The energy change associated with the transition from n = 2 to n = 5 in the hydrogen atom is 2.856 eV.
Planck's equation, E = h, relates the energy change connected to a transition to the frequency of the electromagnetic wave. The equation c = then links the wave's frequency to both its wavelength and the speed of light.
The expression for the change in energy for a transition from a state to a state in a hydrogen atom is
E = -13.6Z² (1/Nf² - 1/Ni²)
where Z is the atomic number, which is 1 for hydrogen. Substituting
Nf= 5 and Ni= 2
E = -13.6 × (1/ (5)²- 1/ (2)²)
E = -13.6 × - 0.21
E = 2.856 eV
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The direction of force of Earth's magnetic field is from the geographic South
Pole to the geographic North Pole. Where is Earth's magnetic south pole?
• A. Near Earth's equator
• B. Near Earth's North Pole
• C. Near Earth's center
• D. Near Earth's South Pole
SUBMIT
If x = − 4, which number line shows the value of |x|? (5 points) Group of answer choices
If x = − 4, number line shows the value of |x| is 4 tick mark to the left of zero.
given that :
x = -4
The absolute value is the distance from zero. The absolute value is always positive.
| x | = | -4 | = 4
The absolute value = distance from the zero.
a number line contains negative and positive number . number to the right side of zero is positive and to the left side of zero is negative. Absolute value means how far the number is from zero.
Thus, If x = − 4, number line shows the value of |x| is 4 tick mark to the left of zero.
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Help pls I have 5 min pls
Energy and Temperature Activity Worksheet
Instructions: Follow the directions below to complete part one and part two of this activity. You will submit both parts once completed.
Note: You are not performing the experiment—only designing it.
Shape
Introduction
The purpose of this assignment is to design an experiment that another student could follow and use to test whether land or water heats faster.
You will complete the following:
Part One: Experimental Design. Plan out an experiment by answering the guiding questions below.
Part Two: Design a Lab Report. Write the outline of a lab report so that another student could complete the experiment by using the materials listed below:
sand
water
heat lamps
thermometers
cups
Shape
Part One: Experimental Design
Use these guiding questions to create the experiment. Answer each question below:
What hypothesis will the experiment test?
What are the variables?
What purpose would the sand serve?
What purpose would the water serve?
What purpose would the heat lamps serve?
What purpose would the thermometers use?
How can you use these materials to test whether land or water heats faster?
How would you compare whether land or water heats faster?
Within a 24-hour period, at what three points should the temperature be taken? Why?
What would an effective conclusion need to include?
can someone help me with part one please ☆ ～('▽^人) you'll receive 100 points
Land surfaces are much darker so they absorb much more solar radiation than water. Most of the solar radiation is reflected by water which leads in reflecting the solar radiation that reaches the surface back in to the atmosphere.
How does this occur?
Due to lower specific heat of sand it heats up faster than water. On the other hand water requires one calorie of energy to raise the temperature of one gram of water by one degree Celsius. Sand takes 19 calories per gram to raise the temperature of the sand by 1 degree Celsius. While Sand requires fewer calories to raise its temperature one degree Celsius and that’s why it heats up faster than water.
Land absorbs more solar radiation the land surface retains more heat as do the vegetation for energy.
Therefore, during this experiment the sand heats up much faster than water. This happens because of the specific heat of the sand that initiates the heating rapidly under the lamp as the time passes.
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pls answer question will mark brainliset tyty
The option (1) water supply i.e. the biotic factor that affect the human most.
Competition is a biotic element that prevents population increase in an aquatic habitat since it involves living things.Competition is an interaction between individuals or species where the presence of another reduces the fitness of one. A factor may be the limited availability of at least one resource (such as food, water, and territory) used by both.Abiotic elements including as depth, sunlight, nutrients, and oxygen availability have an impact on population increase in aquatic ecosystems.An ecosystem's overall health is also influenced by biotic factors such as the diversity of consumers and the presence of autotrophs, or self-sustaining organisms like plants. Abiotic variables have an impact on an organism's capacity for survival and reproduction. Abiotic barriers prevent the formation of population .
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If the mole fraction of K2SO3 in an
aqueous solution is 0.0328,
what is the weight/weight %
(percent by mass) of K₂SO3?
Molar Mass
K₂SO3: 158.26 g/mol
H₂O: 18.016 g/mol
Enter text here
Based on the mole fraction, the mass percentage of K₂SO₃ in the solution is 23.0%
What is the mass percentage of K₂SO₃ in the given solution?The mass percentage of K₂SO₃ in the given solution is determined from the mole fraction as follows:
The mole fraction of K₂SO₃ = 0.0328 moles
The moles of water in the solution = 1 - 0.0328 moles
The moles of water in the solution = 0.9672 moles
mass of substance = moles * molar massThe mass of K₂SO₃ = 0.0328 * 158.26 g
The mass of K₂SO₃ = 5.19 g
The mass of water in the solution = 0.9672 * 18.016
The mass of water in the solution = 17.42 g
Total mass of solution = 5.19 + 17.42
Total mass of solution = 22.61 g
Mass percent of K₂SO₃ = 5.19/22.61 * 100%
Mass percent of K₂SO₃ = 23.0%
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I onlyI and II onlyII onlyII and III onlyI and III onlyIII only
The species that act as acid are the ones that donates H⁺ in the reaction.
Since we are working with an equilibrium, we have to consider both directions.
From left to right, we have H₂O turning into OH⁻ because it lost one H⁺, so H₂O is acting as an acid in the forward reaction.
From right to left, we have CH₃NH₃⁺ tunrning into CH₃NH₂ because it lost one H⁺, so CH₃NH₃⁺ is acting as an acid in the backwards reaction.
So, the species that act as acids are H₂O and CH₃NH₃⁺, I and II only.
The empirical formula for a compound that contains 89.3% potassium and 10.7% nitrogen is:A)K2NB)KNC)K3ND)KN3
Explanations:
1. Calculate number of moles for K and N(i) Moles for K
mass = 89.3% = 89.3g
Mol. mass K =39.0983g/mol
∴ n = mass/molmass
=89.3/39.0988
=2.28 moles
(ii) Moles for N
mass = 10.7% = 10.7 g
Mol. mass N =14.0067g/mol
∴ n = mass/molmass
=10.7g/ 14.0067g/mol
=0.76 moles
2. Divide all components by the smallest value:• K= 2.28 /0.76 = 2.9898240669737 ≈ 3
• N=0.76/0.76 = 1
Therefore emperical formula has 3 K and 1 N = K3NThe chemical equation below shows the reaction of sodium (Na) and chlorine (Cl) to form sodium chloride (NaCl).
2Na + Cl2 → 2NaCl
The chemical equation below shows the reaction of sodium (Na) and chlorine (Cl) to form sodium chloride (NaCl).
2Na + Cl₂ ----> 2NaCl, NaCl formed is an ionic compound.
Sodium is a metal and have tendency to donate an electron and form Na⁺ .The chlorine is a non metal and have tendency to accept electron and form Cl⁻ ion. The positively charged Na⁺ ion and negatively charged Cl⁻ ion form ionic bond . An ionic bond is formed by the complete transfer of electrons. The product is form is NaCl , sodium chloride.
Thus, The chemical equation below shows the reaction of sodium (Na) and chlorine (Cl) to form sodium chloride (NaCl).
2Na + Cl₂ ----> 2NaCl, NaCl formed is an ionic compound.
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pls answer quick ty will mark brainliest
Answer:
The process of separating a metal from its ore is known as smelting.
What trend in electronegativity do you see as you go across a period/row on the table? What causes this trend?
Answer: It decreases as it goes down and increases as it goes to the right.
Explanation: This is because as it goes down, the elements are becoming bigger which makes the distance from the proton and electron to become further, causing the attraction to weaken. While as it goes to the right across a period, it increases because the number of protons increase and we know that if there are more protons, the pull of the electrons from the nucleus becomes stronger.
What does a scientist mean when he or she says an object is at rest?(1 point) Responses The object is not speeding up or slowing down. The object is not speeding up or slowing down.
The object has no forces acting on it.
The object has no forces acting
on it. The object has no attractive forces acting on it. The object has no attractive forces acting on it. The object is not moving relative to its surroundings.
Scientist mean when he or she says an object is at rest then the object is not moving relative to its surroundings
Velocity of the object is said to be uniform when its speed and direction does not change and the object at rest has uniform speed of zero all the time and does not even change the direction and when object is at rest position then the velocity is zero such an object will not change its state of motion that's why when he or she says an object is at rest the scientist says that the object is not moving relative to its surroundings
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How many valance electron‘s are in potassium 
Answer:
one valence electron
Explanation:
K is the symbol for potassium, and the number of valence electrons can be found through its' group on the periodic table. Hence, it has one valence electron.
PLEAE HELP SCIECE I WILL GIVE YOU BRAINLIEST
Answer:
You have to record it before
What is the electron configuration of Silicon in Ground state ?
A) 1s22s22p63s23p14s1
B) 1s22s22p63s4
C) 1s22s22p63s23p2
D) 1s22s22p63s23p3
In each sentence, choose the number that represents the correct answer. A. Under certain conditions, 6 units of hydrogen will burn in 1 second. This process releases energy at a rate of 286/572/1,716 kJ per second. B. Under the same conditions, 1 unit of ethanol will burn in 1 second. This process releases energy at a rate of 686 /1,371/8,226 kJ per second. C. Under these conditions, hydrogen / ethanol will release more energy in 1 second.
C. Under these conditions, hydrogen / ethanol will release more energy in 1 second is the correct answer.
The energy change that occurs when one mole of a compound is burnt in excess oxygen under standard conditions is called the standard enthalpy change of combustion. The standard enthalpy change of combustion of hydrogen is -286kJ/moL.Ethanol combustion is an exothermic process. The chemical reaction that occurs when ethanol burns releases a lot of heat and energy, 277.7 kJ per mole of ethanol, in addition to the creation of new compounds. In conclusion, ethanol burns by combining with oxygen to create carbon dioxide, water, and heat.The standard enthalpy change of combustion is the energy change that happens when one mole of a compound burns in excess oxygen under typical conditions. Enthalpy change for hydrogen combustion is typically -286kJ/moL.To know more about Hydrogen check the below link:
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Which set
correctly orders
the atoms from
lowest to highest
ionization
energy?
PLEASE HELP
Answer:
Pb, Sn, Te, S, Cl
Explanation:
silicon, tin, and lead are all in the same group. the density of tin is about 7.28 g/cm3 and the density of lead is about 11.34 g/cm3. based on this group trend, what do you estimate the density of silicon to be?
The atom's radius and mass increase from top to bottom. The density of elements from top to bottom also increases in a periodic table.
Density of Sn= Mass of Sn/Volume of Sn
=24.3968/7.28
=3.49 g/ml*ml/cm³
=3.49 g/cm³
It is accurate to assume that the density of Sn will fall between that of Si and lead . the mass number and radius of the atoms increase from group to group as we move from top to bottom in a periodic table.. The density rises because the increase in mass number is greater than the increase in radius. Simply multiplying by the molar mass of the gas allows one to derive the formula for mass density from the formula for number density. Do not forget that the mass is equal to the moles (n) times the molar mass (M). Smaller masses can be measured in grams instead of kilograms (kg), which is the standard SI unit for mass.
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What is the isotope name of the element that has 9 neutrons?
1)Beryllium-4
2 ) Beryllium-9
3) Fluorine-9
4) Fluorine-19
5)Not enough information to tell
We do not have enough information to deduce the isotope that would have nine neutrons. Option 5
What is the neutron?The atom is composed of subatomic particles. The subatomic particles that are in the atom are such that we have the electrons that are negatively charged, the protons that are positively charged and the neutrons that are uncharged.
Now, we know that the number of neutrons is obtained as the difference between the mass number and the atomic number of the atom. In this case, we only have the mass numbers and not the atomic numbers thus we do not have sufficient information.
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Lead ions can be removed from solution by precipitation with sulfate ions. Suppose a solution contains lead(II) nitrate.
1) List the compounds involved in the reaction.
Lead (II) nitrate
Potassium sulfate
Lead (II) sulfate
Potassium nitrate.
2) Write the formula of every compound.
Lead (II) nitrate: Pg(NO3)2
Potassium sulfate: K2SO4
Lead (II) sulfate: PbSO4
Potassium nitrate: KNO3
3) Write the chemical equation
.
[tex]Pb(NO_3)_2+K_2SO_4\rightarrow PbSO_4+KNO_3[/tex]List the elements (or polyatomic ions) in the reactants.
Pb: 1
NO3: 2
K: 2
SO4: 1
List the elements (or polyatomic ions) in the products.
Pb: 1
NO3: 1
K: 1
SO4: 1
Balance K.
[tex]Pb(NO_3)_2+K_2SO_4\rightarrow PbSO_4+2KNO_3[/tex]List the elements (or polyatomic ions) in the reactants.
Pb: 1
NO3: 2
K: 2
SO4: 1
List the elements (or polyatomic ions) in the products.
Pb: 1
NO3: 2
K: 2
SO4: 1
4) Balanced chemical equation.
[tex]Pb(NO_3)_{2(aq)}+K_2SO_{4(aq)}\rightarrow PbSO_{4(s)}+2KNO_{3(aq)}[/tex].
Match the definitions to the atomic models. Model names may be used more than once.
Question 3 options:
Supported by Rutherford's gold foil experiment
A small, dense, positively-charged nucleus surrounded by a negatively-charged electron cloud.
The atom has a small positively-charged nucleus with negatively-charged electrons orbiting in different energy levels.
This is the current model of atomic structure which explains the existence of electron clouds and their discrete energy levels.
Sometimes referred to as the Planetary Model
Was disproved by Rutherford's gold foil experiment
Negatively-charged electrons randomly dispersed in a sea of positive charge.
1.
Plum Pudding Model
2.
Bohr Model
3.
Quantum Mechanical Model
4.
Nuclear Model
Nuclear Model - Supported by Rutherford's gold foil experiment.
Nuclear Model - A small, dense, positively-charged nucleus surrounded by a negatively-charged electron cloud.
Quantum Mechanical Model - This is the current model of atomic structure which explains the existence of electron clouds and their discrete energy levels.
Plum Pudding Model - Was disproved by Rutherford's gold foil experiment.
Plum Pudding Model - Negatively-charged electrons randomly dispersed in a sea of positive charge.
Bohr Model - Sometimes referred to as the Planetary Model.
Bohr Model - The atom has a small positively-charged nucleus with negatively-charged electrons orbiting in different energy levels.
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What is the mass of a helium sample that contains 0.448 moles of He has?
To calculate the mass of Helium, we look up in the periodic table the atomic mass. This is equal to 4.003 g/mol.
Now, we apply the following relation to doing the conversion:
[tex]\begin{gathered} gH_{}e=\text{Given moles He}\times\frac{AtomicMass,\text{gHe}}{1\text{mol He}} \\ gH_{}e=\text{0.448}\times\frac{4.003\text{gHe}}{1\text{mol He}}=1.793\text{gHe} \end{gathered}[/tex]The mass of a Helium sample that contains 0.448 moles of He is 1.793 g
15 grams of water into moles
0.83 moles present in 15 grams of water .
moles=given mass/molar mass
given mass=15 grams
molar mass, water=18 gram
moles=given mass/molar mass
moles=15/18
moles=0.83
The mole concept is a helpful technique to quantify the amount of a material. When dealing with particles at the atomic (or molecular) level, it is recognized that even one gram of a pure element has a vast number of atoms. The mole concept is widely used in this context. The most used unit of measurement is the "mole," which is a count of a significant number of particles.
The number 6.02214076*1023, also known as the Avogadro constant, is usually denoted by the letter "NA". Among the elementary things that may be represented in moles are atoms, molecules, monoatomic and polyatomic ions, as well as other particles (such as electrons).
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Drag the number to the correct location based on the number of significant figures.
Significant figures
0.0093: Leading zeros are never significant. This number has two significant figures, nine and three.
120.9: Nonzero numbers are significant and zeros between those numbers are significant, too. This number has four significant figures.
1.000: Trailing zeros are significant if there is a decimal point. This number has four significant figures.
1.008: Nonzero numbers are significant and zeros between those numbers are significant, too. This number has four significant figures.
670: Trailing zeros are not significant. This number does not have a decimal point. So, it has two significant figures.
0.184: Nonzero numbers are significant. This number has three significant figures.
1.30: Trailing zeros are significant if there is a decimal point. This number has three significant figures.
is making glass wool a physical or chemical change?
(Multiple choice) Of the following species, which is most likely to be oxidized?
An element that is oxidized is one that loses electrons, losing electrons increases its oxidation state. Now, the more electrons there are in the last energy level of the element, that is, valence electrons, the easier it will be for this element to lose them. We can identify valence electrons in the periodic table, the group to which the element belongs indicates how many valence electrons it has. Let's see what the oxidation state of the elements is:
F:7
Li:1
N:5
Be:2
O:6
We see that Lithium is the one with the fewest valence electrons, it has only one valence electron, so this will be the element that is most likely to be oxidized.
Answer: 2. Li
Which of the following is an empirical formula?A.) P4O10B.) C2H4C.) H2O2D.) N2O
Answer:
N2O is an empirical formula
Explanation:
A.) P4O10 NO: Can be reduced to P2O5
B.) C2H4 NO: Can be reduced to CH2
C.) H2O2 NO: Can be reduced to H O
D.) N2O YES, the formula cannot be reduced any further.
PLEASE HELP 50 POINTS. PLEASE !!! BALANCING CHEMICAL EQUATIONS
Answer: 1st one is 1 N2 + 3 H2 > 2 NH3
2nd one is 2 KCLO3 > 2 KCL+3 O2
3rd one is 2 NaCL + 1 F2 > 2 NaF+CL2
> are the arrows
The numbers in front of the other numbers are the coefficient.
The numbers behind the numbers are the exponents.
Hi everyone,
The General formula for relative abundance
First 1:
Copper is made up of two isotopes.
Cu-63(62.9296 amu)
Cu-65(64.9278 amu)
Giving copper atomic weight of 63.546. What is the percentage abundance of each isotope?
Copper is made up of two isotopes ⁶³Cu(62.9296 amu) ⁶⁵Cu(64.9278 amu) Giving copper atomic weight of 63.546 then the percentage abundance of each isotope ⁶³Cu = 70% and ⁶⁵Cu = 30.848%
Isotopes are the members of a family of elements that all have the same number of protons and different numbers of neutrons
Here given data is
⁶³Cu = 62.9296 amu
⁶⁵Cu = 64.9278 amu
atomic weight = 63.546
We have to calculate percentage abundance of each isotope = ?
Let the natural abundance of ⁶³Cu is x
The natural abundance of ⁶⁵Cu 100−x
atomic weight is 63.546
Then 100×63.546 = 63x + 65(100−x)
= 6354.6 = 63x + 6500−65x = 6500−2x
= 2x = 145.4
= x = 72.7≃70
Hence the natural abundance of ⁶³Cu is is 70%
Therefore for ⁶⁵Cu the calculation the also same and ⁶⁵Cu = 30.848%
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How many electrons does hydrogen need in order to have a full shell of valence electrons?(1 point).
The number of electrons that hydrogen needs in order to have a full shell of valence electrons are one valence electron.
What are valence shell electrons?Valence shell electrons refer to the electrons that are found in the outermost shell of atoms of elements.
Valence electrons are the electrons that are involved in the chemical reactions of atoms of elements.
Atoms of elements take part in chemical reactions in order to achieve an octet or duplet structure which confers stability to the atoms.
Duplet refers to two complete valence electrons while octet refers to eight complete valence electrons.
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