1. What is the charge of an atom with 20 protons and 18 electrons

Answer:

linear particle accelerator

A type of microscope known as an electron microscope uses an accelerated electron beam as its illuminating source.

The electron microscope offers benefits and drawbacks. One of the biggest drawbacks of the electron microscope, though, is that it cannot examine live samples. As a result of utilizing this microscope to view microorganisms, the following drawbacks are listed:

*Samples must be exposed to analysis in a vacuum state since other molecules in the air easily scatter electrons. This states that using this microscope to study live specimens is not possible.

*Additionally, the requirement that the sample be evaluated in a vacuum state makes it impossible to comprehend biological interactions in various bacteria.

*When investigating microorganisms, an electron microscope can only provide black-and-white images, which is not ideal.

* Equipment as expensive and specialised as electron microscopes. The employment of an electron microscope in the research could be counterproductive because most studies have little funding.

* For proper use of this technology, specialized operators, who may need years of training, are needed to operate electron microscopes.

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Hybridization is Sp2 if the bond angle between two adjacent hybrid orbitals is 180 degrees.

What exactly is an orbital?

How do orbitals get started?

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The major product of the reaction is (2S,3R)-3-methoxy - 3-methylpentan-2-ol

Epoxide reacts with methanol in the presence of sulfuric acid.

In this chemical reaction, methanol act as nucleophile and sulfuric acid act as catalyst.

What are Epoxides?

Epoxides are a type of cyclic ether in which a three-membered ring is formed by a oxygen atom bonded to two adjacent carbon atoms. They are also known as oxiranes. Epoxides are used in a variety of applications, including as chemical intermediates, catalysts, and as raw materials for a range of products.

What is sulfuric acid?

Sulfuric acid is a strong, corrosive acid that is used in a variety of industrial applications. It is also known as battery acid, as it is used in car batteries to facilitate a chemical reaction. Sulfuric acid is colorless and odorless, and is composed of two hydrogen atoms, one sulfur atom, and four oxygen atoms.

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Answer:

According to the graph, during year 14, revenue from online ads is approximately $4.2 million, while revenue from online ads has more than doubled revenue from printed ads (at least by year 14)

Both curves intersect between the seventh and eighth year, I would say around the middle of year 7, and both online ads and printed ads generated an approximate revenue of $2.2 million each

Explanation:

This indicates that the neuron's inside potential is 70 mV lower than its outside. At rest, the potassium ions inside the cell outnumber the sodium ions by a somewhat large margin.

Potassium ions are kept at high concentrations inside neurons whereas sodium ions are kept at high quantities outside the cell.

The potassium and sodium cations can diffuse down their concentration gradients because the cell has leaky channels that allow them to do so.

For cells to operate normally, these variations are essential. Outside of the cell, sodium ions are far more common than within.

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The product of the combustion reaction of lithium is = Lithium Oxide

Lithium-like elements such as sodium and potassium are always stored in air-tight storage to avoid exposure to the air because they start a reaction with the gases present in the atmosphere to avoid this these elements are stored in oil (Lithium in fact float on the oil but the reaction is prevented).

When the process of combustion of lithium starts, a strong red-tinted flame is observed because of its burning.

The following equation shows what happens during the combustion of Lithium in the presence of Oxygen-

              4Li + [tex]O_{2}[/tex]  →  2[tex]Li_{2}[/tex]O

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E=2.1781018J is the ratio for an atom energy (n2Z2). wavelength of light required to shift an electron in a hydrogen atom between level n=1 to n=2.

The wavelength, which will also apply to troughs, is the separation between two wave crests. The frequency is measured in frames a second (Hz), which is the quantity of vibrations that cross a specific area in a second (Hertz).

When wavelength is expressed in metres, 1/ represents the amount of waves in a wave train that can be discovered in a duration of one metre, or for the number in a height of one centimeter if wavelength is expressed in centimeters. Its amplitude of the wave of the spectra line is the name given to this figure.

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The total number of molecules that are present in 4.6×[tex]10^{3}[/tex] mg of NaCl is 0.47×[tex]10^{23}[/tex]

Atomic masses:

Na=23  , Cl=35.5

The molar mass of NaCl=58.5

1gm of NaCl contains=1/58.5 moles of NaCl

And,

      1gm of NaCl contains=1/58.5×6.022×[tex]10^{23}[/tex] molecules of NaCl

4.6x[tex]10^{3}[/tex] mg =(4.6x[tex]10^{3}[/tex]x[tex]10^{-3}[/tex] gm) of NaCl contains= [tex]\frac{1}{58.5}[/tex] ×6.022×[tex]10^{23}[/tex]×4.6

                                                                              =0.017×27.70×[tex]10^{23}[/tex]

                                                                              =0.47×[tex]10^{23}[/tex]

Therefore the total number of molecules present in 4.6×[tex]10^{3}[/tex] mg NaCl is 0.47×[tex]10^{23}[/tex]

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Isotopes are any of two or more forms of an element where the atoms have the same number of protons, but a different number of neutrons within their nuclei. Thus, isotopes have the same atomic number but a different mass number.

In an atom, there are three components called subatomic particles as follows:

In a neutral atom, the number of protons, which is the atomic number, equate the number of electrons.

According to this question, the transparent subatomic particle inside the atom's nucleus is proton while the blue colored particle is the neutron.

In atom A, there are 3 protons, hence the atomic number of atom A is 3. However, in atom B, the number of protons and neutrons are 4 and 3 respectively, hence, the mass number i.e. protons + neutrons is 7.

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The response dates back 141 years. The formula (1/2)n = x can be used to compute it. x is the remaining fraction, There are n half-lives in total.

The amount of time needed for the reactant concentration to drop to half its initial value is known as the half-life of a reaction. A first-order reaction's half-life is a constant that is correlated with its rate constant radioactive atoms: t1/2 = 0.693/k.

The period of time it takes for half of the atoms in a given sample to experience radioactive, or nuclear, decay, is known as the half-life of a radioisotope.

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Answer:

c. decomposition

Explanation:

it formula is splitting between O2 and 2H2O

If the solution absorbs large amount of light, then it will transmit very less amount of light. Therefore, A high absorbance corresponds to a Low transmittance.

What is spectrophotometer?

A spectrophotometer is a device that accurately measures electromagnetic energy at specific wavelengths of light. It uses properties of light and energy to identify colors and determine the amount of each color in a ray. The two main components of a spectrophotometer are the spectrometer and the photometer.

Spectrometer: A spectrometer sends a straight beam of light through a lens to a prism, which splits it into individual wavelengths. A wavelength selector then filters only the specified wavelengths and sends them to the photometer.

Photometer: A photometer is a piece of device that detects the number of photons absorbed and transmits that measurement to a digital readout.

Therefore, A high absorbance corresponds to a Low transmittance.

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According to the given statement The amount of heat that water absorbs is 878.64 J.

Equation q = -CT, where C seems to be the calorimeter's heat capacity and T is the temp change, can be used to determine how much heat is released during the reaction. Since the combustion takes place at a fixed volume, the reaction's q is equal to E.

Amount of water = m = 75.0 g

Specific heat capacity of water = c = 4.184 J /g⁰C

Initial temperature of water = T = 23.0⁰C

Final temperature of water = T' = 20.2⁰C

The phrase for how much heat water absorbs is presented below.

q = mcΔT

q = 75.0 g * 4.184 J /g⁰C * (23.0 - 20.2)⁰ C

q = 878.64

The amount of heat that water absorbs is 878.64 J

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The balanced chemical equation for the reaction is as follows:

6 Li[s] + [tex]N_{2}[/tex][g] = 2[tex]Li_{3}[/tex]N[s]

Meaning of the reaction is that 6 moles of lithium reacts with nitrogen to form two moles of lithium nitride.

The product formed is:

Highly flammable and reactive chemical and a Dangerous fire and explosion hazard.

Lithium Nitride can affect you when breathed in and may be absorbed through the skin.

Contact can severely irritate and burn the skin and eyes. Breathing Lithium Nitride can irritate the nose and throat.

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Therefore, 0.25 moles of unit cells will be present in 58.5 g.

Therefore, 6.0231023 6.023 10 23 molecules make up 1 mole of NaCl. The total number of atoms in 1 mole of NaCl N a C l is twice Avogadro's number, or 6.0231023 6.023 10 23 because each molecule of the salt has two atoms (Na and Cl).

Similar to covalent compounds, the formula mass of an ionic compound is determined by adding the average atomic masses of all the atoms in the compound's formula.

1 mole of NaCl

Avogadro's number, or 6.0231023

0.25 moles of unit cells will be present in 58.5 g.

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The pressure of this sample at 27° c and at the same volume is  calculated to be 0.6 atm.

Law of Gay-Lussac states that pressure of a given mass of gas varies directly with Kelvin temperature when the volume is constant.

Given that the volumes of the two states are equal. At constant volume, we use the Gay-Lussac equation:

As, P₁/T₁ = P₂/T₂

Given P1= 0.8 , T1= 127°

and T2= 27°

Now, (0.8)/(127+273) = (P₂)/(27+273)

We get, P₂ = 0.6 atm

The pressure of this sample at 27° c and  at same volume is 0.6 atm.

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Hello,

I hope you and your family are doing well!

To calculate the ∆H for the solution process of NaOH, you can use the equation:

∆H = q/n

where q is the heat absorbed or released during the process, and n is the number of moles of solute that are dissolved.

To find the heat absorbed or released during the process, you can use the equation:

q = m * C * ∆T

where m is the mass of the solvent (water), C is the specific heat of the solvent, and ∆T is the change in temperature of the solvent.

Substituting the given values into this equation gives us:

q = 100.0 g * 4.18 J/g-K * (37.8°C - 21.6°C) = 10,019 J

To find the number of moles of NaOH dissolved, you can use the molar mass of NaOH:

n = 6.50 g / 39.9968 g/mol = 0.1625 mol

Substituting these values into the equation ∆H = q/n gives us:

∆H = 10,019 J / 0.1625 mol = 61,726 J/mol

Converting this to kJ/mol gives us:

∆H = 61,726 J/mol / 1000 J/kJ = 61.726 kJ/mol

Therefore, the ∆H for the solution process of NaOH is approximately 61.726 kJ/mol.

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The reason that methyl salicylate be much more volatile than salicylic acid is because:

Salicylic acid's COOH group is esterified with methanol in methyl salicylate (oil of wintergreen), whereas acetylsalicylic acid (aspirin) has acetic acid as the acid component of the ester and salicylic acid provides the phenolic OH group.

Note that Methyl salicylate, a volatile methyl ester of salicylic acid, can also diffuse into the atmosphere and aid in plant-plant communication.

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the pH at the equivalence point in the titration of 25.6 ml is.

=12×14+12×3.74+12log 0.1=8.37.

The weak acid salt hydrolysis determines the pH at the equivalence point in the titration of weak acid with strong base.As a result, we must determine the pKb of the conjugated base, compute the concentration of OH- beginning from there, and then utilize the pH=14-pOH formula.

The pH at the equivalence point is more than 7 in a weak acid/strong base titration.This is because the mixture contains water, the neutral cation of a strong base, and the anion of a weak acid (a base).

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Half life Of Radioactive Element is 18 days

Percentage of original sample remained after 108 days is 1.5625%

The amount of time needed for a reactant to achieve half of its starting concentration or pressure is known as the half-life of a reaction. The half-life for a first-order reaction is concentration-independent and stable over time.

It is denoted by the symbol ‘t1/2’ and is usually expressed in seconds.

Given;

t 1/2 = 18 days;

t = 108 days;

Amount of remaining radioactive element

R = [tex]\frac{Ro}{2^n}[/tex], where n = [tex]\frac{t}{t1/2}[/tex]

⇒n= 108/18

n= 6;

so,

[tex]\frac{R}{Ro}[/tex] = [tex]\frac{1}{2^6}[/tex]

= 0.015625

⇒ Percentage of original sample remained , [tex]\frac{R}{Ro}[/tex] × 100 = 1.5625 %

Half life Of Radioactive Element is 18 days

Percentage of original sample remained after 108 days is 1.5625%

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Answer: Li2S  and Al because metals replace metals

Explanation:

The chemical reaction between Al₂S₃ and lithium is a single displacement reaction which forms products of lithium sulfide Li₂S and Al.

Chemical reactions are defined as reactions which occur when a substance combines with another substance to form a new substance.Alternatively, when a substance breaks down or decomposes to give new substances it is also considered to be a chemical reaction.

There are several characteristics of chemical reactions like change in color, change in state , change in odor and change in composition . During chemical reaction there is also formation of precipitate an insoluble mass of substance or even evolution of gases.

There are three types of chemical reactions:

1) inorganic reactions

2)organic reactions

3) biochemical reactions

During chemical reactions atoms are rearranged and changes are accompanied by an energy change as new substances are formed.

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There are 3.00 molecules of CO2 in 132.03 grams of CO2.

Mass is quantitative measure of interia a fundamental quantity of all matter.

Mass of CO2 = 132.03 grams

Number of molecules of CO2 = ?

Molar mass of CO2 = ?

For the molar mass of CO2: Atomic mass of Carbon = 12; Oxygen = 16

= 12 + (16 x 2)

= 12 + 32 = 44g/mol

Apply the formula:

number of molecules = (mass in grams/molar mass)

N = (132.03 grams/44g/mol)

N = 3.00 molecules

Thus, there are 3.00 molecules of CO2 in 132.03 grams of CO2.

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When an atom X of an element in Group 1 reacts to become X+, number of filled energy levels decreases. The correct option is D.

An atom's electrons typically fill all of the lowest energy levels first, followed by the higher ones. The electrons are in the lowest energy state possible thanks to this filling order.

Atom X will lose an electron to become atom [tex]X^{+1}[/tex], since the atom is neutral and the electron is unit negatively charged. While the nonmetal picks up one or more electrons, the metal loses one or more. The amount of electrons lost is a function of the metal's position in the periodic table. Elements in group 1 lose one electron, while those in group 2 lose two. When one electron is lost, a positive charge results because there are more protons than electrons. With the negative charge, the opposite occurs.

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The complete question is:

When an atom X of an element in Group 1 reacts to become X+ -

A mass number of X increases.

B atomic number of X decreases.

C charge of the nucleus increases.

D number of filled energy levels decreases.

The volume of sulfur tetrafluoride gas that is collected is 13.17L.

The volume of an ideal gas can be calculated using the following ideal gas equation;

PV = nRT

Where;

P = pressure (atm)

V = volume (L)

n = number of moles (mol)

T = temperature (K)

R = gas law constant

According to this question, a reaction occurs at 32.0°C and evolves 526mmol of sulfur tetrafluoride gas. The volume of sulfur tetrafluoride gas collected assuming the pressure in the room is exactly 1 atm can be calculated as follows:

1 × V = 0.526 × 0.0821 × 305

V = 13.17L

Therefore, 13.17L is the volume of the gas.

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Answer:

The "control" is a group that continues under normal conditions in an experiment.

Explanation:

The control group regulates the experiment and serves as a reference point for changing variables.

Answer:

The corrrect answer will be option-A.

Explanation:

A scientific experiment contains two types of groups: the control and the experimental groups. The control group in any scientific experiment is the sample which does not receive the variable we need to test which is provided in the experimental groups.

In the given question, the scientist wanted to study the effect of fertilizers on the growth of the grass. so the parameter (variable) to be studied is fertilizer. The experimental samples are provided with different concentration of the fertilizer but the control sample will not receive the fertilizers as the control sample provides the base or reference to the experimental group to increase the accuracy of the results obtained.

Thus, option-A is the correct answer.

Answer:

Density = 3 g/cm³

Explanation:

Density is a ratio which compares an object's mass per every 1 unit volume. Grams is a unit of mass and cm³ is a unit of volume. Since you have been given values for both a mass and volume, you can use them to determine the density.

Density = g/cm³                                     <----- Density units

Density = 90 g / 30 cm³                        <----- Insert values

Density = 3 g / 1 cm³                              <----- Simplify

Density = 3 g/cm³

The average atomic mass of the element which is represented in the above diagram is 16.

An element is defined as a substance which cannot be split into simpler forms by ordinary chemical process. There are different categories of elements including the metals, nonmetals and metalloids.

That being said, the oxygen is a chemical element which belongs to group 6 and period 2 in the periodic table, has valence electron of 6, and an average mass of 16. In addition to this, oxygen is a metal. Some few examples of other chemical elements include:

So therefore, it can be deduced from the explanation given above that oxygen is a chemical element which is diatomic.

Complete question:

What is the average atomic mass of the element represented above

a. 8

b. 16

c. 32

d. 64

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