Please help I am kinda confused

The value of Sn = 1/3(2^n + 2cosnπ/3) if n is not a multiple of 3, when Sn =  nc0 + nc3 + nc6 + nc9 +...

Given that Sn = nC0 + nC1 + nC2 + nC3 +.....

We know that : (1 + x)^n = nC0 + nC1x + nC2x^2 + nC3x^3 +........+ nCnx^n

Let x = 1 then:

(1 + 1)^n = nC0 + nC1 + nC2 + nC3 +........+ nCn

2^n =  nC0 + nC1 + nC2 + nC3 +........+ nCn

Let x = ω then:

(1 + ω)^n = nC0 + nC1ω + nC2ω^2 + nC3ω^3 +........+ nCnω^n

Let x = ω^2 then:

(1 +ω^2)^n = nC0 + nC1ω^2 + nC2ω^4 + nC3ω^6 +........+ nCnω^2n

Adding the above three equations we get:

3(nC0 + nC3 + nC6 + nC9 + .....) = 2^n - (ω^2)^n + (-ω)^n

(nC0 + nC3 + nC6 + nC9 + .....) = 1/3(2^n + 2cosnπ/3)

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Yes they are

According to definition of an element

An element consists of several atoms of one type

So they are identical

Answer:

Although it may seem weird, the answer is actually yes.  An element is a pure substance consisting only of atoms that all have the same numbers of protons in their nuclei.  This means that all of the atoms are all the same because they contain the same amount of protons.

In conclusion, the atoms that make up an element are identical.

Explosive materials need to be handled carefully and stored appropriately to avoid the possibility of initial combustion.   The following are some of the precautions to take when handling explosive materials: Avoid any type of friction, impact, or shock, whether small or large, when handling explosive materials.

Keep the containers of explosive materials tightly sealed to prevent the infiltration of moisture or contaminants. Store the explosives in a cool, dry, and well-ventilated environment, keeping them away from any heat sources or flammable materials. Keep the explosives away from direct sunlight to prevent the heat from building up and causing an explosion.

In conclusion, explosive materials should be handled and stored with care to prevent initial combustion, which may lead to an explosion. Explosives should be stored in a dry, cool, and well-ventilated area, and containers should be kept tightly sealed to prevent moisture or contaminants from entering. Explosives should also be kept away from any heat sources or flammable materials.

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Answer: Percent composition by element

Element Symbol Mass Percent

Hydrogen H 6.498%

Carbon C 19.357%

Nitrogen N 22.574%

Oxygen O 51.571%

HOPE THIS HELPS

On the basis of classification, electrolytic cells use non-spontaneous reactions which require an external power source in order to proceed.

On the other end, galvanic cells are spontaneous reaction, meaning it occurs with no outside intervention

A chemical change or reaction simply refers to a change which is not easily reversed and in which no new substance is formed.

So therefore, On the basis of classification, electrolytic cells use non-spontaneous reactions which require an external power source in order to proceed.

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Answer:

C

Explanation:

When a line segment and a plane intersect, they intersect at a point. They both coincide on point C

The correct hydration equation for the formation of an aqueous solution of calcium iodide (CaI2) can be written as:

CaI2(s) + xH2O(l) ⟶ CaI2(xH2O)(aq)

In this equation, "x" represents the number of water molecules that are hydrated with each formula unit of calcium iodide. The value of "x" can vary depending on the conditions and the degree of hydration. Typically, calcium iodide forms a hexahydrate compound, so the equation can be further specified as:

CaI2(s) + 6H2O(l) ⟶ CaI2·6H2O(aq)

This means that each formula unit of calcium iodide reacts with six water molecules to form a hydrated calcium iodide complex in the aqueous solution.

Therefore,the correct hydration equation for the formation of an aqueous solution of calcium iodide (CaI2) can be written as:

CaI2(s) + xH2O(l) ⟶ CaI2(xH2O)(aq).

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Answer:

The answer to this question is 2.

The current would need to be applied for approximately 0.71 hours (or 42.6 minutes) to plate out 4.90 g of nickel.

To determine how long the current must be applied to plate out a certain amount of nickel, we need to use Faraday's laws of electrolysis, which relate the amount of material deposited on an electrode during electrolysis to the amount of electric charge passed through the solution.

The first step is to calculate the amount of electric charge that would be passed through the solution during the plating of 4.90 g of nickel. We can do this using the following equation:

Q = nF

where Q is the amount of electric charge (in coulombs), n is the number of moles of nickel being plated out, and F is Faraday's constant (96485 coulombs per mole of electrons).

The number of moles of nickel being plated out can be calculated from its molar mass:

molar mass of nickel = 58.69 g/mol

moles of nickel = 4.90 g / 58.69 g/mol = 0.0834 mol

Substituting into the equation above, we get:

Q = 0.0834 mol × 96485 C/mol = 8040 C

The next step is to use the current to determine the time required to pass this amount of electric charge. We can use the following equation:

Q = It

where I is the current (in amperes), t is the time (in seconds), and Q is the amount of electric charge (in coulombs).

To convert hours to seconds, we multiply by 3600:

t = Q / I = 8040 C / 3.16 A = 2544 s = 2544/3600 hours

Therefore, by calculating we can say that the current would need to be applied for approximately 0.71 hours (or 42.6 minutes) to plate out 4.90 g of nickel.

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The true statements are:

Options 2, 6 and 4 are correct.

The respiratory rate is described as  the rate at which breathing occurs; it is set and controlled by the respiratory center of the brain.

Sudden severe pain can cause a reflexive apnea whic is a temporary cessation of breathing but prolonged somatic pain typically leads to an increase in respiratory rate as part of a stress response, helping to provide oxygen and remove metabolic waste products.

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The formation of solid magnesium chloride (MgCl₂) by the reaction between chlorine gas (Cl₂) and magnesium metal (Mg) at high temperatures is classified as a synthesis reaction or a combination reaction.

Synthesis reactions involve the combination of two or more substances to form a single product. In this case, chlorine gas and magnesium metal combine to produce magnesium chloride as the sole product.

The balanced chemical equation for this synthesis reaction is:

Mg + Cl₂ ⇒ MgCl₂

Hence, the reaction between chlorine gas and magnesium metal to form solid magnesium chloride indicates a synthesis reaction, as the elements combine to form a compound.

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Answer:

D

Explanation:

First you multiply 4.65 with 21.82 to get the mols of hcl, which is 101.463. Then you make an ice table. The ice table should look like this:

HCl       +  NaOH     =  12NaCl + H2O

101.463   6.022e23   1.989e30

As the ice table above shows, you will have 1.989e30 mols of nacl after the reaction. With that information, you can then divide it by 2.833333333333333e30 to get 0.702 M.

D. The limb bones do not look as developed as

they do in the amphibian.

Answer:

it has fins like a fish

Explanation:

because it has a fin bone

The concentration of the diluted solution is 6.67 ppm, calculated using the given volumes and the concentration of the stock solution.

To find the concentration in ppm of the diluted solution, we can use the formula:
Concentration (ppm) = (Volume of solute / Volume of solution) * 10^6
Volume of solute (V1) = 5.00 ml
Volume of solution (V2) = 10.00 ml
We need to determine the concentration of the diluted solution.
First, we calculate the concentration of the stock solution:
Concentration of stock solution = 20.0 ppm
Next, we calculate the volume of the diluted solution:
Volume of diluted solution = V1 + V2 = 5.00 ml + 10.00 ml = 15.00 ml
Now, we can substitute the values into the formula to find the concentration of the diluted solution:
Concentration (ppm) = (V1 / V2) * Concentration of stock solution
Concentration (ppm) = (5.00 ml / 15.00 ml) * 20.0 ppm
Concentration (ppm) = 1/3 * 20.0 ppm
Concentration (ppm) = 6.67 ppm
Therefore, the concentration of the diluted solution is 6.67 ppm, reported with the correct number of significant figures.

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A gaseous mixture of O2 and N2 contains 30.8 % nitrogen by mass and if the total pressure is 465 mmhg then the partial pressure of oxygen in the mixture is 306.9 mmHg.

If a gaseous mixture of O2 and N2 contain 30.8% nitrogen by mass. It means 100 g of the mixture, there will be 30.8 g of N2.

So, the mass of O2 in 100 g of mixture is

m(O2) = 100 g - 30.8 = 69.2 g

Now, we will calculate the moles of O2 and N2

For N2 = 30.8 g × 1 mol/ 28 = 1.1 mole

For O2 = 69.2 / 32 = 2.16 mole

The mole fraction of O2 can be calculated as

X(O2) = 2.16/(2.16 + 1.1)

= 2.16 / 3.26

= 0.66

Given,

Total pressure = 465 mm hg.

Now, we will calculate the partial pressure of oxygen as below

pO2 = P × x(O2) = 465 × 0.66 = 306.9 mmHg.

Thus, we concluded that if a gaseous mixture of O2 and N2 contains 30.8 % nitrogen by mass and if the total pressure is 465 mmhg then the partial pressure of oxygen in the mixture is 306.9 mmHg.

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By replacing one hydrogen atom of 2,2-dimethylbutane with a chlorine atom, 3 different compounds can be obtained, ignoring optical isomers.

To determine the number of different compounds that can be formed by replacing one hydrogen atom of 2,2-dimethylbutane with a chlorine atom, we need to identify the unique hydrogen positions in the molecule.

2,2-dimethylbutane has the following structure: CH3-C(CH3)2-CH2-CH3

There are three unique hydrogen positions:
1. Hydrogen atoms on the two terminal CH3 groups (methyl groups) - There are 6 hydrogen atoms in total at this position (3 on each methyl group), but they are equivalent. Replacing one of them will create the same compound.
2. Hydrogen atoms on the central C(CH3)2 carbon - There are 2 equivalent hydrogen atoms in this position.
3. Hydrogen atoms on the CH2 group - There are 2 equivalent hydrogen atoms in this position.

Now let's consider the possible compounds that can be formed:
1. Replace one hydrogen atom from the terminal methyl groups: CH2Cl-C(CH3)2-CH2-CH3
2. Replace one hydrogen atom from the central C(CH3)2 carbon: CH3-C(CH3)2-CHCl-CH3
3. Replace one hydrogen atom from the CH2 group: CH3-C(CH3)2-CH2-CH2Cl

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(a)

pH = 4.77

; (b)

[

H

3

O

+

]

=

1.00

×

10

-4

l

mol/dm

3

; (c)

[

A

-

]

=

0.16 mol⋅dm

-3

Explanation:

(a) pH of aspirin solution

Let's write the chemical equation as

m

m

m

m

m

m

m

m

l

HA

m

+

m

H

2

O

⇌

H

3

O

+

m

+

m

l

A

-

I/mol⋅dm

-3

:

m

m

0.05

m

m

m

m

m

m

m

m

l

0

m

m

m

m

m

l

l

0

C/mol⋅dm

-3

:

m

m

l

-

x

m

m

m

m

m

m

m

m

+

x

m

l

m

m

m

l

+

x

E/mol⋅dm

-3

:

m

0.05 -

l

x

m

m

m

m

m

m

m

l

x

m

m

x

m

m

m

x

K

a

=

[

H

3

O

+

]

[

A

-

]

[

HA

]

=

x

2

0.05 -

l

x

=

3.27

×

10

-4

Check for negligibility

0.05

3.27

×

10

-4

=

153

<

400

∴

x

is not less than 5 % of the initial concentration of

[

HA

]

.

We cannot ignore it in comparison with 0.05, so we must solve a quadratic.

Then

x

2

0.05

−

x

=

3.27

×

10

-4

x

2

=

3.27

×

10

-4

(

0.05

−

x

)

=

1.635

×

10

-5

−

3.27

×

10

-4

x

x

2

+

3.27

×

10

-4

x

−

1.635

×

10

-5

=

0

x

=

1.68

×

10

-5

[

H

3

O

+

]

=

x

l

mol/L

=

1.68

×

10

-5

l

mol/L

pH

=

-log

[

H

3

O

+

]

=

-log

(

1.68

×

10

-5

)

=

4.77

(b)

[

H

3

O

+

]

at pH 4

[

H

3

O

+

]

=

10

-pH

l

mol/L

=

1.00

×

10

-4

l

mol/L

(c) Concentration of

A

-

in the buffer

We can now use the Henderson-Hasselbalch equation to calculate the

[

A

-

]

.

pH

=

p

K

a

+

log

(

[

A

-

]

[

HA

]

)

4.00

=

−

log

(

3.27

×

10

-4

)

+

log

(

[

A

-

]

0.05

)

=

3.49

+

log

(

[

A

-

]

0.05

)

log

(

[

A

-

]

0.05

)

=

4.00 - 3.49

=

0.51

[

A

-

]

0.05

=

10

0.51

=

3.24

[

A

-

]

=

0.05

×

3.24

=

0.16

The concentration of

A

-

in the buffer is 0.16 mol/L.

hope this helps :)

The equilibrium constant of this reaction is 1.80×10-5

Given data,

pH of solution = 2.873

Number of moles of acetic acid (m) = 0.05 moles

Volume of water (V) =  500 mL = 0.5L

So, concentration (C) = m/V in lit = 0.05/0.5 = 0.1 M

Equilibrium constant ( K ) = \([CH_{3} COO-]\)×\([H+_{} ]\)/\([CH_{3} COOH]\)

Since, acetic acid is weak acid,

So, Equilibrium constant ( K ) = \([H+]^{2}\)/\([CH_{3} COOH]\)   ....(i)

As the pH = 2.873, the \([H+_{} ]\) is antilog of -2.873 or 1.34×10-3 M.

Putting the value of concentration of \(H+_{}\) and \(acetic_{} acid\) in equation (i).

Equilibrium constant ( K ) = 1.80×10-5

The acid which is partially dissociates into ions on dissolving in aqueous solution is called weak acid.

Example: \(acetic_{} acid\).

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1/3 fraction of the original uranium-235 should be left after 3.5 billion years

The only naturally occurring isotope of this radioactive metal, uranium-235, is capable of supporting a nuclear fission reaction, making it special. A variation of an element called an isotope has a different number of neutrons in its nucleus. Approximately 93.5 percent of the uranium used in modern nuclear bombs is enriched.

On average, plutonium-239 makes up 93% or more of nuclear bombs, whereas plutonium-240 makes up less than 7% and other plutonium isotopes are present in extremely minute amounts. A nuclear bomb requires around 33 pounds (15 kilograms) of enriched uranium to function, according to the Union of Concerned Scientists.

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Answer:

Chlorine, astatine, bromine, and fluorine.

Answer:

Fluorine, Chlorine, Bromine, and Astatine

Explanation:

they are all in group 17 meaning they have similer chemical properties.

Answer:

B

Explanation:

Oxidation

Zn---> Zn2+ 2e

Reduction

Cu2+ + 2e ---->Cu

The formation of the enzyme-substrate complex stressed/distorts chemical bonds to form a transition state, making the substrate more reactive and accelerating the reaction.

When the enzyme binds to the substrate, it creates an environment that is conducive to the formation of the transition state, which is the intermediate state between the substrate and the product. The enzyme stabilizes the transition state by creating an environment that is conducive to its formation, which reduces the activation energy required for the reaction to occur. This makes the substrate more reactive, allowing it to form the product more quickly than it would without the enzyme.

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Answer:

36kcal

Explanation:

There are three things that occur in the process not converting ice to steam. They are;

I) fusion of ice

ii) heating of water to 100°C

iii) vaporization of water at 100°C to yield steam

Hence, total heat required to convert ice to steam=

Latent heat of fusion of ice + heat required to raise the temperature of water to 100°C + Latent heat of vaporization of water

Thus;

H= mLfus + mcθ + mLvap

H= m(Lfus + cθ + Lvap)

H= 50(80 + 1(100) + 540)

H= 36000cal

H= 36kcal

A solution can be said to be unsaturated if additional solute can be dissolved without any external stress or pressure.

For example, when sugar is dissolved in water, the sugar is a solute and the water is the solvent. If more sugar is added, it will dissolve into the solution until it reaches its maximum solubility. This is an unsaturated solution since more sugar can still be dissolved without external stress.

Solutions are homogeneous mixtures of two or more substances in relative amounts that can be varied continuously up to a certain limit. Solutions are made up of a solute, which is the substance being dissolved, and a solvent, which is the substance that the solute is dissolved in. Solutions can be liquid, gaseous, or solid, depending on the type of solute and solvent present.

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Answer:

The answer is

Explanation:

The mass of a substance when given the density and volume can be found by using the formula

From the question

density of liquid = 0.70 g/mL

volume = 130 mL

The mass is

mass = 0.7 × 130

We have the final answer as

Hope this helps you

In the preparation of methyl benzoate, the following steps  a) washing the organic layer with sodium bicarbonate, b) washing it saturated NaCll, and c) treating it CaCl₂ pellets  serve specific purposes:

a) Washing the organic layer with sodium bicarbonate: This step helps neutralize any remaining acidic impurities (such as unreacted benzoic acid) in the organic layer. Sodium bicarbonate reacts with the acids to form water-soluble salts, which can be separated from the organic layer.

b) Washing with saturated NaCl: This step aims to remove any remaining water from the organic layer. The addition of saturated NaCl increases the ionic strength, making the water layer more polar, and thus promoting the separation of water from the organic layer.

c) Treating with CaCl₂ pellets: Calcium chloride is a desiccant, meaning it can absorb moisture from its surroundings. Treating the organic layer with CaCl₂ pellets helps to further remove any trace amounts of water, resulting in a drier, more purified methyl benzoate product.

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Answer:

when a substance is cool the particles in the substance contracts, but when heated the particles expand and pressure becomes high that way the particles tend to move faster in the container, in other to escape.

Answer:

A dono wat is da anser sori man hehe

Answer:

(a).

→ Hydroxyl group.

→ Carbon-carbon double bond. ( alkene )

→ Esters.

(c).

(I). A colourless solution : with bromine atoms on cyclo hexene.

or: A white precipitate due to bromine atoms formed on phenol.

(ii). The purple solution turns colourless due to oxidation of the cyclo hexene.

(iii).

Bubbles of a colourless gas ( hydrogen gas ) formed when sodium reacts with the hydroxyl group to form Sodium oate ions.

(iv). Am not sure about my answer.

(v).

A red dye is formed. ( and azo dye is formed due to benzenediazonium salt reacting with phenol ).

Answer:

The average rate of climb in miles per minute is 8.2x10⁻⁴ miles/min.

Explanation:

The average rate can be calculated as follows:

\( \overline{v} = \frac{y_{f} - y_{0}}{t_{f} - t_{0}} \)

Where:

\(y_{0}\): is the initial height = 24976 ft

\(y_{f}\): is the final height = 29035 ft

\(t_{0}\): is the initial time = 0

\(t_{f}\): is the final time = 15 hr, 35 min = 935 min      

Then, the average rate of climb in miles per minute is:

\( \overline{v} = \frac{y_{f} - y_{0}}{t_{f} - t_{0}} \)

\( \overline{v} = \frac{29035 ft - 24976 ft}{935 min - 0} = 4.34 \frac{ft}{min}*\frac{1 mile}{5280 ft} = 8.2 \cdot 10^{-4} miles/min \)      

Therefore, the average rate of climb in miles per minute is 8.2x10⁻⁴ miles/min.

I hope it helps you!      

Answer:

Yes is incorrect

Explanation:

not all veins carry blood rich in CO2 , the pulmonary vein carries blood with O2 which means that not all veins carry blood rich in CO2