What is the main element that stars are made of

1. The period number tells us about the number of shells in an element(for example Na located in third period has three electron shells)

2. Group number tells us the amount of electrons present in the valence shell thus also tells us about the ionic charges they form

3. They all have a stable electronic configuration with complete valence shells hence they also don't form ions.

Final answer:

The period of an element denotes the number of electron shells, while the group indicates the number of valence electrons. Group 18 elements, noble gases, share the common trait of having a full valence shell, making them non-reactive.

Explanation:

Understanding Periods and Groups on the Periodic Table

1. The period (row) in which an element is located corresponds to the number of electron shells that contain electrons. Elements in the same period have the same number of shells, with the number of electrons increasing as you move from left to right across the table.

2. The group (column) identifies the number of valence electrons in an element's outer shell. For example, all Group 1 elements have one valence electron, whereas Group 17 elements have seven valence electrons, which is significant for their chemical properties and reactivity.

3. The elements in Group 18, known as the noble gases, have a common characteristic in their electron configurations: they all have filled outer electron shells. This complete valence shell renders them very stable and non-reactive, thus they are also called inert gases.

Final answer:

The fluoride concentration is 1 ppm for a solution of 500 grams of fluoride in 500,000 liters of water. Following the WHO's guidelines, an average person would ingest 1.92 milligrams of fluoride ion by drinking 1,920 mL of water at this concentration.

Explanation:

To calculate the concentration of fluoride in parts per million (ppm) for a solution that consists of 500 grams of fluoride in 500,000 liters of water, you can use the definition of parts per million. Parts per million is the ratio of solute-to-solution mass multiplied by 106. Therefore, you first need to convert the mass of fluoride from grams to milligrams and then divide by the total volume of solution in liters.

To get the mass of fluoride in milligrams, multiply 500 grams by 1000 (since there are 1000 milligrams in a gram). That gives you 500,000 milligrams. Next, since the volume of water is already in liters, we keep it as is. We then use the formula for ppm:

ppm = (mass of solute in mg) / (volume of solution in L)

Now, by substituting the values we have:

ppm = 500,000 mg / 500,000 L = 1 ppm

Assuming the World Health Organization's maximum recommended concentration of fluoride ion is 1.0 ppm, then an average person drinking 1,920 mL (1.92 liters) of this water would consume:

fluoride intake = concentration (ppm) × volume of water (L)

In milligrams, this becomes:

fluoride intake = 1 ppm × 1.92 L = 1.92 mg

Thus, an average person would ingest 1.92 milligrams of fluoride ion per day.

Answer:

                     BaI₂.5H₂O

Explanation:

Given Data:

                   Mass of Hydrated BaI₂ = 10.222 g

                   Mass of dried BaI₂ = 9.520 g

                   Mass of Water removed  =  10.222-9.520 = 0.702 g

                   M.Mass of BaI₂ = 391.136 g/mol

                   M.Mass of Water  =  18.02 g/mol

Now,

         Calculate moles of dried BaI₂ as,

Moles  =  Mass / M.Mass

Moles  =  9.520 g / 391.136 g/mol

Moles  =  0.02434 moles

         Calculate moles of Water as,

Moles  =  Mass / M.Mass

Moles  =  0.702 g / 18.02 g/mol

Moles  =  0.0389 moles

Then,    

          Calculate Mole ratio of BaI₂ and water as,

              = 0.02434 moles BaI₂ / 0.0389 moles Water

              =  0.625

Now,

We will convert this mole ratio to a whole number by multiplying it with a nearest integer,

             =  0.625 × 8

             =  5

Hence, this means for every one mole of BaI there are 5 moles of Water.

Result:

                                             BaI₂.5H₂O

Answer:

The volume is 214, 3 ml

Explanation:

We calculate the weight of 1 mol of  NH4OH:

Weight  1 mol NH4OH=  Weight N + (Weight H) * 5 + Weight 0

Weight  1 mol NH4OH= 14g + 1 g* 5 + 16g = 35 g/mol

1 mol NH4OH-----35 g

0,6mol NH4OH----X=(0,6mol NH4OHx 35 g)/1 mol NH4OH= 21 g

We have 0,6 mol in 1000ml of solution (0,600 M)

21g NH4OH-----------1000ml

4,50 g NH4OH------x= (4,50 g NH4OH  x 1000ml)/21 g NH4OH= 214, 2857143 ml

Answer:

                      36.46 g of HCl

Explanation:

                    The balance chemical equation for given single replacement reaction is as follow;

                              Mg + 2 HCl → MgC₂ + H₂

Step 1: Calculate Moles of HCl required:

According to equation,

                   1 mole of Mg reacted with  =  2 moles of HCl

So,

                0.5 moles of Mg will react with  =  X moles of HCl

Solving for X,

                     X =  0.5 mol × 2 mol / 1 mol

                      X =  1 mol of HCl

Step 2: Calculate Mass of HCl as;

                    Moles  =  Mass / M.Mass

Or,

                    Mass  =  Moles × M.Mass

                    Mass  =  1 mol × 36.46 g/mol

                   Mass =  36.46 g of HCl

Final answer:

To react 0.50 moles of magnesium completely with HCl, 36.46 grams of HCl are required, based on the stoichiometric ratio from the balanced chemical equation.

Explanation:

To find the number of grams of HCl needed to react completely with 0.50 moles of magnesium, we must refer to the balanced chemical equation Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g). According to the equation, 1 mole of magnesium reacts with 2 moles of HCl. Therefore, 0.50 moles of magnesium will require 1 mole of HCl (0.50 moles Mg × 2 moles HCl/mol Mg = 1 mole HCl).

The molar mass of HCl is approximately 36.46 g/mol. Now, we can calculate the mass of HCl needed:

Mass of HCl = moles HCl × molar mass of HCl = 1 mole × 36.46 g/mol = 36.46 grams of HCl.

Answer:

it is  0.0572

Hope you will find my answer helpful

To find the mole fraction of the solute in a 3.73 m aqueous solution, one must calculate the moles of solute and solvent. Upon doing so, the mole fraction is determined by dividing the moles of solute by the total moles of the mixture. The approximate mole fraction for the solute in this case is 0.063.

To calculate the mole fraction of solute in a 3.73 m aqueous solution, we need to know both the number of moles of the solute and the solvent. The given information indicates that we have 3.73 mol of solute (e.g., NaCl) per 1 Kg of water (solvent).

In this example, we calculate the number of moles of water using its molar mass, which is approximately 18.015 g/mol. Since we have 1.0 kg (or 1000 g) of water, we divide the mass by the molar mass to get the moles of water: 1000 g / 18.015 g/mol ≈ 55.5 mol. Now, we have the necessary information to calculate the mole fraction.

The mole fraction is the moles of solute divided by the total moles of both solute and solvent. Using the moles we found earlier:

So, the mole fraction of the solute is approximately 0.063.

D. Electronegativity and first ionization energy both increase as you

move up the periodic table.

There are various kind of elements that are present in periodic table. Some elements are harmful, some are radioactive, some are noble gases. Therefore, the correct option is option D that is Electronegativity and first ionization energy both increase as you move up the periodic table.

Periodic table is a table in which we find elements with properties like metals, non metals, metalloids and radioactive element arranges in increasing atomic number.

Periodic table help a scientist to know what are the different types of elements are present in periodic table so that they can discover the new elements that are not being discovered yet. Electronegativity and first ionization energy both increase as you move up the periodic table.

Therefore, the correct option is option D.

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If the applied force on a car is cut in half, the acceleration is also halved, as acceleration is directly proportional to force.

Based on Newton's second law of motion, acceleration (a) is directly proportional to the net applied force (Fnet) and inversely proportional to the mass (m) of the object, which is expressed by the formula a = Fnet/m. From the question, if the applied force to a car is cut in half, the acceleration would also be reduced by half, assuming the mass of the car remains constant. If the initial acceleration was a, then the new acceleration would be a/2 when the force is halved.

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Answer: The earth is only several thousands years old is not true.

Explanation:The age of Earth is estimated to be 4.54 ± 0.05 billion years .

This age may represent the age of Earth's accretion, or core formation, or of the material from which Earth formed.

NaCl, H₂O₂ and CaF₂ are electrolytes, whereas CO₂ and Al₂O₃ are non-electrolytes.

Explanation:

An electrolyte is a liquid or solution contains ions which may be decomposed by means of electrolysis.

NaCl dissociates into Na⁺ and Cl⁻ ions in solution is an electrolyte.

CO₂ is a Non-electrolyte.

Al₂O₃ is a Non-electrolyte.

H₂O₂ is an electrolyte

CaF₂ is an electrolyte

Final answer:

The compounds NaCl are electrolytes because they are ionic and can dissociate into ions in solution or when molten. CO are molecular compounds and do not dissociate into ions when dissolved in water, making them non-electrolytes.

Explanation:

The question is asking whether certain compounds are electrolytes or non-electrolytes. An electrolyte is able to conduct electricity when dissolved in water because it separates into ions that are mobile and can move from one electrode to the other. In contrast, a non-electrolyte does not dissociate into ions and hence does not conduct electricity in solution.

Answer:

Direct relationship.

Explanation:

Answer:

A. The electric energy is due to the protons’ charges and positions within an electric field, so their energy is a form of potential energy.

Explanation:

Proton is subatomic particle with positive charge. Things with charge will pull the opposite charge and repel/push the same charge. The closer their position, the higher the energy will be. It should be potential energy since your location(how close it is) determine how strong the energy.

It's not thermal or kinetic energy since this doesn't involve any movement yet.

Answer : The volume of [tex]O_2[/tex] gas needed are, 90 L

Explanation : Given,

Volume of [tex]H_2S[/tex] = 60 L

Now we have to determine the volume of [tex]O_2[/tex] needed.

As we know that at STP, 1 mole of gas contains 22.4 L volume of gas.

The given balanced chemical reaction is:

[tex]2H_2S(g)+3O_2(g)\rightarrow 2SO_2(g)+2H_2O(g)[/tex]

By the stoichiometry we can say that, 2 moles of [tex]H_2S[/tex] react with 3 moles of oxygen gas to give 2 moles of [tex]SO_2[/tex] gas and 2 moles of water vapor.

From the balanced reaction we conclude that,

As, [tex]2\times 22.4L[/tex] volume of [tex]H_2S[/tex] react with [tex]3\times 22.4L[/tex] volume of [tex]O_2[/tex] gas

So, [tex]60L[/tex] volume of [tex]H_2S[/tex] react with [tex]\frac{3\times 22.4L}{2\times 22.4L}\times 60L=90L[/tex] volume of [tex]O_2[/tex] gas

Thus, the volume of [tex]O_2[/tex] gas needed are, 90 L

Answer:

A and i think D

Explanation:

Answer:

Can confirm that its A and D.

Explanation:

ape-x

Answer: 9.18 L

Explanation: Solution attached.

Convert mass of CH2O to moles

Derive V from PV= nRT

Substitute the values.

Answer:

D. If the distance between the crests of the waves increase, the frequency decreases.

Explanation:

Wavelength is the distance between two successive crests and troughs while frequency is the number of complete cycle per seconds

Velocity = Frequency × wavelength

Frequency and wavelength are inversely proportion

Final answer:

Wavelength and frequency are inversely related. As the distance between the crests of the waves increases (wavelength increases), the frequency decreases. The correct answer is D.

Explanation:

The question asks how wavelength and frequency are related. The relationship between wavelength and frequency is an important concept in physics, particularly in the study of waves. Wavelength and frequency are inversely related, meaning as one increases, the other decreases. This inverse relationship is explained by the equation c = λν, where c is the speed of the wave, λ (lambda) is the wavelength, and ν (nu) is the frequency. Therefore, if the distance between the crests of the waves increases, which means the wavelength increases, the frequency of the waves decreases since the number of waves passing a given point per unit time becomes fewer.

Given this explanation, the correct answer to the question is: D. If the distance between the crests of the waves increases, the frequency decreases. This is because the increase in distance between crests (increase in wavelength) leads to a reduction in how many waves can pass a given point in a specific amount of time (decrease in frequency).

Answer: B. Pressure, temperature, and volume

Explanation:

I took the test

hope this helped

The three physical properties of gases are pressure, temperature and volume and the correct option is option B.

Gasses do not possess any definite volume or shape. They totally fill all the space accessible to them. The characteristic or properties of gases to fill the available volume within a container is the result of the freedom that gas particles have to move everywhere in the accessible space.

Gases are physical properties of mark sensitivity of volume change with the change of temperature and pressure.

Thus the gases are generally concerned with the relations among four properties, namely mass, pressure, volume, and temperature.

Therefore, The three physical properties of gases are pressure, temperature and volume and the correct option is option B.

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It is a radio wave

Explanation:

The energy of an electromagnetic waves is related to its frequency by the equation:

[tex]E=hf[/tex]

where

h is the Planck constant

f is the frequency of the wave

We notice that the energy of an electromagnetic wave is proportional to its frequency. This means that waves with higher frequencies, such as gamma rays, x-rays, are more energetic, while waves with lower frequencies, such as microwave and radio waves, are the less energetic.

In this case, we want to find the frequency of a wave with energy

E = 0.000001 eV

Converting into Joules,

[tex]E=1\cdot 10^{-6} eV \cdot 1.6\cdot 10^{-19} J/eV=1.6\cdot 10^{-25} J[/tex]

Solving for the frequency,

[tex]f=\frac{E}{h}=\frac{1.6\cdot 10^{-25}}{6.63\cdot 10^{-34}}=2.4\cdot 10^8 Hz = 240 MHz[/tex]

Which falls in the range of frequency of radio waves.

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Answer:

Radio waves,because a radio wave has a longer wavelength than both infrared and X-rays, so it has less energy

Explanation:



Answer:

8 electrons

Explanation:

For the two atoms to have an octet configuration, they must share

8 electrons. Two of the atom with six valence electron will bond with one of the atom with four valence electrons. This is clearly seen when carbon react will sulphur to form carbon disulfide. They form covalent double bond (S=C=S)

Answer:

The answer is D~all of these

Answer:

Yes there is

Explanation:

For facts

The maximum limit of a metal to which the force applied will not leave any deformation, this limit is called as elastic limit. If the force is applied beyond the elastic limit the metal will retain the deformation.

A metal  is an element that can easily form positive ions called cations and tends to make metallic bonds. Some of the important properties of metal are :

Elasticity of the metals by which the metal are able to regain the original shape and size even after the removal of the load; all cutting tools and metallic objects maintain their original shape due to this property.

Every metal has an optimal limit of deformation called as elastic limit, beyond this the metal will retain the deformation even after the removal of applied forces.

Plasticity is the another property of metal in which a permanent deformation occur without any fracture whenever it is subjected by external forces, it can be used  in forming shaping an extruding operation.

Ductility is the property of metals in which they can be drawn into wires or elongated, it is completely depend on tenacity and hardness, it can be higher in cold condition; For example Gold, Platinum, silver, iron etc.

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Answer: Organic chemistry

Explanation:

There are 12.052 ×10²³ atoms in 54 g of aluminium according to the concept  of Avogadro's number.

Avogadro's number is defined as a proportionality factor which relates number of constituent particles with the amount of substance which is present  in the sample.

It  has a SI unit of reciprocal mole whose numeric value is expressed in reciprocal mole which is a dimensionless number and is called as Avogadro's constant.It relates the volume of a substance with it's average volume occupied by one of it's particles .

According to the definitions, Avogadro's number depend on determined value of mass of one atom of those elements.It bridges the gap between macroscopic and microscopic world by relating  amount of substance with number of particles.

Number of atoms can be calculated using Avogadro's number as  follows: mass/molar mass×Avogadro's number

Substituting the values in the formula,54/26.98×6.022×10²³=12.052×10²³ atoms .

Hence, there are 12.052×10²³ atoms in 54 g of aluminium.

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Final answer:

To find the number of atoms in 54.0 g of aluminum, you need to convert the mass of aluminum to moles, and then use Avogadro's number to convert moles to atoms.

Explanation:

To find the number of atoms in 54.0 g of aluminum, you need to convert the mass of aluminum to moles, and then use Avogadro's number to convert moles to atoms.

The molar mass of aluminum is 26.98 g/mol, so you can calculate the number of moles by dividing the mass of aluminum by its molar mass:

54.0 g Al / 26.98 g/mol = 2.001 moles Al

Finally, you can determine the number of atoms by multiplying the number of moles by Avogadro's number (6.022 × 10²³ atoms/mol):

2.001 moles Al * 6.022 × 10^23 atoms/mol = 1.204 × 10²⁴ atoms

Resulting pressure is 13.6 atm.

Explanation:

Using Ideal gas equation, we can find the pressure of the gases formed in the reaction.

PV = nRT

Number of moles, n = given mass / molar mass = 20 g / 18 g/mol

                           = 1.11 moles

Volume, V = 2 L

Temperature, T = 25°C + 273 = 298 K

R = gas constant = 0.08206 L atm K⁻¹ mol⁻¹

P = nRT/V

 = 1.11×0.08206 ×298 / 2

 = 13.6 atm  

Answer:

1,100,160J or 262.94 kcal

Explanation:

The juice is frozen at 0 degrees Celsius and I assume that it will become gas at 100 degrees Celsius. So we change the form of the water from solid to liquid, then to gas. That means we have to find out how much heat needed to change water form too, not only the heat needed to increase its temperature.

The latent heat of water is 4.2J/g °C while the heat of fusion is 334 J/g and the heat of vaporization is 2260 J/g. The energy needed will be:

360g * 4.2J/g °C * (110-0°C ) + 360g * 334 J/g + 360g * 2260 /g = 1,100,160J or 262.94 kcal.

Final answer:

The energy required to heat the frozen can of juice from 0 degrees Celsius to 110 degrees Celsius is 163.08 kJ.

Explanation:

To calculate the amount of energy required to heat the frozen can of juice, we need to consider three steps:

Heating the can from 0 degrees Celsius to its melting point, which is 0 degrees Celsius

Melting the ice at 0 degrees Celsius

Heating the water from 0 degrees Celsius to 110 degrees Celsius

The energy required for each step can be calculated using the formula Q = mcΔT, where Q is the energy, m is the mass, c is the specific heat capacity, and ΔT is the change in temperature.

For the first step, Q = (360g)(4.18 J/g°C)(0 - 0) = 0 J.

For the second step, Q = (360g)(333.55 J/g)(0 - 0) = 0 J.

For the third step, Q = (360g)(4.18 J/g°C)(110 - 0) = 163,080 J = 163.08 kJ.

Adding up the energies from each step, the total energy required to heat the frozen can of juice is 163.08 kJ.

According to law of conservation of mass, conservation of mass is illustrated by none of the equation  as  the  number of atoms of reactants and products is  not same in any equation.

According to law of conservation of mass, it is evident that mass is neither created nor destroyed rather it is restored at the end of a chemical reaction .

Law of conservation of mass and energy are related as mass and energy are directly proportional which is indicated by the equation E=mc².Concept of conservation of mass is widely used in field of chemistry, fluid dynamics.

Law needs to be modified in accordance with laws of quantum mechanics under the principle of mass and energy equivalence.This law was proposed by Antoine Lavoisier in the year 1789.

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Answer:

yes

Explanation:

Hydroelectric energy is a renewable energy source that uses the potential energy of water to generate electricity. It's a significant contributor to renewable energy consumption but does come with environmental concerns that need to be addressed.

Yes, hydroelectric energy is considered a renewable energy source. Hydroelectric power plants use the potential energy stored in water held in dams or flowing in rivers to generate electricity. When water is released from the dam, it flows through turbines, converting potential energy into kinetic energy, which is then used to generate electricity.

This process is renewable because it relies on the water cycle, which is a natural and continuous process on Earth. Water evaporates, forms clouds, and then falls as precipitation, continually replenishing the water in rivers and reservoirs. Hydroelectric power does not produce direct pollutants, making it a clean energy source.

While hydroelectric power is a significant portion of renewable energy consumption, accounting for about 35% of the United States' renewable energy, it is not without environmental concerns. Dams can disrupt local ecosystems and obstruct the migratory paths of fish. However, with proper management and environmental considerations, such as fish ladders, these impacts can be mitigated, allowing hydroelectric power to remain a valuable part of our renewable energy portfolio.

Answer:

I got the answers but it won't let me post it correctly on here....

Explanation:

9.) 10-2.76 =0.0174 [H30+]= 1.74*10-3 M

10.)10-3.65=0.00224  [H3O+] =2.24*10-2 M

11.)10-3.65=0.00224 [OH-]= 2.224*10-4M

12.)10-6.87=0.00000135  [OH-]= 1.35*10-7M

The [H3O+] and [OH-] of solutions a, b, c, and d are calculated using the formulas for pH and pOH. The [H3O+] for solutions a and b come out to be 1.74 x 10^-3 M and 2.2 x 10^-4 M respectively, while the [OH-] for solutions c and d are 2.2 x 10^-4 M and 1.37 x 10^-7 M respectively.

To calculate the [H3O+] and [OH-] in solutions, we need to use the formulas for pH and pOH. Where pH = -log[H3O+] and pOH = -log[OH-]. Therefore, for a solution with a given pH, [H3O+] can be calculated as [H3O+] = 10^-pH, and for a solution with a given pOH, [OH-] is calculated as [OH-] = 10^-pOH.

For solution a, pH = 2.76, [H3O+] = 10^-2.76 = 1.74 x 10^-3 M. Similarly, for solution b, pH = 3.65, [H3O+] = 10^-3.65 = 2.2 x 10^-4 M. For solution c, pOH = 3.65, [OH-] = 10^-3.65 = 2.2 x 10^-4 M. For solution d, pOH = 6.87, [OH-] = 10^-6.87 = 1.37 x 10^-7 M.

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The volume of a gas that has its Celsius temperature increased from 2°C to 4°C, while the pressure remains constant, would increase slightly due to the principles of Charles's Law in physics.

The concept behind this question is called Charles's Law from physics. This law states that the volume of a given mass of an ideal gas is directly proportional to its temperature on the absolute temperature scale (Kelvin), if pressure and the amount of gas remain unchanged.

In your case, the Celsius temperature of a fixed mass of gas is increased from 2°C to 4°C, a change of 2 degrees. In Kelvin this is a change from 275K to 277K since we add 273 to convert Celsius to Kelvin. Using Charles's Law, under these conditions, the volume of the gas would increase slightly, not significantly. As the change in temperature is very small, the change in the volume would also be small.

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Increasing the temperature from 2°C to 4°C while keeping pressure constant will result in a slight increase in the gas's volume, according to Charles's law.

The student's question is about what happens to the volume of a gas when its Celsius temperature is increased from 2°C to 4°C while the pressure remains constant.

Charles's law states that the volume of a gas is directly proportional to its temperature when the pressure is held constant. Hence, increasing the temperature in degrees Celsius – or more relevantly, in Kelvin – will also increase the volume of the gas slightly.

Since the increase in temperature from 2°C to 4°C is minimal (equivalent to an increase from 275.15K to 277.15K), the change in volume will be correspondingly small. Thus, the correct answer is that the volume of the gas will be increased slightly.

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