What is TRUE about expert witnesses?

A.
They offer personal and professional knowledge.

B.
They are not allowed to practice their testimony.

C.
They are required to link all evidence to the crime.

D.
They have all written a book about their area of expertise.

Explanation:

We have to find the empirical formula for sulfur dioxide. The compound contains two elements: Sulfur and oxygen.

As it name says, it is a dioxide, it means that one molecule of the compound contains two atoms of O.

The empirical formula of sulfur dioxide is: SO₂.

Answer: d. SO₂.

By following Daltons laws of partial pressure .

" the pressure that eachgaswould have exerted ,Add up to the total pressure" .

• Therefore :

• Total Pressure = P.Pressure (oxygen) + P.Pressure of (He)

15 atm = 6atm + Pressure of He

P.Pressure ofHe = 15atm-6atm

= 9 atm

This means that the partial pressure of He = 9atm +

There are some compounds in which the electrons move from one side to anothe, and it is a continous movement. For that reason, the resonance structure is created. It works as a theorical structure which is not exact, but it helps us to approach to the real structure.

For example, for the bencene, there are 3 different resonance structures:

And they are the same compound. It means that the answer is B. Alternate structures of the same compound.

Answer:

The car will most likely move the fastest on the wood. Carpet will create drag due to the friction between the car's wheels and the carpet. Bricks are not smooth so drag will occur, however it will be minimal. Wood is usually smooth and there is almost no drag or friction...the car will glide easily over the surface.

Explanation:

Hope this helps!!

Action and response are two forces that have the same magnitude but opposing directions.

Explanation.

The force used by a dog as it moves across the ground is known as the action force. The force that the earth exerts on the dog is the reaction force, on the other hand. Newton's third law of motion serves as its foundation.

When we walk on the ground, we push the earth backward with our feet, but the ground pushes our feet forward with an equal force, which propels us forward. Because of this, the action is the force that pushes the ground backward, and the reaction is the force by the ground on our feet.

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Answer:

4.839 × 10^14 Hz or s^-1

Explanation:

speed of light = wavelength times frequency

frequency = speed of light ÷ wavelength

3.00 x 10^8 = speed of light

3.00 x 10^8 m/s ÷ 6.2 x 10^-7 m = 4.839 × 10^14 Hz or s^-1

socraticorg

The concentration of methylamine chloride in the solution is 0.44 M.

given that :

concentration of methylamine , [ base ] = 0.15 M

pH = 10.20

pH + pOH = 14

pOH = 14 - pH = 14 - 10.20 = 3.8

Kb = 4.6 × 10⁻⁴

concentration of methylamine chloride , [ acid ] = ?

The equation of POH is given by the following formula :

POH = pKb + log [ acid ] / [ base ]

pkb = -log kb

pkb = - log ( 4.6 × 10⁻⁴ )

pkb = 3.33

now, substituting the values, we get:

POH = pKb + log [ acid ] / [ base ]

3.8 = 3.33 + log [ acid ] / [ 0.15 ]

0.47 = log  [ acid ] / [ 0.15 ]

10^0.47 =  [ acid ] / [ 0.15 ]

2.95 = [ acid ] / [ 0.15 ]

[ acid ] = 0.44 M

Thus, A 0.15M solution of methylamine CH3NH2 contains an unknown concentration of methylamine chloride CH3NH3Cl. If the solution has a pH of 10.20,what is the concentration of methylamine chloride in the solution is 0.44 M.

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When something heats up energy is absorbed from another system and when something cooler down energy is released to another system.

When a reaction releases heat, it is classified as exothermic. The absorption of heat in a reaction makes it endothermic.

Answer:

Explanations:

a) The balanced chemical reaction for the complete combustion of pentane is expressed as:

Note that oxygen, carbondioxide and water are all in gaseous state.

Nuclear fission causes a neutron to split the isotope U-235 when it collides with its nucleus. When a slow neutron interacts with a heavy nuclide like 235U, nuclear fission can occur (0.025 eV).

When a slow neutron interacts with a heavy nuclide like 235U, nuclear fission can occur (0.025 eV). If a fission (or splitting apart) occurs, the nuclear material splits into two (on average) about equal fragments that travel away with kinetic energy, producing heat.

Nuclear fission causes a neutron to split the isotope U-235 when it collides with its nucleus. Two or three additional neutrons as well as fission products are released during this fission process. The chain reaction is continued by some of the emitted neutrons. There is significant energy released in every fission reaction.

When a uranium atom divides, additional neutrons are also released. The process keeps repeating again as these neutrons keep crashing into more uranium atoms. This process is called a nuclear chain reaction. This reaction is controlled in nuclear power plant reactors to produce a desired amount of heat.

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The percentage of the sample of As-81 remaining undecayed after 43.2 seconds is 40.6%

We'll beging by calculating the number of half lives that has elapsed. This can be obtained as follow

The following data were obtained from the question:

n = t / t½

n = 43.2 / 33

n = 1.3

Finally, we shall determine the percentage remaining undecayed. This is shown below:

N = N₀ / 2ⁿ

N = 100 / 2^1.3

N = 40.6%

Thus, we can conclude that the percenatge undecayed is 40.6%

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The correct statement about the description of ion whose symbol is Ca2+ among the choices above are:

The options b and d are correct.

It follows that elements whose charge on them are positive are called cations. In order words, in the periodic table of science of chemistry, the positively charged ions of elements are known as cations. Calcium has a positive of 2 on as it ion and this makes it a cation.

In addition to the above, calcium ion helps in signal transduction pathways of cells of living organisms. This goes to say that they also help in the body's normal functioning of the human body.

However, on a second note, calcium in the periodic table belongs to group 2, has a valence electrons of 2 and a metallic element; thereby making it a divalent metal.

In conclusion, we can now confirm from all said above that calcium above is a cation.

Complete question:

Check all of the following statements that are true about the ion whose symbol Ca2+

a. It is an anion

b. It is a cation

c. Its atoms is connected by tripple bonds

d. It is a divalent metal

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The concentration of C₂H₅OH in the resulting solution is 1.332 M.

given that :

mass of C₂H₅OH = 30.7 g

molar mass =46.07 g/mol

volume =  500 ml = 0.5 L

number of moles can be calculated by the following formula :

number of moles = mass / molar mass

no. of moles = 30.7 g / 46.07 g/mol

no. of moles = 0.666 mol

now, the concentration of C₂H₅OH :

Molarity = no. of mole / volumes in l

Molarity = 0.666 / 0.5

Molarity = 1.332 M

Thus, If 30.7 g of C₂H₅OH (MM = 46.07 g/mol) are added to a 500.0 mL volumetric flask, and water is added to fill the flask, The concentration of C₂H₅OH in the resulting solution is 1.332 M.

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Answer:

Explanation:

Here, we want to get the molar mass of the gas

Let us call it M

From the ideal gas equation, we can get the number of moles of the gas

Mathematically:

Also, n is the mass divided by the molar mass of the gas:

Where:

M is the molar mass that we want to calculate

m is the mass of the gas sample which is 1.45 g

P is the gas pressure which is 733 torr (to convert to atm, we multiply by 0.00131579 : 733 * 0.00131579 = 0.96 atm)

V is the volume which is 931 mL (We convert to L by dividing by 1000:

931/1000 = 0.931 L)

R is the molar gas constant which is 0.0821 L.atm/mol.K

T is the temperature that we convert to K by adding 273 K : 273 + 16 = 289 K)

Substituting the values, we have it that:

Answer

Volume = 0.5 L

Explanation

Mass of NaOH = 26.0 g

Molarity = 1.3 M

Molar mass of NaOH = 39.997 g/mol

Volume = ?

The volume of NaoH can be calculated using

But the number of mole of NaOH, n = mass of NaOH / Molar mass of NaOH

Therefore, the volume of NaOH is

Answer:

The Chlorine atom has higher ionization energy.

Explanation:

Ionization energy is the energy needed to separate an electron from an atom of an element in the gaseous state.

In the Periodic Table of Elements, Ionization energy increases from bottom to top (in a group), and increases from left to right (in a period).

In the folowing drawing we can see the variation of the Ionization energy and the location of the magnesium atom and chlorine atom:

Magnesium atom and Chlorine atom are located in the same period, but Mg is in group 2 (left side) and Cl in in group 17 (right side), so the Chlorine atom has higher ionization energy.

Answer:

Not enough information to tell.

Explanation:

What is given?

Mass of Zn = 10.0 g,

Mass of HCl = 10.0 g,

Molar mass of Zn = 65.4 g/mol,

Molar mass of HCl = 36.4 g/mol,

Molar mass of ZnCl2 = 136.2 g/mol,

Molar mass of H2 = 2 g/mol.

Step-by-step solution:

First, let's convert 10.0 g of each reactant to moles using their respective molar mass:

Now, let's identify what is the limiting reactant. Let's see how many moles of ZnCl2 can be produced by 0.153 moles of Zn if 1 mol of Zn reacted produces 1 mol of ZnCl2, and how many moles of ZnCl2 can be produced by 0.275 moles of HCl if 2 moles of HCl reacted produces 1 mol of ZnCl2:

You can realize that the limiting reactant, in this case, is HCl because is the first reactant consumed first and this reactant 'impose' the limit to produce the products.

So now, let's find how many moles of H2 are being produced by 0.275 moles of HCl if 2 moles of HCl reacted produces 1 mol of H2:

The final step is to convert each number of moles of each product to grams using their respective molar mass, as follows:

We're producing 18.8 g of zinc chloride (ZnCl2), and 0.276 g of hydrogen (H2), so based on this logic the answer would be not enough information to tell.

Explanations:

• We will follow Hess's Law of Constant Heat Summation:

(that states that if a reaction occurs in more than one route, then the the total enthalpy change for the reaction is the sum of all changes.)

For reaction :

this can be expressed as :

Step 1

Charles's law states that the volume (V) of a gas is directly proportional to its absolute temperature. It is assumed that the pressure and the quantity of gas remain constant.

Mathematically:

-------------------

Step 2

Information provided:

T1 = 10 °C + 273 = 283 K

V1 = 3 L

---

T2 = Unknown

V2 = 10 L

-------------------

Step 3

Procedure:

Answer: 943 K or 670 °C

3.786137931L of chlorine are needed.

1st) It is necessary to write the balanced equation of the reaction between chlorine gas (Cl2) and sodium (Na) to produce sodium chloride (NaCl):

Now we know that 1 mol of chlorine gas is needed to react with 2 moles of sodium in the production of sodium chloride. With the molar mass of Na (23.0g/mol) and Cl2 (71.0g/mol), we can see that 71.0g of Cl2 are needed to react with 46.0g of sodium.

2nd) Knowing that 71.0g of Cl2 are needed to react with 46.0g of sodium, we can use a mathematical rule of three to calculate the amount of Cl2 that will react completely with 12.0g of sodium:

3rd) Now it is necessary to convert the mass of chlorine gas into moles, so we can use it in the Ideal gas formula:

So, 0.26 moles of chlorine gas are needed.

4th) With the formula of Ideal gases and replacing the values of Pressure (P), number of moles (n) and Temperature (T, in Kelvin), we can calculate the volume of Cl2:

Finally, 3.786137931L of chlorine are needed to react completely with 12.0g of sodiu.

In order to calculate this question, we will use the reaction quotient Q, which has a very similar formula as the equilibrium formula, but this Q can be calculated not just in equilibrium (where Q = K) but in any part of the reaction, so K is the equilibrium, and Q is what is used to see where the reaction will shift towards until it reaches equilibrium, we can have three possible outcomes:

Q = K, the reaction is already in equilibrium

Q > K, the reaction will proceed in the reverse direction

Q < K, the reaction will proceed in the forward direction

Let's set up the formula:

Q = [products]/[reactants], the brackets mean Concentration of each compound. Now adding our compounds

Q = [BrCl]^2/[Br2]*[Cl2], the BrCl is raised to 2 because we have 2 BrCl in the reaction, this is a rule for the equilibrium formula, we use the coefficient in front of the compound and raise its concentration to this number

Now we need the concentration of each compound, to find it we will use the Molarity formula

M = n/V

M = 0.15/2

M = 0.075M, notice that since we have the same number of moles and volume for every compound, we will have the same concentration for every compound, going back to our formula

Q = [0.075]^2/[0.075][0.075]

Q = 1.0

Since K = 7.0 and Q = 1.0

K > Q, the reaction will proceed in the forward direction in order to increase the concentration of 2 BrCl in order to finally reach Q=K

The Lewis Structure for NH₄⁺ (Ammonium ion) is described as having four sigma bonds around a Nitrogen Atom. It is also to be noted tha there is a +1 charge on the Nitrogen atom.

The nitrogen atom is surrounded by four sigma bonds. As a result, the form of NH4+ is tetrahedral. The total number of sigma bonds and lone pairs surrounding the nitrogen atom is four. As a result, the geometry should be tetrahedral.

Lewis structures also referred as Lewis dot formulas, Lewis dot frameworks, electron dot structures, or Lewis electron dot structures, are schematics that depict the bonding between atoms in a molecule as well as any lone pairs of electrons that may occur.

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First, we have to remember what a mass percentage means (in this particular case):

It is the amount of each element in a compound, and it is calculated as follows:

The addition of the different mass percentages is equal to 100%.

In this case, we have the percentage of one of the elements of the compound, we can make the respective subtraction:

Then, the answer is that the iodine mass percentage is 86.4%

Na+ (g) --> Na+ (aq) AH = -364 kJmol 1 is endothermic reaction. The given reaction is False, As H is negative hence exothermic reaction not endothermic

What is endothermic  reaction?

Chemical processes referred to as endothermic reactions occur when the reactants take in heat energy from their environment to create products. These reactions produce a cooling effect by bringing the temperature of the space around them down. Ice cubes absorb heat energy from their surroundings and melt to generate liquid water as an example of an endothermic physical process (no chemical bonds are broken or formed).

False, As H is negative hence exothermic reaction not endothermic

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Answer:

Explanation:2H2 + O2 —-> 2H2O

The mole ratio of H2 to H2O is 2 : 2 = 1:1

4 moles of H2 = 4 moles of H2O

Moles of H20 = 4mol

Molar mass of H2O = 18g/mol

Mass = moles X Molar mass

= 4mol x 18g/mol

= 72g

We can see that the solution has a boiling point of 80.93°C.

The atmospheric pressure does equal the pressure of a liquid as we heat the system. The temperature at which this occurs is called the boiling point. Now we know that the boiling point of the pure benzene is 80.1 °C.

Given that;

ΔT = K m i

ΔT = boiling point elevation

K = boiling point constant

m = molality of the solution

i = Van Hoff factor (molecular solute)

ΔT = 2.53°C /m * 0.33 m * 1

ΔT =  0.83°C

The boiling point of the solution is now gotten from ; 0.83°C + 80.1 °C

= 80.93°C

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A)Nuclear fusion releases protons and neutrons, so the total number of protons and neutrons in a star changes throughout its life is the true statement.

A suggested method of producing energy would use heat from nuclear fusion processes to produce electricity. A heavier atomic nucleus is created by the fusion of two lighter ones, which also produces energy. Fusion reactors are devices created to use this energy.

Nuclear fusion is less risky than nuclear fission because the fuel rods produced by nuclear fission include dangerous radioactive waste that may be used in weapons and must be maintained carefully for thousands of years.

Powering the Sun and other stars are nuclear fusion processes. Two light nuclei combine to produce one heavy nucleus during a fusion process. The resultant single nucleus's total mass is less than the mass, which causes the process to release energy.

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Answer:

121 I think not sure tbh......

The reaction to produce nitrogen dioxide from nitrogen and oxygen is as follows:

Since all the reactants and products are gases, we can take the coefficients as liters of substance.

Dividing the volumes we have of each reactant by their corresponding coefficient we can determine the limit reagent:

From this we can conclude that the limit reagent is oxygen.

We have to base our calculations on this substance.

According to the given equation, 2 L of O2 produce 2 L of NO2, use this ratio to find the volume of nitrogen dioxide produced:

It means that 60.6 liters of nitrogen dioxide gas are made.

5998kJ

Given the reaction between ethanol and oxygen expressed as:

For the product

We have 2 moles of CO2 and 3 moles of water. The total bond energy in the product is expressed as:

Hence the total energy transferred to build all the bond energy in the product is 5998kJ