Answer:
23 atoms
Explanation:
Krypton (Kr) exists naturally as a mixture of six isotopes with atomic number of 36. These six isotopes occupy different percentages of the mixture. Below is a list of the isotopes and there percentage in a given mixture
1) Krypton-78 (⁷⁸Kr) ⇒ 0.35%
2) Krypton-80 (⁸⁰Kr) ⇒ 2.25%
3) Krypton-82 (⁸²Kr) ⇒ 11.6%
4) Krypton-83 (⁸³Kr) ⇒ 11.5%
5) Krypton-84 (⁸⁴Kr) ⇒ 57%
6) Krypton-86 (⁸⁶Kr) ⇒ 17.3%
To determine the amount of ⁸³Kr present in a mixture of 200 atoms of krypton, you will multiply the it's percentage of occurrence in nature by the amount of atoms in a given mixture
11.5/100 × 200 = 23 atoms
Hence, there should be 23 atoms of krypton-83 in the mixture of 200 atoms of Krypton.
Determine the number of KNO3 molecules in 0.750mol KNO3
The number of KNO3 molecules in 0.750 mol of KNO3 would be 4.52 x [tex]10^{23}[/tex] molecules
Number of moleculesThe number of molecules of a substance is defined by Avogadro's constant, such that:
1 mole = 6.022 x [tex]10^{23}[/tex] molecules
In this case, the number of mole is 0.750
Thus, the number of molecules in 0.750 moles of KNO3 can be calculated as:
0.750 x 6.022 x [tex]10^{23}[/tex] = 4.52 x [tex]10^{23}[/tex] molecules
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6. What are the correct coefficients in order for the equation to be balanced?
Explanation:
8O² + 1S⁸ ----> 8SO²
this is the true coefficient...
6. Macromolecules represent which level of organization in the body?
cellular
tissue
o
chemical
organ
Answer:
Chemical
Explanation:
Macromolecules are part of the chemical components of cells. For example, DNA, proteins, and lipids.
Cells of similar types/function form tissues. Different types of tissues interact together to form organs. Organs form a common function.
How many molecules are in 56.2 L
of CO2 at STP?
Answer:
0.25 moles (See below for explanation)
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Heather mixes two white liquids together. Immediately, a gray liquid forms.
How is the gray liquid related to the white liquids?
ОА
There is no relationship between the gray liquid and white liquids.
B
The gray liquid was released from inside the atoms of the white liquids.
С
The gray liquid is made up of the same kinds of atoms as the white liquids, but the atoms are arranged differently.
D
The gray liquid is made up of the same kinds of molecules as the white liquids, but the molecules are a different color.
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O
Answer:
A is the correct answer
Explain the difference between a working theory and a paradigm? PLEASE ANSWER QUICK I WILL MARK BRAINLIEST
Answer: The theory explains the phenomenon based on certain criteria while the paradigm provides the background or the frame that allows a theory to be tested and measured.
Explanation:
What is the temperature shown on the thermometer below?
A. 8 °F
B. 4 °F
C. –4 °F
D. –8 °F
All of the rocks in the world used to be _________________ rock called molten rock.
How many moles of sodium sulfate will be produced from 25.6 grams of sodium hydroxide? Moles to sodium sulfate to mol
es una muy buena experiencia para poder conseguir una buena respuesta
(2.6 x 10^6) / (2.0 x 10^8)
Answer:
0.013
Explanation:
Why is this important in chemistry to balance equations?
Answer:
The bonds between atoms in the reactants are rearranged to form new compounds in chemical reactions, but none of the atoms disappear and no new ones are formed. As a consequence, chemical equations must be balanced, meaning that the number and kinds of atoms must be the same on both sides of the reaction arrow.
Answer:
The Law of Conservation of Mass states that mass is neither created nor destroyed, it only changes.
So when you balance a chemical equation, what you get is the same equation, but with the same number of atoms of each chemical element in the reactants and in the products. In this way the conservation of mass is achieved, because the same number of atoms that exists in the reactants is the one that is later transformed and appears in the products.
A balanced equation is the following:
H2 + 1/2O2 --------> H2O
Reactants: Products:
Amount of H = 2 Amount of H = 2
Amount of O = 1 Amount of O = 1
It is a balanced equation because each element has the same number of atoms in the reactants and in the products.
Explanation:
If I help you give me points, thanks.
Which relationship is present in a solution that has a pH of 7
Answer:
neutral
Explanation:
pH is usually (but not always) between 0 and 14. Knowing the dependence of pH on [H +], we can summarize as follows: If pH < 7, then the solution is acidic. If pH = 7, then the solution is neutral
5. 2.83 g of a sample of haematite iron ore [iron (II)oxide, Fe2O3] were dissolved in c oncentrated hydrochloric acid and the solution diluted to 250 cm3. 25.0 cm3 of this so lution was reduced with tin(II) chloride (which is oxidised to Sn4+ in the process) to for m a solution of iron(II) ions. This solution of iron(II) ions required 26.4 cm3 of a 0.020 0 mol/dm3 potassium dichromate(VI) solution for complete oxidation back to iron(III) ions. (a) given the half-cell reactions (i) Sn4+ (aq) +2e==> Sn2+ (aq) and (ii) Cr2O72- (aq) + 14H H(aq) + 6e- ==> 2Cr3+(aq) +7H206) deduce the fully balanced redox equations for the reactions (i) the reduction of iron(III) ions by tin(II) ions (ii) the oxidation of iron(II) ions by the dichromate(VI) ion (b) Calculate the percentage of iron (II) oxide in the ore.
From the solution of hydrochloric acid that is in the reaction with pottassium dichromate, the fully balanced equation for the reaction is K₂Cr₂O₇+6FeCl + 14HCI→ 2KCl +6FeCl₃ + 2CrCl₃+7H₂0
What is oxidation?This is the chemical reaction that takes place due to the fact that oxygen has been added to a substance.
a. Fe2O3+ 6HCl→2FeCl₂ + 3H₂O
Fe³⁺+e→Fe2+
2FeCl₃+SnCl₂ → 2FeCl₂ + SnCl₄
Fe²⁺ - e→Fe³⁺
K₂Cr₂O₇+6FeCl + 14HCI→ 2KCl +6FeCl₃ + 2CrCl₃+7H₂0
b. 0.02 mol/dm³ = 2x10⁻⁵ mol/ml
26.4 cm³ is the same as 26.4 ml
n(K₂Cr₂0₇) = 26.4 x2x10⁻⁵
This gives 52.8x10⁻⁵
n(FeCls) = 6n(K₂Cr₂0₇) = 3.168 x 10⁻³
n(FeCl₂)= n(FeCl₃) = 3.168x10⁻³
2 x 56 + 3x16 = 160 gram/mol
3.168x10⁻³/2 = 1.584x10⁻³
1.584x10⁻³ x 160 = 0.253
0.253 x 100/2.83 = 8.96 percent
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42. Water is a neutral solution, what is the pH of water?
O pH = 7
pH = 6
pH = 2
pH = 10
Calculate the volume occupied by 1.68 g of He gas at STP.
Answer:
Explanation:
It can be written as: V = nRT/P. "P" is pressure, "V" is volume, n is the number of moles of a gas, "R" is the molar gas constant and "T" is temperature. Record the molar gas constant "R". R = 8.314472 J/mole x K.
If you had excess chlorine, how many moles of aluminum chloride could be produced from 28.0 g of aluminum?
Answer:
1.04 moles of AlCl₃
Explanation:
Balanced Equation: 2Al°(s) + 3Cl₂(g) => 2AlCl₃(s)
Approach => convert given data (28 g Al°) to moles. The number of moles AlCl₃ would equal the number of moles aluminum because coefficients for Aluminum and Aluminum Chloride are equal.
moles Al° = (28g)/(27g/mole ) = 1.04 mole Al°
From balanced equation moles AlCl₃ produced equals moles of Al° produced = 1.04 mole AlCl₃ because coefficients of Al° & AlCl₃.
At what number carbon does the phosphate group connect to the sugar?.
Answer:
5' carbon
Explanation:
Attaching a phosphate group
A phosphate group is attached to the sugar molecule in place of the -OH group on the 5' carbon.
Answer:
The phosphate group on one nucleotide links to the 3' carbon atom on the sugar of another one. In the process, a molecule of water is lost - another condensation reaction.
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Type the correct answer in the box. Round your answer to the nearest whole number.
Dylan has two cubes of iron. The larger cube has twice the mass of the smaller cube. He measures the smaller cube. Its mass is 20 grams, and its
density is 7.87 g/cm? What's the larger cube's volume?
The larger cube's volume is about cm?
Reset
Next
Answer:
Rounding volume to nearest whole number is 5cm³.
Explanation:
Given data:
Mass of smaller iron cube = 20 g
Density of cube = 7.87 g/cm³
Volume of larger cube = ?
Solution:
The mass of larger iron is twice of smaller iron cube.
It will be 40 g.
Now we will apply the density formula.
d = m/v
7.87 g/cm³ = 40 g/ v
v = 40 g/ 7.87 g/cm³
v = 5.08 cm³
Rounding answer to nearest whole number is 5cm³.
name any three chemical pollutants
Answer:
Ozone (O3) Nitrogen dioxide (NO2) Carbon monoxide (CO) Sulphur dioxide (SO2)
Explanation:
Answer:
Particulate matter (PM10 and PM2. ...
Ozone (O3)
Nitrogen dioxide (NO2)
Carbon monoxide (CO)
Sulphur dioxide (SO2)
Explanation:
Particulate matter (PM10 and PM2. ...
Ozone (O3)
Nitrogen dioxide (NO2)
Carbon monoxide (CO)
Sulphur dioxide (SO2)
As the pH of ocean water decreases, it becomes more _____.
Question 2 options:
acidic
basic
Answer:
Acidic
Explanation:
The average pH of the ocean is now around 8.1, which is basic (or alkaline), but as the ocean absorbs more CO2, the pH drops and the ocean becomes more acidic.
Challenge: Make another comparison.
Earth's outer layer is like because...
Answer:
Imagine that the planet is an onion. When you open it, you will discover that it can be separated into layers that are perfectly independent from each other, but that they make sense if they are united. The central part of the onion is different, almost circular.
Explanation:
The center of the planet is known as the nucleus. This layer is shaped like a sphere, and in turn is made up of two layers: the inner core (where the temperature reaches up to 5000 degrees Celsius) and the outer core (whose consistency is semi-liquid). The core is made up of nickel, iron, sulfur, oxygen, and copper.
What do Px Pz and Py represent.
Answer:
Explanation:
The names Px, Py and Pz, indicate the orientation of the orbital in space. The key difference between Px Py and Pz orbitals is that Px orbital has two lobes oriented along the x-axis and Py orbital has two lobes oriented along the y-axis whereas Pz orbital has two lobes oriented along the z-axis.
Answer:
Px can stand for Picture Pixel Prescription Prognosis Post Exchange or Physical Exam Personal Exchange Price.
Pz can stand for Precautionary Zone
Py can stand for Program Year or Python
Explanation:
hope this helps
How many moles are in 7.0g of NaF?
there are .1667 (.17) mols in 7 grams of Sodium Fluoride (NaF)
hope this helps :)
Why is it so many numbers
Answer:
Bro what numbers? And whats the question?
what is electronegativity and how can it be used in determining the polarity of nonpolar
Answer:
See explanation
Explanation:
Electro negativity refers to the ability of an atom in a molecule to attract the shared electrons of a bond towards itself.
Electro negativity is a property of elements. It increases across the period and decreases down the group in the periodic table.
When two elements with differing electronegativities form a bond, the atom that has a greater electro negativity tends to pull the shared electrons of the bond towards itself. By so doing, there is greater electron density around that atom compared to the other atom. The more electronegative atom therefore acquires a partial negative charge while the other atom acquires a partial positive charge. This leads to a dipole in the molecule.
A molecule is said to be polar when it possess a dipole, that is, a positive end and a negative end. This phenomenon in turn arises when there is a significant difference in electro negativity between two atoms that compose the bond.
For instance, consider the formation of HF. Hydrogen has an electro negativity of 2.2 while fluorine has an electro negativity of 3.98. The difference in electro negativity between the both atoms is about 1.78. The molecule is polar with the negative end of the dipole at fluorine and the positive end at hydrogen.
50 POINTS
When air heats up, it will _____, cool, and then _____ back down. The creates a convection cell.
1. heat ; fall
2. condense ; fall
3. fall ; rise
4. rise ; fall
Answer:
rise the fall
Explanation:
when air is heated it become lighter then rise but when cooled it becomes heavy and fall
A block has dimensions 1.0 dm, 4.2 cm, and 25 mm, with a mass of 5.326 kg. Calculate the density of this block in g/cm 3 .
Answer:
1 dm equals about 10 cm
25 mm equals 2.5 cm
and then we have 4.2 cm, including a mass of 5.326 kg
How do we find the density of the block?
First, lets rewrite our formula.
d = mass divided by volume.
lets multiply 10 cm x 2.5 cm x 4.2 cm
this equals 105.
Now, lets turn 5.326 kg into what we need to divide.
1000 cm x 5.326 kg is 5326 cm
now lets do 5326 into 105
thats 50.
Explanation:
50 is the answer.
A chemist uses atomic absorption spectroscopy to measure the amount of calcium in a urine sample. When preparing the sample for analysis, the chemist adds an excess of La3 to the sample. Why is La3 added to the urine sample
Answer: La+3 binds to PO4-3 in the urine sample which prevents the formation of Ca3(PO4)2 and frees the Ca+2 in the sample to be atomized.
Explanation:
In the presence of phosphates, the calcium ions form a refractory compound (calcium phosphate) which is not atomized in the plasma/flame in atomic absorption spectroscopy.
The addition of a releasing agent like lanthanum to the sample minimizes the formation of refractory compounds as the lanthanum binds with the phosphate ions to form more volatile compounds.
The 1995 Nobel Prize in Chemistry was shared by Paul Crutzen, F. Sherwood Rowland, and Mario Molina for their work concerning the formation and decomposition of ozone in the stratosphere. Rowland and Molina hypothesized that chlorofluorocarbons (CFCs) in the stratosphere break down upon exposure to UV radiation, producing chlorine atoms. Chlorine was previously identified as a catalyst in the breakdown of ozone into oxygen gas. Using the enthalpy of reaction for two reactions with ozone, determine the enthalpy of reaction for the reaction of chlorine with ozone.
ClO(g)+O3(g)â¶Cl(g)+2O2(g) ÎHârxn=â122.8 kJ
2O3(g)â¶3O2(g) ÎHârxn=â285.3 kJ
O3(g)+Cl(g)â¶ClO(g)+O2(g) ÎHârxn= ?
Answer:
ΔH = -162.5 kJ.
Explanation:
Hello.
In this case, we first rearrange the reactions:
ClO(g) + O₃(g) ⇒ Cl(g) + 2O₂(g); ΔH =-122.8 kJ
2O₃(g) ⇒ 3O₂(g); ΔH=-285.3 kJ
O₃(g) + Cl(g) ⇒ ClO(g) + O₂(g); ΔH= ?
Thus, we are going to use the Hess law, as an strategy to rearrange the known chemical reactions and thereby compute the enthalpy of reaction of the unknown one.
1. The first reaction must be inverted in order to obtain chlorine as a reactant in the third one, therefore, the enthalpy of reaction becomes positive:
Cl(g) + 2O₂(g) ⇒ ClO(g) + O₃(g); ΔH = 122.8 kJ
2. Second reaction remains the same:
2O₃(g) ⇒ 3O₂(g); ΔH=-285.3 kJ
Then, we add them to obtain:
Cl(g) + 2O₂(g) + 2O₃(g) ⇒ ClO(g) + O₃(g) + 3O₂(g)
Whereas we can subtract both oxygen and ozone to obtain the third one:
O₃(g) + Cl(g) ⇒ ClO(g) + O₂(g)
Therefore, the enthalpy of reaction turns out:
ΔH = 122.8 kJ + (-285.3 kJ )
ΔH = -162.5 kJ.
Best regards.
using the Polymers: A Property Database provide the following
properties for high density Polyethylene (use HDPE): Density, Specific Heat Capacity, and Melting Temperature.
Polyethene is a polymer composed of repeating units of the monomer ethene.
The properties of polyethene are as follows:
density- ranges 0.857 g/cm3 to 0.975 g/cm3.specific heat capacity is 1.9 kJ/kg.melting temperature is approximately 110 °C.What are polymers?Polymers are large macromolecules consisting of long repeating chains of smaller molecules known as monomers.
An example of a polymer is polyethene composed of repeating units of the monomer ethene.
The density of polyethylene ranges 0.857 g/cm3 to 0.975 g/cm3.
The specific heat capacity of polyethene is 1.9 kJ/kg.
The melting temperature of polyethene is approximately 110 °C.
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