The sun, like 80 to 90 percent of stars, is in which stage of life?(1 point) responses dying star dying star main sequence main sequence stellar formation stellar formation red giant red giant

Entropy has been defined as the unavailable energy for the thermodynamic system. The total change in the entropy of the reservoir with 400 J energy is 0.15 J/K.

Entropy change has been the measure of the energy that got dispersed in the thermodynamic system. The change in energy and the change in temperature are used to give the entropy change.

Given,

Heat transferred (ΔQ) = 400 Joules

Temperature of hot reservoir (Th) = 30°C (30 +273) = 303K

The temperature of the cold reservoir (Tc) = 0°C (273K)

Using ΔS = Q ÷ T as:

For hot resorvoir:

ΔShot = - 400 ÷ 303

ΔShot = - 1.32 J/K

For cold reservoir:

ΔScold = 400 ÷ 273

ΔScold = 1.47 J/K

Total change in entropy (ΔStotal) is given as:

ΔStotal = ΔShot + ΔScold

= - 1.32 + 1.47

= 0.15 J/K

Therefore, 0.15 J/K is the change in the entropy of the reservoir when heat is transferred from hot to cold.

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Positively charged aluminum ions gain electrons from the cathode and form molten aluminum. Electrolysis is used to perform the extraction. The aluminum oxide must let the ions to travel freely in order for electricity to flow through it.

Due to its extremely high melting point (about 2000°C), aluminum oxide would be expensive to melt. Although it doesn't dissolve in water, aluminum oxide does in molten cryolite. The melting point of this aluminum compound is lower than that of aluminum oxide. Cryolite utilization lowers some of the energy expenses associated with aluminum extraction. Carbon dioxide bubbles off once the oxygen and carbon in the electrodes react. The positive electrodes must consequently be replaced regularly since they lose carbon over time. This raises the price of the procedure.

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Order of decreasing average speed is Nitrogen>oxygen>carbon dioxide

According to Graham's law of diffusion, the rate of diffusion is inversely proportional to the vapour density of the molecule and therefore the smaller the weight of the molecule the faster the rate of diffusion.

Because of the above reason nitrogen has the lowest vapour density followed by oxygen and carbon dioxide with the highest and therefore nitrogen will possess the greatest speed than the others and the decreasing order are nitrogen>oxygen>carbon dioxide.

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Answer:

False.

Explanation:

Dimensional analysis is a way of converting quantities. The study of space and time is cosmology.

The term combustion has to do with a situation in which a substance is burnt in oxygen. When we burn a substance in oxygen, we say that the substance is oxidized.

Methanol is a member of the alkanol series of organic compounds. The equation for the combustion of methanol is shown to be as follows;

[tex]CH_{3} OH + 3O_{2} ---- > 2O_{2}+ 4H_{2}O[/tex].

Looking at the set up as we can see it in the question, we can observe the following;

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The lactase enzyme lowers the activation energy required to begin breaking down lactose. Therefore, option (B) is correct.

The lactase enzyme is a part of the β-galactosidase family, found along the membrane of villi in the small intestine.

In the human body, the optimum temperature and pH for lactase are 37 ° C and 6 pH respectively. Lactase helps in the complete digestion of milk in the small intestine in the human body.

The lactase enzyme catalyzes the hydrolysis of the β-glycosidic bond of D-lactose. After the completion of the hydrolysis, D-glucose and D-galactose are obtained.

The lactase provides the path of low activation energy to initiate the breakdown of the lactose.

Therefore, option (B) is correct that lactase lowers the activation energy.

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Answer:

Compounds change properties when the number of atoms changes

The statement best explains the compound H₂O is not toxic to drink, but H₂O₂ is toxic to drink is compounds change properties when the number of atoms changes. The correct option is C.

H₂O is the chemical formula of water. It is made up of joining hydrogen and oxygen. Water is an essential compound of life. It is present in three forms on the earth.

H₂O₂ is the chemical formula of hydrogen peroxide. It is more viscous than water, and it is used as an antiseptic and used in cleaning cut areas and wounds.

When the atoms are more added to a compound. It changes its property because it becomes a new and different compound. Water and hydrogen peroxide are different compounds.

Thus, the correct option is C. compounds change properties when the number of atoms changes.

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The final concentration after adding 2L of water to a 0.50 L volume of 12 M KCl is 2.4 M.

The concentration of a solute in terms of molarity is expressed as the number of moles of solute per liter of solution. The problem is regarding the dilution process of KCl. The molarity can be calculated using the dilution formula, expressed as (initial concentration of 1st solution)(initial volume)=(final concentration)(final volume). This formula shows that the number of moles remained the same throughout the process.

(12 M KCl) * ( 0.50 L) = (final concentration) ( 0.50 L + 2.0 L)

final concentration = 2.4 M KCl

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A student says that all pure substances are elements. Do you agree? Why or why not?

i don't. pure substances include elements, compounds and crystals. they would've been correct if they stated all elements were pure substances.

or

I disagree. Elements form all pure substances, but some pure substances include elements bonded together to form molecules and compounds.

The equation showing process for ionization energies -

a) For lead,

           First Ionization energy :       Pb (g)  + IE₁  →  Pb+ (g) + e-

           Second Ionization energy:  Pb+ (g)  + IE₂  →  Pb₂+ (g) + e-

b) Fourth ionization energy of zirconium -

          Zr₃+(g)   →    Zr₄+(g)+e−

To remove an electron from a gaseous atom then the energy that is required is known as Ionization Energy.

Amount of energy required to remove the most loose bounded electrons form an isolated gaseous atom to form a gaseous ion, it is called the ionization enthalpy or ionization energy. It is usually represented in the units of kJ mol-1

The first two ionization energies of lead -

Lead is a heavy metal whose atomic number is 82. It has electronic configuration : [Xe] 4f14 5d10 6s2 6p2

Thee general formula to write the equation .

           First :              Pb (g)  + IE1  →  Pb+ (g) + e-

           Second:         Pb+ (g)  + IE2  →  Pb2+ (g) + e-

The first and second ionization energies of Lead, Pb is equal to =

First = 715.6 kJ mol⁻¹

Second = 1450.5 kJ mol⁻¹

The fourth ionization energy of zirconium is:  

                     Zr₃+(g)  →  Zr₄+(g)+e−

The fourth ionization energy is 3313 kJ mol⁻¹

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Answer:

4

Explanation:

Number--Scientific Notation--Significant Figures

9000      9.0×103                                    1

91010      9.101×104                                 4

956              9.56×102                             3

9010.0      9.01×103                                 5

Answer:

Number; 91010

Scientific Notation; 9.101×10^4

Significant Figures; 4

Explanation:

Answer:

its molecule remain in position without vibrating

Answer:

The Answer is C; There is little, if any, space left between its adjacent molecules.

Explanation:

Because it is so compact, it cannot be compressed any further. Imagine trying to press down on a piece of bread versus a brick. The bread would flatten because it is full of air, but the brick would not because it is compact.

I hope this helps, have a nice day! :)

"perform multipule trials for each measurment instead of just one"  is the way that student can improve the experiment.

Because it controls the sorts and types of aquatic life, limits the maximum dissolved oxygen concentration of the water, and affects the speed of chemical and biological reactions, temperature is a crucial water quality and environmental characteristic.

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Overlapping of an sp³ orbital (which has high electron density) with an s orbital forms a stronger bond than that formed by overlapping of an s orbital with p orbital.

What is Orbital Overlapping?

When two interacting orbitals are in same phase, then the overlapping is positive and this lead in the formation of bond.  

    2. Negative Overlapping of Atomic Orbital –

 When two interacting orbitals are in opposite phase,  then the overlapping is positive and bond is not formed.

    3. Zero Overlapping of Atomic Orbital

When orbitals do not overlap each other then the overlapping is known as Zero overlapping orbital.

 Now,

    Overlapping of an sp³ orbital (which has high electron density) with an s orbital forms a stronger bond than that formed by overlapping of an s orbital with p orbital.

From the above conclusion we can say that , Overlapping of an sp³ orbital (which has high electron density) with an s orbital forms a stronger bond than that formed by overlapping of an s orbital with p orbital.

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Influenza viruses spread mainly through droplets of respiratory secretions in the air, typically generated by coughing and sneezing.

A contagious illness brought on by influenza viruses, influenza is also referred to as "the flu." Flu-like symptoms, which can range in severity from moderate to severe, frequently include fever, runny nose, sore throat, muscle discomfort, headache, coughing, and exhaustion. After being exposed to the virus, these symptoms usually appear one to four days later and remain for two to eight days.

Especially with children, diarrhea and vomiting can happen. Pneumonia, which can be brought on by the influenza virus or a subsequent bacterial infection, may develop from the viral-related illness. Other side effects of infection include meningitis, encephalitis, acute respiratory distress syndrome, and deterioration of pre-existing conditions like asthma and cardiovascular disease.

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Explanation:

Color is one of the nature of the substance, then is color a physical property?

For better understanding, let us assume that a band of the color spectrum falls on the material, absorbing the wavelength of 540 and 460 nm and reflecting the wavelength of 680nm. The resulting color of the material is red because red has a wavelength of 700-635nm. The absorbed colors are green and blue because the wavelength of green is 560-520nm and blue is 490-450nm. As the green and blue colors are absorbed by the material and red is reflected, the composition of the material does not alter; hence the color is the physical property of the material.

R

Answer: This is True

Explanation: I'm only writing this part so that it counts. :)

Answer: True

Explanation: because you got to understand we use electricity every day.

Answer:

-bubbles produced when iron placed in acid -two liquids combined and a solid appeared -white substance turned blue when water was added

Explanation:

all the other answers could be turned back into their previous state, or haven't really changed.

Balanced equation for the first step of dissotiation:

H₃PO₄(aq) + H₂O(l) ⇄ H₂PO₄⁻(aq) + H₃O⁺(aq).

Balanced equations for the second step of dissotiation:

H₂PO₄⁻(aq) + H₂O(l) ⇄ HPO₄²⁻(aq) + H₃O⁺(aq).

Balanced equations for the third step of dissotiation:

HPO₄²⁻(aq) + H₂O(l) ⇄ PO₄³⁻(aq) + H₃O⁺(aq).

A phosphoric acid or orthophosphoric acid (H₃PO₄)  is three protic acid, which means that in water it releases three hydrogen ions. A phosphoric acid ionizes in three steps in water.

Species that are present: H₃PO₄, H₂PO₄⁻, HPO₄²⁻, PO₄³⁻ and H₃O⁺.

Hydronium ion (H₃O⁺ ) is the type of oxonium ion produced by protonation of water.

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Answer:

The correct answer is Calcium Carbonate.

Explanation:

Please ask questions correctly

Answer:

A has Larger volume by 0.5cm^3

Density = Mass/ Volume

Volume = Mass / Density

So, for A,

Volume = 9/10 = 0.9cm^3

For B, Volume = 4/10 = 0.4cm^3

Therefore Volume of A is larger.

Alternatively, since density of both objects are same, the object with greater mass will have larger volume.

The statement metals can hammered into thin sheets and non metals are brittle is correct. Thus option C is true.

Metals is defined as a substance with good conductor of electricity, luster and malleability, which are ready to lose electron to form a positive ion i.e. cation. Metals can also be defined according to their periodic table.

Non metals is defined as a substance which are poor conductor of electricity, luster and malleability which are ready to gain electron to form a negative ion i.e. anion. They can be gas, liquid or solid.

Thus, metals can hammered into thin sheets and non metals are brittle is correct. Thus option C is true.

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20.7 kJ energy is required to raise the temperature of 2kg of iron from 20 c to 23 c.

Specific heat capacity refers to the amount of heat required to raise the temperature of a substance. Specific heat capacity is denoted by c.

The formula is Q = mcΔT

Given:

Solution:

Put the values in the formula given below

Q = mcΔT

Q = (2.00 kg) (449 J/ kg°C) ( 23°C)

Q = 20654 J or Q = 20.7 KJ

Approximately 20.7 kJ heat is required to raise the temperature of 2kg of iron from 20°C to 23°C.

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Answer:

Scientific learning is the study methodology used through testing and experimentation.

Answer:

The Science of Learning is an approach that recognizes the value and importance of cross-fertilization across traditional fields of study, drawing on many different methods and techniques to understand how learning occurs— with the ultimate goal of optimizing learning for all.

According to Bohr's concept of the atom, an atomic system with an orbiting system of electrons and a small, dense nucleus is drawn by electrostatic forces rather than gravity and has a structure similar to that of the solar system.

Electrostatic forces, for example, pull or push on items without actually coming into touch with them.

Charge can be transferred from one surface to another when specific materials are rubbed together.

Charged objects pull uncharged ones, and other charged objects may push or pull against them.

According to Bohr's hypothesis, atoms have a tiny, positively charged nucleus that is around by negatively charged electrons.

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The Phlogiston Theory of ordinary burning posited that the materials that were combustible all contained a material called Phlogiston.

In science, theories are often put forward to explain a phenomenon.  theory may not survive the test of time when contrary evidences begin to emerge.

The Phlogiston Theory of ordinary burning posited that the materials that were combustible all contained a material called Phlogiston  which is released when the material is burnt.

However, Lavoisier was able to show by experiment that this position was a mere speculation and the the combustion of a substance was due to its reaction with oxygen.

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Hydrogen bond are help in stabilizing the alpha helix structure of a protein.

Alpha helix structure is a structure whose inner section is tightly coiled main chain, its side chain extending outward in helical array. alpha helix structure is a element of secondary structure in which amino acid structure is arranged in spiral. alpha helix structure for proteins is stabilizing by intramolecular hydrogen bonding between C=O and N-H group of different peptide bond.

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