Answer:
m × 10n.
Explanation:
where m is a number between 1 and 10 ( 1 ≤ |m| < 10 ) and the exponent n is a positive or negative integer.
You have a substance with a half-life of 9 days. How much of it will be left after 36 days?
Answer:
A half life is the amount of time it takes for half of a mass of a given radioactive element to decay to something else. 36 days is 4 1/2 life cycles, so by running 1/2*4 , we get how much of the original substance would be left. That would be 1/16 of the original substance left.
Explanation:
Of course, this is not always perfect, and can vary. In addition, if less than 16 atoms of the original substance are present, there is instead a 1/16∗a chance of at least one remaining.
The amount of substance left after 39 days will be 1/16th of the original amount.
What is the half-life of a radioactive element?The half-life period of the radioactive material can be defined as the time required to reduce its actual amount to half after disintegration. The half-life period of a radioactive substance is independent of the initial amount of the substance.
Consider that N₀ is the initial amount of the substance
Consider that 'n' is the number of half-lives of given substance.
The time for which substance decay, t = 36 days
Half-life of substance (t½) = 9 days
t = n ×t½
36 = n × 9
n = 4 days
Assume that N is the amount of the substance after decay for 39 days.
N ×2⁴ = N₀
N × 16 = N₀
N = N₀/16
Therefore, one-sixteenth of the initial amount of the substance will be left after 39 days.
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Based on the amino acid sequences of each histone, estimate the charge of a histone octamer at ph 7. Assume that histidine residues are uncharged at this ph.
The charge on histone octamer at ph7 is +146.
What are histones and how the charge on histone octamer at ph7 is +146?In genetics we read about DNA, but there is a term histone also , simply it is the structure around which DNA wraps.Histone is made of proteins , arginine and lysine.The number of negative charges is 9 , and the number of positive charged is 26.We call it histone octamer because it is made up of eight protein sub units.We use histone octamer , along with DNA for packaging purposes, in nucleosome is also a commonly used term.Nucleosome consist of 200 base pairs.To know more about histone visit:
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calculate what volume of 0.3 mol dm-3 oxylic acid contains 22.5 grams of oxylic acid ((COOH)2)
The volume of 0.3 M oxalic acid(C2H4O2) solution containing 22.5 grams of oxalic acid is 833.3 ml.
The molarity(M) of a solution can be expressed by the following formula,
Molarity(M) = Mass of solute/Molar mass of solute x 1000/Volume of the solution
We are given that, the molarity of a solution containing 22.5 grams of oxalic acid(Molar mass= 90 g) is 0.3 M.
Putting these values in the given formula, we can calculate the volume of the solution
0.3 = 22.5/90 x 1000/V
V = 22.5/90 x 1000/0.3
V = 833.3 ml.
Thus, The volume of 0.3 M oxalic acid(C2H4O2) solution containing 22.5 grams of oxalic acid is 833.3 ml.
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A yellow-gold sphere has a mass of 15.2g when passed in the orange liquid the volume was 43ml
A yellow-gold sphere has a mass of 15.2 g when passes in the orange liquid with volume 43 mL
Density= mass/volume
Density = 15.2 g/ 43mL
Density = 0.35 g/mL
Question is to find density
investigation of magnetic properties and electronic structure of layered-structure borides alt2b2 (t
AlT₂B₂ (where T=Fe, Mn, Cr) and AlFe₂₋ₓMnₓB₂ were formed by a technique referred to as arc-melting.
By victimization arc melting to form the quaternary phases AlFe2-xMnxB2 and therefore the ternary phases AlT2B2 (T=Fe, Mn, Cr), these materials are studied and represented.
AlT₂B₂ (where T=Fe, Mn, Cr) and AlFe₂₋ₓMnₓB₂ were formed by a technique referred to as arc-melting.
AlMn₂B₂ and AlCr₂B₂ don't carries with it any form of magnetic ordering.
Nonmagnetic and magnetic attraction cluster in AlFe₂–xMnₓB₂.Ferromagnetism is suppressed by weakening of antibonding T–T interactions.The third phases AlT₂B₂(whereT=Fe, Mn, Cr) and fourth phases AlFe₂–xMnₓB₂ that are shaped by Arc-Melting and powder by X-ray diffraction.
The activity of magnet tells that AlFe₂B₂ could be a ferromagnet with Tₓ=282 K. AlMn₂B₂ and AlCr₂B₂ don't show any form of magnetic ordering within the studied of temperature vary of one.8–400 K.A systematic investigation of solid solutions AlFe₂−xMnxB₂ showed a non-linear modification. The magnetic attraction ordering temperature is step by step small because the content of Mn will increase.Calculation of Quantum chemical and crystal orbital Hamilton population analysis provides a transparent rationalization of the excellence in properties of series of compounds.
Thus, we are able to say that, AlT₂B₂ (where T=Fe, Mn, Cr) and AlFe₂₋ₓMnₓB₂ were ready by a technique referred to as arc-melting.
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someone can anyone answer this question pleaseeee ?
Which statement about bases is true?
(a) They are all alkalis
(b) They can neutralize acids
(c) They are all soluble
answer this question pleaseeeeeeeeeeeee
Answer:
either (a) or (b)
PLEASE HELP MEEE
The concentration of a basic solution is determined by which of the following?
Select one:
a. The number of base molecules in solution.
b. The degree of dissociation of base molecules in solution.
c. The rate at which a base solution neutralizes an acid solution.
d. The temperature of the solution.
The concentration of a basic solution is determined by the degree of dissociation of base molecules in solution (option B).
What is a basic solution?A basic solution is an aqueous solution containing more OH-ions than H+ions.
In other words, a basic solution can be said to be an aqueous solution with a pH greater than 7, which is the neutral range.
The concentration of a basic solution is a function of the OH- ions in the solution. Therefore, the concentration of a basic solution is determined by the degree of dissociation of base molecules in solution.
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(Bonus) Which element is more reactive? (1 pt)
*
1 point
Sodium
Neon
They are equally reactive
an excess of o2 reacted with 3.82 g of fe. what is the percent yield if 4.77 g of fe2o3 are isolated?
Percentage yield = 87.3%
How to find percentage yield ?
As ,the reaction is :
4Fe + 3O2 →2Fe2O3
Molar mass of Fe = 55.8 g
Molar mass of Fe2O3= 159.6 g
According to the balanced equation :
4×55.8 g of Fe produce 2×159.6 g of Fe2O33.82 g of Fe produce X g of Fe2O3 X = ( 2×159.68×3.82)/( 4×55.8) = 5.46 gThis is the theoretical mass obtained .
Actual mass is 4.77
So, % yield is = (actual /theoretical )/100 =( 4.77/5.46 )/100 = 87.3%
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Explain how the solubility of water is useful in maintaining various life processes
The solubility of water is useful in maintaining various life processes because its capability to dissolve a variety of molecules.
Water is a “universal" solvent.
The ability of water to function as a versatile solvent arise from the structure of water molecules are because:
Water molecules form hydrogen bonds with atoms that are part of polar covalent bonds other molecules.
Water's versatility as solvent arises from the polar covalent bonds of water molecules.
Hydrogen bond is an electrostatic attraction between two polar groups that occurs when a hydrogen atom (H), covalently bound to a highly electronegative atom such as flourine (F), oxygen (O) and nitrogen (N) atoms.
In water, atoms of hydrogen (H) and oxygen (O) are connected by polar covalent bonds.
Covalent bond is bond between nonmetals. Hydrogen and oxygen are nonmetals.
Solvation is the interaction of solvent (water) with molecules or ions (for example K⁺ and I⁻) in a solute.
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consider the equilibrium that exists for a saturated aqueous solution of pbcl2. pbcl2s⇄pb2 aq 2 cl-aq which expression gives the solubility product constant ksp for pbcl2 if the [pb2 ]
The solubility product is 4n³.
The equilibrium constant for a solid's dissolving into an aqueous solution is called the solubility product constant. It is represented as K(sp).
A solution is said to be saturated when it has dissolved all of the solutes it can. At a certain temperature, no additional solute can dissolve in a saturated solution.
Consider the equilibrium for a saturated PbCl₂ aqueous solution.
PbCl₂(s) ⇄⇄ Pb₂ (aq) + 2Cl⁻ (aq)
The equilibrium constant for the dissociation reaction of the PbCl₂ solution is:
K(sp) = [Pb²⁺] [Cl⁻]²
Now, [Pb²⁺] = n mol/L
In the solution, there is one-mole Pb²⁺ and two moles of Cl⁻ .
Therefore,
[Cl⁻] = 2n mol/L
So, the equilibrium constant for the dissociation reaction will be:
K(sp) = [Pb²⁺] [Cl⁻]²
K(sp) = n × (2n)²
K(sp) = n × 2n × 2n
K(sp) = 4n³
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which material is said to have a high permeability? group of answer choices nickel bismuth soft iron
Iron l is said to have a high permeability. High coercivity, high retentivity, and high permeability materials make up the permanent magnets. An object made of a substance that has been magnetized and produces its own persistent magnetic field is referred to as a permanent magnet.
In contrast to an electromagnet, which is made of a coil of the wire wrapped around a ferrous core and needs an electric current to create a magnetic field, a permanent magnet's magnetism is "always on" and it creates its own permeability magnetic field. A common example is a refrigerator magnet used to the keep notes on the door of the refrigerator.
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Paint is a type of mixture called a(n) ____________ because it is a
heterogeneous mixture with large particles that will settle to the
bottom if undisturbed for a long period of time.
Solution a has a hydrogen ion concentration of 3. 2 x 10-9 and solution b has a hydrogen ion concentration of 6. 9 x 10-5. Which solution is more basic?.
Solution a is more basic.
Basic solutions are those solutions whose pH is greater than 7.
The pH of a solution is calculated or determined by the hydrogen ion concentration of the solution. The relation between pH of a solution and the hydrogen ion concentration in it is given by :
pH = -log[ H+]
From this relation we can conclude that if the hydrogen ions concentration in a solution is more , the value of pH will become lower.
For Solution a, the pH is given by :
pH(a) = -log [ 3.2 x 10^-9 ] = 8.4948 ≅ 8.5
For Solution b, the pH is given by :
pH(b) = -log [ 9 x 10^-5 ] = 4.04 ≅ 4
Since the pH of solution b is lower than the pH of solution a , solution a is more basic than solution b. Moreover, the pH of solution a is approximately 8.5 which makes it a moderately strong basic solution.
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you wish to make 0.357m nitric acid from a stock solution of 3.00m nitric acid. how much concentrated acid must you add to obtain a total volume of 150ml of the dilute solution
17.85 mL of 3.0 M stock solution of nitric acid is needed to make a 150 mL 0.357 M nitric acid.
The dilution of a stock solution can be solved by using the formula below, which indicates that the concentration of the solution changes but the number of moles of the solute remains the same.
(concentration of stock solution)(volume of stock solution) = (concentration of diluted solution)(volume of diluted solution)
Given:
Stock solution: 3.0 M nitric acidDiluted solution: 150 mL of 0.357 M nitric acid(3.0 M)(volume of stock solution)=(0.357 M)(150 mL)
volume of stock solution = [(0.357 M)(150 mL)] / (3.0 M)
volume of stock solution = 17.85 mL
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Explain why gases are compressible, but solids and liquids are not.
Answer:
The reason why solids and liquids can't compress is because there is no space between the individual particles, so they cannot pack together
Explanation:
The kinetic-molecular theory explains why gases are more compressible than either liquids or solids. Gases are compressible because most of the volume of a gas is composed of the large amounts of empty space between the gas particles.
An oxide of iron is found to be 70. 00% iron by mass. Determine the empirical formula for this compound and name it.
The empirical formula of the compound is Fe2O3 and its name is Iron(III) oxide or ferric oxide.
The oxide of iron has 70% of iron by mass.
This means that in every 100 grams of this oxide,70 grams is of iron and the other 30 grams are of oxygen.
To calculate the empirical formula, we have to first find the number of moles of iron and oxygen by dividing the given mass by their molar mass.
Moles of iron = 70/56 = 1.25 moles
Moles of oxygen = 30/16 = 1.875 moles
Now we need to divide the moles of iron and oxygen by the lowest common number i.e. 1.25
Moles of iron/1.25 = 1.25/1.25 = 1
Moles of oxygen/1.25 = 1.875/1.25 = 1.5
The ratio of iron(Fe): to oxygen(O) comes out to be 1:1.5.
Hence, we should multiply this ratio by 2 to get a whole number.
The ratio of Fe:O comes out to be 2:3.
Thus, the empirical formula of the compound is Fe2O3 and its name is Iron(III) oxide or ferric oxide.
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6. Which of the following examples describes
a physical change?
Answer:
•Melting of solid ice
• Evaporation of liquid
• Sublimation of solid cheese
since we don’t know the examples I can’t really answer your question but I can say a physical change alters the form or appearance of matter but doesn’t turn any substance in the matter into a different substance once you provide me with the examples I’ll let you know ok
a solution containing ethylene glycol and water has a vapor pressure of 7.88 torrtorr at 10 ∘c∘c . pure water has a vapor pressure of 9.21 torrtorr at 10 ∘c∘c . what is the mole fraction of ethylene glycol in the solution?
Mole fraction of ethylene is = 0.144
How to find mole fraction ?
As, Given that vapor pressure = 7.88 torr
pure water vapor pressure = 9.21 torr
∆P solvent = (X Solute)(Pº solvent)
∆Psolvent = change in vapor pressure = 9.21 torr - 7.88 torr = 1.33 torr
Xsolute = mole fraction of the solute = ?
Pºsolvent = vapor pressure of the pure solvent = 9.21 torr
1.33 torr = (Xsolute)(9.21)
Xsolute = 1.33 torr/9.21 torr)
Xsolute = 0.144
Hence the mole fraction of ethylene is = 0.144
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Sorry about asking this question again. I figured out the number of protons electrons and neutrons. 92,92 and 146. The mass number and atomic number are 238 and 92. I still can't figure out how to find the charge. The internet says +92, but I don't know how that works.
If you see the nuclide notation of uranium (u).
The letter in the mid is the symbol of the element.
The number in the bottom left corner is atomic number (Tells you the number of protons)
The number on the upper left corner is the mass number (equal to the mass number ; = the neutrons and protons added together)
At the last, the charge is on the upper right corner, if there is no +ve and -ve symbol then the charge is neutral.
To find the number of neutrons, protons and electron :
1. No. of protons = Atomic Number (Z)
2. No. of neutrons = Mass number (A) - Atomic number(Z)
3. No. of electrons = Atomic number - Charge
To find the charge it is find by the periodic table suppose group 1 alkali metals have +1 charge and in the same way group 16 -2 charge .
Uranium is a radioactive element and hence it is an alpha particle and hence it has a positive charge.
There are many radioactive element who are alpha particles like thorium and plutonium. Beta particles have negative charge.
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in metal IE 1 < IE 2 < IE 3. why?
Answer:
Explanation:
in metal IE 1 < IE 2 < IE 3. why
True or false: Properties that cannot be observed are due to the structure of atoms and molecules that can be observed.
Properties that cannot be observed are due to the structure of atoms and molecules that can be observed.
The correct option is True.
What are molecules?A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds.
It is true that properties that cannot be observed are due to the structure of the atoms and molecules of that matter.
Physical properties are often referred to as those properties we can observe with our eyes.
Molecules made up of two or more elements are called compounds Example of molecules includes water, calcium oxide, glucose etc.
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ernest rutherford developed an experiment that showed protons can pass through gold atoms untouched and/or un-deflected. sometimes the protons were deflected by something, but this did not happen too often. most of the atoms pass straight through. his experiment changed the way scientists viewed the structure of an atom. what conclusion did rutherford draw from his experiment?
Rutherford conclusion was: Inside of the gold atom consists of empty spaces.
Rutherford theorized that atoms have their charge concentrated in a very small nucleus.
This was famous Rutherford's Gold Foil Experiment: he bombarded thin foil of gold with positive alpha particles (helium atom particles, consist of two protons and two neutrons).
Rutherford observed the deflection of alpha particles on the photographic film and notice that most of alpha particles passed straight through foil.
That is different from Plum Pudding model, because it shows that most of the atom is empty space.
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here are four sketches of substances. each sketch is drawn as if a sample of the substance were under a microscope so powerful that individual atoms could be seen. decide whether each sketch shows a sample of an element, a compound, or a mixture.
Substance X - compound because it is a combination of elements
Substance Y - Mixture because it is a combination of substances
Substances Z - Element because it contains atoms
Substance T - compound because it is a combination of elements
What are the samples?We know that an atom is the smallest particle of a substance that can take part in a chemical reaction. A compound is formed by a mixture of atoms. An element is obtained as the smallest independent part of a substance.
Now let use classify the samples shown in the images attached.
Substance X - compound because it is a combination of elements
Substance Y - Mixture because it is a combination of substances
Substances Z - Element because it contains atoms
Substance T - compound because it is a combination of elements
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3.5 g of hydrogen gas reacts with 2.6 g of oxygen gas and produces water. Determine how much water forms.
Amount of water form will be 2.925 gram
2H2 + O2 -------> 2H2O
4 gram + 32 gram 36 gram
2 moles + 1 mole 2 mole
Moles = Given mass/molar mass
Moles of Oxygen = 2.6 gram/32gram = 0.08 moles
Moles of Hydrogen = 3.5 gram/2 gram = 1.75 moles
Here, we can see that Oxygen moles are less than Hydrogen moles so it is the limiting reagent and it will determine how much water will be formed
The substance that is entirely consumed at the end of the chemical reaction is known as the limiting reagent. This limiting reagent is required for the reaction to proceed since it limits the amount of product that can be produced.
32 gram of O2 produces water = 36 gram
1 gram of O2 produces water = 36/32 = 1.12 gram
2.6 gram of O2 produces water = 1.12 x 2.6 = 2.925 gram
Hence, amount of water form will be 2.925 gram
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what is the cell potential at 250c for the following galvanic cell?pb(s)|pb2 (1.0m)||cu2 (1.0 x 10-4 m)|cu(s)
The cell potential at 250c for the following galvanic cell
pb(s)|pb2 (1.0m)||cu2 (1.0 x 10-4 m)|cu(s)
is 0.345V.
What is Electrolytic cell?It is a device that is used for the conversion of the electrical energy of the redox reactions into a chemical energy.
What is redox reaction?The reaction in which reduction and oxidation reaction both take place in the reaction is known as redox reaction.
What is oxidation reaction?Oxidation reaction are those reaction in which compound or substance looses its electron. In this type of reaction, oxidation state of an element increasing.
What is reduction reaction?Reduction reaction are those reaction in which compound or substance accept the electron. In this type of reaction, oxidation state of an element goes on decreasing.
Reaction at cathode:
Cu+2 + 2e ------ Cu E°(anode) = -0. 126V
Reaction at anode:
pb ------- pb(+2) + 2e E°(cathode) = 0.337
E°cell = -0.126 -0.337
= -0.463V.
As we know that,
E cell = E°cell -0.059/2(log([cathode]/[anode])
= -0.463 - (0.059/2) × (-4)
= -0.463 + 0.118
= 0.345V
Thus, we concluded that the cell potential at 250c for the following galvanic cell
pb(s)|pb2 (1.0m)||cu2 (1.0 x 10-4 m)|cu(s)
is 0.345V.
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What is a mathematical formula you can make to determine the mass number?
Answer:
Together, the number of protons and the number of neutrons determine an element's mass number: mass number = protons + neutrons.
If limestone (CaCO3) is heated, 2.8Kg of calcium oxide (CaO) and 2.2Kg of carbon dioxide are produced.
a. Write the balanced chemical equation.
b. Determine mass of the used limestone
The balanced chemical equation is CaCO3---> CaO+CO2 and the mass of the used limestone is 5.0 kg
The heating of limestone yields calcium oxide and carbon dioxide. It is a decomposition reaction.
The reaction is as follows;
CaCO3---> CaO+CO2
According to the law of conservation of mass, mass is conserved in a reaction,
So the mass of limestone used will be (2.8+2.2=5.0 kg)
All balanced chemical equations follow the law of conservation of mass.It says mass is neither created nor destroyed but conserved during a reaction.That is to say, the mass of any one element at the start of a reaction will be equal to that element's mass at the conclusion of the reaction.To learn more about conservation of mass visit:
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Titanium (Ti, #22) atoms bond with Oxygen (O, #8) atoms. What type of bond will hold them together? (1 pt)
*
1 point
ionic
covalent
metal
intermolecular (hydrogen, dipole, etc.)
Titanium (Ti,) atoms bond with Oxygen (O,) atoms. covalent type of bond hold them together.
What is covalent bond?An electron exchange that results in the formation of electron pairs between atoms is known as a covalent bond.
When atoms share electrons, a permanent equilibrium of the attractive and repulsive forces between them is known as covalent bonding.
These electron pairs are referred to as shared pairs or bonding pairs.
Thus ,Titanium (Ti,) atoms bond with Oxygen (O,) atoms. covalent type of bond hold them together.
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Question 1
Convert 4136mg to g
4136mg x
Answer: 4.136 g
Explanation:
1000 mg=1 g
4136 mg * 1 g/1000 mg=
4136*1/1000=
4136/1000=4.136 g