Which scientist developed a model of the atom that looked like a nucleus surrounded by electrons?

Assessing the maximum number of cross-linkages from vulcanizing 100 g of polyisoprene is not possible without detailed conditions of vulcanization. Vulcanization creates cross-linkages at different densities for various rubber characteristics, with 2-3% and 25-35% crosslinking producing soft and hard rubber, respectively.

The question "What is the greatest number of theoretical cross-linkages possible by vulcanizing 100 g of polyisoprene chains?" pertains to the chemical process of vulcanization, which is used to strengthen rubber. Vulcanization involves adding sulfur or other curatives to polymers, like polyisoprene, which creates cross-linkages between the polymer chains. This process transforms rubber into a more durable, elastic material commonly used in a variety of products including tires and seals.

However, without specific information on the conditions of vulcanization, such as the amount of sulfur or the extent of heat applied, or the exact structure of the polyisoprene used, it is impossible to calculate the exact maximum number of cross-linkages. What we can acknowledge is that cross-linkages occur at varying densities depending on the desired characteristics of the rubber produced. For example, at 2 to 3% crosslinking, a soft rubber suitable for many everyday applications is obtained, while at 25 to 35% crosslinking, a hard rubber product is achieved.

the greatest number of theoretical cross-linkages possible by vulcanizing 100 g of polyisoprene chains is approximately[tex]\(1.77 \times 10^{24}\).[/tex]

The number of theoretical cross-linkages possible by vulcanizing polyisoprene chains depends on the number of repeat units in the polymer and the stoichiometry of the vulcanization reaction. Vulcanization typically involves the formation of sulfur bridges between polymer chains, leading to cross-linkages.

Polyisoprene (natural rubber) is a polymer composed of repeating isoprene units [tex](\(C_5H_8\)).[/tex] The molar mass of isoprene is approximately 68.12 g/mol.

To find the number of moles of polyisoprene in 100 g, we divide the mass by the molar mass:

[tex]\[ \text{Moles of polyisoprene} = \frac{\text{Mass of polyisoprene}}{\text{Molar mass of polyisoprene}} \][/tex]

[tex]\[ \text{Moles of polyisoprene} = \frac{100 \, \text{g}}{68.12 \, \text{g/mol}} \][/tex]

[tex]\[ \text{Moles of polyisoprene} \approx 1.47 \, \text{mol} \][/tex]

Now, let's assume that each cross-linkage involves one sulfur atom (S). The molar mass of sulfur is approximately 32.07 g/mol.

For every mole of polyisoprene, a certain ratio of sulfur atoms is used in the vulcanization process. This ratio depends on the specific vulcanization method and conditions. Let's assume a simplified scenario where each isoprene unit can potentially form a cross-linkage with a sulfur atom.

The molar ratio of sulfur atoms to isoprene units is 1:1. Therefore, the number of moles of sulfur required is the same as the number of moles of polyisoprene.

[tex]\[ \text{Moles of sulfur} = 1.47 \, \text{mol} \][/tex]

Now, let's calculate the number of sulfur atoms:

[tex]\[ \text{Number of sulfur atoms} = \text{Moles of sulfur} \times \text{Avogadro's number} \][/tex]

[tex]\[ \text{Number of sulfur atoms} = 1.47 \times 6.022 \times 10^{23} \][/tex]

[tex]\[ \text{Number of sulfur atoms} \approx 8.84 \times 10^{23} \][/tex]

Each sulfur atom can potentially form two cross-linkages (one with each isoprene unit). Therefore, the maximum number of theoretical cross-linkages possible is twice the number of sulfur atoms.

[tex]\[ \text{Maximum number of theoretical cross-linkages} = 2 \times \text{Number of sulfur atoms} \][/tex]

[tex]\[ \text{Maximum number of theoretical cross-linkages} = 2 \times 8.84 \times 10^{23} \][/tex]

[tex]\[ \text{Maximum number of theoretical cross-linkages} \approx 1.77 \times 10^{24} \][/tex]

So, the greatest number of theoretical cross-linkages possible by vulcanizing 100 g of polyisoprene chains is approximately[tex]\(1.77 \times 10^{24}\).[/tex]

Final answer:

Carbon dioxide is produced as a byproduct of cellular respiration, where sugar reacts with oxygen to release energy, water, and CO2. The CO2 is then transported to the lungs as bicarbonate and exhaled.

Explanation:

We inhale oxygen (O2) and exhale carbon dioxide (CO2). Carbon dioxide is produced in the body because every cell requires oxygen for the oxidative stages of cellular respiration, a process by which energy is produced in the form of adenosine triphosphate (ATP). During this process, sugar (C6H12O6) reacts with oxygen to produce carbon dioxide, water, and energy according to the balanced equation: C6H12O6 + 6O2 → 6CO2 + 6H2O + energy.

Carbon dioxide is then transported back to the lungs as bicarbonate via the bloodstream, where it dissociates readily from hemoglobin and diffuses across the respiratory membrane into the air within the alveoli to be expelled as a waste product.

Final answer:

Carbon dioxide is produced as a byproduct of cellular respiration, during which cells use oxygen to convert nutrients into energy, and is excreted by exhaling after being carried to the lungs in the form of bicarbonate.

Explanation:

We inhale oxygen when we breathe, which is essential for the process of cellular respiration. In this process, our cells use oxygen to convert nutrients, such as sugars, into energy in the form of adenosine triphosphate (ATP), carbon dioxide , and water. Carbon dioxide is produced as a waste product during the oxidative stages of cellular respiration. It is then transported back to the lungs via the blood, where it is converted largely into bicarbonate ions by the enzyme carbonic anhydrase within red blood cells.

The high concentrations of carbon dioxide in areas of high metabolic rate lead to its diffusion into blood capillaries and eventual transport to the lungs. Gas exchange within the alveoli of the lungs allows carbon dioxide to be exhaled and fresh oxygen to be taken up by the bloodstream, continuing the cycle of respiration. The respiratory quotient (RQ) can vary depending on the type of nutrient being metabolized—fats, proteins, or carbohydrates—but it generally represents the ratio of carbon dioxide produced to oxygen consumed.

Mercury is the answer

Final answer:

Evaporation of water is a physical change because it involves a change from liquid to gas without altering the chemical composition of the water (H₂O). The water molecules remain the same before and after evaporation.

Explanation:

The evaporation of water is a physical change, not a chemical one. During the evaporation process, liquid water (H₂O (l)) turns into water vapor (H₂O (g)), but the molecular structure of water does not change. The molecules gain energy and move apart to transition from the liquid to the gas phase, but they remain as H₂O molecules throughout this process, indicating that no chemical reaction has occurred, only a change in state.

Examples of physical changes include the dissolving of sugar in water, the melting of solid gold, and the conduction of energy through a material. None of these processes result in a change to the underlying chemical composition of the substance involved. For example, even when sugar dissolves in water, it still remains sugar and can be recovered by evaporating the water.

answer: 43 grams.

This problem is a good example to understand  the law of conservation of mass. This law states that mass can neither be created nor destroyed , meaning that the final mass is the same that what you started with..

You didn't measure the weight of the oxygen that entered the reaction, so the weight of the rustic nail, plus the weight of the oxygen, will be the equal to the final mass. 

100 +43 = 143g 

Answer:

43 Grams:) I hope that this helped!

To solve this, we must first find the value of the wavelength using the formula:

1/ʎ = R [1/(nfinal)^2 – 1/(ninitial)^2]

where ʎ is wavelength and R is Rydberg’s constant = 10,973,731.6 m-1

1/ʎ = 10,973,731.6 m-1 [1/2^2 – 1/4^2]

1/ʎ = 2,057,574.675 m-1

ʎ = 4.86 x 10^-7 m

Then compute for energy using the equation:

E = hc / ʎ

where h is Plancks constant = 6.63 x 10^-34 J s, c is speed of light = 3 x 10^8 m/s

E = (6.63 x 10^-34 J s) (3 x 10^8 m/s) / 4.86 x 10^-7 m

E = 4.09 x 10^-19 J

Answer: Option (c) is the correct answer.

Explanation:

Neon has atomic number 10 and its electronic distribution is 2, 8. As it has completely filled valence shell therefore, it does not need to gain or lose an electron.

Hence, neon is stable in nature and does not form bonds with any other atom.

Whereas atomic number of gold is 79 and its electronic configuration is [tex][Xe] 4f^{14}5d^{10}6s^{1}[/tex]. Hence, in order to attain stability, it loses one electron and thus, it is likely to form a bond.

Oxygen atom has atomic number 16 and its electronic distribution is 2, 8, 6. Hence, to attain stability it needs 2 electrons. Hence, it is likely to form a bond.

Magnesium has 2 valence electrons and chlorine has 7 valence electrons. So, they combine chemically to form [tex]MgCl_{2}[/tex].

Thus, we can conclude that out of the given options neon atoms are not likely to form bonds.

Tin -118 is the isotope with 50 protons, 68 neutrons, and 50 electrons.

Isotopes can be described as elements that contain the same atomic number but a different atomic mass. Isotopes of an element possess an equal number of electrons and protons. The number of neutrons in the respective nucleus of that element is different.

For example, the isotope of oxygen can be written as oxygen- 16, oxygen - 17, and oxygen-18 as all of them contain eight electrons or protons.

Tin metal has 29 isotopes but all the isotopes have the same number of electrons and protons. Among these only ¹²⁶Sn isotope is long-lived while the rest 28 isotopes of tin with a half-life of less than one year. The mass number of the given isotope of tin = 50 + 68 = 118. Therefore, the given isotope of tin is ¹¹⁸Sn. It has an abundance of 24.22%.

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The electrons in bonds (bonding domains) differ from lone pairs (non-bonding domains) is because the bonding domains are bonded to the central atom vs the lone pairs are just stuck on as extra electrons. The difference of bonding domains from non-bonding domains is that the bonding domains are bonded to the central atom and the non-bonding domains are just stuck on as extra electrons.

Answer:

The bonding electrons are different from nonbonding electrons by the arrangement with the central atom. Bonding electrons are bonded with the central atom. Nonbonding electrons appear are electron clouds.

Explanation:

During the formation of a chemical bond, there are bonding electrons and loan pairs.

The electrons of both the atom in a chemical bond share with each other and form a stable sigma bond. The electrons are linearly bonded with each other.

The electrons which are not directly bonded with other atoms, occupy the space at the top and bottom of the sigma bond. These electrons are present as the electron cloud and are termed the non-bonding electrons.

The bonding electrons differ from non-bonding electrons as bonding electrons are bounded by the central atom. Loan pair of electrons or nonbonding electrons are present as the electron cloud above or below the bond.

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Answer: adaptation

natural selection

Natural selection refers to the differential survival of the organisms in the population. It describe the fact that individual that have favorable phenotypic characteristics have better chances of survival over others in the changing environment. Adaptation is a genetic change or mutation that helps organism to survive in it's ecological niche. Due to the helpful nature of these genetic changes they are passed down from one generation to the next generation and favors the survival and abundance of a species.

Adaptation and natural selection has resulted in the change in the population of the giraffes. The giraffes being in short neck adapted the increase in neck length with an effort to obtain leaves from tall tries. The long neck giraffe got the better chances of survival and reproduction, due to natural selection the trait was passed on to generation. This resulted in the evolution of long neck giraffe species.

To calculate the number of atoms in 5.40g of Boron, we first convert grams to moles using Boron's atomic weight, resulting in 0.5 moles. Then, using Avogadro's number (6.022 x 10²³ atoms/mole), we can find the number of atoms. Hence, 5.40g of Boron contains approximately 3.011 x 10²³ atoms.

The number of atoms in 5.40g of Boron (B) can be found by first determining the number of moles. Boron's atomic weight is approximately 10.81 g/mol. Therefore, 5.40g of Boron would consist of 0.5 moles.

Next, using Avogadro's number (approximately 6.022 x 10²³atoms/mole), used to convert moles to atoms, we can find out the number of atoms.

Therefore, 5.40g of Boron contains approx 3.011 x 10^23 atoms.

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The pressure of the hydrogen gas collected by water displacement at a temperature of 26°C is obtained by measuring the height of the displaced mercury, considering the presence of water vapor and it is calculated as 725 torr.

The question is requesting the pressure of hydrogen gas collected by water displacement at a temperature of 26°C. The pressure of a gas sample can be determined using a variety of methods. One such approach is measuring the displacement of a column of mercury. If the column of mercury is 26.4 cm high, the pressure of the gas is equivalent to this height, or 264 torr.

However, the presence of water vapor can affect the calculated pressure of the gas. At 26°C, the pressure of water vapor is 25.2 torr. Hence, we need to subtract this value from the total pressure to obtain the pressure of hydrogen gas.

Therefore, the pressure of the hydrogen gas collected by water displacement at a temperature of 26°C is 725 torr.

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The pressure of the collected hydrogen gas is equal to the atmospheric pressure.

A sample of hydrogen gas was collected by water displacement at 26°C. To determine the pressure of the collected hydrogen gas, we need to consider the relationship between pressure, volume, temperature, and the number of moles of gas.

Using the ideal gas law, we can calculate the number of moles of hydrogen gas from the volume and temperature. Then, using the molar mass of hydrogen gas, we can determine the mass of the collected gas. Finally, we can relate the mass of the gas to the pressure using the density formula.

Since the hydrogen gas was collected by water displacement, we can assume that it occupies the same volume as the displaced water. Given the temperature of 26°C (299 K) and assuming atmospheric pressure (1 atm), we can calculate the number of moles of hydrogen gas using the ideal gas law.

Once the number of moles is known, we can determine the mass of the hydrogen gas using its molar mass (2.016 g/mol). Finally, we can calculate the pressure of the gas using the density formula, considering the mass of the gas and the volume of the displaced water.

Therefore, the pressure of the collected hydrogen gas is approximately 1 atm, which is the same as the atmospheric pressure.

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Answer:pookie dookie

Explanation:

The statements that describe metalloids are these are elements that have both metal and nonmetal properties. The correct option is A.

Metalloids are chemical elements that have the properties of both metals and non-metals. Metalloids are brittle and good conductors of electricity. They form alloys with metals. They have various chemical and physical properties that are used in many things like catalysis, flame, or glasses.

So, metalloids are elements that contain both metals and non-metals. They are not the metals that don't lose. They always do not attract electrons and only metal properties are also wrong because it has the properties of both.

Thus, the correct option is A. Metalloids are elements that have both metal and nonmetal properties.

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This organism would be found in a marine ecosystem.

> How many valence electrons does a helium atom have?

The electron configuration of Helium is simply 1s2. We see that its outermost shell is the s shell and it contains 2 electrons, therefore the number of valence electrons is also 2.

> What is the formula of the ion formed when potassium achieves noble-gas electron configuration?

Potassium has a electron configuration of [Ar] 4s1. To have an electron configuration of only [Ar] which is a noble gas, the one electron from 4s1 should be removed, hence:

K+

Electrons are the smallest of the three particles that make up atoms. Electrons are found in shells or orbitals that surround the nucleus of an atom. Protons and neutrons are found in the nucleus. They group together in the center of the atom.

The electron shell of an atom contains electrons, negatively charged subatomic particles. Protons and neutrons, the other subatomic particles, reside in the atom's nucleus.

The electron shell of an atom contains one type of subatomic particle known as the electron. Electrons are very small particles with a negative charge, often represented by 'e⁻' in scientific notation. In contrast, two other subatomic particles, the proton and neutron, are located in the nucleus of the atom. Protons have a positive charge and are denoted by 'p⁺', while neutrons have no charge and are represented by 'n' or 'n⁰'. The combination of electrons, protons, and neutrons constitutes the fundamental architectural makeup of an atom, determining its element, isotopes, and chemical behavior.

Amanda dropped a rock into a graduated cylinder containing water. The water level in the cylinder increased. Density is the  property of the rock.

Density is the mass of a specific material per unit volume. d = M/V, at which d is density, M is weight, and V is volume, is the formula for density. Grams per cubic centimeter are a typical unit of measurement for density. For instance, whereas Earth has a density of 5.51 grams, water has a density of 1 grams.

Another way to state density is in kilograms per cubic meter (in metre-kilogram-second or SI units). For instance, air weighs 1.2 pounds per cubic metre. Amanda dropped a rock into a graduated cylinder containing water. The water level in the cylinder increased. Density is the  property of the rock.

Therefore, the correct option is option A.

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Answer:

Option B.Mitochondria

Explanation:

I took a unit test and this question was on it, the mitochondria is the correct answer

Hope this helps