The energy levels in which electrons orbit around the ____________ are also called ____________ .

Answer:

A. Chemical composition of the star

Explanation:

'Each element absorbs light at specific wavelengths unique to that atom. When astronomers look at an object's spectrum, they can determine its composition based on these wavelengths' - astronomy.com

'Atomic emission spectra are unique spectra of light emitted by an element when electricity is run through it or when it is viewed through a prism. Because they are unique, they can act as an element s fingerprint' - brightstorm.com

Answer:

The science of spectroscopy is quite sophisticated. From spectral lines astronomers can determine not only the element, but the temperature and density of that element in the star. The spectral line also can tell us about any magnetic field of the star. The width of the line can tell us how fast the material is moving.

Attractions between the negative oxygen atom of one water molecule and the positive hydrogen atom of another water molecule is called hydrogen bond.

Water molecule is made up of one oxygen atom and one hydrogen atom. Each hydrogen atom shares an electron pair with the oxygen atom. The water molecule also contains two unshared lone pairs of electrons.

The lone pair of electrons repel each other and also repel the hydrogen atoms. This gives the water molecule a bent shape, with a hydrogen atom at each of the two corners and the unshared pairs of electrons at the other two corners. The angle between the hydrogen atoms is 104.5 degrees.

This unequal sharing of electron causes the oxygen atom to have a partial negative charge and the hydrogen atom to have a partial positive charge, causing electrostatic attractions between the hydrogen atom of one water molecule and the oxygen atom of another hydrogen atom. This attraction is called hydrogen bond.

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The mass of the compound that contains 185.0 g of hydrogen is 2384.02 g

The following data were obtained from the question:

Percentage of carbon = 92.24%

Percentage of hydrogen = 7.76%

Mass of hydrogen = 185.0 g

Mass of compound =?

The mass of the compound can be obtained as illustrated below:

Percentage of hydrogen = (mass of hydrogen / mass of compound) × 100

7.76% = 185 / mass of compound

0.0776 = 185 / mass of compound

Cross multiply

0.0776 × mass of compound = 185

Divide both sides by 0.0776

Mass of compound = 185 / 0.0776

Mass of compound = 2384.02 g

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Answer:

Positive catalysts are those catalysts which increase the rate of the reaction This means that the activation energy of the reaction is lowered, and the speed of the reaction also increases. An example of positive catalysis is decomposition of potassium chlorate.

Explanation:

The pH be lower in the beaker with the strong acid because strong acid gives more hydrogen ions.

pH (potential of hydrogen) is a numeric scale used to specify the acidity or basicity an aqueous solution.

When pH is less than seven (pH<7), solution is acidic.

Hydrochloric acid is strong acid and in water dissociates completely:

HCl(aq) → H⁺(aq) + Cl⁻(aq)

Amount of hydrogen ions are the same as amount of hydrochloric acid.

At other hand, acetic acid (CH₃COOH) is weak acid and does not dissociate completely as HCl, so concentration of hydrogen ions in a solutions are very low.

Strong acids: HNO₃(nitric acid), HCl(hydrochloric acid), H₂SO₄(sulfuric acid), HI(hydroiodic acid).

Weak acids:CH₃COOH (acetic acid), H₂CO₃ (carbonic acid), HCN (cyanic acid).

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The energy and intermolecular forces involved for liquid solid and gas are as follows:

Intermolecular forces are forces of attraction that exists between the molecules of a substance.

The strength of the intermolecular forces and hence, the kinetic energy vary inversely in molecules of solids, liquids and gases.

The energy and intermolecular forces that are involved for liquid solid and gas are explained below:

In conclusion, intermolecular forces decrease with increase in the kinetic energy of molecules.

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Oxygen (O₂) is the limiting reactant.

Balanced chemical equation for reaction of disilane with oxygen:

2Si₂H₆ + 7O₂ → 4SiO₂ + 6H₂O.

Word equation: disilane + oxygen → silicon dioxide + water.

n(Si₂H₆) = 8.4 mol; amount of disilane

n(O₂) = 15.1 mol; amount of oxygen

From balanced chemical equation: n(Si₂H₆) : n(O₂) = 2 : 7

mole ratio for disilane = 8.4 mol / 2 = 4.1 mol

mole ratio for oxygene = 15.1 mol / 7 = 2.15 mol

Oxygen is the limiting reactant, because it has smaller mole ratio than disilane.

Limiting reactant determine amount of the product formed in a reaction.

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312 grams of oxygen reacts.

Balanced chemical equation for the reaction of hydrogen and oxygen to produce water: 2H₂ + O₂ → 2H₂O.

m(H₂) = 39.3 g; mass of hydrogen

n(H₂) = m(H₂) ÷ M(H₂).

n(H₂) = 39.3 g ÷ 2 g/mol.

n(H₂) = 19.65 mol; amount of hydrogen

m(H₂O) = 351 g; mass of water

n(H₂O) = 351 g ÷ 18 g/mol

n(H₂O) = 19.5 mol; amount of water

From chemical equation: n(O₂) : n(H₂O) = 1 : 2

n(O₂) = 19.5 ÷ 2

n(O₂) = 9.75 mol; amount of oxygen

m(O₂) = 9.75 mol × 32 g/mol

m(O₂) = 312 g; mass of oxygen

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1. Apple juice has a pH of around 3 and lemon juice has a pH near 2. to neutralize with baking soda lemon juice would need more baking soda because it is more acidic than aple juice. the less  ph present the more baking soda need to neutralize.

2. A "mole" is the quantity of a material that is precisely 6.02214076 X 1023 particles in the International System of Units. Ions, atoms, or molecules might make up the particles.

The number of moles of a solute in a litre of solution is known as molarity (M). The symbol for molarity is M, which stands for mole/liter.

Molarity is a measure of a solution's concentration that is expressed in units of moles per litre. Therefore, molarity is utilised to calculate the solute's volume.

3 Hexane will  dissolve in  ionic salt like LiCl because both of the compound are covalent and non-polar and like dissolves like.

4.Every enzyme has a preferred pH range. Outside of this range, pH changes will limit enzyme activity. Enzymes can denature at extreme pH levels. If there is a substrate available for the enzyme to bind to, increasing the concentration of the enzyme will hasten the process.

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Correct compound is [Co(H2O)6]^+3

The oxidation state of Co is +3

[Co(H2O)6]^+3

Let

 Co be x

 H2O = 0

 x + (0)6 = 3

 x = 3

What is oxidation state?

The oxidation state, commonly known as the oxidation number, is the potential charge that an atom would have if all of its bonds to other atoms were fully ionic. It describes the degree of atom oxidation within a chemical compound.The oxidation state may be positive, negative, or zero in theory.

The oxidation number, sometimes referred to as the oxidation state, is the total number of electrons that an atom gains or loses while uniting with another atom to form a chemical bond.

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The correct matching of the properties of the elements are;

Rubidium - catches fire as soon as it s exposed to air and burns fiercely

Lithium - hard to set alight but burns with a deep red flame

Potassium - Melts readily on heating with a Bunsen flame and catches fire easily. Burns with a mauve flame.

Sodium - Melts fairly readily with  Bunsen flame then catches fire and burns with a deep yellow flame

We know that elements are classified into groups. The groups are a family of elements that have similar chemical and physical properties. Now we have the to match the properties of the elements as shown;

Rubidium - catches fire as soon as it s exposed to air and burns fiercely

Lithium - hard to set alight but burns with a deep red flame

Potassium - Melts readily on heating with a Bunsen flame and catches fire easily. Burns with a mauve flame.

Sodium - Melts fairly readily with  Bunsen flame then catches fire and burns with a deep yellow flame

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Answer:

151 g SO₂ × [1 mol SO₂/64.06 g SO₂] = 2.36 mol SO₂

Explanation:

Answer:

2.36

Explanation:

got ir right on plato

The ph of a buffer solution prepared with 0.055 m sodium acetate and 0.01m acetic acid at the pka value of acetic acid is 4.76 at 250c is 5.5.

A weak acid and its conjugate base, or vice versa, are combined to form an aqueous solution known as a buffer solution (more specifically, pH buffer or hydrogen ion buffer). A little bit of a strong acid or base applied to it barely affects its pH.

Strong acids or bases applied in modest amounts don't cause buffer solutions to shift pH. An illustration of a buffer made up of a weak acid and its salt is a solution of acetic acid and sodium acetate CH3COOH + CH3COONa.

The three primary buffer systems in the human body are the phosphate, protein, and carbonic acid bicarbonate systems.

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Answer: The answer Option is A.

Explanation: Both the Ions have the electronic configuration 2,8,8

The electronic configuration of an ion is 2.8.8. This ion is S²⁻.

The term electronic configuration is defined as the arrangement of electrons in orbitals around an atomic nucleus.There are four different types of orbitals (s,p,d, and f) have different shapes, and one orbital can contain a maximum of two electrons.

The symbols used for writing the electron configuration start with the shell number (n) and then the type of orbital and finally the superscript represent how many electrons are present in the orbital.

The electronic configuration of an ion is 2.8.8. This ion is S²⁻. Because S²⁻ contain  electronic configuration of an ion is 2.8.8 while electronic configuration of S is 2, 8, 6.

Thus, The electronic configuration of an ion is 2.8.8. This ion is S²⁻.

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The half-life of strontium-90 is 28 years. It will take 52 years a 100-mg sample to decay to a mass of 56 mg.

Given that one half life is equal to 28 years, we must find n in this situation, and the remainder will be equal to 16/56, or 0.28.

0.28  = 0.52^n n = 2

after 1 half life = 0.52 remains.

after 2 half lives= 0.28 remains

Therefore, one half life is 28 years, it will take two half lives for 56 mg to decompose into 16 mg, which is equal to 52 years.

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Taking into account the definition of density and Avogadro's number,  65.07×10²³ molecules of ethanol are present in 630 ml of ethanol.

We can calculate density to determine how much mass there is in a given volume of a substance. The quotient of a body's mass and the volume it occupies is therefore the formula for calculating density:

Density = mass / volume

So, 0.789 = mass / 630

mass =497.07grams

Then the number of moles that 110.46 g of ethanol contain is calculated by: 497.07/46 = 10.80 moles

The number of particles that make up a substance (often atoms or molecules) and may be found in a mole of that substance is known as Avogadro's Number or Avogadro's Constant. The number of particles per mole is [tex]6.022*10^{23}[/tex]. Any substance can be calculated using Avogadro's number.

So, amount of molecules= (10.80 moles× 6.023×10²³ molecules)÷ 1 mole = 65.07×10²³ molecules.

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Mass of acetone is 69.147 grams.

V(acetone - C₃H₆O) = 9.85 × 10⁻² l

V(acetone) = 0.0985 l

V(acetone) = 98.5 ml; volume of acetone

d(acetone) = 0.702 g/mL; density of acetone

m(acetone) = V(acetone) × d(acetone).

m(acetone) = 98.5 ml × 0.702 g/ml.

m(acetone) = 69.147 g; mass of acetone

Acetone or propanone is the colorless, volatile, flammable organic compound (ketone).

Density is the mass of an object divided by its volume. The SI derived unit for density is the kilogram/cubic meter, but chemist usually use gram per milimeter.

Mass is a fundamental measure of the amount of matter in the object.

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After 5.00 s, the speed of the mailbag is 50.63 m/s.

v = 1.63 m/s; the initial speed of a small mailbag

a = 9.8 m/s²; the acceleration of a small mailbag

t = 5.00 s; time

Ending speed is defined as the speed attained by a body after completing distance at certain time interval:

v(ending speed) = v(initial speed) + a × t

v(ending speed) = 1.63 m/s + 9.8 m/s² · 5.00 s.

v(ending speed) = 50.63 m/s

Velocity is equivalent to a specification of its speed and direction of motion, for example 100 km/h to the east.

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Answer:

Electric current generates an accompanying magnetic field, as in electromagnets. When an electric current flows in an external magnetic field, it experiences a magnetic force, as in electric motors. The heat loss, or energy dissipated, by electric current in a conductor is proportional to the square of the current.

Explanation:

An ion is a charged version of an atom that is formed by losing or gaining electrons compared to the atom.

Cations are positively charged atoms.

Anions are negatively charged atoms.

For example, calcium atom forms cation.

Electron configuration of calcium atom: ₂₀Ca 1s² 2s² 2p⁶ 3s² 3p⁶ 4s².

Electron configuration of calcium cation: ₂₀Ca²⁺ 1s² 2s² 2p⁶ 3s² 3p⁶.

Calcium cation is smaller than neutral calcium atoms, because when an electrons are lost, electron-electron repulsion decreases and the protons are better able to pull the remaining electrons towards the nucleus.

When calcium loose two electrons, it will have 20 protons (positive charge) and 18 electrons (negative charge), which means it has two protons more and it has +2 oxidation number.

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Al is equal to 0.0463 moles of aluminum in 1.25 grams.

The ratio of aluminum to alum is 1:1, meaning that for every mole of aluminum consumed, 1 mole of alum is created.

The calculated yield is 21.96 g of alum.

Yield as a percentage is 68.97%.

Acute and chronic oral LD50 values for aluminum sulfate are both more than 5,000mg/kg, making it relatively non-toxic. Alum can nonetheless irritate the skin, burn, and worsen respiratory conditions. It can lead to headaches, nausea, and respiratory irritations when breathed.

It is an astringent, which means it causes the skin to constrict or shrink, first of all. Astringents have the short-term ability to shrink pores and tighten skin. Alum is a helpful preservative because it is bacteriostatic, which means it inhibits the growth of bacteria.

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Mycolic acids are found in the cell wall of acid-fast bacteria, preventing these cells from being gram-stained.

Acid-fast bacteria are a kind of bacteria that contains waxy material called mycolic acid in their cell wall making them water-resistant against staining procedures and materials such as gram stain.

Mycolic acids are lengthy chains of fatty acids found in bacteria and, therefore, are called acid-fast bacteria.

When these bacteria come into contact with substances like acidic alcohol, they develop resistivity against them to prevent decolorization.

In short, mycolic acids prevent the decolorization and staining of bacteria due to their characteristics of resistance and reluctance.

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The quantity of matter in an item is its mass. Scientists frequently use balances to quantify mass. Using an electronic balance or a beam balance, one may directly determine the mass of solids.

The quantity of matter in an item is its mass. Scientists frequently use balances to quantify mass. Using an electronic balance or a beam balance, one may directly determine the mass of solids. A liquid's mass can be calculated by measuring its volume and using the density table to determine the liquid's density.

The kilograms is the SI unit of mass (Kg). To get an object's mass, divide its weight by the acceleration of gravity. The weight units must be changed to Newtons. For instance, 1 kg equals 9.807 N. If you want to know an object's mass on Earth, divide its weight in Newtons by the Earth's gravitational acceleration, which is 9.8 meters per second2.

Here, solute is solid cocl2 and our solvent is distilled water.

The volume of solute is generally ignored, so we would dissolve,

[tex]$250 \mathrm{~mL} \cdot \frac{\mathrm{L}}{10^3 \mathrm{~mL}} \cdot 0.150 \mathrm{M} \cdot \frac{129.9 \mathrm{~g}}{\mathrm{~mol}} \approx 5.68 \mathrm{~g}$[/tex]

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The object at rest moves to the direction of the greater force when it is pulled in opposite directions by unequal forces.

According to Newton’s first law of motion, a body at rest does not move until an external force is applied to it.

When an equal force is applied in the opposite directions, the object remains at rest as the net force becomes zero.

When an unequal force is applied in the same direction, the body moves in the direction of the force being applied, but when the unequal forces are in opposite direction, the object moves in the direction which has greater force.

The net force, which results from the difference between two unequal forces acting in opposition on an object, is what moves it. Resultant is the name given to the overall or net force and its direction.

For example, a force of 30N is applied from the right and 55N is applied from the left on an object. The net force will be 55 – 30 = 25N. Therefore, the object will move to the left with a force of 25N.

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The volume of the air occupies can be 0.001922 L = 1.92mL.

To calculate the volume , the given data's are,

P₁ = 1.0 atm,

V₁ = 1 L,

T₁ = 37°C

P₂ = 500.0 atm,

T₂ = 25°C

The standard definition of the ideal gas law can be stated as that for any gas, its volume (V) multiplied by its pressure (P) is equal to the number of moles of gas (n) multiplied by its temperature (T) multiplied by the ideal gas constant, R.

we can use the formula for general law of ideal gas:

                                 PV = nRT.

where, P is the pressure of the gas in atm,

V is the volume of the gas in L,

n is the no. of moles of the gas in mol,

R is the general gas constant,

T is the temperature of the gas in K.

If n is constant, and have two different values of (P, V and T):

P₁V₁T₂ = P₂V₂T₁

P₁ = 1.0 atm, V₁ = 1 L, T₁ = 37°C + 273 = 310 K.

P₂ = 500.0 atm, V₂ = ??? L, T₂ = 25°C + 273 = 298 K.

Hence,

V₂ = P₁V₁T₂/P₂T₁

     = (1.0 atm)(1 L)(298 K)/(500.0 atm)(310 L)

     = 0.001922 L

     = 1.92 mL.

Hence, the volume of the air occupy is 1.92 mL.

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A protein mixture is commonly applied to a HIC column under high salt conditions, and the protein of interest is eluted with a buffer of decreasing ionic strength.

Structured salts added to the equilibration buffer and sample promote ligand-protein interactions in HIC. The amount of bound protein decreases as the salt concentration decreases, as does the risk of protein precipitation at lower ionic strength.

Despite the fact that sodium, potassium, or ammonium sulfates have a higher precipitation effect, these salts effectively promote ligand-protein interactions in HIC. Most bound proteins are eluted by washing with water or a dilute buffer with a pH close to neutral.

What exactly is HIC?

Hydrophobic interaction chromatography (HIC) is a technique used to separate molecules based on their hydrophobicity. HIC is a useful separation technique for purifying proteins while retaining biological activity due to the use of less denaturing conditions and matrices.

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The spectator ions are Na+ and I when mixing aqueous solutions of BaI2 and Na2SO4 to create a precipitate of BaSO4.

What are spectator ions?

Spectator ions are ions that are present on both sides of chemical reactions but do not take part in the reaction itself. In the net chemical reaction, the spectator ions on both sides of the equation are cancelled. So, to "spectate" is to "see" the other ions in an aqueous solution interact with one another.

The spectator ions are Na+ and I when mixing aqueous solutions of BaI2 and Na2SO4 to create a precipitate of BaSO4.

Let's look at the chemical formula for the reaction that happens when BaI2 and Na2SO4 are combined in aqueous solution. This reaction involves two displacements.

BaSO4(s) + 2 NaI = BaI2(aq) + Na2SO4(aq) (aq)

Let's now have a look at the net ionic equation, which takes into account both the insoluble species and the reacting ions (not spectator ions).

Ba2+(aq) SO42(aq) BaSO4 (s)

As we can see, Na+ and I are the spectator ions that are missing from the net ionic equation.

The spectator ions are Na+ and I when mixing aqueous solutions of BaI2 and Na2SO4 to create a precipitate of BaSO4.

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Answer:

The answer is there are 9.57 x 10²⁰ number of Cl atoms in 0.0728 g of PCl₃.

Number of moles = mass / molar mass

Mass of PCl₃ = 0.0728 g and molar mass of PCl₃ = 137.33g/mol

Number of moles of PCl₃ = 0.0728 / 137.33 = 5.3 x 10⁻⁴

In one mole there are Avogadro’s number of molecules that is 6.02 x 10²³

So, in 5.3 x 10⁻⁴ moles of PCl₃, there are =5.3 x 10⁻⁴ x 6.02 x 10²³ = 3.19 x 10²⁰

Now there is 3 atoms of Cl in PCl₃ so in 3.19 x 10²⁰ molecules of PCl₃, number of Cl atoms = 3.19 x 10²⁰ x 3 = 9.57 x 10²⁰ atoms

The molar fraction of 25% w/w acetic acid solution is 0.069.

The molar fraction of solute in a solution is given by the following formula

Molar fraction of solute = No. Of Moles of solute/No. Of Moles of solute + No. of Moles of solvent

In this case the solute is acetic acid and solvent is water.

It is given that the acetic acid is 25% weight by weight(w/w), which means that 25 grams of acetic acid is present in 100 grams of water.

To calculate the moles, we need to divide the given mass by the molar mass of the compound

No. of moles of Acetic Acid(CH3COOH)= 25/60 = 0.416

And no. of moles of water (H2O) = 100/18 = 5.55

Putting the values in the given formula

Molar fraction of solute = 0.416/5.55+0.416

= 0.069

Hence, the molar fraction of 25% w/w acetic acid solution is 0.069.

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