer:
its C and D
C. The brown substance is molecular
D. The blue substance is ionic
Explanation:
did the test !
Two correct statements are B) The silver substance is ionic
C) The brown substance is molecular.
What kind of substance is silver?Silver is a chemical element with the symbol Ag and atomic wide variety 47. categorized as transition steel, Silver is stable at room temperature.
Which substance is molecular?It is a molecular substance, that's a substance with or more atoms, the smallest gadgets of remember joined together via a covalent bond. A covalent bond is a hyperlink created via the sharing of electrons that holds these atoms collectively.
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The escape velocity from Earth’s surface is 1.12*10^4 meters per second. At this speed, how many kilometers would a rocket travel in 3 minutes
Answer:
2016 Km.
Explanation:
The following data were obtained from the question:
Speed (S) = 1.12×10⁴ m/s
Time (t) = 3 mins
Distance (d) =.?
Next, we shall convert 3 mins to seconds. This can be obtained as follow:
1 min = 60 s
Therefore,
3 mins = 3 min × 60 s / 1 min
3 mins = 180 s
Next, we shall determine the distance travelled by the rocket. This is illustrated below:
Speed (S) = 1.12×10⁴ m/s
Time (t) = 180 s
Distance (d) =.?
Speed (S) = distance (d) /time (t)
S = d/t
1.12×10⁴ = d/ 180
Cross multiply
d = 1.12×10⁴ × 180
d = 2016000 m
Finally, we shall convert 2016000 m to Km. This can be obtained as shown below:
1000 m = 1 Km
Therefore,
2016000 m = 2016000 m × 1 Km / 1000 m
2016000 m = 2016 Km
Therefore, the rocket will travel 2016 Km in 3 mins
How many moles of H2 are needed to produce 24 moles of NH3?
Answer:
36 mol of H2
Explanation:
The balanced equation of the reaction is given as;
3H2 + N2 --> 2NH3
From the reaction;
It takes 3 mol of H2 reacting with 1 mol of N2 to form 2 mol of NH3
3 mol of H2 = 2 mol of NH3
x mol of H2 = 24 mol of NH3
x = (24 * 3) / 2 = 36 mol of H2
What is cellulose and what does it do?
Answer:
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β linked D-glucose units. Cellulose is an important structural component of the primary cell wall of green plants, many forms of algae and the oomycetes.
Explanation:
Answer:
Hope this helped.
Explanation:
Cellulose is a molecule, consisting of hundreds – and sometimes even thousands – of carbon, hydrogen and oxygen atoms. Cellulose is the main substance in the walls of plant cells, helping plants to remain stiff and upright. Humans cannot digest cellulose, but it is important in the diet as fibre.
Enough of a monoprotic weak acid is dissolved in water to produce a 0.0129 M solution. The pH of the resulting solution is 2.65 . Calculate the Ka for the acid.
Answer:
Ka = 4.70x10⁻⁴M
Explanation:
The general dissociation of a weak acid, HX, is:
HX(aq) ⇄ H⁺(aq) + X⁻(aq)
And Ka is written as:
Ka = [H⁺] [X⁻] / [HX]
Where [] represents the molar concentration in equilibrium of each specie.
The equilibrium is reached when X of HX is dissociate in X H⁺ and X X⁻, that is:
[HX] = 0.0129M - X
[H⁺] = X
[X⁻] = X
As pH = -log [H⁺]:
10^-pH = [H⁺] = X = 2.239x10⁻³M
Solving:
[HX] = 0.0129M - 2.239x10⁻³M = 0.01066M
[H⁺] = 2.239x10⁻³M
[X⁻] = 2.239x10⁻³M
Ka = [H⁺] [X⁻] / [HX]
Ka = [2.239x10⁻³M] [2.239x10⁻³M] / [0.01066M]
Ka = 4.70x10⁻⁴M
Help, 8th grade Science
Organisms in overpopulated area do not survive well due to which of the following
Answer:
Reductions in available food and shelter
Explanation:
To solve this we must be knowing each and every concept related to population. Therefore, organisms in over-populated areas do not survive well due to reduction in available food and shelter.
What is population?The group of people from whom a quantitative sample is gathered for a research is referred to as a population. Therefore, a population is any collection of people who have anything in common.
A sample is a representative group of a population chosen at random. This is a smaller group that was selected from the population and possesses all of the population's traits. The observations and inferences drawn from the sample data then applied to the entire population.
Therefore, organisms in over-populated areas do not survive well due to reduction in available food and shelter.
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How many lbs are in 5 kilograms ?
Answer:
11.023 pounds
Explanation:
Which property of a substance can be determined using a pH indicator?
A. acldity
B. bolling polint
C. density
D. electrical conductivity
E. thermal conductivity
Answer:
the correct answer would be A. acidity
Answer:
The answer is A.) Acidity
Georgia discovered a piece of metal. She measured its mass as 14 grams and its volume as 2 cm3. Georgia then compared the metal she found with the metals in the table below.
DENSITY OF METALS
Which type of metal did Georgia most likely find?
A.Gold
B.Lead
C.Silver
D.Zinc
Answer:
try dividing the grams and the volume and see what number matches up with your answer
Explanation:The distribution coefficient between methylene chloride and water for solute Y is 14. An amount of 72.0 g of Y is dissolved in 180 mL of water. a) What weight of Y would be removed from water with a single extraction with 180-mL of methylene chloride? Report to 1 decimal place. b) What total weight of Y would be removed from water (the original solution) with two successive extractions with 90-mL portions each of methylene chloride?
Answer:
a)Weight of Y extracted from water in single extraction = 67.2 g
b) Total weight of Y extracted from water in two successive extractions = 70.9 g
Explanation:
Distribution coefficient, Kd = Cs / Cm
where Cs is concentration of solute in methylene chloride; Cm is concentration of solute in water
a) Let x g of solute Y be extracted into methylene chloride
72.0 - x g of Y will be left in water
Kd = (x/180 mL of methylene chloride) / (72.0 - x/180 mL of water) = 14
14 = 180 * x / 180 * 72.0 - x
x = 14(72.0 - x)
x = 1008 - 14x
15x = 1008
x = 1008/15
x = 67.2 g
Weight of Y extracted from water in single extraction = 67.2 g
b) First extraction: Let x g of solute Y be extracted into methylene chloride
72.0 - x g of Y will be left in water
14 = x/90 / 72.0 - x/180
14 = 180x/ 90(72.0 - x)
14 = 2x/ 72.0 - x
2x = 14(72.0 - x)
2x = 1008 - 14x
16x = 1008
x = 63.0 g
Second extraction: Amount of solute left in water after first extraction = 72 - 63 = 9.0 g
Let x g of solute Y be extracted into methylene chloride
9.0 - x g of Y will be left in water
14 = x/90 / 9.0 - x/180
14 = 180x/ 90(9.0 - x)
14 = 2x/ 9.0 - x
2x = 14(9.0 - x)
2x = 126 - 14x
16x = 126
x = 7.90 g
Total weight of Y extracted = (63 + 7.90) g
Total weight of Y extracted from water in two successive extractions = 70.9 g
a) The Weight of Y extracted from water in single extraction is 67.2 g
b) The Total weight of Y extracted from water in two successive extractions should be 70.9 g
Calculation of weight:Here
The distribution coefficient, Kd should be
= Cs / Cm
where
Cs should be a concentration of solute in methylene chloride;
Cm should be a concentration of solute in water
a) Let us assume x g of solute Y that should be extracted into methylene chloride
So,
72.0 - x g of Y will be left in water
And, now
Kd = (x/180 mL of methylene chloride) / (72.0 - x/180 mL of water) = 14
So,
14 = 180 * x / 180 * 72.0 - x
x = 14(72.0 - x)
x = 1008 - 14x
15x = 1008
x = 1008/15
x = 67.2 g
b)
Now First extraction:
Let x g of solute Y be extracted into methylene chloride
So,
72.0 - x g of Y will be left in water
14 = x/90 / 72.0 - x/180
14 = 180x/ 90(72.0 - x)
14 = 2x/ 72.0 - x
2x = 14(72.0 - x)
2x = 1008 - 14x
16x = 1008
x = 63.0 g
Second extraction:
Amount of solute left in the water after the first extraction that should be
= 72 - 63
= 9.0 g
Now
Let x g of solute Y be extracted into methylene chloride
9.0 - x g of Y will be left in water
14 = x/90 / 9.0 - x/180
14 = 180x/ 90(9.0 - x)
14 = 2x/ 9.0 - x
2x = 14(9.0 - x)
2x = 126 - 14x
16x = 126
x = 7.90 g
Total weight of Y extracted = (63 + 7.90) g
= 70.9g
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What is the mass number of an element?
A. Mass number is the number of protons in the nucleus.
B. Mass number is the mass of the protons in the nucleus.
C. Mass number is the mass of the most abundant isotope.
D. Mass number is the atomic mass of a particular isotope.
The mass number of an element is the sum of the protons and neutrons present in the nucleus of the atoms of the element.
What is mass number?The mass number of an element is the number obtained when the number of protons and neutrons in the nucleus of an atom of the element are summed together.
The sum of protons and neutrons in the nucleus of an atom is collectively known as the nucleon. Thus, the mass number of an atom can also be referred to as the nucleon of the atom.
This can be mathematically expressed as:
Mass number = number of protons + number of neutrons.
Atoms generally contain protons, neutrons, and electrons. The protons are positively charged and are located in the nucleus, the neutrons are also located in the neucleus but have no charges. The electrons, on the other hand, are located outside the nucleus in regions referred to as orbitals.
The sum of the protons and neutrons determine the mass of an atom because the contribution of electrons to the mass of atoms is negligible.
Thus, the mass number of an element is the sum of proton and neutron numbers present in the nucleus of the atoms of the element.
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What color is the acetic acid plus methyl orange solution and what does this tell you about where the equilibrium is
Answer:
Red
Explanation:
Acetic acid is an acidic medium. Recall that indicators are organic substances whose color changes in response to change in the pH of the solution. often times, the protonated and deprotonated forms of an indicator have different colors.
However, an equilibrium is set up when an indicator is in acid/ basic medium. Methyl orange is red in acid medium and yellow in basic medium.
Hence while in acetic acid, the equilibrium lies towards the protonated form of acetic acid, hence the solution appears red.
SOMEONE PLEASE HELP I WILL GIVE BRAINLIEST PLEASEEEEE!!!!!!!!!!
MY ELEMENT IS NICKEL!!
Answer:
Metallurgy can be isolate other elements. Iron and bronze are the common metalsNickel is the metal which reacts with many metalsSome halogen and discredited metalscharacteristic line spectra only appear in the visible region of light. true or false
Answer:
The answer is true
Explanation:
bc I took this on edgeunity
Which 2 main body systems work alongside the digestive system?
Which of the following statements is true during a solar eclipse?
The moon's light is blocked by the Earth.
The Sun's light is blocked by the Earth.
The Sun's light is blocked from another planet.
The Sun's light is blocked by the Moon.
Answer:
The sun's light is blocked by the moon.
Explanation:
During the eclipse, the moon rotates right in front of the sun, that's why the eclipse is so rare and only happens every four(?) years/
How many liters of H2(g) at STP are produced per gram of Al(s) consumed in the following reaction? 2Al(s)+6HCl(aq)→2AlCl3(aq)+3H2(g)
Answer:
1.24 L of H₂ at STP .
Explanation:
2Al(s) +6HCl(aq) → 2AlCl₃(aq) + 3H₂(g)
2 moles 3 x 22.4 L
2 x 27 g of Al reacts to give 3 x 22.4 L of H₂ at STP .
1 g of Al will react to give 3 x 22.4 / ( 2 x 27 ) L of H₂ at STP .
= 1.24 L of H₂ at STP .
The volume of hydrogen produced by 1 grams of Al has been 1.24 L.
The balanced chemical reaction has been given as:
[tex]\rm 2\;Al\;+\;6\;HCl\;\rightarrow\;2\;AlCl_3\;+\;3\;H_2[/tex]
From the equation, 2 moles of Aluminum gives 3 moles of Hydrogen
The mass of the compound from moles can be given as:
Mass = moles × molecular mass
Mass of 2 moles Al = 2 × 27 g
Mass of 2 moles Al = 54 g
Mass of 3 moles hydrogen = 3 × 2 g
Mass of 3 moles hydrogen = 6 g
From the equation,
54 g aluminum gives = 6 grams hydrogen
[tex]\rm 1\;gram\;aluminum\;=\;\dfrac{6}{54}\;\times\;1[/tex]
1 gram Aluminum = 0.11 grams hydrogen
The mass of hydrogen produced by 1 gram Al has been 0.11g. The moles equivalent to 0.11g hydrogen has been given as:
Mass = moles × molecular mass
0.11 g = moles × 2 g/mol
Mole of hydrogen = 0.055 mol
The moles of hydrogen produced by 1 gram of Al has been 0.055 mol.
According to the ideal gas equation, any gas at STP has 1 mole equivalent to 22.4 L. So,
1 mol = 22.4 L
0.055 mol = 0.055 × 22.4 L
0.055 mol = 1.244 L.
The volume of hydrogen produced by 1 grams of Al has been 1.24 L.
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Which statement best describes the octet rule?
A. When an atom becomes an ion, it gains or loses electrons so that its valence shell holds eight electrons.
B. When an atom becomes an ion, it gains or loses protons so that its nucleus holds eight protons.
C. When an atom becomes an ion, it gains or loses eight electrons.
D. When an atom becomes an ion, it gains or loses eight neutrons.
Cathode rays are deflected toward a negatively charged plate in an electric field.
True
False
Answer:
true. cathode rays are deflected
Which is the best molecule to build collegen, muscle repair, and tendon repair?
a
carohydrates
b
lipids
c
nucleic acids
d
Proteins
Answer:
d
Explanation:
collagen is made of proteins
Carbonic acid, H2CO3, has two acidic hydrogens. A solution containing an unknown concentration of carbonic acid is titrated with potassium hydroxide. It requires 22.9 mL of 1.430 M KOH solution to titrate both acidic protons in 54.2 mL of the carbonic acid solution.
Required:
a. Write a balanced net ionic equation for the neutralization reaction. Include physical states.
b. Calculate the molarity of the carbonic acid solution.
Answer:
a. H₂CO₃(aq) + KOH(aq) ⇄ K₂CO₃(aq) + H₂O(l)
b. 0.603 M
Explanation:
Step 1: Write the neutralization reaction
H₂CO₃(aq) + KOH(aq) ⇄ K₂CO₃(aq) + H₂O(l)
Step 2: Calculate the reacting moles of KOH
22.9 mL of 1.430 M KOH react.
0.0229 L × (1.430 mol/L) = 0.0327 mol
Step 3: Calculate the reacting moles of H₂CO₃
The molar ratio of H₂CO₃ to KOH is 1:1. The reacting moles of H₂CO₃ are 1/1 × 0.0327 mol = 0.0327 mol.
Step 4: Calculate the molarity of H₂CO₃
0.0327 moles of H₂CO₃ are in a volume of 54.2 mL. The molarity of H₂CO₃ is:
M = 0.0327 mol/0.0542 L = 0.603 M
Which pair of elements will form a covalent bond?
You have a carbonate buffer with pH 10.3 and a concentration of 2.0 M. What is the buffer capacity of 100 mL of the buffer against 3.0 M CsOH?
Answer:
Explanation:
pH = 10.3
[ H] = 10⁻¹⁰°³
= 5 x 10⁻¹¹ M
concentration of CsOH C = 3 M
pKa of carbonate = 6.35
Ka = 10⁻⁶°³⁵ = 4.46 x 10⁻⁷
Buffer capacity = 2.303 x C x Ka x [ H⁺] / ( Ka + [ H⁺]² )²
= 2.303 x 3 x 4.46 x 10⁻⁷ x 5 x 10⁻¹¹ / ( 4.46 x 10⁻⁷ + 25 x 10⁻²² )²
= 154 x 10⁻¹⁸ / 19.9 x 10⁻¹⁴
= 7.74 x 10⁻⁴ .
It is critical to watch or _________________ what is happening with every step of your experiment
It is critical to watch or observe what is happening with every step of your experiment
Which question must be answered to complete the table below?
A 3-column table with 3 rows. Column 1 is labeled alpha decay with entries alpha particles, plus 2 and low. Column 2 is labeled Beta Decay with entries no entry, electron negative 1 positron positive 1, and medium. Column 3 is labeled Gamma decay with entries gamma rays, 0 and high.
a. What kind of shielding will block beta decay?
b. What is the penetrating power of beta decay?
c. What kind of particles are produced by beta decay?
d. How massive are the particles in beta decay?
Answer:
c
Explanation:
Having the same number of valence electrons means having similar chemical properties.
True or False
Answer:
True
Explanation:
Because atoms with the same number of valence electrons react in similar ways with other elements.
Which of the following best describes the structure of a nucleic acid?
a
Carbon ring(s)
b
Globular or fibrous
c
Single or double helix
d
Hydrocarbon(s)
A certain chemical reaction releases of heat for each gram of reactant consumed. How can you calculate the heat produced by the consumption of of reactant? Set the math up. But don't do any of it. Just leave your answer as a math expression. Also, be sure your answer includes all the correct unit symbols.
Complete Question
The complete question is shown in the first uploaded image
Answer:
So the math expression is
[tex]heat = \frac{ 35. 7 KJ * 1900 \ gram }{ 1 \ gram }[/tex]
Explanation:
From the question we are told that
The heat released for 1 gram of reactant consumed is [tex]H = 37.5 \ KJ/g [/tex]
The mass of reactant considered is [tex]m = 1.9 \ kg = 1900 \ g[/tex]
So if
[tex]37.5 \ KJ [/tex] is produced for 1 gram
Then
x kJ is produced for 1900 g
=> [tex]x = \frac{ 35. 7 KJ * 1900 \ gram }{ 1 \ gram }[/tex]
So the heat released is
[tex]heat = \frac{ 35. 7 KJ * 1900 \ gram }{ 1 \ gram }[/tex]
Find ΔHrxn for the following reaction:
2PbS(s)+3O2(g)→2PbO(s)+2SO2(g)
Answer:
ΔH°rxn = -827.5 kJ
Explanation:
Let's consider the following balanced equation.
2 PbS(s) + 3 O₂(g) → 2 PbO(s) + 2 SO₂(g)
We can calculate the standard enthalpy of reaction (ΔH°rxn) from the standard enthalpies of formation (ΔH°f) using the following expression.
ΔH°rxn = [2 mol × ΔH°f(PbO(s)) + 2 mol × ΔH°f(SO₂(g) )] - [2 mol × ΔH°f(PbS(s)) + 3 mol × ΔH°f(O₂(g) )]
ΔH°rxn = [2 mol × ΔH°f(PbO(s)) + 2 mol × ΔH°f(SO₂(g) )] - [2 mol × ΔH°f(PbS(s)) + 3 mol × ΔH°f(O₂(g) )]
ΔH°rxn = [2 mol × (-217.32 kJ/mol) + 2 mol × (-296.83)] - [2 mol × (-100.4) + 3 mol × 0 kJ/mol]
ΔH°rxn = -827.5 kJ
The standard enthalpy of the reaction is -827.5 kJ/mol
The standard enthalpy of reaction [tex]\mathbf{\Delta H^0_{rxn}}[/tex] is the enthalpy change that happens in a system whenever one mole of the matter is converted through a chemical process under normal conditions.
The given reaction can be expressed as:
2PbS(s) + 3O₂(g) → 2PbO(s) + 2SO₂(g)
The standard enthalpy can be represented by the equation:
[tex]\mathbf{\Delta H^0_{rxn} = \sum \Delta _f ^0(products) - \sum \Delta _f^0(reactants)}[/tex]
At standard conditions, the standard enthalpies of formation of the given species are:
ΔH°f(PbO(s)) = 219 kJ/molΔH°f(SO₂(g)) = -296.83 kJ/molΔH°f(PbS(s)) = 100.4 kJ/molΔH°f(O₂(g)) = 0 kJ/mol
∴
[tex]\mathbf{ \Delta H^0_{rxn} = \Big[2 mol \times \Delta H^0_f(PbO(s)) + 2 mol \times \Delta H^0_ f(SO_2(g) )\Big] - \Big[2 mol \times \Delta H^0_f (PbS(s))} + \mathbf{ 3 mol \times \Delta H^0_f(O_2(g) )\Big] }}[/tex]
[tex]\mathbf{\Delta H^0rxn = [2 mol \times (-217.32 kJ/mol) + 2 mol \times (-296.83)] - [2 mol \times (-100.4)} \\ \mathbf{+ 3 mol \times 0 kJ/mol]}}[/tex]
[tex]\mathbf{\Delta H^0rxn = -827.5 \ kJ/mol}}[/tex]
Therefore, we can conclude that the standard enthalpy of the reaction is -827.5 kJ/mol
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