What is the value for the potential energyfor a n = 6 Bohr orbit electron in Joules?

As the volume of confined gas decreases at the constant temperature, the pressure exerted by the gas increases .  The correct option is C.

Boyle–Mariotte law is a gas law, shows the relation between pressure and volume. With the increase in the volume, the pressure decreases.

The pressure exerted by the mass, is inversely proportional to the volume of the gas.

Thus, the correct option is C, increases.

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Answer:

Due to the low difference of electronegativity in carbon and nitrogen, these will form a covalent bond, and this covalent union of C-N is one of the most common bonds in the organic chemistry and biological systems. This type of bonds can be found in amines, amides, imines, etc. Also, a single atom of C and a single atom of N can form a cyanide, that is a triple covalent bond between the atoms.

The correct chemical formula for Iron(III) hydroxide is Fe(OH)3, which is formed by combining one iron ion with a +3 charge (Fe3+) with three hydroxide ions (OH-).

The chemical formula for Iron(III) hydroxide is Fe(OH)3. This compound consists of an iron ion with a +3 charge (Fe3+) and three hydroxide ions (OH-). The number in parentheses after iron indicates the oxidation state of iron, which in this case is +3. The formula reflects the stoichiometry required to balance the charges, resulting in one Fe3+ for every three OH- ions to form the neutral compound. Therefore, the correct answer is Fe(OH)3.

The correct answer is d. Fe(OH)₃.

Answer:

The percentage mass of Manganese is 34.76%

Explanation:

The formula of potassium permanganate is KMnO4

Its molar mass is 158.034 g/mol.

The molar mass of Mn is 54.938 g/mol.

Percentage mass of Mn is:

[tex]Mn=\frac{54.938}{158.034}100[/tex]

Mn=34.76%

Answer:

Q = 47.1 kW

Texit = 25.93ºC

Explanation:

The heat transfer is occurring by convection, which means that the heat is flowing from different materials (tube for water). So, by Newton Cooling Law:

Q = h x A x ΔT

The area of the tube will be :

A = πdL

Where d is the diameter and L is the length.

d = 2.5 cm = 0.025 m

A = 3.14x0.025x4 = 0.314 m²

Then

Q = 3000x0.314x50

Q = 47100 W = 47.1 kW

By the heat equation for water, knowing that the specific heat (c) of water is 4.5 kJ/ºC

Q = mcΔT

47.11 = 0.5x4.5x(Texits - Tenters)

47.1 = 2.25x(Texits - 5ºC)

Texits - 5ºC = 20.93 ºC

Texits = 25.93ºC

47.1 kW is the rate of heat transfer and 25.93ºC is the temperature of the water at exit.

We can calculate the rate of heat transfer of the water by using the Newton's cooling law as:

Q = h x A x ΔT, where

h = heat transfer coefficient = 3000 W/m².°C (given)

A = surface area of heat transfer

ΔT = change in temperature = 50°C (given)

First we calculate the area by using the below formula:

A = πdL, where

d = diameter of tube = 2.5cm = 0.025m

L = length of tube = 4m

A = 3.14 x 0.025 x 4 = 0.314 m²

Therefore, rate of heat transfer is:

Q = 3000 x 0.314 x 50 = 47100 W = 47.1 kW

Now we calculate the rise in temperature by using the below formula:

Q = mcΔT

47.11 = 0.5 x 4.5 x (Texits - Tenters)

47.1 = 2.25 x (Texits - 5ºC)

Texits - 5ºC = 20.93 ºC

Texits = 25.93ºC

Hence, 47.1 kW is the rate of heat transfer and 25.93ºC is the temperature of exit water.

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Answer:

The list and discussions are stated below:

Explanation:

Good Laboratory Practice (GLP) is extremely important.

1. Organization

With GLP we can guarantee an organized work environment, which is essencial in a laboratory.

2. Safety

GLP promotes laboratory safety for personell, avoiding unecessary risks and preventing accidents.

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GLP ensures that experiments made and products developed in a laboratory have the demanded quality.

4. Reliability of results

GLP promotes quality of results reporting, wich directly influences the reliability of results.

The coffee solution is unsaturated with sugar.

A sugar and water solution is created when sugar dissolves in water. In this case, Vanessa pours 52 kilograms of table sugar, which is the solute, into 100 mL of coffee, which is the solvent. Since most of the sugar does not dissolve, the coffee solution can be considered unsaturated with sugar.

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Answer:

[tex]3.4\times 10^3 eggs[/tex] are produces are in a month.

Explanation:

Quantity of eggs produced by the chicken in a month = 284 dozens

1 dozen = 12 eggs

Number of eggs in a month:

[tex]284 dozens = 284\times 12 eggs =3,408 eggs\approx 3.4\times 10^3 eegs[/tex]

[tex]3.4\times 10^3 eggs[/tex] are produces are in a month.

Answer:

Few important points related to [tex]S_N2[/tex] reaction:

1. [tex]S_N2[/tex] is a one-step reaction that follows second order kinetics.

2. In [tex]S_N2[/tex] reaction, a transition state is formed in situ.

3. Strong nucleophiles like [tex]OH^- \ or\  CN^-[/tex] are used in case of bi-molecular nucleophilic substitution reaction.

Ethyl acetate can be prepared by a second-order nucleophilic substitution reaction between acetic acid and ethyl bromide.  

The reaction between acetic acid and ethyl bromide is drawn below:

In the SN2 reaction to create ethyl acetate, the nucleophile acetate ion attacks the alkyl bromide, leading to the formation of ethyl acetate and bromide ions.

Ethyl acetate can be prepared by an SN2 reaction. In this context, an alkylbromide and nucleophile initiate the reaction. Ethyl bromide (CH3CH2Br) would be the alkylbromide used in the reaction. The nucleophile, in this case, would be acetate ion (CH3COO-).

Ethyl bromide is a good leaving group and acetate ion is a strong nucleophile, which comes from acetic acid (ethanoic acid). In SN2 reactions, the nucleophile attacks the substrate, and the leaving group (Br- in this case) leaves, leading to a reverse configuration. In this reaction, the nucleophile (acetate ion) will attack the alkyl bromide, resulting in the formation of ethyl acetate, CH3COOCH2CH3, and bromide ions, which is a good leaving group.

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Answer:

[tex]T_{2}=16,97^{\circ}C[/tex]

Explanation:

The specific heats of water and steel are  

[tex]Cp_{w}=4.186 \frac{KJ}{Kg^{\circ}C}[/tex]

[tex]Cp_{s}=0.49 \frac{KJ}{Kg^{\circ}C}[/tex]

Assuming that the water and steel are into an adiabatic calorimeter (there's no heat transferred to the enviroment), the temperature of both is identical when the system gets to the equilibrium [tex]T_{2}_{w}= T_{2}_{s}[/tex]  

An energy balance can be written as

[tex] m_{w}\times Cp_{w}\times (T_{2}- T_{1})_{w}= -m_{s}\times Cp_{s}\times (T_{2}- T_{1})_{s} [/tex]  

Replacing

[tex] 1.28Kg\times 4.186\frac{KJ}{Kg^{\circ}C}\times (T_{2}-10^{\circ}C)= -0.385Kg\times 0.49 \frac{KJ}{Kg^{\circ}C} \times (T_{2}-215^{\circ}C)[/tex]

Then, the temperature [tex]T_{2}=16,97^{\circ}C[/tex]

The equilibrium temperature given that You drop a piece of steel at 215 °C into the water at 10.0 °C in the calorimeter is 16 °C

The equilibrium temperature given that You drop a piece of steel at 215 °C into the water at 10.0 °C can be calculated as follow:

[tex]MC(T - T_e) = M_wC_w(T_e - T_w)\\\\0.385\ \times\ 420(215 - T_e) = 1.28\ \times\ 4184(T_e - 10)[/tex]

[tex]34765.5 - 161.7T_e = 5355.52T_e - 53555.2\\\\34765.5\ +\ 53555.2 = 5355.52T_e\ +\ 161.7T_e\\\\88320.7 = 5517.22T_e\\\\T_e = \frac{88320.7}{5517.22} \\\\T_e = 16\ \textdegree C[/tex]

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Answer:

The required volume is 1.6 x 10³mL.

Explanation:

When we want to prepare a dilute solution from a concentrated one, we can use the dilution rule to find out the required volume to dilute. This rule states:

C₁ . V₁ = C₂ . V₂

where,

C₁ and V₁ are the concentration and volume of the concentrated solution

C₂ and V₂ are the concentration and volume of the dilute solution

In this case, we want to find out V₁:

C₁ . V₁ = C₂ . V₂

[tex]V_{1} = \frac{C_{2}.V_{2}}{C_{1}} = \frac{1.5M \times1.11.10^{4}mL }{10.2M} =1.6\times10^{3} mL[/tex]

Answer: The weight fraction of ethanol in the mixture is

Explanation:

We are given:

Mass of water = 1 kg = 2.205 lb   (Conversion factor:  1 kg = 2.205 lb)

Mass of ethanol = 1.9 lb

Mass of ethyl acetate = 4.6 lb

Mass of mixture = [2.205 + 1.9 + 4.6] = 8.705 lb

To calculate the percentage composition of ethanol in mixture, we use the equation:

[tex]\%\text{ composition of ethanol}=\frac{\text{Mass of ethanol}}{\text{Mass of mixture}}\times 100[/tex]

Mass of mixture = 8.705 lb

Mass of ethanol = 1.9 lb

Putting values in above equation, we get:

[tex]\%\text{ composition of ethanol}=\frac{1.9lb}{8.705lb}\times 100=21.8\%[/tex]

Hence, the weight fraction of ethanol in the mixture is 21.8 %

Answer:

For 1: The correct answer is Ge.

For 2: The correct answer is Te.

For 3: The correct answer is Ba.

For 4: The correct answer is Ag.

Explanation:

Ionization energy is defined as the energy required to remove an electron from the outermost shell of an isolated gaseous atom. It is represented as [tex]E_i[/tex]

[tex]X(g)\rightarrow X^+(g)+1e^-;E_i[/tex]

Ionization energy increases as we move from left to right in a period. This happens because the atomic radius of an element decreases moving across a period, which increases the effective attraction between the negatively charged electrons and positively-charged nucleus. Hence, the removal of electron from the outermost shell becomes difficult and requires more energy.

Ionization energy decreases on moving from top to bottom in a group. This happens because the number of shells increases as we move down the group. The electrons get added in the new shell. So, the shielding of outermost electrons from the inner ones is more which decreases the attraction between the electrons and the nucleus. Hence, the removal of electron from the outermost shell becomes easy and requires less energy.

For the given options:

Chlorine is the 17th element of the periodic table belonging to Period 3 and Group 17.

Germanium is the 32nd element of the periodic table belonging to Period 4 and Group 14.

Hence, germanium will have smaller first ionization energy.

Tellurium is the 52nd element of the periodic table belonging to Period 5 and Group 16.

Selenium is the 34th element of the periodic table belonging to Period 4 and Group 16.

Hence, tellurium will have smaller first ionization energy.

Barium is the 56th element of the periodic table belonging to Period 6 and Group 2.

Titanium is the 22nd element of the periodic table belonging to Period 4 and Group 4.

Hence, barium will have smaller first ionization energy.

Copper is the 29th element of the periodic table belonging to Period 4 and Group 11.

Silver is the 47th element of the periodic table belonging to Period 5 and Group 11.

Hence, silver will have smaller first ionization energy.

Ionization energy increases across the period but decreases down the group.

First ionization energy of an element refers to the energy required to remove an electron from the atom. Ionization energy is a periodic trend that increases across the period but decreases down the group.

The following are true regarding the statements in the question;

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Answer:

There are three major sources of errors in numerical method, namely human error, truncation error and round off error, but here we have to discuss only two sources-

Answer:

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Explanation:dsf

Answer:

12.4 × 10∧3 atoms

Explanation:

Given data:

moles of oxygen molecule= 1.0000 x 10-20 mol

atoms =?

Solution:

32 g O2 = 1 mol = 6.02 × 10∧23

1.0000 x 10∧-20 mol × 6.02 × 10∧23 × 2 = 12.4 × 10∧3 atoms

Answer:

d. 1600 calories

Explanation:

The heat of fusion of water, L, is the amount of heat per gram required to melt the ice to water, a process which takes place at a constant temperature of 0 °C. The specific heat of water, c, is the amount of heat required to change the temperature of 1 gram of water by 1 degree Celsius.

We will convert the units of c from Jg⁻¹°C⁻¹ to cal·g⁻¹°C⁻¹ since the answers are provided in calories. The conversion factor is 4.18 J/cal.

(4.18 Jg⁻¹°C⁻¹)(cal/4.18J) = 1 cal·g⁻¹°C⁻¹

First we calculate the heat required to melt the ice, where M is the mass:

Q = ML = (15 g)(80 cal/g) = 1200 cal

Then, we calculate the heat required to raise the temperature of water from 0 °C to 25 °C.

Q = mcΔt = (15 g)(1 cal·g⁻¹°C⁻¹)(25 °C - 0 °C) = 380 cal

The answer is rounded so that there are two significant figures

The total heat required for this process is (1200 cal + 380 cal) = 1580 cal

The rounded answer is 1600 calories.

Answer: liquid water

Explanation:

Entropy is the measure of randomness or disorder of a system. If a system moves from an ordered arrangement to a disordered arrangement, the entropy is said to decrease and vice versa.

[tex]\Delta S[/tex] is positive when randomness increases and [tex]\Delta S[/tex] is negative when randomness decreases.

Gases have more entropy than liquids and liquids have more entropy than solids due to movement of particles.

Thus liquid water will have more entropy than crushed ice.

The correct answer is liquid water. Liquid water has a higher entropy than crushed ice because the transition from solid to liquid increases the disorder and number of possible microstates for water molecules.

The question of which substance, liquid water or crushed ice, has the highest entropy touches upon the concept of phase transitions and the disorder of molecular systems. The entropy of a system is a measure of its randomness or disorder, where a greater number of possible microstates corresponds to higher entropy.

When ice melts into water, the structure of water molecules becomes less ordered, allowing more freedom of movement. This transition from a solid to a liquid state results in an increase in entropy. Therefore, liquid water has a higher entropy than crushed ice because the molecules in the liquid state have more freedom to move and occupy a greater number of microstates.

Explanation:

(a)  An isochoric process is defined as the process in which volume of a system remains constant.

For example, an air conditioner follows an isochoric process.

(b) As pressure and temperature can change in an isochoric process but volume will remain the same.

Hence, heat can also be exchanged in an isochoric process. Whereas in an adiabatic process heat remains 0. Therefore, it means the in adiabatic process there occurs no exchange of heat between the system and its surrounding.

(c) It is given that V = 100 L = 0.1 [tex]m^{3}[/tex]   (as 1 L = 0.001 [tex]m^{3}[/tex])

               [tex]P_{1}[/tex] = [tex]10 \times 10^{6} Pa[/tex]

               [tex]P_{2}[/tex] = [tex]15 \times 10^{6} Pa[/tex]

Relation between work, pressure and volume is as follows.

                     W = [tex]\Delta PV[/tex]

                         = PdV + VdP

                          = 0 + 0.1 [tex]m^{3} (15 - 10) \times 10^{6}[/tex]

(Since V = constant so, dV = 0)

                          = [tex]5 \times 10^{5} J[/tex]

Thus, we can conclude that work done is [tex]5 \times 10^{5} J[/tex].

Answer:

49.3% 81Br and 50.7% 79Br or [tex]\frac{493}{1000}[/tex] 81Br and [tex]\frac{507}{1000}[/tex] 79BR

Step-by-step explanation:

To get the fraction-of-occurrences of the isotopes we must write the following equation. x is the isotopic abundance of 81Br, we can use 1 - x to get the isotopic abundance of 79Br.

(78.918)(1 - x) + (80.916)(x) = 79.903

78.918 - 78.918x + 80.916x = 79.903

1.998x = 0.985

x = 0.493

0.493 × 100 = 49.3% 81Br

100 - 49.3 = 50.7% 79Br

49.3% 81Br and 50.7% 79Br or [tex]\frac{493}{1000}[/tex] 81Br and [tex]\frac{507}{1000}[/tex] 79BR

A theory is a well-substantiated explanation of observed phenomena that has undergone rigorous testing and validation through the scientific method.

A consistent explanation of known observations is called a theory. In the realm of science, a theory is more than just a simple guess; it is a well-substantiated explanation that is grounded in a significant body of evidence. This evidence consists of a series of facts and observations that, when considered collectively, give a reliable account of a part of the natural world. To arrive at a theory, the scientific method is typically employed, involving systematic observations, forming hypotheses, conducting experiments, and refining those hypotheses based on experimental results. When a hypothesis withstands rigorous testing and is capable of explaining a large and diverse range of phenomena, it can evolve into a theory. Scientific theories are valued because they offer comprehensive explanations that are testable and can be modified in the face of new evidence.

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Answer:

The sample of lithium occupies the largest volume.

Explanation:

Given the densities for the four elements, we have the expression [tex]d=\frac{m}{V}[/tex] that shows the relationship between mass and Volume to express the density of an element.

For each element we have:

[tex]d_{lithium}=\frac{m_{lithium}}{V_{lithium}}=0.53g/mL[/tex]

[tex]d_{gold}=\frac{m_{gold}}{V_{gold}}=19.3g/mL[/tex]

[tex]d_{aluminum}=\frac{m_{aluminum}}{V_{aluminum}}=2.70g/mL[/tex]

[tex]d_{lead}=\frac{m_{lead}}{V_{lead}}=11.3g/mL[/tex]

The problem says that all the samples have the same mass, so:

[tex]m_{lithium}=m_{gold}=m_{aluminum}=m_{lead}=m[/tex]

it means that m is a constant

Now, solving for the Volume in each element and with m as a constant, we have:

[tex]V_{lithium}=\frac{m}{d_{lithium}}[/tex]

[tex]V_{lithium}=\frac{1}{0.53\frac{g}{mL}} *m[/tex]

[tex]V_{lithium}=1.88\frac{mL}{g}*m[/tex]

[tex]V_{gold}=\frac{m}{d_{gold}}[/tex]

[tex]V_{gold}=\frac{1}{19.3\frac{g}{mL}} *m[/tex]

[tex]V_{gold}=5.18*10^{-2}\frac{mL}{g}*m[/tex]

[tex]V_{aluminum}=\frac{m}{d_{aluminum}}[/tex]

[tex]V_{aluminum}=\frac{1}{2.70\frac{g}{mL}} *m[/tex]

[tex]V_{aluminum}=3.70*10^{-1}\frac{mL}{g}*m[/tex]

[tex]V_{lead}=\frac{m}{d_{lead}}[/tex]

[tex]V_{lead}=\frac{1}{11.3\frac{g}{mL}} *m[/tex]

[tex]V_{lead}=8.85*10^{-2}\frac{mL}{g}*m[/tex]

If we assume m = 1g, we find that:

[tex]V_{lithium}=1.88mL[/tex]

[tex]V_{gold}=5.18*10^{-2}mL[/tex]

[tex]V_{aluminum}=3.70*10^{-1}mL[/tex]

[tex]V_{lead}=8.85*10^{-2}mL[/tex]

So we can see that the sample of lithium occupies the largest volume with 1.88mL

Note that m only can take positive values, so if you change the value of m, always will be the lithium which occupies the largest volume.

Answer:

The answer is b)

Explanation:

In packed column the mass transfer area is higher and the packing can be random, that could provoque an increase in the pressure, because obstruction of the mass flux, While in a tray column the sieves can have specific porosity and the flux of mass can be facilitated, thus the pressure drop.  

Answer: The number of hydrogen molecules in the given amount is [tex]1.454\times 10^{25}[/tex]

Explanation:

To calculate the number of moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]

Given mass of hydrogen gas = 48.3 g

Molar mass of hydrogen gas = 2 g/mol

Putting values in above equation, we get:

[tex]\text{Moles of hydrogen gas}=\frac{48.3g}{2g/mol}=24.15mol[/tex]

According to mole concept:

1 mole of a compound contains [tex]6.022\time 10^{23}[/tex] number of molecules

So, 24.15 moles of hydrogen gas will contain = [tex]24.15\times 6.022\times 10^{23}=1.454\times 10^{25}[/tex] number of molecules.

Hence, the number of hydrogen molecules in the given amount is [tex]1.454\times 10^{25}[/tex]

Answer:

The expression to calculate the mass of the reactant is [tex]m = \frac{1.080kJ}{31.2kJ/g}[/tex]

Explanation:

The amount of heat released is equal to the amount of heat released per gram of reactant times the mass of the reactant. To keep to coherence between units we need to transform 1,080 J to kJ. We do so with proportions:

[tex]1,080J.\frac{1kJ}{10^{3}J } =1.080kJ[/tex]

Then,

[tex]1.080kJ=31.2\frac{kJ}{g} .m\\m = \frac{1.080kJ}{31.2kJ/g}[/tex]

Answer:

1. The expression is: [tex]m=\frac{E}{\Delta _rH}[/tex]

2. The computed mass is: [tex]m=0.0346g[/tex]

Explanation:

Hello,

In this case, we know the so called enthalpy of reaction whose symbol and value is shown below:

[tex]\Delta _rH=31.2\frac{kJ}{g}[/tex]

In addition, we know that the energy released by the involved reactant is:

[tex]E=1080 J[/tex]

Therefore, the expression to compute the required mass, based on the given units is:

[tex]m=\frac{E}{\Delta _rH}[/tex]

Finally, the computed mass turns out:

[tex]m=\frac{1080J*\frac{1kJ}{1000J} }{31.2\frac{kJ}{g}} \\m=0.0346g[/tex]

Best regards.

Answer: Option (a) is the correct answer.

Explanation:

Alkynes are the hydrocarbons, that is, they contain only atoms of carbon and hydrogen. Their general chemical formula is [tex]C_{n}H_{2n-2}[/tex], where n is a whole number.

A compound that contains a double or triple bond is known as an unsaturated compound. An alkyne contains a triple bond and it is also an unsaturated compound.

Thus, we can conclude that alkynes are hydrocarbons that have at least one triple bond between carbon atoms.

Answer:

pH of acetic acid solution is 2.88

Explanation:

[tex]pK_{a}=4.75[/tex]

or, [tex]-log(K_{a})=4.75[/tex]

or, [tex]K_{a}=10^{-4.75}=1.78\times 10^{-5}[/tex]

We have to construct an ICE table to determine concentration of [tex]H^{+}[/tex] and corresponding pH. Initial concentration of acetic acid is 0.1 M.

[tex]CH_{3}COOH\rightleftharpoons CH_{3}COO^{-}+H^{+}[/tex]

I(M):  0.1                            0                    0

C(M): -x                              +x                 +x

E(M): 0.1-x                         x                    x

So, [tex]\frac{[CH_{3}COO^{-}][H^{+}]}{[CH_{3}COOH]}=K_{a}[/tex]

or, [tex]\frac{x^{2}}{0.1-x}=1.78\times 10^{-5}[/tex]

or, [tex]x^{2}+(1.78\times 10^{-5}\times x)-(1.78\times 10^{-6})=0[/tex]

So, [tex]x=\frac{-(1.78\times 10^{-5})+\sqrt{(1.78\times 10^{-5})^{2}+(4\times 1\times 1.78\times 10^{-6})}}{2\times 1}[/tex](M)

so, [tex]x=1.33\times 10^{-3}M[/tex]

Hence [tex]pH=-log[H^{+}]=-log(1.33\times 10^{-3})=2.88[/tex]

Answer:

Each cyclist will need to drink 619 l

Explanation:

Hi there!!

First, let´s convert the miles to kilometers:

If 1.0 mi = 1609 m, then 385 mi will be:

385 mi · (1609 m/ 1.0 mi) ·  (1 km/ 1000 m) = 619 km

Now, if each cyclist need to drink one liter water per kilometer ( I think that´s a lot of water!), for the entire journey each cyclist will need to drink:

619 km · 1 l/km = 619 l

Then, each cyclist will need to drink 619 l.

Answer:

There are 1.041×10²³ atoms in 4.20g of Magnesium.

Explanation:

To find the amount of atoms in 4.20 g of Magnesium we need de molar mass of Mg: 24.305 g/mol

According to Avogadro number there are 6.022×10²³ particles in 1 mol, so the number of atoms of Mg is:

[tex]4.20 g Mg*\frac{1 molMg}{24.305gMg} *\frac{6.022*10^{23}atoms }{1 mol Mg} = 1.041*10^{23}atoms Mg[/tex]

Answer: The number of atoms found in given amount of magnesium is [tex]1.042\times 10^{23}[/tex]

Explanation:

To calculate the number of moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]

Given mass of magnesium = 4.20 g

Molar mass of magnesium = 24.31 g/mol

Putting values in above equation, we get:

[tex]\text{Moles of magnesium}=\frac{4.20g}{24.31g/mol}=0.173mol[/tex]

According to mole concept:

1 mole of an element contains [tex]6.022\times 10^{23}[/tex] number of atoms

So, 0.173 moles of an element contains = [tex]0.173\times 6.022\times 10^{23}=1.042\times 10^{23}[/tex] number of atoms

Hence, the number of atoms found in given amount of magnesium is [tex]1.042\times 10^{23}[/tex]

Answer:

Exit velocity of air is 96.43 m/s.

Explanation:

Given that

[tex]V_1=400\ m/s[/tex]

[tex]T_1=25C[/tex]

[tex]T_2=100C[/tex]

For air

[tex]C_p=1.005\ KJ/kg.K[/tex]

Now from first law of thermodynamics for open system at steady state

[tex]h_1+\dfrac{V_1^2}{2000}+Q=h_2+\dfrac{V_2^2}{2000}+w[/tex]

For diffuser

[tex]h_1+\dfrac{V_1^2}{2000}=h_2+\dfrac{V_2^2}{2000}[/tex]

We know that

[tex]h=C_pT[/tex]

[tex]h_1+\dfrac{V_1^2}{2}=h_2+\dfrac{V_2^2}{2000}[/tex]

[tex]1.005\times 25+\dfrac{400^2}{2000}=1.005\times 100+\dfrac{V_2^2}{2}[/tex]

[tex]V_2=96.43\ m/s[/tex]

So the exit velocity of air is 96.43 m/s.

Answer:

pH = 11

Explanation:

The concentration of OH⁻ in pure water is 10⁻⁷ M. If a substance increases OH⁻ concentration by 10⁴, the new concentration will be:

[OH⁻] = 10⁴ x 10⁻⁷ M = 10⁻³M

We can calculate pOH using it's definition:

pOH = -log[OH⁻] = -log (10⁻³) = 3

Then, we can find out pH using the following relation:

pH + pOH = 14

pH = 14 - pOH = 14 -3 = 11

Since pH = 11 is higher than 7, we can confirm that the substance is a base.