true or false: sn2 mechanism for nucleophilic substitution reactions involves one step and occurs with inversion of configuration.

Answer: D. negative

Explanation:

By the half-life of radioactive, the remaining mass of radioactive elements is  7.8125 x 10¯³ gram.

We need to know about the half-life of the radioactive elements to solve this problem. The radioactive element will decay over time and follow the equation

N = No(1/2)^(t/t'')

where N is the final quantity, No is the initial quantity, λ is the decaying constant, t is time and t'' is the half-life of a radioactive element.

From the question above, we know that

t'' = 14 days

No = 2 grams

t = 112 days

Calculate the remaining mass

N = No(1/2)^(t/t'')

N = 2(1/2)^(112 / 14)

N = 7.8125 x 10¯³ gram

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Answer: 15910 meters

Explanation:

1 kilometer = 1000 meters

15.91 kilometers * 1000 meters/1 kilometer =

15.91 * 1000/1=

15.91*1000=15910 meters

A molecule with a long chain of carbons bonded together and flanked by hydrogens with an acid group on one end and a methyl group on the other end is called a fatty acid.

A fatty can be saturated as well as unsaturated. Saturated fatty acids are the ones that do not have any double or triple bond in them. Unsaturated fatty acids are the ones that have double bonds or triple bond in them.

Some of the examples of fatty acids are stearic acid, palmitic acid, linoleic acid etc.

Some common examples of food products having fatty acid in them are walnuts, fish, butter, milk etc.

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Passive transport obtains energy from the gradient of the substance or molecule being transported.

Passive transport is the movement of a solute from one side of the cell membrane where there is a high electrochemical potential to the other side where there is a lower electrochemical potential.

A kind of cellular transport known as passive transport involves the movement of molecules and ions along concentration gradients. In contrast to active transport, the mechanism doesn't need metabolic energy (such as ATP) because the movement is downhill or down the concentration gradient.

A few characteristics of passive transport are as follows:

1) The molecule must be bound in order to be transported.

2) The chemical being delivered is particular to it.

3) The gradient of the material being carried produces the energy needed for passive transport.

4) A conformational shift leads to the substance's transport.

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Answer:

C

Explanation:

Cells be in osmotic equilibrium but chemical and electrical disequilibrium because water moves freely between most cells and the extracellular fluid

When the concentrations are equal on both sides of the membrane called osmotic equilibrium in cell  this results in zero osmotic pressure as there is no force needed to prevent any flow. in other words, the tonicity is the same on both sides of the membrane. by diffusion of water or solutes, osmotic balance ensures that optimal concentrations of electrolytes and non-electrolytes are maintained in cells in this method osmosis maintain equilibrium in the cell not chemical and electrical equilibrium that's why osmotic equilibrium in the cell but chemical and electrical disequilibrium in the cell.

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Answer: D

Explanation: Co 2 and H2O

Answer: Replication duh NO offensene

Explanation:

The atom that has the smallest atomic radius is Tellurium(Te).

The modern periodic table contains 118 elements which have been divided into 18 groups horizontally and 7 periods vertically, as shown in the adjoining diagram.

In the second diagram, the trends that vary across periods and groups are shown.

We can see that the atomic radius increases on going down the group in the periodic table and decreases on moving left to right.

We have to compare the radius of the following four elements:

Strontium Sr (Group 2, Period 5)

Polonium Po (Group 16, Period 6)

Tellurium Te (Group 16, Period 5)

Barium Ba (Group 2, Period 6)

Among the above elements, Tellurium has the smallest atomic radius according to the trends in the periodic table.

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The mass of air inside the balloon is an independent variable, whereas the balloon's volume is a dependent variable.

When compared to the deflated balloon, the expanded balloon has a bigger capacity.

The following are some of the variables connected to the inflated and deflated balloons:

volume of the balloon and the amount of air inside it

The amount (mass) of air inside the balloon determines the balloon's volume.

There are often two different sorts of variables in analytical health research. We anticipate that independent variables will have an impact on dependent variables. What occurs as a result of the independent variable is referred to as a dependent variable.

As a result, we can say that the balloon's volume is a dependent variable and its air mass is an independent variable.

The balloon's volume grows as the volume of air inside it does.

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The strength of a carbon-oxygen double bond exceeds that of a carbon-carbon double bond.

A double bond is a covalent link between two atoms in chemistry that involves four bonding electrons rather than the two in a single bond. In alkenes, for instance, double bonds typically form between two carbon atoms.

There is always a sigma and a pi bond present in a double bond. Carbon dioxide is a common instance of a chemical having a double bond. The structure of organic substances like ethene, commonly referred to as ethylene, methanoic acid, and acetone, includes double bonds.

Carbon-carbon double bonds are found in alkenes, which are hydrocarbons. For molecules with a single double bond, their typical formula is CnH2n ( no rings). Because ethene was originally called olefiant gas, another name for alkenes is olefins.

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The Balanced redox reaction is:

[tex]2H_2O + Zn (s) + 2OH^- \rightarrow Zn(OH)_4^2^- (aq) + H_2 (g)[/tex]

In that total redox reaction,

one half reaction of cell is [tex]Zn \rightarrow Zn^2^+ + 2e^-[/tex]

the other reaction is [tex]2OH^- + 2e^- + 2H_2O \rightarrow H_2 + 4OH^-[/tex]

Redox reactions are balanced in basic solution just as they would be in acid. You utilize [tex]OH^-[/tex] for conversion to base at the end.

The steps for balancing a redox reaction in a basic solution are as follows:

1. Split the reaction into half reactions.

2. Balance the other elements, except H and O.

3. By adding water, the O atoms are balanced.

4. By adding [tex]H^+[/tex], balance the H atoms.

5. To remove any [tex]H^+[/tex], add [tex]OH^-[/tex] ions to both sides.

6. To create [tex]H_2O[/tex], combine [tex]H^+[/tex] and [tex]OH^-[/tex].

7. Make things simpler by removing extra water.

8. Equalize the charges by including [tex]e^-[/tex]

9. Combine the half reactions, then simplify.

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In a sample of sodium bromide, NaBr contains 22.34% of sodium. If the sample was contaminated with sodium chloride, NaCl, then the mass percent of Na in the contaminated sample would be higher than the pure sample.

Mass percent can be determined by the formula:

Mass percent = (mass of substance/Total mass of the sample) × 100

The sample contains NaBr which has 22.34 g of Na in 100g of the sample.

If only NaBr was added then, the mass percent would not increase as the the amount of increase in Na is same as the increase in the amount of total sample.

But, NaCl is added as a contaminant so the increase in amount of sample is more than the increase in amount of total sample because the mass of Cl is   is less as compared to Br. so, mass percent increases on contamination of NaBr with NaCl

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The descriptive term applied to the type of diene represented by 2,4-hexadiene is conjugated diene.

Dienes are compounds which contains two double bonds. These dienes can be non conjugated or conjugated.

Conjugated diene are those compound which have two double bonds  joined by a single σ bond. Conjugated dienes can also be called 1,3-diene. To know if diene is conjugated or non conjugated, sp³ hybridization is to b checked and the number of double bonds and single sigma bond is checked.

Conjugated dienes are found in many different molecules. 2,4-hexadiene is a conjugated diene with two carbon-carbon double bonds that are separated by one sigma bond.

The stabilization of dienes by conjugation is better than the aromatic stabilization. Conjugated dienes are more stable than non conjugated or cumulative diene because it has higher electron density of molecules delocalized.

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Given:

      Mole = 1

Formula:

      Moles = Given mass / Molar mass

a) Molar mass of hydrogen = 2.016

   Mass = 1 * 2.016

  Mass = 2.02g

b)Molar mass of Helium = 4

  Mass = 1 * 4

  Mass = 4g

c)Molar mass of carbon monooxide = 28

  Mass = 1 * 28

  Mass = 28g

d)Molar mass of water = 18

  Mass = 1 * 18

  Mass = 18g

The substance's intense property, the molar mass, is independent of the sample's size. The coherent unit of molar mass in the SI is kilograms per mole (kg/mol). Molar masses are, however, virtually generally given in g/mol due to historical considerations.

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The mass of CO2 gas is 19.725 grams when a 25.00 ml sample of ethanol with a density of 0.789 g/ml combusts.

Density may be defined as a type of physical property that significantly deals with the description of how much space an object or substance takes up with respect to the amount of matter in that object or substance.

In a more simple sense, it is characterized as the measurement of quantity or mass per unit of volume in a particular substance.

According to the question,

The mass of the CO2 = ?

The density of the CO2 gas = 0.789 g/ml.

The volume of CO2 gas = 25.00 ml.

The formula for calculating the density is as follows:

                  = 0.789 g/ml × 25.00 ml. = 19.725 grams.

Therefore, the mass of CO2 gas is 19.725 grams when a 25.00 ml sample of ethanol with a density of 0.789 g/ml combusts.

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The molecular formula for both the cis-2-butene and trans-2-butene is c4h8. The compounds which have the same molecular formula but have different structures are called isomers.

Isomerism, the existence of molecules that have same numbers of the same kinds of atoms (and hence the same formula) but differ in chemical and physical properties.

Stated colloquially, isomers are chemical compounds that have same parts but are nonetheless not the same. To make crude analogy, two bracelets, each consisting of five red and five green beads, could be arranged in many different isomeric forms, depending on the order of the colors.

Each bracelet would have the same parts—that is, five red and five green beads—but each variation would be different. One could also imagine combinations of those same beads in which the pendant chains were attached to a bracelet in a variety of ways. One might imagine two bracelets of the same red-green order but with the identical chains attached in different orientations. Such structures also would be analogous to the isomers. In a more subtle analogy, one’s hands can be seen as an isomeric. Each hand possesses same kinds of fingers, but a right hand can never be superimposed perfectly on a left hand; they are different.

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The most abundant tripeptide species at neutral ph (ph 7.0) the overall charge 0

A peptide consisting of three amino acids. a tripeptide is a peptide derived from three amino acids joined by two or sometimes three peptide bonds function of peptides is determined by the constituent amino acids and their sequence Glutathione (γ-glutamyl-cysteinyl-glycine)  is the example of tripeptide called tripeptide. here at 7 ph the overall charge of the most abundant tripeptide species is 0 because at 7 ph means it is in neutral condition so net charge is 0

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Some examined meteorites contain would be lipids, nucleotides, amino acids, and monosaccharides.

Meteorites are considered to be the pieces of rocks or metals that fall into the earth from outer space. These rocks/metals have been extensively studied/analyzed by some researchers, especially those seeking to prove/disprove Panspermia theory that life originates from other planets.

Several studies conducted found the compounds such as lipids, DNA, RNA, and amino acids.

There has been no evidence for the monosaccharides for a long time until 2019 when an international team discovered sugars such as xylose and arabinose in certain meteorites.

No polypeptide has been discovered in the meteorites, but its precursor, amino acids, have been discovered.

Therefore, the correct answer to the molecules that have been found in the some meteorites would be lipids, nucleotides, amino acids, and monosaccharides.

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Oxygen is a good oxidant because it has the highest electronegativity, which is 3.44.

A reactant that oxidizes or eliminates electrons from other reactants in a redox reaction is referred to as an oxidant. An oxidizer, oxidizing agent, or oxidant are several terms for the same thing. An oxygenation reagent or oxygen-atom transfer (OT) agent is a term that may be used to describe an oxidant that contains oxygen.

The loss of electrons in oxidation (OIL RIG). A material that oxidizes therefore steals electrons from the other substance. As a result, an oxidizing agent needs to pick up electrons.

Flourine is the most effective oxidizer. The highest positive electrode potential value is present in it. Halogens function as a potent oxidizing agent because of their high electronegativity and electron affinity.

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Colligative properties are properties of a solution that depend only on the number of solute particles in a given volume of solution, not on their type.

What are Colligative properties?

Colligative properties of solutions are characteristics that depend on the quantity of molecules or ions in the solute, but not on the kind of solute. Osmotic pressure, boiling point elevation, freezing point depression, and vapor pressure reduction are examples of Colligative properties.

A property of a solution is said to be collative if it depends simply on the proportion of solute to solvent particles in the solution and not on the nature of the solute.

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When titrating a weak acid with a strong base The equivalence point for a weak acid-strong base titration has a pH > 7.00.

If the concentration of weak acid is adequate to the concentration of the conjugate base, then the ratio of their concentrations is adequate to one. and therefore the log of one is equal to zero. Therefore, the pH is adequate to the pKa value of the weak acid at the half equivalence point

Why is pH at half titration adequate to pKa?

Because of the incomplete dissociation of the acid, the reaction is in equilibrium, with an acid equilibrium constant , Ka, which is restricted to that acid. point are the identical . Therefore, at the half-equivalence point, the pH is adequate to the pKa.

What does one mean by titration?

titration, process of qualitative analysis in which the quantity of some constituent of a sample is determined by adding to the measured sample an exactly known quantity of another substance with which the desired constituent reacts in a definite, known proportion

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The reaction is double displacement reaction of potassium phosphate and magnesium sulfate between balanced equation for the precipitation reaction is

2 K3PO4 + 3 MgSO4 → Mg3(PO4)2 + 3 K2SO4

Here reaction is  between potassium phosphate and magnesium sulfate we have to understand the balance chemical equation. precipitation reactions are double displacement reactions in which the conversion of a solution into solid by converting the substance into insoluble form or by making the solution a super saturated one. here the reaction is two mole of  aqueous tribasic potassium phosphate react with three mole of aqua magnesium sulphate to form one mole of solid farringtonite and three mole of aqueous potassium sulphate this is balanced chemical reaction of potassium phosphate and magnesium sulfate.

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Answer:

Acrylonitrile and ethyl acetate will be collect together since they both have the same boiling point. The method of distillation between the boiling points of the acrylonitrile and ethyl acetate. Since they have the same boiling point the two substances turn into vapor at the same temperature and are collected simultaneously. Hence separation is not achieved by distillation

Explanation:

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Chernobyl expelled lots of cs-137 radioisotopes in the environment in 1986. the half-life of cs-137 is 30 years. in 2046, 60 years later, the radioactivity will be zero times the original activity in 1986.

What is half life of a substance?

A drug's half-life is an estimation of how long it will take for its concentration or amount in the body to exactly halve (or 50%) in size. T12 represents half-life.

This well-known phrase was first used in 1907 by renowned physicist Ernest Rutherford, who used the half-life formula to estimate the age of rocks by observing how long radium took to decay into lead.

Here, its said that the half life of Cs-137 is 30 years, that is after 30 years, half of the Cs-137 would have disintegrated, and after 60 years the entire molecule would have disintegrated, hence, after 60 years that is in 2046 the radioactivity would be zero.

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Direct nucleophilic substitution between NH₃ and alkyl halide be made more practical than reacting NH₃ and the alkyl halide in a 1:1 ratio By Using a large excess of NH₃.

Why is direct nucleophilic substitution of an haloalkane with NH₃ not a very useful method for preparing primary amines?

Polyalkylation of the amine will end in multiple products

Ch₂₂: RX + NH₃. Ammonia reacts as a nucleophile with alkyl halides to offer primary amines in a nucleophilic substitution reaction. Yields are often poor because the product, a primary amine, RNH₂, is itself a nucleophile and may react with more alkyl halide.

Is NH₃ a robust nucleophile?

NH₃(Ammonia) has the stronger nucleophilic character than water molecule. Because the Oxygen within the water molecule doesn't likely to bond with any carbon atom compared to Nitrogen atom. Since Oxygen has more electronegativity than Nitrogen. Hence it holds onto its lone pair tightly than Nitrogen.

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Formation of hydrogen bonds require hydrogen atoms and Oxygen atoms, fluorine atoms, or nitrogen atoms.

Hydrogen bond is a special case of dipole-dipole force of attractions. Here there are two polar molecules in which one of them has hydrogen atom with partial positive charge on it and the other molecule can be O, F or N with partial negative charge. Since, these dipole-dipole force of attractions are stronger than other dipole-dipole force of attractions we name it as Hydrogen bonds.

Some of the examples where hydrogen bonding is present are- H₂O, HF, NH₃ etc

Since, Hydrogen bonds are a type of dipole-dipole forces of attraction, they are present in polar covalent molecules.

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Answer: p = 4.0E-7 g/cm^3

[tex]Moles \: of \: H _2SO_{4} \: is \: is \: 2.9 \: moles.[/tex]

[tex]Moles \: of \: C _2H _4O _2 \: is \: 1.4 \: moles. [/tex]

[tex]Moles \: of \: NaOH\: is \: 5.8 \: moles.[/tex]

The total number of moles of hydrogen in all the compounds = 5.8 mol.

The number of hydrogen present in sulphuric acid = 2.

Let the number of moles of the sulphuric acid present

be X. [tex]Number \:of \: mol \: of H_2SO _4 \:present [/tex]

is,

[tex]1 \: mole \: of \:H _2SO_{4} \: has \: 2 \: moles \: of \: H.[/tex]

[tex]X = 5.8 \times \frac{1}{2} [/tex]

[tex]X = 2.9 \: moles[/tex]

Thus, the number of moles of sulphuric acid present is 2.9 moles.

Number of hydrogen present in acetic acid = 4

Let the number of moles of acetic acid be Y.

[tex]Number \:of \: mol \: of C _2H _4O _2 \:present [/tex]

is,

[tex]Y = 5.8 \times \frac{1}{4} [/tex]

[tex]Y = 1.4 \: moles[/tex]

Thus, the number of moles of acetic acid is 1.4 moles.

The number of hydrogen present in sodium hydroxide = 1.

Let the number of moles of sodium hydroxide be Z.

[tex]Number \:of \: mol \: of \: NaOH\:present [/tex]

is,

[tex]Z = 5.8 \times \frac{1}{1} [/tex]

[tex]Z = 5.8 \: moles[/tex]

Thus, the number of moles of sodium hydroxide is 5.8 moles.

5.8 moles. [tex]Therefore, \: moles \: of \: H _2SO_{4} \: is \: [/tex]

[tex]is \: 2.9 \: moles. \: \:Moles \: of \: C _2H _4O _2 \: is[/tex]

[tex]is \: 1.4 \: moles. \: Moles \: of \: NaOH\: is[/tex]

5.8 moles.

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