Bohr used the emission spectrum of hydrogen to support his idea that:

a. electrons travel around the nucleus in a circular orbit
b. there are limited number of energy levels an electron may occupy
c. the energy of an electron is related to its distance from the nucleus
d. electrons move in discrete energy levels around the nucleus

The number of CaSO4 molecules in 2.9 moles is 17.458 x 10^23.

Avogadro's number or Avogadro's constant refers to the quantity of units contained in one mole of any substance. The value is 6.0221408571023. Depending on the nature of the reaction and the substance, the units may be electrons, ions, atoms, or molecules.

Number of moles X Avogadro’s number => Number of molecules

number of CaSO4 molecules => 2.9 x 6.02 x 10^23

                                                  => 17.458 x 10^23 molecules.

The amount of atoms, molecules, or other particles that make up one mole of a substance is known as Avogadro's Number. One mole of hydrogen, for instance, is represented by 6.022 x 1023 hydrogen atoms.

Thus, the mole and the number 6.022 1023 mol1 were invented by Avogadro, Horstmann introduced the idea of the mole into science/chemistry, and Loschmidt and Than were the researchers who first determined Avogadro's number.

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4.2 moles of PO4 contains 399g of PO4

As, Atomic mass of PO4 = 31g + 64g = 95g

1 mole of PO4 contains --> 95g of PO4

4.2 mole of PO4 contains --> 399g of PO 4

A total of 373.7 grams of the combination should be made up of 254.7 grams of water and 119 grams of CaCl2.

In physics, mass is a way to numerically express inertia, a fundamental property of all matter. In essence, a body of matter is the resistance it provides to a change in its speed or position brought on by the application of a force. The more mass a body has, the smaller the change that a force causes is.

One of a body's essential properties is its mass. It was commonly believed to be related to the quantity of matter in a physical body before to the discovery of the atom and the science of particle physics.

Since the solution contains 32.0% CaCl2 by mass, we may calculate the mass of CaCl2 by multiplying the total mass by 32.0(35%).

0.320 x  373.7 = 119.584g =  119 g CaCl2

Simply deduct the amount of CaCl2 from the total mass to determine the mass of H2O:

mass H2O = 373.7 g - 119 g = 254.7g H2O

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H2O2 (hydrogen peroxide) is the reagent to look out for because as seen below it turns:

- Ends of alkenes with 1 –H = Aldehydes but Carboxylic Acids instead

The pressure of the car tire in December will be 259.7 kPa.

The pressure of a given mass of gas is directly proportional to the temperature of the gas.

Hence, the relationship between pressure and temperature is that the pressure increases with temperature.

The pressure of the car tire in December is determined as follows:

P₁/T₁ = P₂/T₂

where;

P₁ is the initial pressure

T₁ is the initial temperature

P₂ is the final pressure

T₂ is the final temperature

The pressure of the car tire in December = 300 * (273 - 15) / (25 + 273)

The pressure of the car tire in December = 259.7 kPa.

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The question in a investigation is the problem that we are asked to find and the hypothesis states what we thinks the answer to that question.

In a scientific experiment, the problem on which we work to solve or the question addressing an unknown thing is called a scientific question. The scientific question have to be precise and experientable.

A scientific hypothesis is a predictive statement describing the possible answer of the problem under study based on the observations and some previous scientific reports.

A hypothesis must be rectifiable, testable and falsifiable. We are checking whether our hypothesis is true or false through an experiment. Hence, second option is correct.

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Water and sodium metal react violently to form sodium hydroxide and hydrogen gas. Both hydrogen gas, solid metal itself may spontaneously ignite due to the exothermic heat produced by this reaction.

Sodium hydroxide is also known as caustic soda and lye. It is a common component of cleansers and soaps. At room temperature, sodium hydroxide is essentially a simple white, odorless solid. Hydroxide is a liquid that has no color or smell. Water can ignite explosive reactions when combined with appropriate acids.

Manufacturers use the chemical sodium hydroxide to create items including soap, rayon, newspaper, explosives, pigments, and crude oil. Hydrochloric acid is also used for cleaning and preparing metal, coating with oxide, electroplating, and electromechanical recovery.

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Answer:

you are a monkey JK

melanin is DARK SIR

Explanation:

heheh

The 38.945 kJ/mol is the activation energy .

What is moles ?

The mole, denoted by the sign "mol," is the volume of a system that has the same number of atoms in 0.012 kilograms of carbon-12 as there are elementary particles.  Similar to how having a dozen eggs says you have twelve eggs, having a mole of something indicates that you have 602,214,076,000,000,000,000,000 of that particular thing.

What is activation energy ?

Even simply getting started takes some energy from them. This force is referred to as activation energy. An automobile engine, for instance, requires activation energy to start. When the key is turned, a spark is produced, starting the engine's burning of gasoline.

It is found that in a chemical reaction, rate constant of the reaction nearly doubled with the rise in temperature by every 10 degree. The temperature dependence  of the rate constant can be explained by Arrhenius equation.

k = A e-Ea /RT

where k = rate constant

A = Arrhenius factor

Ea = Activation energy in Joule/mole

R = Universal gas constant

T = Temperature in Kelvin

Taking natural logaritham

ln k = -Ea / RT + lnA [ lnAB = lnA+ lnB & ln ex = x]

Let k1 and k2 be the rate constants at temperatures T1 and T2 respectively,

then,

ln k1 = -Ea /RT1 + lnA --------------(1)

ln k2 = -Ea /RT2 + lnA --------------(2)

Subtracting (1) from (2)

lnk2- ln k1 = -Ea / R x [ (1/T2 ) - (1/T1)]

ln(k2/k1) = Ea/R x [ (1/T1)- (T2)]-------- [ lnA - lnB = ln(A/B)]

log (k2/k1) =Ea / 2.303R x [ T2- T1 / T1T2] ----- [ natural logarithm can be converted to common logarithm by multiplying with 2.303]

Here T1= 255K

T2 = 265 K

T2- T1 = 265K - 255K

= 10 K

Here the rise in temperature is 10 degree, so the rate constant is to be doubled

That is   k2 = 2 k1

or k2/k1 = 2

R = 8.314 J K-1mol -1

Substituting the values,

log 2= Ea / 2.303x 8.314 x[ 10/255x265]

0.3010= Ea / 19.147 x 10/ 67575 [log 2= 0.3010]

Ea = (0.3010 x19.147x67575) / 10

=38945 Joules/mol

or

Ea = 38.945 kJ/mol

Thus activation energy (Ea) of 38.945kJ/mol is required to double the rate constant for the given reaction

Therefore, 38.945 kJ/mol is the activation energy .

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Answer: Here is your answer Abraham Lincoln was a basketball player for the New York Knicks in 1642 He got drafted by the washinton capitals in 1707 and now he's currently still alive living in 2030.

Explanation:

Answer:

ask a pro

Explanation:

hope this was helpful

C. CaCl₂ (aq) and K₂CO3(aq)  will produce a precipitation reaction among the following.

A precipitation reaction is a type of chemical reaction in which an insoluble solid (precipitate) is formed from two or more soluble compounds. The formation of a precipitate is often indicated by a change in the color of the solution or by the appearance of a solid.In option C, CaCl2 and K2CO3 are both dissolved in water and when they are mixed, a precipitation reaction occurs, where the calcium ions in CaCl2 react with the carbonate ions in K2CO3 to form solid calcium carbonate (CaCO3), which is insoluble in water. Thus, it will precipitate out of the solution as a solid. Option A, LINO3 and Nal, and option B, HNO3 and Sn(OH)2, are both acid-base neutralization reactions, in which an acid and a base react to form water.

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the standard genetic code, in which a group of three nucleotides codes for the synthesis of a particular amino acid.

The standard genetic code, in which a set of three nucleotides specifies how an amino acid will be synthesised. DNA is a type of. DNA molecules' nucleotide sequences, which is how live cells' genetic information is carried in those molecules.

An amino acid is encoded by a codon, a triplet of nucleotides. An amino acid is encoded by each trio of nucleotides. The degenerate code consists of 20 amino acids and 64 combinations of four nucleotides taken three at a time (more than one codon per amino acid, in most cases).

A triplet code would therefore be the smallest set of four bases capable of encoding all 20 amino acids.

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The balanced half-reactions for the oxidation and reduction in the reaction 2Fe + 3[tex]I_2[/tex] → 2[tex]Fe_3[/tex] + 6[tex]I^-[/tex] are Fe(s) → [tex]Fe^{3+}[/tex](aq) + 3[tex]e^-[/tex] and 3[tex]I_2[/tex](s) + 6e → 6[tex]I^-[/tex](aq) respectively.

The balanced half-reactions for the oxidation and reduction that happen in the reaction 2Fe + 3[tex]I_2[/tex] → 2[tex]Fe^{3+}[/tex] + 6[tex]I^-[/tex] are as follows:

Oxidation half-reaction (Fe → [tex]Fe^{3+}[/tex]):

Fe(s) → [tex]Fe^{3+}[/tex](aq) + 3[tex]e^-[/tex]

Reduction half-reaction (I2 → I^-):

3[tex]I_2[/tex](s) + 6e → 6[tex]I^-[/tex](aq)

The oxidation half-reaction describes the oxidation of iron (Fe) to iron(III) ion ([tex]Fe^{3+}[/tex]). In this process, Fe loses 3 electrons, becoming [tex]Fe^{3+}[/tex].

The reduction half-reaction describes the reduction of iodine ([tex]I_2[/tex]) to iodine ions ([tex]I^-[/tex]). In this process, iodine gains 6 electrons, becoming [tex]I^-[/tex].

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3.115 moles of hydrogen were produced when 6.23 moles of Li were combined. Utilizing 80.57 grams of Li, 11.60 grams of hydrogen were produced.

Hydrogen is most frequently found in water on earth. The hydrogen atoms in each hydrogen atom (H2 O) total two. On the surface of the earth, hydrogen can also be found in a variety of compounds, such as molecules, acids, and hydroxides.

Hydrogen retail costs ranged from $8.50/kg to $10.80/kg more than gasoline prices in 2021 for hybrid or traditional gasoline vehicles, respectively, matching a same gasoline cost per mile. Since hydrogen has been utilized in industry for more than 80 years, it is highly developed.

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The rate at which an enzyme-catalyzed reaction takes place is faster than that of an uncatalyzed reaction.

Structure of organisms as enzymes allow our bodies' phase changes, or combustion, to progress more quickly. Others are broken down while others are built. Enzymes exist in every living organism. Enzymes are created in our bodies by nature.

Foods that naturally contain digestive enzymes include kefir, sauerkraut, kimchi, miso, kiwifruit, mangoes, pineapples, papayas, mangoes, honey, bananas, avocados, and ginger. A diet that includes any of these foods may assist to improve gut health and digestion.

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Each atom's valence electrons added together make up the total number of electrons in a molecule's Lewis structure.

The smallest unit of a material, a molecule is made up of two or more atoms that are joined by chemical bonds and preserve the structure and characteristics of the larger substance. Chemistry is built on molecule-level principles. A subscript indicating the number of atoms is used after the element symbol to identify molecules.

Atoms are singular, uncharged particles. By bonding together two or more atoms, molecules are neutral particles. Ions are charged particles, either positively or negatively.

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One of the reactants is H2O2, therefore raising its concentration would accelerate the process.

As the reactant concentration increases, more reactant particles are moving together. The reaction rate will increase since there will be more collisions. The concentration of the reactants will affect how quickly a reaction proceeds.

A higher concentration of H2O2 would speed up the reaction because it is one of the reactants.

b. As the amount of water increases, the concentration of the reactant falls, which lowers the rate.

S2O3- is one of the reactants, hence boosting its concentration would accelerate the reaction.

d. Starch is solely utilized as an endpoint indication. On the rate, there is no difference.

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In the provided question, [tex]-1.383 \times 10^{-11}[/tex] Joules is the equivalent energy of the mass defect of an atom of [tex]\rm _8 ^{18}O[/tex] .

The mass defect is the difference between the mass of an atom's nucleus and the sum of the masses of its individual protons and neutrons.

The mass of an atom of [tex]\rm _8 ^{18}O[/tex] is 17.99916 u. The sum of the masses of its eight protons (1.00728 u each) and ten neutrons (1.00867 u each) is 16.99776 u. Therefore, the mass defect is:

Δm = (mass of nucleus) - (sum of masses of protons and neutrons)

Δm = 17.99916 u - 16.99776 u

Δm = 0.0014 u

The equivalent energy ([tex]\rm E_b[/tex]) of the mass defect can be calculated using Einstein's famous equation:

[tex]\rm E=mc^2[/tex], where E is energy, m is mass, and c is the speed of light.

[tex]\rm E_b[/tex] = Δm [tex]\rm \times c^2[/tex]

where c is the speed of light, which is approximately [tex]3.00 \times 10^8[/tex] m/s.

Plugging in the values, we get:

[tex]\rm E_b[/tex]= [tex]\rm (0.0014 \ u) \times (1.66 \times 10^{-27 }\ kg/u) \times (3.00 \times 10^8 \ m/s)^2[/tex]

[tex]\rm E_b = -1.383\times 10^{-11} J[/tex]

Therefore, the equivalent energy ([tex]\rm E_b[/tex]) of the mass defect of an atom of  [tex]\rm _8 ^{18}O[/tex] is [tex]-1.383 \times 10^{-11}[/tex] Joules.

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The enthalpy change for the following reaction:

CH4 + 2O2 = CO2 + 2H2O is (-890) kJ/mol and it is exothermic

The bond enthalpy values for the reactants and products can be used to calculate the enthalpy change for the following reaction:

CH4 + 2O2 = CO2 + 2H2O

The bond enthalpies for the individual bonds in each molecule are:

CH4: C-H bond enthalpy = 413 kJ/mol

H-H bond enthalpy = 436 kJ/mol

O2: O=O bond enthalpy = 498 kJ/mol

CO2: C=O bond enthalpy = 799 kJ/mol

H2O: H-O bond enthalpy = 463 kJ/mol

To calculate the overall enthalpy change for the reaction, we need to add up the bond enthalpies for the reactants and subtract the bond enthalpies for the products.

The enthalpy change for the reaction is calculated as follows:

(1*(C-H bond enthalpy + 3H-H bond enthalpy) + 2(O=O bond enthalpy)) - (1*(C=O bond enthalpy) + 2*(2*H-O bond enthalpy))

= (1*(413 + 3436) + 2498) - (1799 + 2(2*463))

= (-890) kJ/mol

So this reaction is exothermic.

Therefore, the correct answer is as given above

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The dose of CaCl₂ are administered in an injection of 5.0mL of a 5.0% (w/v) solution and how many milliequivalents of Ca2+ is 0.09 grams or 4.51 mEq.

An unsafe abnormal heart rhythm (arrhythmia), which develops when the heart's electrical system isn't functioning properly, is what leads to cardiac arrest. Some abnormal heart rhythms prevent the heart from properly pumping blood throughout the body, though not all of them are life-threatening.

A%(w/v) indicates mass of solute dissolved in 100 mL of solution.

So,

Mass of CaCl₂ in solution = 5% (w/v) of 5.0 mL

Mass of CaCl₂ in solution = (5.0 g / 100 mL) x 5.0 mL= 0.25 g

Now, moles of CaCl₂ = Mass / molar mass

Now, moles of CaCl₂ = 0.25 g / 110.9834 g mol⁻¹ = 0.002253 mol

1 mol CaCl2 has 1 mol Ca2+. So, moles of Ca2+ in the solution must be equal to the moles of CaCl2.

So, Ca2+ in the solution = 0.002253 mol

Now,

Mass of Ca²⁺ in the solution = Moles x Molar mass

Mass of Ca²⁺ in the solution = 0.002253 mol x 40.078 g mol⁻¹

Mass of Ca²⁺ in the solution = 0.090279 g = 90.279 mg

Hence, mass of Ca²⁺ in solution = 0.09 g

2. mEq of Ca²⁺ = (mass in mg x Valence) / Formula weight

mEq of Ca²⁺ = (90.279 x 2) / 40.078 = 4.51

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The chemical formula is AB3X, A occupies all the corners & B occupies the faces, So the contribution = ½ × 6 = 3 . X occupies body center So contribution= 1,So atomic formula= AB3X

What is Chemical formula?

A chemical formula is a way of presenting information about the chemical ratios of atoms that make up a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes other symbols such as parentheses, dashes, parentheses, commas, and plus and minus signs

What is chemical compound?

A chemical compound is a chemical substance composed of two or more different chemical elements held together by chemical bonds. It can be either a molecular compound composed of atoms held together by covalent bonds, or an ionic compound composed of ions held together by ionic bonds. Compounds can be composed of elements from the same group, or from different groups.

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The expression for the solubility product constant for Cr₂(CO₃)₃ is

Ksp = [Cr³⁺] [CO₃⁻²]³

The equilibrium constant for the dissolution of a solid substance in an aqueous solution is the solubility product constant, Ksp. The amount that a solute dissolves in solution is what it represents. A substance's Ksp value increases with its degree of solubility.

The solubility product, also known as K s p, is a physical quantity. When a solid material dissolves in a liquid or aqueous solution, it serves as the equilibrium constant for equations.

Cr₂(CO₃)₃ → 2Cr³⁺(aq) + 3CO₃⁻²(aq)

Ksp = [Cr³⁺] [CO₃⁻²]³

Solubility product constant is product of concentrations of ions formed and power on concentration is stoichiometry coefficient.

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The toaster's internal energy reduces as a result of heat entering the bread, hence response option B is correct. For A toaster is used to toast a piece of bread.

When the temperature rises and when a state or phase changes from solid to liquid or liquid to gas, internal energy increases as well. Planetary bodies can be compared to a hybrid of a heat engine and a heat reservoir. Internal energy E is kept in the heat reservoirs. The whole amount of energy that a thermodynamic system has inside of it is known as internal energy. It is the energy required to develop or prepare the system in its current internal condition, and it comprises both internal kinetic energy and potential energy contributions. The net thermal energy of a system is referred to as heat energy.

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Answer:

I believe it's when they share electrons

Explanation:

1. 2SO2 + 2H2 ➡️ 2H2S + 2H20

2. CaCl2 + Na2CO3 ➡️ CaCO3 + 2NaCl

3. 2HNO3 ➡️ NO2 + H2O + 02

4. 12Al + H2SO4 ➡️ A12(SO4)3 + H2

In general, the solubility of compounds containing the carboxylic acid group (COOH) can be increased by reacting a carboxylic acid with sodium hydroxide option - b is correct answer.

Water does not form dimers when carboxylic acids are added. Instead, hydrogen bonds are created between the water molecules and the individual acid molecules. These interactions allow for the dissolution of carboxylic acids to create acidic solutions in water.

Similar to alcohols, aldehydes, and ketones, carboxylic acids are soluble in water. Acids with fewer than five carbons dissolve in water, but those with a higher molecular weight are insoluble because their larger hydrocarbon portion is hydrophobic.

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Surface water and ground water are two sources of watershed. Thus, option A is correct,

A watershed is an area of land and water where water from many sources collects at a location below the surface of the land. The area of land that surrounds a water source and empties into a single location at a lower elevation is called the watershed.

Surface water is defined as water from rivers, oceans, etc. that is on the same level as the land. Groundwater is the liquid that lies below the surface of the earth or the sea.

For instance, the geographical area that drains into a lake's watershed would include include the streams that enter the lake as well as the streams' final destination, the lake. Large watersheds that include the watersheds of numerous smaller rivers and streams are referred to as drainage basins.

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A summary of the C4 plants is given below:

The Hatch-Slack pathway, also known as C4 carbon fixation, is one of three recognized photosynthetic carbon fixation pathways in plants.

The names are a result of Marshall Davidson Hatch and Charles Roger Slack's discovery in the 1960s that some plants, when given 14CO2, integrate the 14C label into four-carbon molecules first.

Corn, sorghum, sugarcane, millet, and switchgrass are examples of C4 plants. C3 plants are often more prolific and efficient at photosynthesizing in cooler conditions because C4 morphological and biochemical adaptations demand more energy and resources from the plant.

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Co(NH3)4Cl2] Due to the presence of 2 Cl- and 4 NH3 in the coordination sphere, Cl has a coordination number of 6. By counting the number of atoms bonded to an atom, one can determine the coordination number of a molecule or polyatomic ion (note: not by counting the number of chemical bonds).

Because there are a total of six atoms, ions, or molecules linked to the center atom, Cr, it has coordination number 6 once more. Because en (ethylenediamine) are bidentate ligands, the coordination number Co is 6 in the complex ion [Co(en)3]3+. A single metal core can be reached by both atoms working together. The cobalt(III) ion has a coordination number of six and is one of three bidentate en ligands in the complex [Co(en)3]3+.

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