Baased on the percent abundances and relative atomic masses of its two naturally occuring isotopes, the average atomic mass of rhenium is 186.252 amu.
To calculate the average atomic mass of rhenium, we need to multiply the relative atomic mass of each isotope with its corresponding percent abundance, and then add the results up.
So, for Re-185:
185 amu * 0.374 = 69.19 amu
(amu = atomic mass unit)
And for Re-187:
187 amu * 0.626 = 117.062
Now we add these two up to reach the average atomic mass of rhenium:
69.19 amu + 117.062 amu = 186.252 amu
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Select the choice that best describes the relationship of the pair of compounds. you might find it helpful to make a model of ceach. two compounds. compound 1 has an isopropyl group pointing up and an ethyl group pointing to the lower left. pointing to the right is a wedged bond to hydroxy and a dashed bond to methyl. compound 2 has an ethyl group pointing up and an isopropyl group pointing to the lower left. pointing to the right is a wedged bond to methyl and a dashed bond to hydroxy. the compounds are: enantiomers constitutional isomers not isomeric the same compound
The compounds are enantiomers.
Enantiomers are pairs of compounds that have exactly the same connectivity but opposite three-dimensional shapes. Enantiomers are not the same. One enantiomer cannot be superimposed on top of the other. Enantiomers are mirror images of each other. The easiest way to distinguish between enantiomers is to recognize that two molecules are mirror images of each other.
Enantiomers must be mirror images. The molecules in the image above are reflected on a thick line representing a specular surface. Examples of enantiomeric pairs of substances are the two optically active forms of tartaric acid called d-tartaric acid and l-tartaric acid. Stereoisomers that are mirror images of each other and are not superimposable are called enantiomers. Molecules whose mirror images are not superimposable and exist as enantiomeric pairs are said to be chiral and exhibit chirality.
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Calculate the mass of 4.00 moles of NH₂OH (s).
Answer:
132.12 grams
Explanation:
The mass of a compound equals the number of moles times the molar mass.
The molar mass of hydroxylamine is 33.03 grams/mole
The number of moles is 4 moles
4 moles * 33.03 grams/mole = 132.12 grams
Hydrated sodium tetraborate is heated
to drive off the water. You find there are
0.01312 mol Na2B4O7 and 0.1311 mol
H2O in the sample. What is the formula
of the hydrate?
A. Na2B4O7 H₂O
B. Na2B4O7 2H₂O
C. Na2B4O7-10H₂O
D. Na2B4O7-13H₂O
Answer: C. Na2B4O7•10H2O
Explanation:
Hope this helps :)
The formula is tetrasodium borate-Na2B4O7.10H2O
Given- 0.0132 mol Na2B4O7 and 0.1311 mol H2O
Step 1Using the molar mass of the anhydrous Na2B4O7 and its mass percentage, we can calculate the molar mass of the hydrate (if we look at it as 100% of the mass) by stoichiometry.
Molar mass of Na = (22.990 g/mol)
Molar mass of B = (10.811 g/mol)
Molar mass of O = (15.999 g/mol)
Molar mass of Na2B4O7= 2⋅22.990 g/mol +4⋅10.811 g/mol +7⋅15.999 g/mol = 201.217 g/mol
201.217g/mol : 52.8%=x g/mol : 100%
x g/mol = 201.217 g/mol⋅100%÷52.8 %
x g/mol= 381.093 g/mol
Step 2In 381.093 g of hydrate, we have 201.217 g of anhydrous Na2B4O7 , the rest of the mass is water.
381.093g−201.217g= 179.876 g of water
Molar mass of H = 1.008 g/mol
Molar mass of O = 15.999 g/mol
Molar mass of H2O= 1.008 g/mol+ 15.999g/mol = 18.015 g/mol
179.876g ÷18.015 = 9.98= 10 moles of water per mole of hydrate.
if the heat of fusion for water is 80. cal/g, how many calories are needed to melt 2.96 g of ice at 0 °c? treat the heat of fusion as an exact value.
The calories needed to melt the ice is 236.8 calories.
Heat of fusion also called latent heat is the heat constant needed to change the phase of a material such as solid to liquid or liquid to gas. The total calories or energy needed depends on the mass of and the heat of fusion and mass. It can be written as
Q = m . L
where Q is total heat, m is mass and L is latent heat.
From the question above, the given parameters are
m = 2.96 g
L = 80 cal/g
By substituting the mass and heat of fusion, we can calculate the total calories
Q = m . L
Q = 2.96 . 80
Q = 236.8 cal
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Min was writing about changes in the state of matter for a research paper. Which of these changes might she include as examples of sublimation? Choose the two statements that apply.
The correct option is D. Dry ice changes directly to carbon dioxide gas
A material can move straight from the solid to the gas state by sublimation without going through the liquid state. The triple point on a material's phase diagram corresponds to the lowest pressure at which the substance can remain as a liquid, and sublimation is an endothermic process that takes place there. Deposition, also known as desublimation, is the opposite of sublimation, in which a material transitions straight from the gas phase to the solid phase. A solid-to-gas transition (sublimation) followed by a gas-to-solid transition has also been referred to as sublimation (deposition)
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complete question:
Min was writing about changes in the state of matter for a research paper. Which of these changes might she include as examples of sublimation?
Choose the two statements that apply.
A. Clothing is hung outside on a day when the temperature is below the freezing point of water. The clothes dry, even though they freeze first.
B. An ice cube melts on the floor, then it evaporates.
C. Bromine is a reddish brown, liquid element. In a closed container, a reddish brown gas exists above the surface of the bromine.
D. Dry ice changes directly to carbon dioxide gas
How is the population of axolotls bred in captivity different from the population that lives in the wild? Pls Help :(
1. Only captive axolotls retain the features of a juvenile as adults.
2. Wild axolotls can survive on land.
3. The skin of axolotls bred in captivity usually has little to no coloring.
4. Only axolotls bred in captivity can regrow limbs
The populations of axolotls that are raised in captivity are able to regrow limbs but those grown in the wild can not.
What are the axolotls ?The axolotls are one of the populations of the organisms that are facing the threat of extinction. This implies that if nothing is seriously done to ensure that the populations do not go into extinction, they would all soon disappear from the face of the earth.
The response to this situation have been to ensure that the there is a conscious effort to make sure that the axolotls does not disappear from the face of the earth and most of this effort have been made by raising some populations in captivity. The populations raised in the wild are different from those raised in captivity.
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Explain why one must use the absolute temperature scale to solve gas problems.
For ease of use, the temperature was set to zero degrees Celsius. The velocity of particles is represented by zero on the absolute (Kelvin) scale. Absolute temperature changes cause corresponding changes in pressure or volume.
Temperature is a physical parameter that describes how hot stuff or radiation is.
such as the SI scale; those that rely solely on purely macroscopic properties and thermodynamic principles, such as Kelvin's original definition; and those that are not defined by theoretical principles but are defined by convenient empirical properties of particulate matter.
A thermometer is used to measure temperature.
The coldest a body can be conceived to be is one with an absolute zero temperature. It can only be approximated extremely closely, but not actually reached, in experiments.
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5 cm³ is a small volume of water for each experiment.
Give one advantage and one disadvantage of using a larger volume.
A smaller volume of an experiment, like 5 cm³, does not lead to wastage of the product and does not alter the testing procedures.
Why should the volume be controlled in an experiment?
The variable, like volume, is regulated (or maintained at the same level) to conduct a fair test. In this case, the object's volume can be altered. The mass of the substance will increase as the volume does. The quantity of atoms inside an object increases with its volume.
Advantage
The margin of error decreases with increasing study sample size. The risk of reporting false-negative or false-positive results can be reduced by researchers by using a larger volume. The accuracy of results will increase as the number of samples increases.
Disadvantage
It takes longer to gather, thus burdening the people collecting the larger volume of samples. In some circumstances, likely, the collection deadline will negatively impact how smoothly the production line runs.
Hence, there are both advantages and disadvantages of using a larger volume.
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1. If a ball starting at rest has a mass of 0.25 kilograms and is pushed with a force of 3.5 N, then what is the acceleration for the object from the applied force? SHOW YOUR WORK.
2. Use this equation to calculate the height a rocket reaches if the rocket were launched and it took 1.3 seconds to reach this unknown height and assuming that the acceleration is 9.81 m/s2. SHOW YOUR WORK.
The acceleration for the object from the applied force is 14 m/s².
The height reached by the rocket is 8.28 m.
What is the acceleration of the ball?
The acceleration of the ball is calculated by applying Newton's second law of motion as shown below.
F = ma
a = F/m
where;
F is the applied force
m is the mass of the balla is the acceleration of the balla = 3.5 N / 0.25 kg
a = 14 m/s²
The height reached by the rocket at the given time of motion is calculated as follows;
h = vt + ¹/₂gt²
where;
v is the initial vertical velocity of the rocket = 0h = 0 + ¹/₂gt²
h = ¹/₂(9.8)(1.3)²
h = 8.28 m
Thus, the acceleration for the object from the applied force is determined from Newton's second law of motion while the height reached by the rocket is determined by applying the second kinematic equation.
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If 100. 0 ml of a 0. 500 m aqueous hydrazine is mixed with 100. 0 ml of 0. 500 m aqueous hydrochloric acid, what will be the ph of the resulting solution?.
The pH of the resulting solution when 100. 0 ml of a 0. 500 m aqueous hydrazine is mixed with 100. 0 ml of 0. 500 m aqueous hydrochloric acid is 4.54
Since hydrazine is a weak base and hydrochloric acid is a strong acid.
No. of moles of hydrazine =( 100 × 0.500 ) mmol
= 50 mmol
No. of moles of hydrochloric acid =( 100 × 0.500 )
= 50 mmol
Since the number of mmol of base and acid is equal. Hence complete neutralization will take place because acid and base react in 1 : 1 mol ratio.
So after neutralization, a salt will be formed which will be acidic in nature because salt formed by the neutralization of strong acid and weak base will be acidic in nature.
Hence pH will be less than 7. Because an acidic solution has pH less than 7 .
The Kb is 3.0x10^-6
pKb=-logKb
pkb=-log(3.0x10^-6)
pkb=5.2287875
The concentration of salt is 50/200=0.25 M
pH=7-1/2pKb-logC
pH=7-1/2(5.2287875)-1/2log(0.25)
pH=4.54
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2. Which metal reacted most vigorously when placed in the acid? Give evidence to
support your answer.
Answer:
The alkali metals (Li, Na, K, Rb, Cs, and Fr) are the most reactive metals in the periodic table – they all react vigorously or even explosively with cold water, resulting in the displacement of hydrogen.
Explanation:
The metal that reacted most vigorously when placed in the acid is sodium, as it is an alkali metal.
What are alkali metals?At standard temperature and pressure, all of the bright, soft, extremely reactive alkali metals rapidly shed their outermost electron to create cations with charge +1.
One of the most reactive metals is the alkali metal. They have greater atomic radii and low ionization energies, which contribute to this. They have an oxidation state of 1, and they frequently give electrons during reactions. These metals stand out for their supple texture and silvery hue.
The alkali metals (Li, Na, K, Rb, Cs, and Fr) are the most reactive metals in the periodic table – they all react vigorously or even explosively with cold water, resulting in the displacement of hydrogen.
Therefore, the correct option is d. sodium.
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The question is incomplete. Your most probably complete question is given below:
Oxygen
magnesium
iron
sodium
Aluminium appears unreactive. This is because it has a layer of what covering its surface?
Enter your answer
Aluminium appears unreactive. This is because of the formation of aluminium oxide layer in its outer surface.
This is because aluminium reacts with oxygen present in air to form a thin layer of aluminium oxide on its surface. This oxide layer is very stable and acts as a protective coating by preventing further reaction of aluminium.
Also, Aluminium is light in weight and a good conductor of heat. Hence, it is used to make cooking utensils.
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what does removing energy from water at 25c do to the temp of the water?
Removing energy from water at 25 °C the temp of the water will decreases.
When we remove the heat from water the temperature of water will falls and water will cool down. The water is cool; down when we remove the heat from it and the kinetic energy decreases of the particles. once the temperature recaches to the freezing point then there will be no further change in temperature. This is the phase transition from liquid to solid. By the removal of heat will cause the particle of water to locking up into place.
Thus, Removing energy from water at 25 °C the temp of the water will decreases.
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The drawing below shows the effect of moving air on a desert sand dune.
Which most likely describes the event in the drawing?
The drawing below shows the effect of moving air on a desert sand dune.
Which most likely describes the event in the drawing?
It is an example of erosion by gravity.
It is an example of erosion by wind.
It is an example of physical weathering by wind.
It is an example of physical weathering by gravity.
The drawing below shows the effect of moving air on a desert sand dune describes the event in the drawing it is an example of erosion by wind
Natural sand dunes usually start as windblown sand that accumulates in a sheltered area behind some type of obstacle such as piles of seaweed and a hill of sand made up of wind on the coast or in a desert and it is because of erosion by wind strong winds blow across the loose sand on the surface of the earth including sands found in deserts and beaches that's why erosion by wind most likely describes the event in the drawing
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[tex]\large{\underline{\underline{\pmb{\sf{\color {yellow}{Question:}}}}}}[/tex]
Arrange the following compounds in decreasing order of basic strength in aqueous solution
C2H5NH2 , (C2H5)2NH , (C2H5)3N
The correct decreasing order of the basic strength of amines in an aqueous solution is (C2H5)3N > (C2H5)2NH > C2H5NH2.
What do you mean by a chemical's fundamental strength?
The ability of a chemical to share electrons with nearby atoms is referred to as the chemical's fundamental strength.
The nitrogen atom becomes electron-rich as a result of the lone pairs. The +I effect is the second component.
Because the three benzene rings are connected to nitrogen and stearic hindrance forms as a result, nitrogen is unable to donate its lone pair to the rings, giving (C2H5)3N the highest degree of +I effect out of all the supplied amines. Lone pairs are so accessible for the incoming atoms.
As a result, (C2H5)3N > (C2H5)2NH > C2H5NH2 is the order.
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Which phase of matter is the least common on Earth?
A. Gases
B. Liquids
C. Solids
D. Plasma
Answer:
the answer is....... D. Plasma
Answer:
Plasma
Explanation:
Got it right
A LOT OF POINTS!!
30.0g sample of calcium sulfide contains 16.4g of calcium. What is the % of sulfur by mass in the compound
Answer:
there you go man
Explanation:
consider the reaction when aqueous solutions of ammonium phosphate and chromium(ii) sulfate are combined. the net ionic equation for this reaction is:
Explanation:
The reaction of aqueous solutions of iron(II) sulfate and ammonium phosphate leads to the formation of solid precipitate of iron phosphate and an aqueous solution of ammonium sulphate.
Molecular equation :
3
F
e
(
S
O
4
)
(
a
q
)
+
2
(
N
H
4
)
3
P
O
4
(
a
q
)
→
F
e
3
(
P
O
4
)
2
(
s
)
+
3
(
N
H
4
)
2
S
O
4
(
a
q
)
Total ionic equation :
3
F
e
+
2
(
a
)
+
3
(
S
O
4
)
2
−
(
a
q
)
+
6
(
N
H
4
)
+
(
a
q
)
+
2
P
O
3
−
4
(
a
q
)
→
F
e
3
(
P
O
4
)
2
(
s
)
+
6
(
N
H
4
)
+
(
a
q
)
+
3
S
O
2
−
4
(
a
q
)
Net ionic equation :
By canceling the spectator ions from total ionic equation, we get
3
F
e
+
2
(
a
q
)
+
2
P
O
3
−
4
(
a
q
)
→
F
e
3
(
P
O
4
)
2
(
s
)
1. What type of TV uses a CCFL for backlighting?
O 3D
O LCD
OLED
O Cathode Ray tube
Explanation:
When a virus infects a bacterial cell, often new viruses are assembled and released when the host bacterial cell is lysed. If these new viruses go on to infect new bacterial cells, the new host cells may not be lysed. What is the most plausible explanation for this?A) The bacterial cell must be resistant to infection by the virus.
B) The virus carries genes that confer resistance to the host bacterial cell.
C) The host bacterium couples the viral infection with transformation.
D) The virus has entered the genome of the bacterial cell and is in the lysogenic stage.When a virus infects a bacterial cell, often new viruses are assembled and released when the host bacterial cell is lysed. If these new viruses go on to infect new bacterial cells, the new host cells may not be lysed. What is the most plausible explanation for this?A) The bacterial cell must be resistant to infection by the virus.B) The virus carries genes that confer resistance to the host bacterial cell.
C) The host bacterium couples the viral infection with transformation.
D) The virus has entered the genome of the bacterial cell and is in the lysogenic stage.Answer:
LCD TV's use a CCFL for backlighting
11. How much energy is required to heat 120.0g of water from 2.0 C to 24 C
Answer:The specific heat of water is 1 calorie/gram °C = 4.186 joule/gram °C.
Explanation:Therefore the required amount of energy is following:
Q = c*m*dT = 4.186 * 120 * (24 - 2) = 11,051 J
what is the proper method to determine the mass number of an isotope
Answer:
Subtract the atomic number (the number of protons) from the rounded atomic weight. This gives you the number of neutrons in the most common isotope. Use the interactive periodic table at The Berkeley Laboratory Isotopes Project to find what other isotopes of that element exist.
Explanation:
Forms of the same atom that differ only in their number of neutrons are called isotopes. Together, the number of protons and the number of neutrons determine an element's mass number: mass number = protons + neutrons.
what are the function and structure of a bacteria
Answer:
the cell wall forms a rigid structure of uniform thickness around the cell and is responsible for the characteristic shape of the cell (rod, coccus, or spiral).
if 1.00 x 1018 singly charged positive sodium ions flow from the anode of an electrochemical cell each second and an equal number of singly charged negative chlorine ions flow from the cathode of the cell, how much current flows through the cell?
Total current flows through the cell I = 0.32 Amp
What is electrochemical cell?An electrochemical cell is a device that either generates energy from chemical reactions inside of it or uses electricity to power various chemical processes inside of it.
Given,
Sodium ion flows from anode and negatively charged ion flowing from cathode
so if you write the equation that will be
Na - e ⇄ Na⁺
Cl⁻ + e ⇄ Cl
Now current flowing is the number of charges flowing per unit second
here total current is due to cation (Na⁺) and anion (Cl)
so only one electron is associated here,
so total current (I) = 10¹⁸ ˣ 1.6 ˣ 10⁻¹⁹ Amp.
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Which is the major organic product of the reaction of 4-aminophenol with 1 equivalent of acetic anhydride?.
The main reaction of 4-aminophenol with acetic anhydride gives paracetamol with acetic acid as a side product.
What is paracetmol?
The most popular analgesic in the world and the first choice for treating pain disorders is acetaminophen (paracetamol), widely known as Tylenol. It is also employed for its antipyretic properties, which lower fever. due to the risk of lethal overdose and liver failure brought on by improper acetaminophen use. For more on the paracetmol structure and uses, see the attached file.
It is frequently used to treat mild to moderate pain, such as headaches, toothaches, and sprains, as well as to lower fevers brought on by ailments like the flu and the common cold. Since it's generally safe to consume and has few side effects, paracetamol is frequently suggested as one of the initial therapies for pain.
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Which statement is correct in the process of balancing the equation?
The correct statement in the process of balancing the equation is option C which is Do nothing, the equation is already balanced.
The chemical equation which is given in the question is -
CH₄ + O₂ → CO₂ + 2 H₂O
This reaction is a balanced chemical reaction as number of atoms of product and reactant are equal.
Number of carbon atoms on reactant side is 1 and number of carbon atoms on product side is also 1. Number of oxygen atoms on product side is 2 and hydrogen atoms is 4 and on reactant side, number of oxygen atom was 1 and number of hydrogen atom was 2 but after adding coefficient 2 in front of H₂O, number of Oxygen atoms became 2 and number of hydrogen atom became 4 making it a balanced reaction.
Therefore, correct option for process of balancing the equation is C.
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Wat units are used to express mass an weight .
Answer:
gram (g), kilogram (kg) and tonne (t).
Explanation:
The hybridization scheme employed by a central atom when forming more than four bonds is.
The hybridization scheme employed by a central atom when forming more than four bonds is sp3d
Hybridization is the mixing of orbitals of different energies to give hybrid orbitals of the same energy.The hybridization sp3d employs five orbitals which can be paired to give the corresponding compound.It involves the mixing of 1s orbital, 3p orbitals, 3p orbital, and 3d orbital to form orbitals of equal energy.An example is PCl5 and it follows trigonal bipyramidal geometry. It has axial and equatorial bonds.It takes place in the presence of weak field ligands.The complex formed by sp3d hybridization is known as the outer orbital complex.To learn more about hybridization visit:
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iodine is one of many compounds that can be used as a stain for tlc, however, there are many stains that can be used to identify specific functional groups. looking online, propose a good tlc stain to identify dehydroabietylamine on a tlc plate?
The iodine staining technique is one of the methods that can be used as a stain for TLC, however, there are many stains that can be used to identify specific functional groups.
The iodine staining technique allows us to carry abound a marked version of owe 'TLC' sun rather than having to pencil sketch ow spots in the UV views. Fore compounds might not even appear under Uv light, making otter visualization ted. such as iodine staining necessary.One of the first techniques for displaying organic chemicals was to stain a TLC plate with iodine vapor. The discovery that iodine has a strong affinity for both unsaturated and aromatic molecules forms the basis for this theory.Iodine is one of the substances that can be used as a TLC stain, however, there are numerous stains that can be used to identify particular functional groups. Iodine sublimes and interacts with the compounds on a produced TLC plate when the chamber is sealed, creating yellow-brown patches.Learn more about TLC stain at:
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Which of these is an example of a resistor?
A
a battery, which has a positive and negative terminal
B
a light bulb that impedes the flow of electricity
C
an electrical charge moving at a constant rate
D
a conductive path that forms a closed loop
The correct example of a resistor is option (B) a light bulb that impedes the flow of electricity.
A light bulb that impedes the flow of electricity is an example of a resistor.
A resistor is a passive two-terminal electrical element that implements electrical resistance as a circuit element. In digital circuits, resistors are used to reduce modern flow, regulate sign stages, to divide voltages, bias lively elements, and terminate transmission lines, amongst different uses.
A resistor is an electrical thing that limits or regulates the flow of electrical current in an electronic circuit. Resistors can also be used to offer a specific voltage for an lively tool such as a transistor.
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How many meters below sea level results in 1 atm of additional pressure?
O 10 feet
O 33 feet
O 10 meters
O 33 meters
10 meters below sea level results in 1 atm of additional pressure.
The pressure increases about one atmosphere for every 10 meters of water depth.
We know,
1 atm pressure = 1.01325 bar equation1
Gravitational acceleration = 9.81 [tex]m/s^{2}[/tex] equation2
Density of water = 1000kg/[tex]m^{3}[/tex] equation3
P = (density of water) (gravitational acceleration) (height under water)
Substitute values from equation1 , equation2 and equation3 in formula of pressure under water.
P = (1000) (9.81) (10.33)
P = 101325 Pa(Pascal) (1bar = [tex]10^{5}[/tex] Pascal)
Now we need to convert Pascal to Bar using the relation (1bar = [tex]10^{5}[/tex] Pascal).
P = 1.01325 bar
Thus we can conclude that 10 meters below sea level results in 1 atm of additional pressure.
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