Which model(s) represents a pure substance?​

Answer:

199

Explanation:

Au has atomic number of 79

so mass number = 79 + 120 = 199

H2O(s) floats on H2O(l) when both are at 0°c because ice is lighter than water which causes water to displace ice.

The density of a substance is calculated by the ratio of the mass of the substance to the volume of the substance.

Ice structure is cage like with more intermolecular spacing and Hydrogen bonds are stable. Water structure is linear and Hydrogen bonds form and reform. It causes more volume for same mass in ice and less volume for same mass in water.

At 0°C the density of ice is less than density of water. At 0°C, density of water is 1.0 gm/cm³ and density of ice is 0.931 gm/cm³, so water causes ice to displace resulting in ice floating over the water.

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Water's physical characteristics include its liquid state at ambient temperature and density of 1.0 g/cm3. Water has the ability to divide into hydrogen and oxygen and react with some metals, among other chemical features.

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Personal protective equipments to be worn while handling corrosive liquids are safety goggles, hand gloves  and closed toed shoes.

Personal protective equipment is a protective clothing which is worn to protect the wearer's body  from hazard or injury.The hazards which can be addressed  by the use of personal protective equipment are physical,chemical and bio hazards.

It imposes a barrier between the user and the working environment.The main purpose of personal protective equipment is to reduce exposure of employees to the hazards.

It has a limitation that it does not eliminate the hazard and may lead to harm to the employee if the equipment is damaged.

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The new chemical formula is [tex] Fe(OH)_{3}[/tex] or ferric hydroxide.

Ion [tex] {Fe}^{3 + } [/tex] will react with NaOH while [tex] {Ni}^{2 + } [/tex] will not. The chemical reaction is as follows -

Chemical reaction stating reaction between [tex] {Fe}^{3 + } [/tex] and NaOH.

[tex] {Fe}^{3 + } [/tex] + NaOH → [tex] Fe(OH)_{3}[/tex] + Na

In the reaction, [tex] {Fe}^{3 + } [/tex] represents ferric ions, NaOH is the chemical formula of sodium hydroxide, [tex] Fe(OH)_{3}[/tex] is the chemical formula of ferric hydroxide and Na represents sodium. The ferric hydroxide precipitates as reddish brown. It does not dissolve in excess is sodium hydroxide.

Chemical reaction stating reaction between [tex] {Ni}^{2 + } [/tex] and NaOH

Nickel does not react with sodium hydroxide due to its basic nature. The reason can be owed to electron donating characteristic of both the metal and base.

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The covalent phosphodiester bonds of DNA are hydrolyzed by restriction enzymes, leaving either "sticky/cohesive" ends or "blunt" ends.

By incubating the target DNA molecule with restriction enzymes, which detect and bind certain DNA sequences and cleave at specified nucleotides either inside or outside of the recognition sequence, restriction digestion is carried out.

An isolated bacterial protein known as a restriction enzyme cleaves DNA at sequence-specific locations to create DNA fragments with a known sequence at either end. Restrictions enzymes are crucial for numerous laboratory processes, including recombinant DNA technology and genetic engineering.

At the particular restriction site, DNA bonds between the 3′ OH of one nucleotide and the 5′ phosphate of the following one are cleaved by restriction enzymes.

In order to prevent the plasmid vector from ligating with itself and to verify that the inserted gene is oriented correctly, two separate restriction enzyme sites might be used.

A) #1 5′ - CGTGATCTCGATTCGCTAGTAACGTT - 3′

         3′ - GCACTAGAGCTAAGCGATCATTGCAA - 5′

    #2 5′ - TCATGAATTCCTGGAATCAGCAAATGCA - 3′

         3′ - AGTACTTAAGGACCTTAGTCGTTTACGT - 5′

B) Recognition sites:

#1 5′ - GAATTC - 3′

    3′ - CTTAAG - 5′

#2 5′ - GAATTC - 3′

    3′ - CTTAAG - 5′

C) Cleavage sites:

#1 5′ - G    AATTC - 3′

    3′ - CTTAA    G - 5′

#2 5′ - G    AATTC - 3′

    3′ - CTTAA    G - 5′

The correct and complete question is in the image.

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When calcium reacts with chlorine, each calcium atom loses 2 electrons, and each chlorine atom gains 2 electrons. There must be one 1 calcium atom for every 2 chlorine atoms in the reaction.

When atoms react, they either lose or gain electron. Atoms do this in order to attain the stable noble gas configuration. Metals are more likely to lose electrons, and non-metals are more likely to gain electrons. Calcium has an atomic number of 20, and its electronic configuration is:

[Ca] = 1s²2s²2p⁶3s²3p⁶4s²

The easiest way for calcium to obtain a stable noble gas configuration is to lose 2 of its electrons, so that it has 18 electrons left. When this happens, calcium becomes a positively charged cation:

Ca ⇒ Ca²⁺ + 2e⁻

Chlorine has 17 electrons with the electronic configuration:

[Cl] = 1s²2s²2p⁶3s²3p⁵

This shows that chlorine only needs one electron to have the stable noble gas configuration. When this happens, chlorine becomes a negatively charged anion:

Cl + 1e⁻ ⇒ Cl⁻

Thus, for calcium to completely react with chlorine, there must be two atoms of chlorine for each carbon atom. This is because calcium loses two electrons, and each chlorine atom only accepts one. Hence:

   Ca²⁺ + 2CL⁻ ⇒ CaCl₂

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The energy of the photon to will be calculated by using E=hv.

Photons are fundamental subatomic particles that carry electromagnetic force — or, to put it another way, they are light particles. The energy of a photon is calculated by determining the wavelength of the photon. To do this, we need to know the frequency of the light and its speed in a vacuum.

A hydrogen atom emits a photon with a frequency of about 6.6x1014 Hz and a speed in a vacuum of 3.0x108 m/s.

The value for E = hν is:

E = hν

= Planck's Constant × Frequency × Wavelength

= hc/(2π×frequency × wavelength)

The unit of energy is given by Joules(J).

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The atomic theory developed along the experiments of the  Cathode Ray Tube, Gold Foil and Atomic Emission Spectra.

The term atomic theory has to do with the arrangement of the particles that compose the atom. Let us look at the development of the atomic theory chronologically.

Cathode Ray Tube - In the cathode ray tube, J.J Thompson was able to pass  an electric discharge through the tube and a color was observed that corresponds to the gas in the tube.

Gold foil experiment - Here, thin gold foils were bombarded with alpha particles and the movement of the alpha particles were tracked.

Atomic emission spectra - Here, electrons were excited to different wavelengths and the corresponding spectra was observed.

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1) C3H6O because there are 6 hydrogen in formula and one oxygen. 2) H2So4 sulphric acid.  

Chemical formulas can be divided into three categories: empirical, molecular, and structural. Molecular formulas display the quantity of each type of atom in a molecule, while structural formulas display the simplest whole-number relationship between the atoms in a compound. Empirical formulas display the simplest whole-number relationship between the atoms in a compound.

3) C2H2 ethyne where carbons have triple bond.

4) CO carbon monoxide where C and O have triple bond between them  .

5) HNO3 is nitric acid .

6) CH2F2

7) Ch2O

8) C2H4 is ethene in which carbon carbon have double bonds.

9) SO3 sulphur trioxide.

10) CH3F

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The noble gases are known to be nonreactive because they have an already filled outer electron shell.

The noble gases is defined as those elements that are located at the group 8 of the periodic table which are also called inert gases.

Examples of six noble gases include the following:

The features of noble gases include the following:

The noble gases are non reactive because the outer atomic shells of these gases are filled up that is to say that they have a full Valence electron shell.

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Homogeneous are hard to seperate but heterogeneous are easy to seperate.

Every day, humans employ heterogeneous mixes that can be found all around them. Particles in heterogeneous mixtures can be recognized after mixing and still maintain their chemical characteristics. Filtration and chemical processes can be used to separate the components of heterogeneous mixes.

All substances exist in one state of matter, which is a homogenous mixture. Solids can combine uniformly with other solids, liquids can combine with other liquids, and so on.

On the other hand, a heterogeneous mixture (derived from the Greek word "hetero" for dissimilar) has a non-uniform composition, which means that different parts may contain more or less of a given component. A heterogeneous mixture allows for the simultaneous existence of solid, liquid, and gas phases as well as other states of matter.

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Answer:

do that in calc

Explanation:

mass of cu = 63.55 ÷ 79.55 × 15.9

Simply subtract the differences in the first derivative values from the differences in the midpoint volumes to obtain the second derivative, and then plot this value at the intersection of the two midpoint volumes.

Potentiometric titration is a laboratory method to determine the concentration of a given analyte.

Na2CO3 and NaHCO3 concentration in a mixture can be determined by accurately weighing 2.0 g of the mixture and making a distilled water solution in a 250 ml standard flask. Use phenolphthalein as an indicator while you gradually titrate 25 ml of this solution against regular hydrochloric acid. To concord, repeat (Vp ml).

In order to locate the equivalency more precisely, a second derivative plot is also generated. point—where the extrapolated line intersects the x-axis (graph 4). A highly precise value for the volume of titrant can be acquired because the x-axis indicates the volume of titrant utilized.

Potentiometric titration is one of the chemical methods of analysis, and it involves adding a titrant with a known concentration and measuring the endpoint of the titration with an indicator electrode that records the change in potential as a function of the amount (often the volume) added.

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The answer is

153.7kJ.

The total energy needed for the water molecules to transition from ice to water and subsequently from water to vapor is what you are asked to calculate.

In order to do this, you'll need to know:

Heat of fusion of water:  ΔHf = 334J/g;

Heat of fusion vaporization of water: ΔHv = 2257J/g;

Specific heat of ice: c = 2.09J/g∘C;

Specific heat of water: c = 4.18J/g∘C;

Specific heat of steam: c = 2.09J/g∘C;

So, the following steps describe the overall process:

1. Calculate the amount of heat needed to raise the ice's temperature from − 15.0∘C to 0∘C:

q1 = m ⋅ Cice ⋅ ΔT = 50.0g ⋅ 2.09J/g⋅∘C ⋅ (0∘C−(−15∘C)) = 1567.5J

2. Calculate the amount of heat needed to convert 0∘C ice to 0∘C water:

q2 = m⋅ ΔHf = 50.0g ⋅ 334J/g = 16700J

3. Calculate how much heat is needed to evaporate water at 0∘C to water at 100∘C:

q3 = m ⋅ Cwater ⋅ ΔT = 50.0g ⋅ 4.18J/g⋅∘C ⋅ (100∘C−0∘C) = 20900J

4. Calculate the amount of heat needed to convert 100∘C water to 100∘C vapor:

q4 = m ⋅ ΔHv = 50.0g ⋅ 2257J/g = 112850J

5. Identify the heat needed to transition from 100∘C vapor to 120∘C vapor:

q5 = m ⋅ Cvapor ⋅ ΔT = 50.0g ⋅ 2.09J/g⋅∘C ⋅ (120∘C−100∘C) = 2090J

Therefore, the total heat required is

qTOTAL = q1 + q2 + q3 + q4 + q5 = 152696.5J = 153.7kJ

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The percentage of acetic acid in vinegar is 4.36%

What is acetic acid?

The scientific name for acetic acid is ethanoic acid. It is an acidic, colorless liquid organic substance having the formula CH3COOH. Vinegar has a minimum of 4% acetic acid by volume, making acetic acid the primary component of vinegar besides water and trace elements.

Given,

Volume=  30.84 ml

Moles= 0.128

mass of vinegar= 5.441g

moles NaOH = 0.03084 ml x 0.128

M=0.00395

mass acetic acid = 0.00395 mol x 60.05 g/mol=0.237 g

Percentage of acetic acid:

= 0.237 x 100/ 5.441

= 23.7/5.441 = 4.36%

Hence, The percentage of acetic acid in vinegar is 4.36%

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Based on the integrated equation used for reactant concentration calculation in a second-order reaction and the data given (initial concentration, reaction rate constant, and time elapsed), the concentration of A after 180.0 min will be 0.20 M.

The integrated equation for the reactant concentration in a second-order reaction looks like this:

1/[A] = kt + 1/[A]₀

k - reaction rate constant (0.0265 min⁻¹M⁻¹)

[A]₀ - initial concentration (3.75 M)

t - time elapsed (180.0 min)

1/[A] = 0.0265 min⁻¹M⁻¹ * 180.0 min + 1/(3.75 M) = 4.77 M⁻¹ + 0.27 M⁻¹ = 5.04 M⁻¹

[A] = 1 / (5.04 M⁻¹) = 0.20 M

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The correct answer is option  C.

The air moving over a cold current cause fog or advection fog when the air is chilled, which decreases the capacity of air to hold water vapor, and eventually, the relative humidity reaches 100% - leading to condensation and fog formation.

What is advection fog?

When warm- moist air or warm air front slides over the cold air front or cold surface, it results in the formation of advection fog.

Resultantly, the air becomes saturated and chilled at high humidity levels due to which water vapors start to condense leading to fog formation.

Moreover, the optimal condition for the formation of advection fog is cloudy windy weather having moderate to powerful winds.

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The complete question is:

Why would air move over a cold current cause fog (advection fog)?

(a)  the cold current produces the fog when kelp beds release condensation nuclei.

(b)  the cold current produces the fog by mixing with the air.

(c) the air is chilled, which decreases the capacity of air to hold water vapor, and eventually, the relative humidity reaches 100% - leading to condensation and fog formation.

A mass of 71.26g of [tex]CoSO_4.6H_2O[/tex] is required to get 42g of the anhydrous compound, i.e., [tex]CoSO_4[/tex].

A compound's molar mass indicates the mass of one mole of that substance. In other words, it informs you how many grams of a substance there are per mole. A covalent compound's formula mass is also known as its molecular mass. The mole is a useful quantity unit for representing very large quantities of atoms or molecules. A substance's molecular mass is the total of the atomic masses of all the atoms that comprise the molecule of the substance.

The term anhydrous means "without water." Anhydrous chemicals are compounds that do not contain water or do not contain water. An anhydrate is formed when water is removed from a hydrate. Suction or high-temperature heating of the chemical removes the water molecules. An anhydrous salt, for example, has had water driven out of its crystals.

Given:

Mass of [tex]CoSO_4[/tex] needed = 42g

To find:

Mass of [tex]CoSO_4.6H_2O[/tex] = ?

Formula:

Mass of [tex]CoSO_4.6H_2O[/tex] = (Mol. Wt. of [tex]CoSO_4.6H_2O[/tex] / Mol. Wt. of [tex]CoSO_4[/tex]) x Mass of [tex]CoSO_4[/tex]

Calculations:

Mol. Wt. of [tex]CoSO_4[/tex] = 155g/mol

Mol. Wt. of [tex]CoSO_4.6H_2O[/tex] = 155 + 6 x 18 = 263g/mol

Mass of [tex]CoSO_4.6H_2O[/tex] = (263 / 155) x 42

Mass of [tex]CoSO_4.6H_2O[/tex] = 71.26g

Result:

71.26g of [tex]CoSO_4.6H_2O[/tex] is required to get 42g of the anhydrous compound.

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Answer: The oxides of hard metal or the transition metals oxides like oxides of copper, zinc, iron, and chromium do not dissolve in water due to their limited basicity. Alkaline earth metal oxides also form hydroxides in water but these hydroxides themselves give slaked solutions and are not completely soluble.

Explanation: The oxides of hard metal or the transition metals oxides like oxides of copper, zinc, iron, and chromium do not dissolve in water due to their limited basicity. Alkaline earth metal oxides also form hydroxides in water but these hydroxides themselves give slaked solutions and are not completely soluble.

Option C (4.8 × 10²³ ions) is correct not option B (1.2 × 10²³ ions) as one molecule of (NH₄)₃PO₄ contains four ions, three NH₄⁺, and one PO₄⁻³.

To calculate ions, first, we have to calculate number of molecules of (NH₄)₃PO₄ in 0.20 moles.

To calculate number of molecules, the number is moles is multiplied by Avogadro number (6 × 10²³).

So, the number of molecules of (NH₄)₃PO₄ in 0.20 moles is,

Number of molecules = 0.20 × 6 ×10²³ = 1.2 × 10²³

One molecule of (NH₄)₃PO₄ contains three ions of NH₄⁺, and one ion of PO₄⁻³. So, number of ions in 0.20 moles of (NH₄)₃PO₄ are

Number of ions = 4 × 1.2 × 10²³ =4.8 × 10²³

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The rate of change of the volume is 0.144 m³/s.

The average temperature of the air is indicated via a properly exposed thermometer at some point in a given term, usually an afternoon, a month, or a yr. For climatological tables, the mean temperature is generally calculated for each month and for the 12 months. Temperature is an amount that determines the course of the float of warmth on preserving two bodies at one-of-a-kind temperatures in contact. Its SI unit is kelvin (k).

The heat of an object is the total power of all the molecular movement interior that object. Temperature is the measure of the thermal power or average warmness of the molecules in a substance. SI Unit. Joule.

rate of change of pressure = 50 kg/m²

temperature = 7.2 K/s

Using ideal gas equation PV = nRT

since nR is constant

V = T/P

  = 7.2/50

  = 0.144 m³

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The addition of water to the acid solution will change the molarity of the solution, but not the amount of base needed to reach the titration endpoint because the total amount of acid hasn't changed.

During this titration, a solution of the base will be added to a solution of the acid, and when the endpoint is reached, the indicator will change color. The titration endpoint is reached when the acid in the sample solution has been completely neutralized, and an excess base is now appearing.

The amount of base required for neutralization is determined by the amount (number of moles) of acid in the starting solution. Although the starting solution would become more dilute (lowering its molarity) upon the addition of water, the total amount of acid will not be reduced, thus requiring the same amount of base.

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that is for hydrogen, fluorine and aluminium

The speed of all electromagnetic waves is equal to the speed of light that is 3 × 10⁸ m/s.

An electromagnetic wave is a wave of certain wavelength of an electromagnetic radiation of the electromagnetic spectrum. There are different types of waves in the spectrum like IR, radio waves etc.

The speed of c of the wave is the product of its frequency and wavelength. The speed of all electromagnetic waves are equal to the speed of visible light.

Hence, the speed of both waves is 3 × 10⁸ m/s.

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Answer:

37.1g of HCl

Explanation:

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Answer:

The bromine gas particles would diffuse from a high to low concentration and so move upwards.

Explanation:

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