is it a compound or mixture when they are separated by chemical bonds

Answer:

It is used in medical research.

Explanation:

So its answer is trends in drug effectiveness

In the given question, epidemiological studies look into trends in statistics. The correct answer is option D.

Epidemiology is the study of how diseases spread and how to prevent them.

Epidemiologists use statistics to understand how diseases spread and how to prevent them from spreading further. They look at trends in:

Therefore, Option D. "Trends in statistics" is the correct answer.

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The stoichiometric table and the rate law for the given elementary liquid phase reaction have been constructed. The rate constant and activation energy have been calculated, and the type of reaction energy has been specified as endothermic.

Stoichiometric table in terms of concentrations:

The stoichiometric table for the given reaction can be constructed as follows:

A + 2B → products

                             A                                B                                products

Feed         0.3*Cf                        0.7*Cf                                       0

Exit              (0.3-0.3X)*C             (0.7-0.7X)*C                                0

Change         -0.3XC                      -0.7XC                                     0

Where:

Cf = Total feed concentration

C = Concentration inside reactor

X = Conversion of A

Rate of reaction of A:

The rate of the reaction can be expressed as:

rA = -1/2 * dCA/dt = k*C^2

where, CA is the concentration of A and k is the rate constant.

Since the reaction is elementary, the rate law is proportional to the concentrations of the reactants raised to their stoichiometric coefficients.

The rate of disappearance of A = rate of appearance of B

rB = -dCB/dt = 2*rA

Therefore, the rate of reaction of A can be expressed as:

rA = (0.7Cf - 0.7C)/V = k*C^2

Substituting values, we get:

rA = (0.710 - 0.70.7X)/5 = k(0.3 - 0.3*X)^2

Calculation of k and E:

The rate constant k can be calculated using the Arrhenius equation:

k = A * exp(-Ea/RT)

where A is the frequency factor, Ea is the activation energy, R is the gas constant and T is the temperature in Kelvin.

Assuming the activation energy is 50 kJ/mol, we can calculate the rate constant at the given temperature of 333 K:

k = 0.00717 * exp(-50000/(8.314*333)) = 0.0001504

The reaction energy can be determined by calculating the activation energy using the rate constant at two different temperatures. Assuming the rate constant at 323 K is 0.000098, we can solve for Ea:

ln(k2/k1) = Ea/R * (1/T1 - 1/T2)

ln(0.000098/0.0001504) = Ea/8.314 * (1/323 - 1/333)

Ea = 43775 J/mol

The positive value of the activation energy indicates that the reaction is endothermic.

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Answer:

The three pKa values for phosphoric acid (H3PO4) are 2.12, 7.21, and 12.32.

The common logarithm by exponentiating all sides with base 10 we obtain [H+] = 10pH. In a solution with a pH near 2, the pOH is 12, the hydrogen ion concentration is 10-2 M, and the hydroxide ion concentration is 10-2 M.

The negative logarithm of the hydrogen ion concentration is used to calculate the pH of a solution. Change the hydrogen ion's value in the equation above. Hence, the pH of [10 - 8] 6.98 M HCl solution.

A solution with such a concentration of hydroxyl ions of 1012 M has a pH of 2. As the pOH is indeed the numerical expression of the OH- ion concentration, such a solution does have a pOH of 12. As the sum of the pH & pOH must equal 14, the pH must be 2.

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The controlled burn cause of wildfires is least likely to lead to catastrophic results. Therefore, option (C) is correct.

A controlled burn is a fire set intentionally for purposes of forest management, prairie restoration, farming, or greenhouse gas. A controlled burn refers to the intentional burning of slash, fuels through burn piles.

Controlled burning can be done during the cooler months to reduce fuel buildup and reduce the likelihood of serious hotter fires. Controlled burning enhances the germination of desirable forest trees, and exposes soil mineral layers which expand seedling vitality.

Controlled burning is also useful in agriculture as it is often referred to as slash and burns. It is one component of shifting cultivation, as a section of field preparation for planting called field burning. This technique is utilized to clear the land of any existing crop residue and kill weeds and weed seeds.

Field burning is less expensive but because it forms smoke and air pollutants, its use is not common in agricultural areas.

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Answer:

12000j

mass=1500kg

velocity=4m/s

Kinetic Energy (K E) = 1/2 mv^2

=1/2*1500(4^2)

=1*750*16

=12000j

Answer:

The falling standards of Ghanaian youths can be minimized by proper upbringing of the children by their parents. The youths should be taught about what is wrong or right and there should be a corresponding reward for those who do good and exceptional in order to encourage others in towing that line and punishment should also be meted out to those who break the law. Mediocrity shouldn’t be celebrated and the elders should lead by example.

These will make the falling standards of Ghanaian youth get reduced.

Answer: .819 Moles of Air

Explanation: To solve this problem, we will use the Ideal Gas Law which states that PV=nRT. P represents pressure or internal pressure, V is volume, T is temperature, n is moles of a gas, and R is the Universal Gas Constant. For the ideal gas law, R is .08206. R is 8.314 for any other calculation. We are solving for the moles of gas. The gas in this case is air which is a mixture of gases but that isn't important.

Our givens are P = 7.3 atm, V = 2.67 L and T = 17.0°C. We convert T to Kelvin because the Ideal Gas Law requires that. We simply add 273 to the value in Celcius to convert it to Kelvin. Our T is now 290 K. We also know R is our Universal Gas Constant. We can now plug into the law.

(7.3 atm)(2.67 L) = n(.08206)(290 K)

n = ((7.3 atm)(2.67 L))/(.08206)(290 K)

n = .819 moles of air

Hope this helps!

Answer: This suggests that low hydrogen peroxide treatments used for shorter periods of time have the least potential to damage teeth. According to another study, scientists found that a 5% hydrogen peroxide solution was just as effective at whitening teeth as a 25% solution.

Explanation:

Answer:

380g

Explanation:

Given parameters:

Number of moles of Fluorine  = 20moles

Unknown:

Mass of Fluorine  = ?

Solution:

The number of moles is the unit of quantifying the amount of particles in a substance.

 So;

      Mass of a substance  = number of moles  x molar mass

Molar mass of F = 19g/mol

 Now;

     Mass of F = 20 x 19 = 380g

When hydrogen bromide is added to 2-methylbut-2-ene, two products are expected to be produced: 2-bromo-2-methylbutane (major product) and 3-bromo-2-methylbutane (minor product).

The addition of HBr to 2-methylbut-2-ene follows the Markovnikov addition rule. This means that the hydrogen atom and the bromine atom will add to the carbon atoms in the double bond, such that the hydrogen atom adds to the carbon with the greater number of hydrogen atoms, and the bromine atom adds to the carbon with the lesser number of hydrogen atoms.

In this case, the hydrogen atom will attach to the second carbon atom, which has three hydrogen atoms, while the bromine atom will attach to the third carbon atom, which has only one hydrogen atom. This produces the major product, 2-bromo-2-methylbutane.

The formation of the minor product, 3-bromo-2-methylbutane, occurs due to the rearrangement of the carbocation intermediate formed during the addition reaction. The carbocation can rearrange either by shifting a methyl group from the second to the third carbon, or by shifting a hydrogen atom from the third to the second carbon. This rearrangement produces the minor product, 3-bromo-2-methylbutane.

In conclusion, the addition of HBr to 2-methylbut-2-ene produces two products: 2-bromo-2-methylbutane (major product) and 3-bromo-2-methylbutane (minor product). The major product forms due to Markovnikov addition rule, while the minor product forms due to carbocation rearrangement.

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The electrons move from left to right through the circle labeled "M" to reach the cathode, where reduction takes place.

If oxidation occurs on the left side of the fuel cell and reduction occurs on the right side, the movement of electrons can be described as follows: Electrons move from left to right through the circle labeled "M."

In a fuel cell, the process of oxidation takes place at the anode (labeled A) where the fuel is oxidized, releasing electrons. These electrons then flow through the external electrical circuit, represented by the wire connecting objects A and B. The electrons reach the cathode (also labeled A) on the right side of the cell, where reduction occurs.The circle labeled "M" represents the membrane or electrolyte in the fuel cell. This membrane allows the transport of ions but blocks the movement of electrons. As a result, electrons cannot flow directly through the electrolyte but must travel through the external circuit.

This movement of electrons through the external circuit is what generates an electric current that can be used to power electrical devices or systems.

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The number of moles of the gas can be determined using ideal gas equation. The number of moles of Br gas in 2.8 L at 1.38 atm and 327 K is 0.144 moles.

Ideal gas law states the relation between temperature, pressure and volume with the number of moles of a gas as written below:

PV = nRT

where, R is the universal gas constant equal to 0.082 L atm/K mol

Given that, T = 327 K

P = 1.38 atm

V = 2.8 L.

Then, n = PV/RT

Number of moles of Br gas, n = (1.38 atm ×2.8 L)/(327 K × 0.082 L atm/K mol ) = 0.144 moles.

Therefore, the number of moles of Br gas in in 2.8 L at 1.38 atm and 327 K is 0.144 moles.

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Answer:

No

Explanation:

Wheat flour is an impure substance because it is made up of two or more types of atom

Answer: c

Explanation: Trust me

Answer:

C

Explanation:

EDG

Answer:n a  red blood cell, the control center is the nucleus. A mitochondria is not a nucleus. It is another organelle that produces energy for the cell.

Explanation:

, we need to use the chemical formula of ammonium acetate, which is NH4C2H3O2. First, we need to calculate the molar mass of ammonium acetate: Molar mass of NH4C2H3O2 = (1 x 14.01 g/mol) + (4 x 1.01 g/mol) + (2 x 12.01 g/mol) + (3 x 16.00 g/mol) = 77.08 g/mol Next, we can use the molar mass to convert 63.3 g of ammonium acetate to moles: 63.3 g NH4C2H3O2 x (1 mol NH4C2H3O2 / 77.08 g NH4C2H3O2) = 0.820 mol NH

Answer:

the answer is (a)

Explanation:

an example of +1 oxidation state is Cu2O, where oxygen is 2- and so to balance the molecule, each copper atom is +1

Answer:

1.34 * 10^-7 M

Explanation:

The Ksp of lead II chromate is 1.8 x 10^-14

So, we have that;

PbCrO4(s) -----> Pb^2+(aq) + CrO4^2-(aq)

                             s                  s

Where s = molar concentration of Pb^2+(aq) and  CrO4^2-(aq)

and;

[Pb^2+] = [CrO4^2-]

This implies that Ksp = s^2

s = √Ksp

s = √1.8 x 10^-14

s = 1.34 * 10^-7 M

The student needs to add approximately 83.3 mL of 12 M HCl solution to the existing 1 L of 2 M HCl solution to increase the concentration to 3 M. It is important to handle concentrated acids with caution and follow proper safety procedures.

To increase the concentration of a 1 L solution of 2 M HCl to 3 M, the student needs to calculate the volume of concentrated HCl needed and add it to the existing solution. Here's how the calculation can be done:

Given:

Initial concentration of HCl solution = 2 M

Final concentration desired = 3 M

Initial volume of HCl solution = 1 L

Step 1: Calculate the moles of HCl in the initial solution.

Moles of HCl = Initial concentration × Initial volume = 2 M × 1 L = 2 moles

Step 2: Calculate the moles of HCl needed for the desired concentration.

Moles of HCl needed = Final concentration × Final volume = 3 M × 1 L = 3 moles

Step 3: Calculate the moles of HCl to be added.

Moles of HCl to be added = Moles needed - Moles present = 3 moles - 2 moles = 1 mole

Step 4: Convert the moles of HCl to the required volume of concentrated HCl.

To calculate the volume, we need to know the concentration of the concentrated HCl solution. Assuming it is 12 M, we can use the following formula:

Volume of concentrated HCl = Moles of HCl to be added / Concentration of concentrated HCl

Volume of concentrated HCl = 1 mole / 12 M = 0.0833 L or 83.3 mL

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Answer:

A. last  F first E second C thrid b foruth A five

Explanation:

The volume of 12 gas forms when 21 L Cl2 react at STP is 21 L.

To determine the volume of 12 gas (I assume you mean I2 gas) formed when 21 L of Cl2 reacts at STP (standard temperature and pressure), we need to use the ideal gas law equation.

The ideal gas law equation is given by:

PV = nRT

Where:

P = pressure

V = volume

n = number of moles

R = ideal gas constant

T = temperature

At STP, the pressure is 1 atm, and the temperature is 273.15 K.

From the balanced equation, we can see that the molar ratio between Cl2 and I2 is 1:1. So, if 21 L of Cl2 reacts, it will produce an equal volume of I2 gas.

Given that the volume of Cl2 is 21 L, we can assume the volume of I2 gas formed will also be 21 L.

Therefore, the volume of I2 gas formed is 21 L.

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Yes, because it describes action-reaction force pairs

Answer:

There would be 4 atoms in a tetrahedral molecule.

Explanation:

Answer: 4 atoms

Explanation:

k=−(slope of plot). The Arrhenius equation, k = A * exp(-E /(R * T)), accurately describes the relationship between the rate constant and temperature. The overall reaction affects the units of rate constant, k.

Water and oxygen are produced as hydrogen peroxide breaks down. The reactions' uncatalyzed activation energy is 86 kJ/mol. Acetanilide and MnO2 have an activation energy value of 112 kJ/mol and 49 kJ/mol, respectively.

To determine the overall reaction order, add the exponents of each component. Typically, this figure is less than or equal to two.

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Answer:

She transfers energy out of the medicine until it is solid. So the answer would be C.

Explanation:

According to the forces of attraction , molecules can be slowed down by moving out of the medicine until it is a solid , it will decrease the rate of absorption of medicine.

Forces of attraction  is a force by which atoms in a molecule  combine. it is basically an attractive force in nature.  It can act between an ion  and an atom as well.It varies for different  states  of matter that is solids, liquids and gases.

The forces of attraction are maximum in solids as  the molecules present in solid are tightly held while it is minimum in gases  as the molecules are far apart . The forces of attraction in liquids is intermediate of solids and gases.

The physical properties such as melting point, boiling point, density  are all dependent on forces of attraction which exists in the substances.

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