Help me out please :)

The Rf values should be kept in the range of the 0.2 to 0.8 for the most effective separation when the more than one compound is present in sample. This statement is True.

The Rf value is dependent on the polarity of the compound. Polar compounds will have the lower Rf values than the nonpolar compounds under the same conditions. The Rf value is defined as the ratio in between the distance the solute travelled and the distance the solvent travelled.

Thus, this statement is true that Rf values should be kept in the range of the 0.2 to 0.8 for the most effective separation when the more than one compound is present in sample.

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Answer:

c+cu

Explanation:

The radius of the strontium atom is 215 pm. The strontium atoms would have to be distance of 3.46 mm is 8.0 × 10⁶ atoms.

The information is given as :

The radius, r = 215 pm = 2.15 × 10⁻¹⁰ m

The distance, d = 3.46 mm = 3.46 ×10⁻³ m

The No. of strontium atoms that  laid side by side is :

n = d / 2 r

n = 3.46 ×10⁻³ m  / (2 × 2.15 × 10⁻¹⁰)

n =  3.46 ×10⁻³ / 4.3  × 10⁻¹⁰  atoms

n = 8.0 × 10⁶ atoms

The number of strontium atoms is 8.0 × 10⁶ atoms.

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The simplification of the expression will return 3. Option 1.

The expression to be simplified is as follows:

3 mol/1 x 1/1 mol

This is the same as: 3 mol x 1/1 x 1 mol

Carrying out the mathematical expressions of the numerator and denominator, we will have:

 3 mol/1 mol

Carrying out the division, the 'mol' will cancel out while 3/1 will give us 3.

In other words, 3 mol/1 x 1/1 mol will return a value of 3.

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The dissociation of ozone layer requires longer wavelength to dissociate.

The absorption of ultraviolet (UV) light by the ozone layer is a vital part of the Earth's atmosphere, as it helps to protect our planet from the harmful rays of the sun. When UV light is absorbed by the ozone layer, it causes the dissociation of oxygen and ozone molecules.

To achieve this process, longer wavelengths of UV light are required. This is due to the fact that UV light of longer wavelengths has more energy, which is needed to break apart the molecules.

The result of this process is that the ozone layer is able to absorb more of the harmful UV radiation and protect the Earth.

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A hydrated sample of sodium acetate is found to have a molar mass of 263. 183g. water molecules are associated with each sodium acetate 1000mL/L of sodium acetate make up the bulk.

sodium volume in mL, molar mass, and molarity = \s1000 \s500 \s​ \s ×0.375×82.0245=15.38. g.The number of moles per litre is the molarity of a solution. In 500 ml, you have 0.75 moles. As a result, you have 0.75 moles per liter, or 1.5 moles per liter, or one pound. A hydrated sample of sodium acetate is found to have a molar mass of 263. 183g. water molecules are associated with each sodium acetate 1000mL/L of sodium acetate make up the bulk.The mass percentage of water in a 20% solution with 100g of water is equal to 100 - 20%, or 80%. <br> 100 grams of the solution, or 80%, 100% of the answer is equal to "(100)/(80)" gram. 20% of the answer is equal to (100/(80) xx 20) = 25 grams. Therefore, 25 grams of sodium sulphate are required to make a 20% (w/w) solution in 100 g of water.

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Answer: At a given temperature and pressure, one mole of any gas occupies the same volume. The molar volume is the volume occupied by one mole of any gas, at room temperature and pressure. The molar volume is equal to 24 dm3 (24,000 cm3).

Explanation: its the internet

1) Nonpolar bond

2) Polar bond

3) Polar bond

4) Non polar bond

5) Polar bond

6) Polar bond

We know that the bonds can be said to be polar when the electronegativity difference between the atoms that compose the bond is high. As such, a bond that we have between two elements that are the same would be non polar.

We know that the element that would be the most electronegative would be the non metallic element that is part of the bond. The more the electronegativity difference, the more polar the bonds.

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The Highly Soluble : NaCl, KOH, CH₃CH₂OH, CH₃COOH, CH₃OH, Na₂SO₄, KNO₃

The Insoluble: C₆H₆, C₆H₁₄, CCl₄, CHCl₃, CH₂Cl₂, CH₃(CH₂)₅OH

1) NaCl : NaCl is a chloride and NaCl is highly soluble.

2)  CH₃C l: This compound is an organic. The electronegativity between C and Cl is high, and is polar. Because water is also polar, it is highly soluble.

3) CH₃OH:  Alcohols are hydrocarbon are is highly soluble in water because of hydrogen bonding.

4) KOH: KOH is highly soluble. This is a strong an readily dissociates in water.

5)  C₆H₆ : It is the benzene ring and is a nonpolar molecule, so it is expect this is insoluble with water.

6) C₆H₁₄ : It is hexane of  long chain of hydrocarbons. There is no hydrogen bonding, this is nonpolar and insoluble in water.

7) KNO₃: It is highly soluble because all nitrates are soluble in the water.

8)  CCl₄ : There is balance of the partial charges which makes it a nonpolar. It  is insoluble in water.

9) Na₂SO₄: It is highly soluble.

10) CH₃CH₂OH: It is highly soluble in water.

11) CH₂Cl₂ : This is polar and due this it is highly soluble in water.

12) CH₃COOH : It is a carboxylic acid. It is highly soluble in water.

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The 2 mol Al moles of Fe2O3 are formed when 4.2 moles of Fe reacts completely with oxygen.

What is moles?

A mole is an extremely important unit of measurement for chemists. A mole of anything denotes 602,214,076,000,000,000,000,000 of that thing, just as possessing a dozen eggs denotes having twelve eggs. Chemists use moles to measure extremely small substances like atoms, molecules, and other particles.

What is oxygen?

Because oxygen contains only one type of atom, it is a chemical element, which is a type of substance. Since oxygen has an atomic number of 8, it is represented by the letter O in its formal chemical formula and has eight protons in its nucleus. In nature, molecular oxygen can be discovered.

2 mol Al, 3 mol Fe.

Therefore,  2 mol Al moles of Fe2O3 are formed when 4.2 moles of Fe reacts completely with oxygen.

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The frequency of electromagnetic radiation with a wavelength of 420 nm is 8 × 10¹⁴Hz.

Wavelength is the length of a single cycle of a wave, as measured by the distance between one peak or trough of a wave and the next.

It is often designated in physics as λ, and corresponds to the velocity of the wave divided by its frequency i.e. λ = v/f

According to this question, a wavelength of 420nm is given, which is equivalent to 4.2 × 10-⁷m.

4.2 × 10-⁷m = 3 × 10⁸/f

f = 3 × 10⁸ ÷ 4.2 × 10-⁷

f = 8 × 10¹⁴Hz

Therefore, 8 × 10¹⁴Hz is the frequency of the wave.

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The rate law that is consistent with the proposed mechanism is [-d[H₂]/dt = k[H₂][ICl].

The sum of the two processes produces the overall reaction, which is:

H₂(g) + 2ICl(g) → 2HCl(g) + I₂(g)

We must take into account the rate-determining step, which is the step with the slowest rate, in order to derive the rate law for the total reaction. It is step 1 in this instance.

H₂(g) + ICl(g) → HI(g) + HCl(g) is the rate-determining step (g)

This step's rate rule is-d[H₂]/dt = k[H₂][ICl]

[ICl]

We can assume that the concentration of HI is always in equilibrium with the concentrations of H₂ and ICl because step 2 is quick.

Therefore, -d[H₂]/dt = k[H₂][ICl] is the rate law for the entire reaction.

Therefore,  [-d[H₂]/dt = k[H₂][ICl] is the rate law that is consistent with the hypothesized mechanism.

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Do not accept the food or throw the products away if the food temperatures fall outside of acceptable ranges or if TCS food exhibits signs of previous temperature abuse. Keep cold food at or below 41°F.

Do not accept the food or throw the products away if the food temperatures fall outside of acceptable ranges or if TCS food exhibits signs of previous temperature abuse. Keep cold food at or below 41°F. At supermarkets, eateries, and other establishments that sell ready-to-eat meals, customers are always demanding TCS food items. At the point of sale, people are pickier and look for foods from vendors they believe will provide a high-quality and safe product. Managers and employees need to be aware of all the supply chain locations where TCS foods are at risk for time and temperature excursions just for this reason.

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Robert Boyle created Boyle's Law, the first law to describe the inverse relationship between the pressure and volume of a gas at constant temperature.

Boyle's Law states that the pressure and volume of a gas are inversely proportional at a constant temperature. This means that as the volume of a gas increases, the pressure decreases and vice versa. Boyle's law is usually represented mathematically as PV=k, where P is the pressure of the gas, V is its volume, and k is a constant. Boyle's law was one of the first laws describing the behavior of gases and laid the foundation for the study of thermodynamics. It was a significant contribution to the field of chemistry and physics, and it is still widely used today in various applications such as in the design of gas storage tanks, scuba diving and many other fields.

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Answer:

To find out how long it took for the round to travel 2,000 m, we can use the formula:

time = distance / speed

In this case, the distance is 2,000 m and the speed is 500 m/s. So we can plug in these values:

time = 2000 m / 500 m/s

time = 4 seconds

So the round took 4 seconds to travel 2,000m.

The rate of change in concentrations of H2O2 and I3- are 2.8 x 10^-3M/s when the concentration of I− drops from 1. 000 M to 0. 871 M in 15s.

We know that the reaction rate is equal to change in concentration of reactant or product/ time taken.

The change in concentration of I− = 1.000 M - 0.871 M = 0.129M

The time taken to drop the concentration of I- (t) = 15s

Then the required reaction rate for I- = 0.129/15 = 0.0086M/s

The rate of change of concentration of H2O2 is

From the reaction: H2O2(aq)+3I−(aq)+2H+(aq)→I3−(aq)+2H2O(l)

(a) 3 moles of I⁻ are used up for every 1 mole of H2O2

Hence, the rate of change in concentration of H2O2 is:

Δ[H2O2]/Δt = 0.0086 M/sec * 1/3 = 0.00286 = 2.8 x 10^-3M/s

(b) Similarly for every 3 moles of I- 1 mole of I3- is used up. So,

The rate of change in concentration of I3- is:

Δ[I3−]/Δt = 0.0086 M/sec * 1/3 = 0.00286 = 2.8 x 10^-3M/s

Hence the rate of change in concentrations of H2O2 and I3- are same.

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36.5 g [tex]CO_2[/tex]  will be produced if 135 grams [tex]ZnO[/tex]  is completely reacted.

First, Write a Balanced Equation

[tex]C+2ZnO[/tex] → [tex]Co_2 +2Zn[/tex]

According to Avogadro's Law, "identical volumes contain equal quantities of molecules." This indicates that, in contrast to solids and liquids, gases have additive volumes. The mole-fraction-weighted average molecular weight is calculated by adding the molecular weights of each component. Of course, the mole fractions and the volume fractions are the same (E.V.E.N. principle.)

According to a scale where the atomic masses of hydrogen, carbon, nitrogen, and oxygen are 1, 12, 14, and 16, respectively, molecular weight is the total of all the atomic masses of the atoms that make up a molecule. For instance, water has a molecular weight of 18 (2 + 16), which is made up of two hydrogen atoms and one oxygen atom. likewise known as molecular mass.

We know,

MW of [tex]ZnO[/tex] = 81.41 g

MW of [tex]CO_2[/tex] = 44.01 g

So, amount of [tex]CO_2[/tex] will be produced,

[tex]\frac{135*44.01}{81.41} = 36.5 g[/tex]

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Nature of reactants, Concentration of reactants, Catalyst, Temperature, Exposure of light.

1) Reactant nature: The reaction rate is influenced by the reactants' physical characteristics, size, and chemical make-up.

2) Reactant concentration: As the reactant concentration rises, there are more collisions and more opportunities for effective collisions, which raises the rate.

3) Reaction rates may be accelerated by a positive catalyst or slowed down by a negative catalyst.

4) The pace of reaction is quadrupled or doubled when the temperature rises due to an increase in the number of effective collisions.

5) The rate of a photochemical reaction is dependent on the amount of light that is shining on the reacting mixture.

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The new temperature be when 150.0 mL of oxygen is 68.6oC collected over water at 19.0oC and 100.0kPa and dry volume becomes 100.0 mL and the pressure of the dry gas becomes 105.0kPa

Given temperature of oxygen (T1) = 19.0oC = 273 + 19 = 292K

The volume of oxygen collected (V1) = 150mL

The pressure of oxygen (P1) = 100kPa

The pressure of dry gas becomes (P2) = 105kPa

The volume of dry gas becomes (V2) = 100mL

The new temperature is = T2

From Gas Laws we know that PV = nRT such that

P1V1/T1 = P2V2/T2

Then T2 = P2V2T1/P1V1

T2 = 105 x 100 x 292 / 100 x 150 = 204.4K = 68.6oC

Such that the new temperature obtained is 68.6oC

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5.75 liters of 3% hydrogen peroxide solution are included by the company in the container.

A measurement used to determine a number's value out of 100 is the percentage.

Due to that,

Hydrogen peroxide solutions in various containers have concentrations of 35% and 3%.

Since the corporation wants an 8-liter container with a 12% hydrogen peroxide concentration.

Use the allegation and combination properties,

35 3 12

9 : 23

Total quantity equals 23x + 9x = 32x.

Since the business requests 8 liters,

Consequently, 32x = 8 x = 1/4.

The concentration of 3% hydrogen peroxide will be equal to = 23x = 23/4 = 5.75.

5.75 liters of 3% hydrogen peroxide solution are needed.

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The balloon's new volume is 24.6L. An arctic weather balloon being inflated using 24.6 litres of helium gas in a prep shed. The shed is seven degrees Celsius inside.

When the balloon is hauled outside, it is seven degrees Celsius outside. Any three-dimensional solid's volume is equal to how much room it occupies. One of these solids can be a cube, a cuboid, a cone, a cylinder, or a sphere. Chemical compounds are composed of a large number of comparable molecules (or molecular entities), which are composed of atoms from various elements bonded together by chemical bonds. Because of this, a molecule composed of atoms from a single element is not a compound.

v1/t1 = v2/t2

24.6/7 = v2/7

v2 = 24.6L

v1 = v2

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The flask will have the greatest number of collisions per second with the walls of the container is Flask A: CO at 760 torr and 0 °C.

The Collision of the molecules with the wall of the container will be  depend on the pressure. Therefore, the flask with the highest pressure have the greatest no of the collisions. As flask A has the highest pressure of 760 torr, Therefore, the flask A has the greatest number of the collusions per second with the walls of the container.

Thus the flask A with CO gas will have the greatest number of collisions per second with the walls of the container.

This question is incomplete, the complete question is :

Consider three identical flasks filled with different gases.

Flask A: CO at 760 torr and 0 °C

Flask B: N₂ at 250 torr and 0 °C

Flask C: H₂ at 100 torr and 0 °C

which flask will have the greatest number of collisions per second with the walls of the container?

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Structural diversity of carbon-based molecules is determined by following properties:1.  ability of those bonds to rotate freely,2. ability of carbon atom to form four covalent bonds,3. orientation of those bonds in the form of  tetrahedron.

Covalent bond is defined as a type of bond which is formed by the mutual sharing of electrons to form electron pairs between the two atoms.These electron pairs are called as bonding pairs or shared pair of electrons.

Due to the sharing of valence electrons , the atoms are able to achieve a stable electronic configuration . Covalent bonding involves many types of interactions like σ bonding,π bonding ,metal-to-metal bonding ,etc.

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Chaulmoogra oil is insoluble in water, which can cause it to form painful bubbles on the skin when injected.

Chaulmoogra oil is an essential oil that has been used historically as a treatment for skin conditions such as leprosy. However, because the oil is not soluble in water, it can be difficult to administer. When it is injected, the oil droplets can form bubbles in the water-based tissue of the skin, causing pain and further damage to already fragile skin.

Additionally, because the oil droplets do not readily mix with the surrounding tissue, they can remain in pockets, leading to irritation and inflammation. This is why chaulmoogra oil is not widely used as a treatment today and have been replaced with other forms of treatment.

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The moles of vanillin are required to produce one mole of iodovanillin is one mole of vanillin.

According to the question the reaction is expressed as :

C₈H₈O₃   +  NaI  +  NaOCl   ---->  C₈H₇IO₃

The vanillin react with sodium iodide and the sodium hypochlorite froms the idovanillin.

The number of moles can be calculated by the formula given below :

The number of moles = mass / molar mass

It is clear from the above balanced equation that :

1 mole of the vanillin required to produce ethe 1 mole of the idovanillin

Thus, the number of moles of the vanillin is one mole to produce the 1 mole of the idovanillin.

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The amount of heat absorbed to raise the temperature of 24.0 grams of aluminum from 300K to 350K is 1080J.

The amount of heat absorbed or released by a substance can be calculated as follows:

Q = mc∆T

Where;

According to this question, a solid aluminum has a specific heat capacity of 0.90J/g K. The amount of heat absorbed or released by the substance is calculated as follows:

Q = 24.0 × 0.90 × {350 - 300}

Q = 24.0 × 0.90 × 50

Q = 1,080 Joules

Therefore, 1080J is the amount of heat absorbed by the aluminium sample.

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The student is correct because organisms are more likely to be preserved in sedimentary rock than in igneous rock.

Sedimentary rocks are formed by the accumulation or deposition of mineral or organic particles at the Earth's surface, followed by cementation. Sedimentation refers to the processes that cause these particles to settle in place. Sedimentary rocks form from previously existing rocks or fragments of once-living organisms. They form as a result of deposits accumulating on the Earth's surface. Layering or bedding in sedimentary rocks is common. Sedimentary rocks are formed by sediment accumulation. Sedimentary rocks are classified into three types. Clastic sedimentary rocks form as a result of mechanical weathering debris accumulation and lithification. Breccia, conglomerate, sandstone, siltstone, and shale are some examples.

Here,

Because organisms are more likely to be preserved in sedimentary rock than in igneous rock, the student is correct.

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In order to build the 5 models of sodium bicarbonate, NaHCO₃, the student requires;

A scientific model is a depiction of a set of concepts, events, or processes that is physical, mathematical, conceptual, or both.

The students need to build five models to represent the molecular structure of sodium bicarbonate, NaHCO₃.

The model is to be built from the following:

Red jelly beans represent sodium atoms

(Na) White jelly beans represent hydrogen atoms

(H) Black jelly beans represent carbon atoms

(C) Blue jelly beans represent oxygen atoms (O)

A molecule of NaHCO₃ contains 1 atom of Na, 1 atom of H, 1 atom of C, and 3 atoms of O.

Therefore, 5 models of NaHCO₃ will require 5 atoms of Na, 5 atoms of H, 5 atoms of C, and 15 atoms of O.

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The moisture content is determined as follows, (weight of the container with wet soil minus weight of the container with dry soil) divided by (weight of the container with dry soil minus weight of the container), then multiplied by 100 to express as a percentage.

The complete question is,

How is water absorption calculated?

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