18. n 1869, Russian chemist Dimitri Mendeleev proposed arranging the known elements by
atomic weights and properties in 17 columns with two partial periods of seven elements
each followed by two nearly complete periods. Rayleigh and Ramsey improved the
periodic table by discovering the inert gases. In 1911, Henry Moseley subjected elements
to x-rays and was able to derive the relationship between x-ray frequency and number of
protons. When Moseley arranged the elements according to increasing atomic numbers
and not atomic masses, some inconsistencies associated with Mendeleev's table were
eliminated. The modern periodic table is based on Moseley's Periodic Law.
How do the scientists Mendeleev and Moseley differ on their arrangement for the periodic
table? (1 point)
O Their periodic table was arranged the same.
Moseley arranged the elements based on atomic masses while Mendeleev arranged
the elements based on atomic number.
Moseley arranged the elements based on the number of protons while Mendeleev
arranged the elements based on x-ray frequency.
Moseley arranged the elements based on atomic numbers while Mendeleev arranged
the elements based on atomic masses.

Answer: True

Explanation: Chadwick, a British physicist, worked to isolate the neutral particle that Rutherford had proposed.  This particle, known as the neutron, was hypothesized by Rutherford to exist within atomic nuclei. In 1932, Chadwick successfully conducted experiments that confirmed the existence of the neutron and provided evidence for its role in nuclear structure.

Rutherford's model of the atom suggested that the nucleus contains positively charged protons and that electrons orbit around it. However, this model could not explain why the positively charged protons did not repel each other and cause the nucleus to break apart. Rutherford proposed the existence of neutral particles, later identified as neutrons, to account for the stability of the atomic nucleus.

Chadwick's work involved bombarding various elements with alpha particles and observing the resulting radiation. Through careful experimentation, he was able to demonstrate that the radiation consisted of neutrons, which had the ability to penetrate and interact with atomic nuclei without being deflected by electromagnetic forces. This discovery revolutionized our understanding of atomic structure and paved the way for further advancements in nuclear physics.

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Answer:

True

Explanation:

I answered so the person who answered first can get branliest!

Hydrolysis occurs when Fe2O3 is dissolved in water, resulting in the formation of Fe(OH)3 and H+ ions. For every Fe in Fe2O3, there are 1.5 O. Thus, the iron content of Fe2O3 is reduced.

Water in the liquid state serves as the solvent in an aqueous solution. In other words, water molecules surround and integrate solute (dissolved) ions and molecules into their web of bonds. Following that, the dissolved species dispersed all over the water.

Aqueous solutions are made up of water and one or more dissolved materials. Solids, gases, or other liquids can all dissolve in an aqueous solution.

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Question:

How Many Particles Fe2O3 Will Produce In An Aqueous Solution (In Water).

Answer:

To solve this problem, we need to use the balanced chemical equation for the reaction between oxygen gas (O₂) and potassium chloride (KCI) to form potassium chlorate (KCIO₃):

2KCI + 3O₂ → 2KCIO₃

We can use the given mass of O₂ (20.8 g) and the molar mass of O₂ (32.00 g/mol) to find the moles of O₂:

20.8 g O₂ x (1 mol O₂ / 32.00 g O₂) = 0.65 mol O₂

According to the balanced equation, 3 moles of O₂ react with 2 moles of KCI to produce 2 moles of KCIO₃. Therefore, we can use the moles of O₂ to find the moles of KCIO₃:

0.65 mol O₂ x (2 mol KCIO₃ / 3 mol O₂) = 0.43 mol KCIO₃

Finally, we can use the molar mass of KCIO₃ (122.55 g/mol) to convert moles of KCIO₃ to grams of KCIO₃:

0.43 mol KCIO₃ x (122.55 g KCIO₃ / 1 mol KCIO₃) = 52.71 g KCIO₃

Therefore, the grams of KCIO₃ that can be produced from 20.8 g O₂ is 52.71 g KCIO₃. However, the problem does not ask for the grams of KCIO₃, but instead asks for the grams of KCIO, which is not a valid compound. It is possible that there is a typo in the problem and that it should have asked for the grams of KCIO₃ instead.

Explanation:

We can determine the equilibrium concentration when we are given the initial concentration and reaction of an acid or base. In the given reaction,

HA is an acid that dissociates in water to form its conjugate base A− and a hydronium ion H3O+.

HA(aq) + H2O(l) ⇌ A−(aq) + H3O+(aq)

For any weak acid, the dissociation constant is defined as follows:

Ka = [A−][H3O+]/[HA]

We can determine the equilibrium concentration from the above formula by using the initial concentration.

Let’s consider a weak acid HA with an initial concentration of [HA]0.

It will form [A−] and [H3O+] at equilibrium.

If the degree of dissociation of the acid is x, then the concentration of [H3O+] at equilibrium will be [H3O+] = x, and the concentration of [A−] will be [A−] = x. And the concentration of [HA] at equilibrium will be [HA] = [HA]0 − x.

So, we can write the equilibrium expression for the dissociation of HA as:

Ka = [A−][H3O+]/[HA]Ka = x * x/([HA]0 − x)

By solving the above equation, we can obtain the value of x, which is the degree of dissociation of the acid.

At equilibrium, the equilibrium concentration of HA is [HA] = [HA]0 − x. The equilibrium concentration of A− is [A−] = x. The equilibrium concentration of H3O+ is [H3O+] = x. Thus, we can determine the equilibrium concentration from the initial concentration of a weak acid or base without using the equilibrium constant Kc.

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The mass of methane (CH4) must be burned to give 1575 kJ of energy is 28.4 g.

The first step is to determine the number of moles of methane required to produce 1575 kJ of energy. We can do this using the conversion factor provided:

891 kJ of energy is produced by 1 mole of methane (CH4)

1575 kJ of energy is produced by how many moles of methane?

1575 kJ / 891 kJ/mol = 1.77 mol

Next, we can use the molar mass of methane to convert it from moles to grams:

Molar mass of methane = 12.01 g/mol (for carbon) + 4 x 1.01 g/mol (for hydrogen) = 16.05 g/mol

Mass of methane = number of moles x molar mass

Mass of methane = 1.77 mol x 16.05 g/mol = 28.4 g

Therefore, 28.4 g of methane must be burned to produce 1575 kJ of energy.

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The factor that is most sensitive to changes in temperature is the fraction of molecules with energy greater than the activation energy.

The statement that best represents the effect of temperature on reaction rates is called the Arrhenius equation. It is expressed as [tex]k = Ae^{-Ea/RT},[/tex]

where k is the rate constant,

A is the pre-exponential factor or frequency factor,

Ea is the activation energy,

R is the gas constant, and T is the absolute temperature.

At high temperatures, the reaction rate increases, and at low temperatures, the reaction rate decreases.

The Arrhenius equation shows that the rate constant depends on two factors:

the activation energy and the fraction of molecules with energy greater than the activation energy.

Thus, the most sensitive factor to changes in temperature is the fraction of molecules with energy greater than the activation energy.

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To calculate the growth rate of the wolf pack, we need to find the difference between the birth rate and death rate and divide that by the total wolf population. Therefore, the growth rate of the wolf pack is 0.27%.

The difference between births less deaths and the difference between immigrants and emigrants in a given country, territory, or geographic area at a given year is what is used to describe the annual increase in population size.

Growth rate = (birth rate - death rate) / total population

Birth rate = 15/51 = 0.294

Death rate = 8/51 = 0.157

Total population = 51

Growth rate = (0.294 - 0.157) / 51 = 0.137 / 51 = 0.0027 or 0.27%

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The forward reaction for Reaction B is endothermic, as indicated by the negative change in enthalpy (-91 kJ/mol) for the forward reaction.

If Reaction B was at equilibrium and then was heated, the amount of CH₃OH would be less after the reaction adjusts to the new temperature. This is because the forward reaction is endothermic, meaning that an increase in temperature would shift the equilibrium towards the reactants side to counteract the increase in temperature.

If the pressure in the container of Reaction B was increased, the amount of CH₃OH would be more after the reaction adjusts to the new pressure. This is because the forward reaction produces fewer moles of gas than the reverse reaction, so increasing the pressure would shift the equilibrium towards the side with fewer moles of gas (the products side) to counteract the increase in pressure.

If H₂ was added to Reaction B at equilibrium, the amount of CH₃OH would be more after the reaction adjusts. This is because H₂ is a reactant in the reverse reaction, so adding more H₂ would shift the equilibrium towards the products side to counteract the increase in H₂.

If H₂ was added to Reaction B at equilibrium, the amount of CO would be less after the reaction adjusts. This is because CO is a product in the forward reaction, so adding more H₂ would shift the equilibrium towards the products side to counteract the increase in H₂, resulting in a decrease in CO.

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The Latent Heat of Fusion of sodium is 2.60 kJ/mol. Fusion is an endothermic process, which means that it requires energy to occur.

What is Fusion?

Fusion, also known as melting, is the physical process in which a substance changes from a solid state to a liquid state as a result of absorbing heat. When a substance is heated to its melting point, the energy absorbed causes the molecules or atoms of the substance to vibrate more rapidly, eventually breaking the bonds between them and allowing them to move more freely. As a result, the substance transitions from a solid state, where the molecules are tightly packed and fixed in position, to a liquid state, where the molecules are more spread out and can move around each other more freely.

The Latent Heat of Fusion (Lf) is defined as the amount of heat required to melt one mole of a substance at its melting point.

Lf = ΔHfus / n

where ΔHfus is the enthalpy of fusion and n is the number of moles of the substance.

In this case, ΔHfus of sodium is given as 2.60 kJ/mol. To calculate the Latent Heat of Fusion, we need to know the number of moles of sodium. Let's assume we have one mole of sodium.

Then,

Lf = ΔHfus / n

= 2.60 kJ/mol / 1 mol

= 2.60 kJ/mol

Therefore, the Latent Heat of Fusion of sodium is 2.60 kJ/mol.

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If the pressure contributed by CH4 is 111.2 atm, the pressure due to NH3 would be 109.1 atm.

To solve the problem, we can use the ideal gas law equation:

PV = nRT

where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant, and T is temperature.

We need to find the pressure due to NH3, so let's start by finding the number of moles of each gas:

Now, we can use the pressure contributed by CH4 to find the total pressure:

Ptotal = PCH4 + PNH3

111.2 atm = PCH4 + PNH3

Finally, we can solve for the pressure due to NH3:

Therefore, the pressure due to NH3 is 109.1 atm.

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Answer:

The balanced chemical equation shows that 1 mole of Ca reacts with 2 moles of H2O to produce 1 mole of Ca(OH)2 and 1 mole of H2.

Therefore, to react with 2.0 moles of Ca, we need 2.0 moles of Ca x (2 moles H2O / 1 mole Ca) = 4.0 moles of H2O.

So, 4.0 moles of H2O are needed to exactly react with 2.0 moles of Ca.

Answer:

A. The acidic concentration of a solution can be determined by titrating with a strong base. You calculate the number of moles of strong base required to reach the equivalence point of the titration. Then, using the mole ratio from the balanced neutralization equation, convert from moles of strong base to moles of acid. [source, Khan Academy]

B. The endpoint is reached in a titration when the indicator used changes color (i.e, pink).

Explanation:

For B, if you do it correctly, the equivalence point is eventually reached and this is signified by the change in color of the indicator in the analyte solution.

Answer:

To answer this question, one must first understand the stoichiometric equation for this particular reaction. The equation states that for each one mole of calcium hydroxide (Ca(OH)2) that reacts with one mole of hydrofloric acid (HF), one mole of calcium fluoride (CaF2) and one mole of water (HOH) is produced. Therefore, if 0.5 moles of hydrofloric acid are reacted with the calcium hydroxide, then 0.5 moles of calcium fluoride will be produced.

To calculate the mass of calcium fluoride that will be produced, one must first look up the atomic mass of both calcium and fluorine and multiply them by the number of moles of each that are present in the reaction. In this case, the atomic mass of calcium is 40.08 and the atomic mass of fluorine is 19. Therefore, the mass of calcium fluoride that will be produced is equal to (40.08 x 0.5) + (19 x 0.5) = 29.54 g.

In conclusion, if 0.5 moles of hydrofloric acid are reacted with calcium hydroxide, then a mass of 29.54 g of calcium fluoride will be produced.

To calculate the difference in volume between the total volume of water and ethanol that were mixed to prepare the solution and the actual volume of the solution, we must first calculate the mass of ethanol present in the solution. We can do this by multiplying the molarity of ethanol (8.407 M) by the volume of ethanol present (529.0 mL) and the molar mass of ethanol (46.07 g/mol).

Mass of ethanol = 8.407 M x 529.0 mL x 46.07 g/mol = 24617.3 g

We can then calculate the volume of ethanol in the solution by dividing the mass of ethanol (24617.3 g) by the density of ethanol (0.7893 g/mL):

Volume of ethanol = 24617.3 g/0.7893 g/mL = 31202.1 mL

Therefore, the difference in volume between the total volume of water and ethanol that were mixed to prepare the solution and the actual volume of the solution is:

Difference in volume = Volume of ethanol + Volume of water - Actual volume of solution

Difference in volume = 31202.1 mL + 594.0 mL - (529.0 mL + 594.0 mL) = 277.1 mL

The difference in volume between the total volume of water and ethanol that were mixed to prepare the solution and the actual volume of the solution is 277.1 mL.

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Answer:

Condensation is the process that took place when the water droplets formed on the grass.

Explanation:

Condensation is the process that took place when the water droplets formed on the grass. This occurs when airborne water vapour meets a colder surface, like the grass blades in the morning, and transforms into liquid form, generating tiny water droplets on the surface.

The concentration of the solution is 7.02 × 10⁻⁴ mol/L.

The Beer-Lambert law or Beer's law states that the amount of light absorbed by a solution is directly proportional to the concentration of the absorbing material in the solution, the path length, and the absorption coefficient.

According to Beer's law,

A = εcl

where A is the absorbance, ε is the molar absorptivity, c is the concentration, and l is the path length.

Let's find the concentration of the solution from the given data using Beer's law.

A = εcl

0.929 = ε × c × l

Let's find the molar absorptivity (ε) from the data given.

Experimental beer's law for copper(ii) ions in solution at 814 nm was determined to be

ε = 1.32 × 10³ mol⁻¹ L cm⁻¹

From the data given, the path length is not mentioned.

Let's consider the path length as 1 cm.

So, l = 1 cm.

0.929 = (1.32 × 10³ mol⁻¹ L cm⁻¹) × c × 1 cmc

= 0.929/1.32 × 10³ mol/L

= 7.02 × 10⁻⁴ mol/L

The concentration of the solution is 7.02 × 10⁻⁴ mol/L.

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The amount of heat transferred would be -8.85 kJ.

To calculate the heat transferred, we need to first determine the limiting reactant, which is the reactant that is completely consumed in the reaction. This will determine the amount of product that can be formed and hence the amount of heat released.

We start by calculating the moles of sulfur and oxygen:

Moles of sulfur = 0.54 g / 32.06 g/mol = 0.0168 mol

Moles of oxygen = 0.54 g / 31.998 g/mol = 0.0169 mol

The balanced equation shows that 2 moles of sulfur react with 3 moles of oxygen to produce 2 moles of sulfur trioxide. So, the ratio of moles of sulfur to oxygen in the reaction is 2:3. Since the ratio of moles of sulfur to oxygen in the reactants is less than 2:3, oxygen is the limiting reactant.

The amount of sulfur trioxide produced can be calculated using the mole ratio from the balanced equation:

Moles of sulfur trioxide produced = 0.0169 mol * (2 mol SO3 / 3 mol O2) = 0.0112 mol

The heat transferred in the reaction can be calculated using the heat of reaction per mole of sulfur trioxide:

Heat transferred = 0.0112 mol * (-790 kJ/mol) = -8.85 kJ

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Mole fraction of the water in the solution made using 145.7 g of water and 120.0 g of ethanol is 0.7564 mole.

Mass of water = 145.7 g

molar mass of water = 18.02 g/mole

Number of moles = mass ÷ molar mass

                             = 145.7 g ÷ 18.02 g/mole

                             = 8.085 mole

mass of ethanol = 120 g

molar mass of ethanol = 46.07 g/mole

Number of moles = mass ÷ molar mass

                              = 120 g ÷ 46.07 g/mole

                              = 2.6047 mole

Total number of moles = moles of water + moles of ethanol

                                      = 8.085 mole + 2.6047 mole

                                      = 10.6897 mole

The term mole fraction is also known as molar fraction. It is defined as unit of the amount of a constituent divided by the total amount of all constituents in a mixture.

Mole fraction of water = moles of water ÷ Total number of moles

                                     = 8.085 mole ÷  10.6897 mole

                                     = 0.756335

                                     = 0.7564 mole approximately.

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At the final temperature, the ice has melted completely and the water has cooled down to the same temperature. Therefore, we can set the final temperature as T_f for both ice and water.

To determine the final temperature of the system, we need to use the principle of conservation of energy. The energy lost by the water when it cools down must be equal to the energy gained by the ice when it melts and warms up. We can express this as:

Q_water = Q_ice

where Q_water is the heat lost by the water and Q_ice is the heat gained by the ice.

The heat lost by the water can be calculated using the formula:

Q_water = m_water * C_water * ΔT

where m_water is the mass of water, C_water is the specific heat capacity of water, and ΔT is the change in temperature of water.

The heat gained by the ice can be calculated using the formula:

Q_ice = m_ice * L_f + m_ice * C_ice * ΔT

where m_ice is the mass of ice, L_f is the heat of fusion of ice, C_ice is the specific heat capacity of ice, and ΔT is the change in temperature of ice

Now we can set up the equation:

m_water * C_water * (T_i - T_f) = m_ice * L_f + m_ice * C_ice * (T_f - T_i)

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Answer:

The balanced chemical equation for the combustion of methane (CH4) with oxygen (O2) is:

CH4 + 2O2 → CO2 + 2H2O

This equation tells us that for every mole of methane that reacts, we get 2 moles of water produced. So, for 3 moles of methane, we would get:

3 moles CH4 × (2 moles H2O / 1 mole CH4) = 6 moles H2O

Now we need to convert moles of water to mass. The molar mass of water (H2O) is 18.015 g/mol. So, the mass of water produced is:

6 moles H2O × 18.015 g/mol = 108.09 g

Therefore, if 3 moles of methane reacts with oxygen to produce carbon dioxide and water, 108.09 g of water is produced.

Explanation:

The molarity of Tylenol is 0.21 M, rounded to two significant figures. Hence, the correct option is (B) i.e. 0.21 M.

To find the molarity of Tylenol, we need to know the number of moles of acetaminophen present in 5 mL of medicine.

First, let's calculate the molecular weight of acetaminophen:

C = 12.011 g/mol x 8 = 96.088 g/mol

H = 1.008 g/mol x 9 = 9.072 g/mol

N = 14.007 g/mol x 1 = 14.007 g/mol

O = 15.999 g/mol x 2 = 31.998 g/mol

Total molecular weight = 96.088 g/mol + 9.072 g/mol + 14.007 g/mol + 31.998 g/mol = 151.165 g/mol

Next, we can use the given mass of acetaminophen in 5 mL of medicine to calculate the number of moles:

0.16 g acetaminophen x (1 mol / 151.165 g) = 0.001058 mol

Finally, we can use the definition of molarity to calculate the molarity of Tylenol:

Molarity = moles of solute / volume of solution in liters

Since we have 0.001058 moles of acetaminophen in 5 mL of medicine, which is equivalent to 0.005 L of solution, we can calculate the molarity as:

Molarity = 0.001058 mol / 0.005 L = 0.2116 M

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Answer:333.3333 mL or 333mL

Explanation:

M1V1 = M2 V2

M1= 3.00 M

V2= 2500 ml

M2= 0.400M

V1= solving for

V1= M2V2/M1

0.400 X 2500 / 3.00  =

The resulting solution is a homogeneous mixture of Na+, NO3^-, NH4+, and Cl^- ions surrounded by water molecules.

When solutions of sodium nitrate (NaNO3) and ammonium chloride (NH4Cl) are mixed, the resulting solution contains the ions Na+, NO3^-, NH4+, and Cl^-. All of these ions are soluble in water, so the solution remains clear and homogeneous. On a molecular scale, the Na+ ions are surrounded by water molecules, as are the NO3^- ions, NH4+ ions, and Cl^- ions. This is known as hydration, and it is the reason why these compounds are soluble in water. The ions are free to move around in the solution, which allows them to conduct electricity.

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Answer:

Explanation:

λν = c

Wavelength, λ (lambda), times frequency, ν (nu), equals the speed of light.

c = 3.0 x 108 m/s

===

We are given a wavelength of 483 nanometers.  1 nanometer = 1x10^-9 meter.   483nm = 4.83x10^-7 meters

---

λν = c

ν = c/λ

ν = (3.0x10^8 m/s)/(4.83x10^-7 m)

ν = 6.21x10^14 Hz  (1/s)

Most of the volume of an atom is taken up by the Electron clouds, and most of the mass of an atom is found in the nucleus.

Most of the volume of an atom is taken up by the electron clouds. This is because electrons occupy the space surrounding the nucleus in orbitals and they have a relatively large amount of space between them. The electron clouds represent the region in which electrons are likely to be found at any given time.

Most of the mass of an atom is found in the nucleus. The nucleus is made up of protons and neutrons, which have a much larger mass compared to electrons. Although the nucleus is much smaller in size compared to the electron clouds, it contains almost all of the mass of an atom.

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Answer:

78 grams of sodium sulfide should be formed

Explanation:

The balanced chemical equation for the reaction between sodium and sulfur is:

2 Na + S → Na2S

According to the equation, 2 moles of sodium react with 1 mole of sulfur to produce 1 mole of sodium sulfide. The molar mass of sodium is approximately 23 g/mol and the molar mass of sulfur is approximately 32 g/mol.

We need to determine which reactant is limiting and which is in excess in order to calculate the amount of sodium sulfide produced.

Using the given masses, we can calculate the number of moles of each reactant:

moles of sodium = 23 g / 23 g/mol = 1 mol

moles of sulfur = 32 g / 32 g/mol = 1 mol

From this calculation, we can see that both reactants are present in the stoichiometric ratio required by the balanced equation, so neither is limiting.

Therefore, the amount of sodium sulfide formed will be based on the amount of either reactant, which is 1 mole. Using the molar mass of sodium sulfide (78 g/mol), we can calculate the mass of sodium sulfide formed:

mass of Na2S = 1 mol x 78 g/mol = 78 g

Therefore, when 23 grams of sodium react with 32 grams of sulfur, a total of 78 grams of sodium sulfide should be formed.

The depth range of the epilimnion in this lake is most likely a. 0 to 3 meters. Option A is correct.

To determine the depth range of the epilimnion, we need to identify the layer of the lake where the temperature change is most rapid, which indicates the transition between the warm surface layer and the colder deep layer.

Looking at the temperature readings, we can see that there is a significant temperature difference between the surface layer (0-3 meters) and the layer below (4-7 meters).

However, the temperature change between 4-7 meters and 8-12 meters is not as dramatic, indicating that the transition between the warm surface layer and the colder deep layer occurs somewhere between 3 and 8 meters.

Hence, A. 0 to 3 is the correct option.

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Answer:

Based on the given scenario, Hodah's leadership style can be described as a transactional theory. This theory suggests that leaders provide rewards or punishments based on the performance of their followers. In this case, Hodah has devised a bonus system to motivate the sales team to perform better by providing them with incentives such as gift cards for every new client and pallets of paper sold. This approach focuses on providing rewards to motivate and improve performance.

Answer:

hydrogen,lithium, sodium