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)
which angles are right
Answer:
a right is 90 degrees
In the reaction between lead(II) nitrate and sodium chloride, what, if any, are the spectator ions
Answer:
Explanation:
Spectator ions are ions in a solution/reaction that do not take part in a chemical reaction (hence are called "spectator" ions). They can be identified when they are found both in the reactant and product sides.
The reaction between lead(II) nitrate, Pb(NO₃)₂ and sodium chloride, NaCl is illustrated below
Pb(NO₃)₂ + 2NaCl ⇒ PbCl₂ + 2NaNO₃
According to solubility rules, all the compounds above (with the exception of PbCl₂) are all soluble and would dissociate when involved in a reaction.
Hence, the ionic equation based on the description above will be
Pb²⁺ + 2NO₃⁻ + 2Na⁺ + 2Cl⁻ ⇒ PbCl₂ + 2Na⁺ + 2NO₃⁻
From the above ionic equation, it can be noted that both 2NO₃⁻ and 2Na⁺ are found on both the reactant and product side and are hence the spectator ions.
What do scientists call all of the compounds that contain carbon and are found in living things?
organic
inorganic
acidic
nonacidic
Answer:
Organic
Explanation:
Edge student
pencil has a density of 14.5 g/mL and a volume of 5 mL. Calculate the mass in grams.
Answer:
The answer is 72.5 gExplanation:
The mass of a substance when given the density and volume can be found by using the formula
mass = Density × volumeFrom the question we have
mass = 14.5 × 5
We have the final answer as
72.5 gHope this helps you
Which of the following objects would have the smallest wavelength at the same velocity?
Baseball
Electron
Planet Earth
Proton
Answer: Planet Earth
Explanation: Wavelength (λ) is equal to h/mυ , where m = the mass of your object and υ = the frequency. Since Earth has the largest mass of the options, we can conclude that Earth will have the smallest wavelengths out of the rest.
The wavelength of matter-waves is given by the De Broglie formula. The larger the object, the smaller the observed wavelength hence the object having the smallest wavelength is Planet Earth.
De Broglie established the relationship between the momentum and the observed wavelength of an object. This proposition came to be known as wave-particle duality.
The wavelength of matter waves is given by;
λ = h/mv
Where;
λ = wavelength
m = mass of object
v = velocity of the object
If all the objects have the same velocity, the magnitude of the wavelength now depends on the mass of the object.
The object having the largest mass among the options is planet earth (5.972 × 10^24 kg).
Hence planet earth has the smallest wavelength among the options listed.
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A rock dropped in a graduated cylinder raises the level of water from 20 mL to 35 mL. The rock has a mass of 45 g. What is the density of the rock?
It has been hypothesized that a chemical known as BW prevents colds. To test this hypothesis, 20,000 volunteers were divided into four groups. Each volunteer took a white pill every morning for one year. The contents of the pill taken by the members of each group are shown in the chart below. What is the independent variable in this experiment? *
1. % Developing Colds
2. Number of Volunteers
3. Grams of sugar
4. Grams of BW
Grams of BW
i think thats irtu9rgirg
Independent variable in an investigation is the variable is does not depends on any other variable and on which we can have the control. Hence, the grams of BW is the independent variable here.
What is independent variables?In an experiment the parameters which changes by control or depending on other changes are called variables. There are two kinds variables namely dependant and independent variables.
The dependant variables are those variable which depends upon other variables and whose changes are studying with respect to certain parameters.
Independent variables does not depends on other variable and can be controlled by the researcher. Here, we are studying the % of developing cold with respect to the amounts of BW. The changing variable is BW amount on which the percentage of cold depends.
Therefore, the independent variable is grams of BW and dependant variable is % development of cold.
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Why is energy involved in changes of state?
Answer:
The energy of particles of matter determines the matter's state. Particles of a gas have more energy than particles of a liquid, and particles of a liquid have more energy than particles of a solid. Therefore, in order for matter to change from a solid to a liquid or from a liquid to a gas, particles of matter must absorb energy. In order for matter to change from a gas to a liquid or from a liquid to a solid, particles of matter must lose energy.
The system will lose or gain energy as a result of changing its state, which is why energy will be involved in state changes.
What is energy?
Energy is a quantitative property that would be transferred to a body or even a physical system and is visible in term of heat as well as light during the performance of work.
Whenever a state changes, energy is involved. When matter transitions through one state to another, it either releases or absorbs energy. When matter transforms from such a liquid to a solid, for example, it loses energy. When matter transforms from a solid to a liquid, the opposite occurs.
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plz help. with both will mark brainest
Answer:
The first one is balanced, but the second one is unbalanced.
Explanation:
Second one is unbalanced because there is an additional H and Cl on the right side. To fix it you would add a two in front of the HCl on the left side.
a. For a two-component alloy, derive the equations that convert the weight percent to atomic percent (for a two-element alloy).
b. Calculate the atomic fraction of Cu in an alloy that consists of 92.5 wt.% Ag and 7.5wt% Cu
Answer:
a. wt% A / Atomic Mass A / (wt% A / Atomic Mass A + wt% B / Atomic Mass B).
b. 11.74%
Explanation:
a. Weight percent is the mass of an element in 100g of the alloy. Atomic percent could be taken as the ratio between moles of an element and the total moles of the alloy.
Assuming a basis of 100g, the moles of A and B (The two elements in the alloy), are:
Moles A:
wt% A / Atomic Mass A
Moles B:
wt% B / Atomic Mass B
And atomic percent of A is:
wt% A / Atomic Mass A / (wt% A / Atomic Mass A + wt% B / Atomic Mass B)b. Atomic fraction of Cu in the alloy is (Molar mass Cu: 63.55g/mol; Molar mass Ag: 107.87g/mol):
7.25wt% / 63.55g/mol / (7.25wt% / 63.55g/mol + 92.5wt% / 107.87g/mol)
Atomic fraction Cu = 0.1174 = 11.74%
While ethanol CH3CH2OH is produced naturally by fermentation, e.g. in beer- and wine-making, industrially it is synthesized by reacting ethylene CH2CH2 with water vapor at elevated temperatures. A chemical engineer studying this reaction fills a 100L tank with 33.mol of ethylene gas and 16.mol of water vapor. When the mixture has come to equilibrium he determines that it contains 26.8mol of ethylene gas and 9.8mol of water vapor. The engineer then adds another 8.0mol of water, and allows the mixture to come to equilibrium again. Calculate the moles of ethanol after equilibrium is reached the second time. Round your answer to 2 significant digits.
Answer:
The value is [tex]k = 7.111 \ moles [/tex]
Explanation:
Generally the reaction between ethylene and water vapor is
[tex]CH_2CH_2_{(g)} \ \ \ +\ \ \ \ H_2O\ \ \ \rightarrow\ \ \ \ C_2H_5OH_{(g)}[/tex]
From the question the initial number of moles of ethylene is 33.mol
the initial number of moles of water vapor is 16.mol
So
At initial
[tex]CH_2CH_2_{(g)} \ \ \ +\ \ \ \ H_2O\ \ \ \rightarrow\ \ \ \ C_2H_5OH_{(g)}[/tex]
33.mol 16.mol 0 mols
Now at first equilibrium the number of moles of ethylene is 26.8mol
the number of moles of water vapor is 9.8mol
So the number of moles of ethanol is 33-26.8 = 6.2 mol
So at equilibrium
[tex]CH_2CH_2_{(g)} \ \ \ +\ \ \ \ H_2O\ \ \ \rightarrow\ \ \ \ C_2H_5OH_{(g)}[/tex]
26.8mol 9.8mol 6.2 mol
Generally the equilibrium constant is mathematically represented as
[tex]K = \frac{[C_2H_5OH]}{[CH_2CH_2] [H_2O]}[/tex]
Here [tex][C_2H_5OH][/tex] is the concentration of ethanol which is mathematically represented as
[tex][C_2H_5OH] = \frac{6.2 \ mol}{100L}[/tex]
=> [tex][C_2H_5OH] = 0.062 mol/L [/tex]
Also
[tex] [CH_2CH_2] = \frac{26.8 \ mol}{100L}[/tex]
[tex] [CH_2CH_2] = 0.268 mol/L[/tex]
Also
[tex][H_2O] = \frac{ 9.8 \ mol}{100L}[/tex]
[tex] [H_2O] = 0.098 mol/L[/tex]
So
[tex]K = \frac{0.062}{0.268* 0.098 }[/tex]
[tex]K = 2.3606 [/tex]
From the question we are told that 8 moles was added to ethylene
So volume of ethylene becomes 26.8 + 8 = 34.8 moles
So after the addition
[tex]CH_2CH_2_{(g)} \ \ \ +\ \ \ \ H_2O\ \ \ \rightarrow\ \ \ \ C_2H_5OH_{(g)}[/tex]
34.8mol 9.8mol 6.2 mol
At the second equilibrium
[tex]CH_2CH_2_{(g)} \ \ \ +\ \ \ \ H_2O\ \ \ \rightarrow\ \ \ \ C_2H_5OH_{(g)}[/tex]
(34.8- z)mol (9.8-z)mol ( 6.2+z) mol
Generally the equilibrium constant is mathematically represented as
[tex]K = \frac{[C_2H_5OH]}{[CH_2CH_2] [H_2O]}[/tex]
Here
[tex][C_2H_5OH][/tex] is now equal to
[tex][C_2H_5OH] = \frac{6.2+z}{100}[/tex]
[tex][CH_2CH_2]= \frac{ 34.8- z }{100}[/tex]
[tex][CH_2CH_2]= \frac{ 9.8-z }{100}[/tex]
So m
[tex]2.3606 = \frac{ \frac{6.2+z}{100}}{[ \frac{34.8- z }{100}] [\frac{ 9.8-z }{100}]}[/tex]
[tex]2.3606 = \frac{ \frac{6.2+z}{100}}{\frac{ z^2 -44.6 z + 341.04}{10000} }[/tex]
=> [tex]2.3606 = \frac{ 620 - 100z}{z^2 -44.6 z + 341.04}[/tex]
=> [tex]2.3606z^2 - 105.283 z + 805.05 =620 - 100z[/tex]
=> [tex]2.3606z^2 - 205.283 z + 185.059 = 0[/tex]
Multiply through by minus
=> [tex]2.3606z^2 -108.498z + 3336.7 = 0[/tex]
Solving this using quadratic equation
So [tex]z = 0.911[/tex]
Hence the number of moles of ethanol present at the second equilibrium is
[tex]k = 0.911 +6.2 [/tex]
[tex]k = 7.111 \ moles [/tex]
Which of the following BEST describes the main function of carbohydrates?
a
Speeding up chemical reactions
b
Fuel
c
Instructions for making proteins
d
Energy storage
The use of water in a heat exchanger is taking advantage of water's A. high specific heat. B. significant expansion during boiling. C. solid state when frozen. D. polar molecular nature
Answer:
A. high specific heat.
Explanation:
Specific heat defines the heat or thermal capacity of a substance.
Water has a high specific heat which adds an advantage to a heat exchanger. Due to the high heat or thermal capacity of the water heat exchanger can transfer a huge amount of heat between two or more fluids.
Hence, the correct answer is "A. high specific heat."
Answer:
A. high specific heat.
Explanation:
If you collect 5.74 mL of O 2 at 298 K and 1.00 atm over 60.0 seconds from a reaction solution of 5.08 mL, what is the initial rate of the reaction
Answer:
7.71 × 10⁻⁴ M/s
Explanation:
The initial rate of the reaction can be expressed by using the formula:
[tex]\dfrac{\Delta [O_2]}{\Delta t}[/tex]
where the number of moles of O₂ = [tex]\dfrac{PV}{RT}[/tex]
where;
Pressue P = 1.00 atm
Volume V =5.74mL = (5.74 /1000) L
Rate R = 0.082 L atm/mol.K
Temperature = 298 K
[tex]= \dfrac{1.00 \ atm \times \dfrac{5.74 }{1000}L}{0.082 \ L \ atm/mol.K \times 298 K}[/tex]
= 2.35 × 10⁻⁴ mol
Δ[O₂] = [tex]\dfrac{moles \ produced - initial \ mole}{\dfrac{5.08 }{1000}L }[/tex]
Δ[O₂] = [tex]\dfrac{2.35 \times 10^{-4} M - 0 M}{\dfrac{5.08 }{1000}}[/tex]
Δ[O₂] = 0.04626 M
The initial rate = [tex]\dfrac{\Delta [O_2]}{\Delta t}[/tex]
= [tex]\dfrac{0.04626}{60}[/tex]
= 7.71 × 10⁻⁴ M/s
The atmospheric conditions that exist for a long period of time in a given area are called what?
Answer:
Climate
Explanation:
Which statement best compares the amount of fossil fuels formed each year to the amount used each year?
Answer: The amount of fossil fuels formed is approximately the same as the amount used.
Explanation:
The amount of fossil fuels formed is approximately the same as the amount used. The amount of fossil fuels formed is much less than the amount used. The amount of fossil fuels formed is greater than the amount used.
The amount of fossil fuels formed is much less than the amount used. The correct option is C.
What is fossil fuel?Fossil fuels are deduced from the putrefaction of both animals and plants. These fuels, which can be discovered in the Earth's crust as well as encapsulate carbon and hydrogen, can be burned for energy.
Fossil fuels include coal, oil, and natural gas. The amount of fossil fuels produced is significantly less than the amount consumed.
The compounds that comprised up plankton as well as plants transform into fossil fuels after millions of years underground. Plants decompose into coal while plankton decomposes into natural gas and oil.
These resources are now extracted by humans through coal mining and the drilling of oil and gas wells on land and offshore.
Warming would certainly slow if we stopped using fossil fuels today, but removing greenhouse gases from the atmosphere will have to happen eventually.
Thus, the correct option is C.
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Your question seems incomplete, the missing options are:
The amount of fossil fuels formed is exactly the same as the amount used.
The amount of fossil fuels formed is approximately the same as the amount used.
The amount of fossil fuels formed is much less than the amount used.
The amount of fossil fuels formed is greater than the amount used.
HELP
Write the chemical name for each compound listed below.
1. NaCl
2. Al2O3
3. K25
4. CuBr2
5. Feo
The rock has a mass of 7.9g and a volume of 3.0 cm3. What is the density of the rock?
Answer:
The answer is 2.63 g/cm³Explanation:
The density of a substance can be found by using the formula
[tex]density = \frac{mass}{volume} \\ [/tex]
From the question we have
[tex]density = \frac{7.9}{3} \\ = 2.633333...[/tex]
We have the final answer as
2.63 g/cm³Hope this helps you
which of the following is an acidic oxide?
A.CO
B.N2O
C.SO2
D.K2O
Answer:
C
Explanation:
A gas has a volume of 300 mL and a pressure of 2 atm. What volume will the gas occupy when the pressure is
increased to 7 atm (total)?
Answer:
The answer is 85.71 mLExplanation:
The new volume can be found by using the formula for Boyle's law which is
[tex]P_1V_1 = P_2V_2[/tex]
where
P1 is the initial pressure
P2 is the final pressure
V1 is the initial volume
V2 is the final volume
Since we are finding the new volume
[tex]V_2 = \frac{P_1V_1}{P_2} \\[/tex]
We have
[tex]V_2 = \frac{300 \times 2}{7} = \frac{600}{7} \\ = 85.714285...[/tex]
We have the final answer as
85.71 mLHope this helps you
Many scientists have contributed to the atomic theory. In 1803 John Dalton gave new insight to this theory. Which desciption of an atom fits our most
current understanding?
Fyry nyyden atom is the same as every hydrogen atom
Using Gizmo ,describe the main use for each fuel Coal: Petroleum: In each case, what is the end product of burning the fossil fuel,and where does it go? Help is for today
Answer:
See explanation
Explanation:
Coal is primarily used for electricity generation. The burning of coal leads to emission of gases such as oxides of carbon, oxides of sulphur, oxides of nitrogen and water vapour. All these go straight into the atmosphere.
Petroleum is primarily used as transportation fuels. The burning of petroleum oils mostly leads to the emission of oxides of carbon and sulphur together with water vapour into the atmosphere.
Describe the relationship of the Earth’s lithosphere to the asthenosphere.
The asthenosphere is composed of rigid plates that “float” on top of the lithosphere.
The lithosphere is composed of rigid plates that “float” on top of the asthenosphere.
The lithosphere is a solid wall around the asthenosphere, and they move as one unit.
The asthenosphere is found in the Earth’s core and is protected by the lithosphere.
Answer:
The lithosphere is the brittle crust and uppermost mantle. The asthenosphere is a solid but it can flow, like toothpaste. The lithosphere rests on the asthenosphere
Explanation:
Answer:
pretty sure its B
Explanation:
might not be tho but pretty sure it is
if u trust urself do it! (not sponsored by nike)
Which is one factor that contributes to the formation of polar, temperate, and tropical zones?
the angle of the Sun’s rays
the direction of seasonal winds
the presence of prevailing winds
the movement of wind near a mountain
Answer: A) The angle of the Sun's rays!
Answer:
A) The angle of the Sun's rays!
Explanation:
HELPPP!!!
Write a definition for fluid that incorporates time
into a model of solids and liquids.
Answer:
Definition: Fluid that can act as a liquid or as a solid depending on the pressure applied on it.
Explanation:
A fluid that incorporates time in a solid and liquid model is a non-Newtonian fluid. This type of fluid can behave as a solid or as a liquid depending on the pressure that is applied on it. This is different from normal fluids that remain the same regardless of the pressure they are subjected to. In the case of non-Newtonian fluids, when submitted to pressure, they are presented as solids, but without pressure, they are presented as liquids. This feature can be seen even within the same system.
In the ionic compound KCL, which ion is the cation, and which is the anion? PLEASE HELP
Answer:
Potassium chloride, KCl , is an ionic compound formed by the electrostatic force of attraction that holds the potassium cations and the chlorine anions together
Explanation:
Enter your answer in the provided box. A sample of an unknown gas effuses in 11.1 min. An equal volume of H2 in the same apparatus under the same conditions effuses in 2.42 min. What is the molar mass of the unknown gas
Answer: The molar mass of the unknown gas is 9 g/mol
Explanation:
From Graham's law of effusion rates, the rate of effusion of a gas is inversely proportional to the square root of its molar mass.
[tex]\frac{rate_1}{rate_2}=\sqrt{\frac{M_2}{M_1}} [/tex]
[tex]rate=\frac{volume}{time} [/tex]
Rate is volume effused per unit time. Since, the volumes are same, the formula could be written as:
[tex]\frac{t_B}{t_A}=\sqrt{\frac{M_B}{M_A}}[/tex]
Putting the values in the formula:
[tex]\frac{2.42min}{11.1min}=\sqrt{\frac{M_{H_2}}{M_A}} [/tex]
[tex]\frac{2.42min}{11.1min}=\sqrt{\frac{2}{M_A}} [/tex]
Squaring both sides:
[tex]\frac{2}{M_A}=0.218[/tex]
[tex]M_A=9g/mol[/tex]
The molar mass of the unknown gas is 9 g/mol
What type of energy is the sun of an objects potential and kinetic energy
All of the energy from the Sun that reaches the Earth arrives as solar radiation, part of a large collection of energy called the electromagnetic radiation spectrum. Solar radiation includes visible light, ultraviolet light, infrared, radio waves, X-rays, and gamma rays. Radiation is one way to transfer heat.
On the graph, indicate the distance that corresponds to the bond length of the N2 molecule by placing an X on the horizontal axis.
Answer:
Check the image in the file attached below.
Explanation:
The objective of this question is to use the diagram provided to indicate the distance that corresponds to the bond length of the N2 molecule by placing X on the horizontal axis.
The bond length shows the distance of the bonds between the nuclei of the bonded atoms between the N2 molecule and O2 molecule. From the diagram, we can see that the bond length of O2 shows a greater tendency over the N2 molecule and it also have higher potential energy than the N2 molecule.
The distance corresponding to the bond length of N₂ is indicated in the attached graph.
Bond length represents/shows the bond distance between the atoms that are chemically bonded in the molecule ( N₂ ) . The bond distance ( average distance ) is measured from the nucleus of one binding atom toward another.
The bond length determines how easy or difficulty atoms bonded in a molecule can be separated. i.e. the longer the bond length the easier it is to separate chemically bonded atoms in a molecule.
Hence we can conclude that the distance corresponding to the bond length of N₂ is indicated in the attached graph.
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On the graph, which shows the potential energy curve of two N atoms, carefully sketch a curve that corresponds to the potential energy of two O atoms versus the distance between their nuclei.
Answer:
Explanation:
We are to carefully sketch a curve that relates to the potential energy of two O atoms versus the distance between their nuclei.
From the diagram, O2 have higher potential energy than the N2 molecule. Because on the periodic table, the atomic size increases from left to right on across the period, thus O2 posses a larger atomic size than N2 atom.
Therefore, the bond length formation between the two O atoms will be larger compared to that of the two N atoms.
