Pleaseee I need help and it is urgent

Answer:

Starch

I hope this helps

The volume occupied by 7.455 moles of pentanol is 553.5 mL or 0.5535 L.

The molar mass of a given compound is the mass of one mole of that compound. It is expressed in unit as grams per mole (g/mol).

To calculate the volume of pentanol occupied by 7.455 moles of the substance, we can use the following formula:

Volume = (number of moles x molar mass) / density

The molar mass of pentanol (C3H8O) can be calculated as:

3 x atomic mass of carbon (12.01 g/mol) = 36.03 g/mol 8 x atomic mass of hydrogen (1.01 g/mol) = 8.08 g/mol 1 x atomic mass of oxygen (16.00 g/mol) = 16.00 g/mol Total molar mass = 60.11 g/mol

Placing the given values into the formula, we get:

Volume = (7.455 mol x 60.11 g/mol) / 0.8110 g/mL Volume = 553.5 mL or 0.5535 L

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Answer:I'm going to give some fictitious values just so that we can get some perspective on the matter.

Let's say that the surface temperature of our sun is 10, the surface temp of the bigger star- the red giant formed from leaving the main sequence, has a temp of 0.2. of that- 2.

We can also say that the radius of our sun is 10, and the radius of the red giant is 1000. (100 times more)

Using the equation:

L

=

σ

A

T

4

σ

= The Stefan-Boltzmann constant =

5.67

×

10

−

8

But we can ignore the constant, as we are only interested in a ratio of these values.

L

S

u

n

=

4

π

(

10

)

2

×

10

4

=

1.26

×

10

7

L

S

t

a

r

=

4

π

(

1000

)

2

×

2

4

≈

2.01

×

10

8

2.01

×

10

8

1.26

×

10

8

≈

16

So the newly formed, red giant star is almost 16 times more luminous than the sun. This is owing to the increased surface area of the star due to the massively increased radius.

A small sidenote:

There is an equation that might be useful for comparing the radii, temperature and luminosity of main sequence stars. As red giants are not on the main sequence it could not be used here, but if you stumble across a question where they ask you to find the radius, luminosity or temperature given the other two, you can relate it to the sun's characteristics:

r

s

t

a

r

r

s

u

n

=

√

L

s

t

a

r

L

s

u

n

×

(

T

s

u

n

T

s

t

a

r

)

2

(I know, it's not a beauty to look at- but it works)

Where

X

s

u

n

is the radius, temperature, and luminosity of the sun. These are not often given in numerical values, but this equation serves well when asked to find e.g the radius of a star, in solar radii given that a star is twice as luminous and has 5 times the temperature of that of the sun.

Hence:

T

s

t

a

r

=

5

T

s

u

n

L

s

t

a

r

=

2

L

s

u

n

r

s

t

a

r

r

s

u

n

=

√

2

L

s

u

n

L

s

u

n

×

(

T

s

u

n

5

T

s

u

n

)

2

(cancel the common terms)

r

s

t

a

r

r

s

u

n

=

√

2

×

(

1

5

)

2

r

s

t

a

r

≈

0.057

r

s

u

n

(divide both sides by 0.0057)

17.5

r

s

t

a

r

≈

r

s

u

n

So the star's radius is almost 17.5 times that of the sun.

Hopefully, you find this info useful!

Explanation:

Answer:

Answer:

                   Potassium Nitride is composed of the greatest number of atoms.

Explanation:

find the number of atoms present in each compound we will write down their molecular formulas and then we will add up the number of atoms present in them.

A: Dinitrogen Monoxide:

                                       Chemical formula of Dinitrogen Monoxide is N₂O. Therefore, it contains two atoms of Nitrogen and one atom of oxygen Hence, in total it contains 3 atoms.

B: Sodium Chloride:

                               Chemical formula of Sodium Chloride is NaCl. Therefore, it contains one atom of Sodium and one atom of Chlorine Hence, in total it contains 2 atoms.

C: Potassium Nitride:

                                       Chemical formula of Dinitrogen Monoxide is K₃N. Therefore, it contains three atoms of Potassium and one atom of Nitrogen Hence, in total it contains 4 atoms.

D: Carbon Dioxide:

                               Chemical formula of Carbon Dioxide is CO₂. Therefore, it contains one atom of Carbon and two atoms of Oxygen Hence, in total it contains 3 atoms.

Explanation:

Answer:

To run a spectrophotometry experiment, begin by warming up the spectrophotometer and preparing the samples. Be sure to select the correct wavelength, then run a measurement on the blank solution. Follow up by running measurements on sample solutions. Once data is collected, turn off the instrument, clean the area, and discard the samples.

Explanation:

The spectrophotometer is a device used in laboratories to carry out analysis in experiments that need to measure and compare the amount of light absorbed or transmitted between samples, regardless of whether the samples are transparent or opaque solid. The spectrophotometer can be single-beam and double-beam. Regardless of the nature of the beam, to perform a spectrophotometry experiment, you must start by heating the spectrophotometer and preparing the samples. Make sure to select the correct wavelength and perform a measurement on the blank solution. Follow up by performing measurements on sample solutions. Once the data is collected, turn off the instrument, clean the area and discard the samples.

Answer:

Exothermic Reaction

Explanation:

Burning wood in air is an exothermic process (it releases heat), but there is an energy barrier, so it requires a bit of heat in the beginning to get the reactions started.

Wood reacts with oxygen in the air to form (mostly) carbon dioxide and water vapor. The process involves many different individual chemical reactions, and it requires some energy to initiate the reactions. This is because it's usually necessary to break some chemical bonds (endothermic) before new stronger bonds can be formed (exothermic). Overall, though, more heat is released in forming the final products than is consumed in starting new reactions.

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In the given question, a burning log is an exothermic event if the log is the system.

An exothermic reaction releases energy to the surroundings, usually in the form of heat. The change in enthalpy is negative.

When a log burns, it reacts with oxygen in the air to produce carbon dioxide, water vapor, and heat. This heat is released to the surroundings, making the burning log an exothermic event.

Therefore, a burning log is an exothermic event if the log is the system. This is due to the fact that the reaction emits heat into the environment, making it an exothermic reaction.

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Answer:

Tell students that sometimes when two (or more) substances are mixed together, a change occurs and another substance (or substances) is created. This is called a chemical reaction. Gas may form, heat may be produced, and color may change. These types of changes indicate that a chemical reaction has occurred.

Answer: There are 1.20 x 1024 atoms of sodium in 2 moles

Explanation:

Answer:

hydro ponic plants

Explanation:

coz they are hydro

Answer:

(i) Change in colour (ii) Change in temperature  (iii) Formation of precipitate

Explanation:

(i) Change in colour: Reaction between lead nitrate solution and potassium iodide solution. Pb(NO3)2(aq)+2KI → PbI2(s)+2KNO3(aq) In this reaction, colour changes from colourless to yellow. (ii)Change in temperature: Action of dilute sulphuric acid on zinc. Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2 In this reaction, heat is evolved (iii) Formation of precipitate: Action of barium chloride on sodium sulphate. BaCl2(aq) +Na2SO4(aq) →  BaSO4(s) +2NaCl(aq) BaSO4(s)

Answer:

If the voltage of circuit A is equal to the voltage of circuit B, then the current in circuit A is less than the current in circuit B

Explanation:

To know the the correct answer to the question, do the following:

Case 1: Let the circuit A and B have equal voltage say 24 V.

For Circuit A:

Voltage (V) = 24 V

Resistance (R) = 7.5 ohms

Current (I) =?

V = IR

24 = I × 7.5

Divide both side by 7.5

I = 24 / 7.5

I = 3.2 A

For Circuit B:

Voltage (V) = 24 V

Resistance (R) = 5 ohms

Current (I) =?

V = IR

24 = I × 5

Divide both side by 5

I = 24 / 5

I = 4.8 A

Thus for the same voltage, current in circuit A is less than the current in B.

Case 2: Let circuit A and B have equal current say 2 A

For circuit A:

Current (I) = 2 A

Resistance (R) = 7.5 ohms

Voltage (V) =?

V = IR

V = 2 × 7.5

V = 15 V

For Circuit B:

Current (I) = 2 A

Resistance (R) = 5 ohms

Voltage (V) =?

V = IR

V = 2 × 5

V = 10 V

Thus, for the same current, the voltage in circuit A is greater than the voltage in B

Case 3: Let circuit A have a current of 4 A and circuit B have a current of 5 A

For circuit A:

Current (I) = 4 A

Resistance (R) = 7.5 ohms

Voltage (V) =?

V = IR

V = 4 × 7.5

V = 30 V

For circuit B:

Current (I) = 5 A

Resistance (R) = 5 ohms

Voltage (V) =?

V = IR

V = 5 × 5

V = 25 V

Thus, when the current in circuit A is less than the current in circuit B, the voltage in circuit A is greater than the voltage in circuit B.

From the illustrations above and the options given in the question, the current answer is:

If the voltage of circuit A is equal to the voltage of circuit B, then the current in circuit A is less than the current in circuit B

Answer:

B

Explanation:

"The temperature increases cause the rate of a reaction to increases the kinetic energy"

What is rate of reaction?

The reaction rate, also known as the rate of reaction, is the rate for which a chemical reaction occurs, and is proportional to increase in product concentration per unit time and the reduction in reactant concentration per unit time. The rate of reaction varies greatly.

What is kinetic energy?

An object's kinetic energy is the energy it has as a result of its motion. It is the amount of work required to push a body of a given mass from rest to a certain velocity. The body keeps its kinetic energy gained during acceleration unless that speed changes.

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Answer:

Answer: 1.38 moles

Explanation: According to Avogadro's law, 1 mole of every substance contains Avogadro number of particles (atoms, molecules or ions) i.e.6.023*10^23  particles.

Given : 1 mole molecule of water contains 6.023*10^23 molecules of water.

6.023*10^23  molecules are present in = 1 mole

 8.30*10^23molecules will be present in =

1/6.023*10^23 ×8.30*10^23=1.38 moles

Thus  molecules is equal to 1.38 moles.

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Answer:

Q = ΔH fusion * mass (g)

when we have:

ΔH fusion (the heat (or enthalpy) of fusion = 0.334 kJ/g

and mass of ice = 22.4 g  

so by substitution, we can get the energy (Q) required to melt this mass of ice:

∴ Q = 0.334KJ/g * 22.4 g  

      = 7.48 KJ

∴ the energy required to melt 22.4 g of ice is = 7.48 KJ

Explanation:

Answer:

increased temperatures

Explanation:

The temperatures are increasing in the ocean because of ocean warming, by climate change. The heat in the ocean stresses healthy corals, which drains them of their vibrant colors, known as bleaching.

Answer:

Can you explain it more please

Explanation:

Answer:

what no entiendo nada jahag6

When 5.86 grams of NaN3, then 22.99 gram of Na are produced by using mole formula.

A thousandth of a kilo-gram in terms of mass in the metric system.

A mole is a unit of measurement for atom amount. A mole of Iron atoms weighs heavier than just a mole of Carbon molecules because it is measured by the number of atoms present instead of by weight.

The reaction can be written as:

[tex]2 Na N_{3}[/tex] → 2Na + [tex]3N_{3}[/tex].

It can be seen that 2 mole of sodium azide give 3 mole of nitrogen molecule.

Calculate the moles of Na.

Moles of Na = 1 mol sodium azide × 2 mol of Na / 2 mol sodium azide = 1 mole of Na.

Calculate the mass of Na.

Mass of Na = 1 mol Na × 22.99 g Na / 1 mol Na = 22.99 gNa.

Therefore, the mass of Na will be 22.99 gram

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There is lesser dissociation of hydrogen cyanide as compared to HCl, as  equilibrium constant for the dissociation of hydrogen cyanide has been smaller than HCl. Hence, option C is correct.

Hydrogen cyanide has been a weak acid that has been dissociated into the constituent ions. The dissociation of the compound in water has been corresponds to the equilibrium constant.

The equilibrium constant has been defined as the ratio of the concentration of solute and solvent ions at equilibrium.

The sample with lesser equilibrium constant tends to dissociate at lesser concentration as well.

The equilibrium constant for the dissociation of hydrogen cyanide has been smaller than HCl. Thus, there will be lesser dissociation of hydrogen cyanide as compared to HCl. Hence, option C is correct.

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Answer:

hello, can you pleas egive me the answer? i have the same exact question. thank you!

Explanation:

Answer:

a

Explanation:

the answer to the question is a

Among the following chemical equations, redox reaction is [tex]3 MnO_2+4 Al\rightarrow 3 Mn +2 Al_2O[/tex].

The redox reaction can be defined as a reaction that involves the transfer of electrons between two species. Redox reactions comprise of two parts a reduced part and an oxidized part, which occur simultaneously . The part which is reduced gain electrons and hence there is a increase in oxidation state of the species.

While, the part which is oxidized looses electrons and hence there is a decrease in oxidation state of the species.During redox reactions, there is no net change in the number of electrons . Electrons which are given off in oxidation are used up in reduction.

Therefore, the correct option is B.

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Answer: Molar mass of [tex]CuSO_4.5H_2O[/tex] is 249.68 g/mol.

Explanation:

Molar mass is the mass of 1 mole of the molecule. It is calculated by adding masses of all the atoms in the given molecule.

[tex]CuSO_4.5H_2O[/tex] contains one atom of copper , 1 atom of sulphur, 9 atoms of oxygen and 10 atoms of hydrogen

Mass of copper = 63.5  g/mol

Mass of sulphur =  32.06 g/mol

mass of oxygen = 16.00 g/mol

Mass of hydrogen = 1.008 g/mol

 Thus mass of [tex]CuSO_4.5H_2O[/tex] = 63.5(1)+32.06(1)+16.00(9)+1.008(10)=249.68 g

Molar mass of [tex]CuSO_4.5H_2O[/tex] is 249.68 g/mol.

Answer:

A  should be the swer n

Explanation:

Answer:

her ugly duck lips

Explanation:

Answer:

her lips.

Explanation:

the dependent variable is the lip stick because it changes but her lips do not actually change at all, ......i think. ;)

ones that are answered through observing :)

Answer: D.

Explanation:

ones that are answered through observing.