Help please I really don’t know what i’m doing.

The events in the life of a star in the correct order is as follows: F, B, C, D, E and A.

The life of a star refers to the the events that occur in a star from when it formed newly until when it finally dies off.

When stars are newly formed, they are formed from star dust, and when just before they die, the form supernovas.

The several events in the life of a star can be arranged thus:

In conclusion, the life of a star is the period of its formation to its burning out or death.

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Note that the complete question is given below:

Arrange the events in the life of a star in the correct order.

A. All that remains of the star now is the core. In some cases, the star turns into a black hole

B. As the nuclear fusion sets off a chain reaction, the nebula gets hotter and brighter and turns into a star.

C. The star stays in the main sequence stage for a long time.

D. The star runs out of hydrogen and turns into a planetary nebula or a supernova, depending on its mass.

E. Heavy elements are created when the supernova explodes.

F. The temperature increases in the center of a nebula, and nuclei begin to fuse.

Answer:

You are on the right track.

Explanation:

Indeed, your approach here will be to use the molar mass of aluminium hydroxide to convert the mass of the sample to moles and the mole ratio that exists between the two reactants to find the number of moles of hydrochloric acid consumed.

Al

(

OH

)

3

(

s

)

+

3

HCl

(

a

q

)

→

AlCl

3

(

a

q

)

+

3

H

2

O

(

l

)

The balanced chemical equation tells you that the reaction consumes

3

moles of hydrochloric acid and produces

3

moles of water for every

1

mole of aluminium hydroxide that takes part in the reaction.

So you can say that you have

0.75

g

⋅

the molar mass of Al

(

OH

)

3



1 mole Al

(

OH

)

3

78

g

⋅

the 1:3 mole ratio



3 moles HCl

1

mole Al

(

OH

)

3

=

0.029 moles HCl

−−−−−−−−−−−−−−

Since you know that the reaction produces the same number of moles of water as the number of moles of hydrochloric acid it consumes--the two chemical species have a

3

:

3

mole ratio in the balanced chemical equation--you can use the molar mass of water to say that the reaction will produce

0.029

moles H

2

O

⋅

18.015 g

1

mole H

2

O

=

0.52 g

−−−−−

The answers are rounded to two sig figs, the number of sig figs you have for the mass of aluminium hydroxide.

Explanation:

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Answer: 0.005 mol

Explanation:

Given information

Volume = 10 mL

Molarity = 0.5 mol / L

Given formula

Molarity = Mole / Volume

Convert volume unit to liters

1 L = 1000 mL

10 mL = 10 / 1000 = 0.01 L

Substitute values into the formula

Molarity = Mole / Volume

Mole = Molarity × Volume

Mole = (0.5) × (0.01)

Simplify by multiplication

[tex]\Large\boxed{Mole~=~0.005~mol}[/tex]

Hope this helps!! :)

Please let me know if you have any questions

Answer:

Polar

Explanation:

Methanol is not electrostatic

It's not metallic as it has no metals in it

It's not ionic as coordinate bonding is made.

It's polar as a lone pair is present over OH-

Answer:

Beryllium-9 is the isotope of beryllium with relative atomic mass 9.

Answer:

okkkk zjjdjdjdjduxuxu

[tex] {\qquad\qquad\huge\underline{{\sf Answer}}} [/tex]

Here we go ~

Energy difference btween the two electronic states can be expressed as :

[tex]{ \qquad \sf  \dashrightarrow \: \Delta E = h\nu} [/tex]

[ h = planks constant,[tex]{\: \nu } [/tex]= frequency ]

[tex] \qquad \sf  \dashrightarrow \:214.68 = 39.79 \times 10 {}^{ - 14} \times \nu[/tex]

[tex]\qquad \sf  \dashrightarrow \: \nu = \cfrac{214.68}{39.79 \times 10 {}^{ - 4} } [/tex]

[tex]\qquad \sf  \dashrightarrow \: \nu = \cfrac{214.68}{39.79 } \times 10 {}^{14} [/tex]

[tex]\qquad \sf  \dashrightarrow \: \nu \approx 5.395 \times10 {}^{14} \:\:hertz[/tex]

Explanation:

composition and interaction of matter included in the study of chemestry

Answer:

No it's correct.

Explanation:

The water temperature is 25 degrees Celsius. it's rigHT.

Taking into account the definition of molarity, the final sugar solution has a concentration of 5.028 M.

Molar concentration or molarity is a measure of the concentration of a solute in a solution and indicates the number of moles of solute that are dissolved in a given volume.

The molarity of a solution is calculated by dividing the moles of solute by the volume of the solution:

molarity= number of moles÷ volume

Molarity is expressed in units [tex]\frac{moles}{L}[/tex].

In this case, you mix 20.0 mL (0.02 L) of a 3.00 M sugar solution with 30.0 mL (0.03 L) of a 6.38 M sugar solution. To know the concentration of the sugar solution, you need to find the total moles of sugar solution from the mixtures as follow:

Now, the total volume of the solution is calculated adding the volume of the two solutions:

total volume= 20 mL + 30 mL= 50 mL= 0.05 L

Replacing the values inf the definition of molarity:

molarity= 0.2514 moles÷ 0.05 L

Solving:

molarity= 5.028 M

Finally, the final sugar solution has a concentration of 5.028 M.

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Answer:

The rate of dissolving is influenced by several factors, including stirring, temperature of solvent, and size of solute particles.

The balanced redox reaction equation is 2Fe^2+  (aq) + H2O2 (aq)+2H + (aq) → 2Fe^3+ (aq)+2e + 2H2O(l).

A redox reaction equation is one in which there is a loss or gain of electrons. We can see that the oxidation number of some species is increased while the oxidation number of some species is reduced.

The oxidation half equation is written as; 2Fe^2+  (aq)→2Fe^3+ (aq)+2e

The reduction half equation is written as; H2O2 (aq)+2H + (aq)+2e  →2H2O(l).

Thus, the overall balanced redox reaction equation is written as;

2Fe^2+  (aq) + H2O2 (aq)+2H + (aq) → 2Fe^3+ (aq)+2e + 2H2O(l).

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The two compounds that are the correct enol tautomers of 2-butnone are the structures shown in Option B.

Isomerism is a situation in which two compounds have the same molecular formula but do not have the same structural formula. This occurs because the atoms in the molecule are arranged differently in space. One of the types of isomerism that we have is the Keto Enol Tautomerism. The Keto Enol Tautomerism occurs between the Keto and the enol forms of a compound via the movement of electrons. It is common in ketone compounds.

In this case, we can see that the compound 2-butanone can give rise to two enol compounds that have the same molecular formula as the 2-butanone.

The two compounds that are the correct enol tautomers of 2-butnone are the structures shown in Option B.

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the rate of cooling decreases

B. At the equivalence point of a titration of the [H+] concentration is equal to 7.

The equivalence point of a titration is a point in titration at which the amount of titrant added is just enough to completely neutralize the analyte solution.

At the equivalence point in an acid-base titration, moles of base equals moles of acid and the solution only contains salt and water.

At the equivalence point, equal amounts of H+ and OH- ions combines as shown below;

H⁺ + OH⁻  → H₂O

The pH of resulting solution is 7.0 (neutral).

Thus, the pH at the equivalence point for this titration will always be 7.0.

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Answer:

c) CuPO₄

Explanation:

Copper commonly forms the cation Cu²⁺.

Phosphate is a polyatomic anion which can be represented by PO₄³⁻.

In order to have proper charge balance (an overall charge of 0), there must be three copper cations and two phosphate anions within the compound. As such, the correct ionic formula is Cu₃(PO₄)₂.

The decrease in the freezing point of the solution is −1.86oC.

Now we know that the freezing point depression of a solid is a colligative property of the solution.

Thus we have that;

ΔT = K m i

ΔT = freezing point depression

K = freezing constant

m = molality of the solution

i = Van't Hoff factor

Thus;

molality =  1 mol/1 Kg = 1 m

ΔT = −1.86oC/m * 1 m * 1

ΔT =−1.86oC

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The statement that best describes how an ionic compound dissolves in water is as follows: it separates into individual molecules and is an electrolyte, which is option C.

Ionic compound is any compound is a chemical compound composed of ions (charged atoms) held together by electrostatic forces termed ionic bonding.

Ionic compounds are electrolytes i.e. a substance when, in solution or when molten, ionizes and conducts electricity.

For example; sodium chloride (NaCl) is an ionic compound breaks down into sodium ions (Na+) and chloride ion (Cl-).

Therefore, the statement that best describes how an ionic compound dissolves in water is as follows: it separates into individual molecules and is an electrolyte.

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From the calculations, the equilibrium constant is 216. Option B

The equilibrium constant can depict the amount of reactants that is converted into products at a given time. We know that if thus number is large and positive, then it means that the reaction would proceed to the right.

Thus, we have the equation of the reaction as; CO(g) + Cl2(g) <--> CoCl2(g) and we know that;

K = [CoCl2]/ [CO]  [Cl2]

[CoCl2] = concentration of CoCl2

[CO] = concentration of CO

[Cl2] concentration of Cl2

Substituting the values into the equation;

K = 0.14/  1.2 x 10-2 *  0.054

K = 216

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Molality of C2H5OH is 1.1.27m.



What is Molality?

Molality is no.of moles present in One Kg solution .

Molality is represented by m

m= no.of moles/ weigt of solution in kg

Given is Molarity= 51.30M

molar mass of C2H5OH is 46g / mol , Density =0.9349g/ ml

Density=m/V

V = 107 ml

Molarity= no of moles/ Volume

51.5×46×107= x × 1000

weight of C2H5OH = 27.7g

molality = 27.7/1000××46

m= 1.27m

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Answer: dentify the acids and bases from which the following salts are obtained. Write the chemical equations.

(i) NaNO

3

​

(ii) NH

4

​

Cl

Medium

Solution

HNO

3

​

+NaOH→NaNO

3

​

+H

2

​

O

Acid used : Nitric Acid -HNO

3

​

Base used: Sodium Hydroxide - NaOH

NH

4

​

Cl  is formed from the reaction of NH

3

​

, a weak base, and HCl, a strong acid.

NH

3

​

+HCl→NH

4

​

Cl

Explanation:

Answer:

Molarity = 0.037 M

pH = 1.43

Explanation:

First, you need to calculate the molarity. After converting mL to L, you can plug the values into the molarity equation and simplify.

2,000 mL / 1,000 = 2 L

Molarity (M) = moles / volume (L)

Molarity = 0.074 moles / 2 L

Molarity = 0.037 M

You can plug the molarity of the hydrogen ion into the pH equation to find the pH. Remember that H₃O⁺ and H⁺ can be considered the same thing. Since HCl dissociates into just one H⁺ and one Cl⁻, the molarity of the HCl solution is the same as the molarity of the H⁺.

pH = -log[H⁺]

pH = -log[0.037]

pH = 1.43

Answer:

0.271 M NO₃⁻

Explanation:

To find the molarity of the nitrate ion (NO₃⁻), you need to (1) convert grams to moles (via molar mass), then (2) convert moles Al(NO₃)₃ to moles NO₃⁻, then (3) convert mL to L, and then (4) calculate the molarity. When (Al(NO₃)₃) dissolves in water, it dissociates into 3 nitrate ions. The final answer should have 3 sig figs.

(Steps 1 + 2)

Molar Mass (Al(NO₃)₃): 26.982 g/mol + 3(14.007 g/mol) + 9(15.998 g/mol)

Molar Mass (Al(NO₃)₃): 212.985 g/mol

1 Al(NO₃)₃ = 1 Al³⁺ and 3 NO₃⁻

6.25 g Al(NO₃)₃            1 mole               3 moles NO₃⁻
-------------------------  x  -----------------  x   -----------------------  =  0.0880 moles NO₃⁻
                                    212.985 g         1 mole Al(NO₃)₃

(Steps 3 + 4)

325.0 mL / 1,000 = 0.3250 L

Molarity = moles / volume

Molarity = 0.0880 moles / 0.3250 L

Molarity = 0.271 M

(i) Make ammonia number of atoms on reactant side is 8 and on product side is 8. (ii) Separate water number of atoms on reactant side is 6 and on product side is 6. (iii) Combust methane number of atoms on reactant side is 9 and number of atoms on product side is 9.  

The balanced chemical equation is the equation in which the number of atoms on the reactant side is equal to the number of atoms on the product side in an equation.

(i) Make Ammonia

First we have to write the balanced chemical equation

             N₂ + 3H₂ → 2NH₃

Reactant side              Product side

N = 2                             N = 2

H = 6                             H = 6

So total number of atoms on product and reactant side is 8.

(ii) Separate Water

First we have to write the balanced chemical equation

            2H₂O → 2H₂ + O₂

Reactant side              Product side

H = 4                             H = 4

O = 2                             O = 2

So total number of atoms on product and reactant side is 6.

(iii) Combust methane

First we have to write the balanced chemical equation

       CH₄ + 2O₂ → 2H₂O + CO₂

Reactant side              Product side

C = 1                             C = 1

H = 4                            H = 4

O = 4                            O = 4

So total number of atoms on product and reactant side is 9.

Thus from the above conclusion we can say that For each balanced reaction, the total number of atoms are

Reaction                            Total number of atoms

                                     Reactant side           Product side

Make Ammonia                   8                               8

Separate Water                   6                               6

Combust Methane              9                               9

Disclaimer: The question was given incomplete on the portal. Here is the complete question.

Question: For each balanced reaction, indicate the total number of atoms in the table below.

Reaction                            Total number of atoms

                                     Reactant side           Product side

Make Ammonia            _________              __________

Separate Water            _________              __________

Combust Methane       _________              __________

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Answer:

I don't know what the hell is going on with the this.

If I study, I will pass the exams.

Taking into account the definition of Avogadro's number and molar mass, 4.806 grams of water are present in 1.61×10²³ molecules.

Avogadro's Number or Avogadro's Constant is called the number of particles that make up a substance (usually atoms or molecules) and that can be found in the amount of one mole of said substance. Its value is 6.023×10²³ particles per mole. Avogadro's number applies to any substance.

The molar mass of substance is a property defined as its mass per unit quantity of substance, in other words, molar mass is the amount of mass that a substance contains in one mole.

Taking into account the definition of Avogadro's Number, you can apply the following rule of three: if 6.023×10²³ molecules are contained in 1 mole of water, then 1.61×10²³ molecules are contained in how many moles of water?

amount of moles of water= (1.61×10²³ molecules× 1 mole)÷ 6.023×10²³ molecules

amount of moles of water= 0.267 moles

Now, taking into account the definition of molar mass, and knowing that the molar mass of water is 18 g/mole, you can apply the following rule of three: If by definition of molar mass 1 mole of the compound contains 18 grams, 0.267 moles of the compound contains how much mass?

[tex]mass= \frac{0.267 molesx 18 grams}{1 mole}[/tex]

mass= 4.806 grams

Finally, 4.806 grams of water are present in 1.61×10²³ molecules.

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Answer:

9.25l

Explanation:

9.25l was correct answer

The ideal gas law is a fundamental equation that describes the behavior of an ideal gas. It relates the pressure (P), volume (V), temperature (T), and number of moles (n) of an ideal gas using the ideal gas constant (R). The volume of the gas is 18.5 L. Hence option D is correct.

We can use the ideal gas law to solve this problem:

PV = nRT

where:

P is the pressure of the gas (in atm)

V is the volume of the gas (in L)

n is the number of moles of the gas

R is the ideal gas constant (0.08206 L·atm/mol·K)

T is the temperature of the gas (in K)

Plugging in the values from the problem, we get:

2 atm * V = 1.5 mol * 0.08206 L·atm/mol·K * 300 K

V = (1.5 mol * 0.08206 L·atm/mol·K * 300 K) / 2 atm

V = 18.5 L

Therefore, the volume of the gas is 18.5 (option D).

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The answer will be - 1.67 x [tex]10^{-6[/tex]

The problem can be solved by using the rule of BODMAS.

21-4/1002-730+83920/839

First, the operation is divided into 3 parts

For the first part:

    21 - 4 = 17

For the second part:

1002-730+83920

According to BODMAS, addition operations come before subtractions.

So, the operation becomes (1002)-(730+83920)

  = (1002) - (84650)  

     = -83648

The entire operation becomes 17/-83648/839

      17/-83648 x 1/839 = -17/70180672

                                  = - 1.67 x [tex]10^{-6[/tex]

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