Which statement is true of an endothermic reaction? a) Weak bonds break and strong bonds form. b) Strong bonds break and weak bonds form. c) The bonds that break and those that form are of approximately the same strength.

Answer:

part of the skeleton that supports the structure of face and forms a cavity from bone.

Hope it help u.

Explanation:

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The energy of a photon that would move an electron from level 2 to level 5 : B. 4.8 eV

The electron energy at the nth shell can be formulated:

Rh = constant 2.179.10⁻¹⁸ J

So the electron transfer energy (ΔE)

ΔE = E final- E initial

energy at n=2(level 2) = -5.3 eV

energy at n=5(level 5) = -0.5 eV

So the energy absorbed :

[tex]\tt \Delta E=-0.5-(-5.3)=-0.5+5.3=4.8`eV[/tex]

The energy required to move an electron from level 2 to level 5 is 4.8 eV.

According to the Bohr model of the atom, an electron moves from a lower to a higher energy level when it absorbs energy. The same energy is released when the atom returns to ground state.

When an electron from level 2 to level 5, the energy of the photon required is;

ΔE = E5 - E2 = -0.5eV - (-5.3eV)

ΔE = 4.8eV

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Answer:

Partial pressure of oxygen = 190 mmHg

Explanation:

From the question;

Mixture contains only nitrogen and oxygen

Total pressure of the mixture = 480 mmHg

Partial pressure of nitrogen = 290 mmHg

Dalton's law states that the pressure of a system is as a result of the sum of the partial pressures of the individual components of the mixture. This means that in this mixture;

Pressure of mixture = Partial Pressure of Nitrogen + Partial Pressure of Oxygen

480 = 290 + Partial pressure of oxygen

Partial pressure of oxygen = 480 - 290

Partial pressure of oxygen = 190 mmHg

Ones day my include eating, resting, exercising. Unfortunately mine included not eating, not sleeping, and not exercising. I lay wife awake on my bed wishing for deaths door to find me sooner than later. I do my chores because if I don’t then my parents may take away the few things I love most. In conclusion, my daily activities include thoughts of “ why am I still alive” and actions of crying, punching ext.

Answer:

V₂ =  511.59mL

Explanation:

Given data:

Initial volume = 450 mL

Initial pressure = 744 mmHg

Initial temperature = 33°C (33 +273 = 306 K)

Final temperature = 66°C (66+273 = 339 K)

Final pressure = 725 mmHg

Final volume =?

Formula:  

P₁V₁/T₁ = P₂V₂/T₂  

P₁ = Initial pressure

V₁ = Initial volume

T₁ = Initial temperature

P₂ = Final pressure

V₂ = Final volume

T₂ = Final temperature

Solution:

V₂ = P₁V₁ T₂/ T₁ P₂  

V₂ = 744 mmHg × 450 mL × 339 K / 306 K ×725 mmHg

V₂ = 113497200 mmHg .mL. K / 221850 K.mmHg

V₂ =  511.59mL

Answer:

Pure covalent bonds exist between two atoms with the same electronegativities. A pure covalent bond has no ionic character at all. Diatomic elements are good examples of pure covalent bonds where the electrons are evenly shared between both nuclei.

Explanation:

Hope this helped!

Explanation:

Generally, temperature increases the rate of any chemical reaction considerably.

In a dissolution process, the solute is solvated in the solvent. Solutes are usually the solids or liquids being dissolved in the solution.

The internal energy of a system : 21.9 kJ

The laws of thermodynamics 1 state that energy can be changed but cannot be destroyed or created  

The equation is:  

ΔU=Q+W    

Energy owned by the system is expressed as internal energy (U)  

The sign rules for heat and work are set as follows:  

• The system receives heat, Q +  

• The system releases heat, Q -  

• The system does work, W -  

• the system accepts work, W +  

The system absorbs 14.73 kJ⇒Q=+14.kJ

The system compressed⇒work done on the gas⇒W=+

W=-PΔV

[tex]\tt W=-1.54(1-5.720)\\\\W=7.2688[/tex]

[tex]\tt internal~energy(\Delta U)=Q+W\\\\\Delta U=14.73+7.2688\\\\\Delta U=21.9[/tex]

To prepare 250 ml 0.25 M hydrogen peroxide, 10.63 ml of 20g/100 ml hydrogen peroxide has been taken and made up the volume to 250 ml.

The dilution of the sample can be prepared with the help of expression:

M1V1 = M2V2

M1 = molarity of the concentrated solution

V1 = volume of concentrated solution

M2 =  molarity of diluted solution

V2 = volume of diluted solution.

The molarity of concentrated solution has been:

Molarity = [tex]\rm \dfrac{weight}{molecular\;weight}\;\times\;\dfrac{1000}{Volume\;(ml)}[/tex]

The 20g/100 ml Hydrogen peroxide has molarity:

Molarity = [tex]\rm \dfrac{20}{34.0147}\;\times\;\dfrac{1000}{100}[/tex]

Molarity of Hydrogen peroxide = 5.879 M

The volume of 5.879 M hydrogen peroxide is required to prepare 0.25 M hydrogen peroxide has been:

Volume of Hydrogen peroxide (20g/100 ml) [tex]\times[/tex] 5.879 = 250 ml [tex]\times[/tex] 0.25 M

Volume of Hydrogen peroxide (20g/100 ml) = 10.63 ml.

To prepare 250 ml 0.25 M hydrogen peroxide, 10.63 ml of 20g/100 ml hydrogen peroxide has been taken and made up the volume to 250 ml.

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Answer:

47900 cm

General Formulas and Concepts:

Chemistry

Explanation:

Step 1: Define

0.479 km

Step 2: Identify Conversions

1 km = 1000 m

1 m = 100 cm

Step 3: Convert

[tex]0.479 \ km(\frac{1000 \ m}{1 \ km} )(\frac{100 \ cm}{1 \ m} )[/tex] = 47900. cm

Step 4: Check

We are given 3 sig figs. Follow sig fig rules.

47900. cm ≈ 47900 cm

Answer: E

Explanation:hope this helps you out

Suppose of sodium chloride is dissolved in of a aqueous solution of silver nitrate. Calculate the final molarity of chloride anion in the solution. You can assume the volume of the solution doesn't change when the sodium chloride is dissolved in it. Be sure your answer has the correct number of significant

The normality of the solution which is prepared by dissolving 75 grams of citric acid in water to make 250 ml solution is 4.68 N. Thus, the correct option is C.

Normality is a measure of the concentration of a solution. Normality of a solution is the number of grams equivalent to solute which is present in a given volume of the solution.

Normality of a solution can be calculated by the formula:

N = Gram eq. of solution/ Volume of solution in liters

N = Weight of the solution/ Equivalent weight ×1000/ Volume of solution

N = 75/ 64.4 × 1000/ 250

N = 1.16 × 4

N = 4.64

The normality of the citric acid solution is approximately 4.68 N.

Therefore, the correct option is C.

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Answer:

Image result for Where do karst regions occur?

Karsts are found in widely scattered sections of the world, including the Causses of France; the Kwangsi area of China; the Yucatán Peninsula; and the Middle West, Kentucky, and Florida in the United States.

Explanation:

Answer:

Middle West Kentucky.

Explanation:

Karst are found in widely scatter sections of the world.

Answer:

[tex]C_{metal}=126.6\frac{J}{g\°C}[/tex]

Explanation:

Hello!

In this case, when two substances at different temperature are put in contact and an equilibrium temperature is attained, we can evidence that the heat lost by the hot substance (metal) is gained by the cold substance (water) and we can write:

[tex]Q_{metal}=-Q_{water}[/tex]

Which can be also written as:

[tex]m_{metal}C_{metal}(T_{EQ}-T_{metal})=-m_{water}C_{water}(T_{EQ}-T_{water})[/tex]

Thus, since we need the specific heat of the metal, we solve for it as shown below:

[tex]C_{metal}=\frac{m_{water}C_{water}(T_{EQ}-T_{water})}{-m_{metal}(T_{EQ}-T_{metal})} \\\\C_{metal}=\frac{250.0g*4.184\frac{J}{g\°C}(29.0\°C-98.0\°C)}{95.0g(29.0\°C-23.0\°C)} \\\\C_{metal}=126.6\frac{J}{g\°C}[/tex]

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Answer:

V₂ = 22.84 L

Explanation:

Given data:

Initial volume = 20.0 L

Initial pressure = 1.50 atm

Initial temperature = 23 °C (23 +273 = 296 K)

Final temperature = 271°C (271+273 = 544 K)

Final pressure = 3.50 atm

Final volume = ?

Formula:  

P₁V₁/T₁ = P₂V₂/T₂  

P₁ = Initial pressure

V₁ = Initial volume

T₁ = Initial temperature

P₂ = Final pressure

V₂ = Final volume

T₂ = Final temperature

Solution:

V₂ = P₁V₁ T₂/ T₁ P₂  

V₂ = 1.50 atm × 29.0L ×544 K / 296 K × 3.50 atm

V₂ = 23664 atm .L. K / 1036 atm.K

V₂ = 22.84 L

Explanation:

even I don't know this answer

but maybe you can solve it by putting the formula

Answer:

The prefixes are fluoro-, chloro-, bromo-, and iodo-. Thus CH 3CH 2Cl has the common name ethyl chloride and the IUPAC name chloroethane. Alkyl halides with simple alkyl groups (one to four carbon atoms) are often called by common names.05‏/06‏/2019

The IUPAC name of this compound is 2,3- dichlorobutane.

Compound is defined as a chemical substance made up of identical molecules containing atoms from more than one type of chemical element.

Molecule consisting atoms of only one element is not called compound.It is transformed into new substances during chemical reactions. There are four major types of compounds depending on chemical bonding present in them.They are:

1)Molecular compounds where in atoms are joined by covalent bonds.

2) ionic compounds where atoms are joined by ionic bond.

3)Inter-metallic compounds where atoms are held by metallic bonds

4) co-ordination complexes where atoms are held by co-ordinate bonds.

They have a unique chemical structure held together by chemical bonds Compounds have different properties as those of elements because when a compound is formed the properties of the substance are totally altered.

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Answer:

someone is in my mind and it is telling me 5.55m

Explanation:

Answer:

4 mL

Explanation:

4mL is 5% of 80mL. Therefore my answer is right.

Answer:

What’s the answer

Explanation:

I neeeddsdd

Dissolving is your answer to this question. Becuase when something dissolves it is no longer in the same shape or state cause if something dissovles then goes away into another state.

Answer: condensing is the correct answer

Explanation:

Answer:

Fire, Air, Water.

Explanation:

Matter is anything that has mass and occupies space. However, not all form of matter are visible. Air is an example of invisible matter.

Note, electricity does not have mass or does not occupy space. Therefore, electricity is not a matter.

Answer:

Fire, Air, Water

Explanation:

Electricity is the of charged particles conducting medium. However, it is the electrons that are matter, not their movement.

Matter is anything that has mass and occupies space. The flame itself is a mixture of gases and so is matter. The light and heat produced are energy not matter.

Like solids and liquids, air is matter. It has a weight and it takes up space.

Water is a liquid and liquids are one of the four fundamental states of matter.

Answer:

The top left number of the symbol of an atom is the sum of the protons and neutrons in the atom known as atomic mass number, while the bottom left number of the symbol of an atom is the number of protons in the atom known as atomic number.

Explanation:

An atom of an element is composed of other subatomic particles; the electron, proton and neutron. The number of protons present in an atom of an element is equal to the number of electrons present in the atom of that element and is known as the atomic number of the element. The number of neutrons present in the atom summed together with the proton number gives the atomic mass number of an atom of the element.

Elements are represented with symbols. In writing the symbols of elements, the atomic number and the atomic mass of an atom of the element is usually written along with the symbol. The top left number of the symbol of an atom is the sum of the protons and neutrons in the atom, while the bottom left number of the symbol of an atom is the number of protons in the atom.

For example, the element sodium has an atomic number of 11 and a mass number of 23. In symbols, it is written as follows: ²³₁₁Na

Answer:

Option A. The carbocation accepts a pair of electrons.

Explanation:

A carbocation is defined as a positively charged carbon, which is bound to 3 substituents. Since it has no electrons  nonbonding, it only has six electrons in its valence shell. With only six electrons in its valence shell, a carbocation is a powerful electrophile (and Lewis acid) and can react with any nucleophile that is found.

Carbocations are proposed as intermediates in many  organic reactions. They also work like free radicals, which are electron-deficient species.

Same as free radicals, the carbocations are stabilized by alkyl substituents.

Answer:

hope it's correct.

Explanation:

element is nickel.

The statements correctly describes the function of cell parts is the mitochondria are the power plants of the cell. Therefore, option C is correct.

The cytoplasm of a cell contains tiny structures (fluid that surrounds the cell nucleus). The majority of a cell's energy is produced by mitochondria, which also have unique genetic material distinct from that present in the nucleus.

Oxidative phosphorylation, which produces ATP using the energy generated during the oxidation of the food we ingest, is the traditional function of mitochondria.

For the majority of biochemical and physiological activities, including growth, mobility, and equilibrium, ATP is used as the main energy source in turn.

Thus, option C is correct.

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Answer:

Mercury Chloride

Explanation:

Trust me, this answer is correct.

Answer:

spermatozoon:A spermatozoon is a motile sperm cell or moving from of the haploid cell that is the male gamete.

spermatogonium : A cell produced at an early stage in the formation of spermatozoa, formed in the wall of a seminiferous tuble and giving rise by mitosis to spermatocytes.

Answer:

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Explanation: