How many moles of sulfur present in a sample containing 7.65 x 1022
atoms?

The element X, which has mass number of 40 and electron number of 20 is Calcium (Ca) with atomic number 20.

What is mass number?

The total number of protons and neutrons, collectively known as nucleons, in an atomic nucleus is known as the mass number, sometimes known as the atomic mass number or nucleon number. It is roughly equivalent to the atomic mass of the atom, also known as its isotopic mass, expressed in atomic mass units. The mass number A is the same as the baryon number B of the nucleus because protons and neutrons are both baryons (and also of the whole atom or ion). Each individual isotope of a chemical element has a unique mass number. The number of neutrons (N) in a given nucleus is therefore determined by the difference between the mass number A and the atomic number Z: N = A-Z.

Here, Number of electrons = 20

Since, Number of electrons = Number of protons

So, Number of protons = 20

Mass number = 40

Mass number - Number of protons = Number of neutrons

Number of Neutrons = 40 - 20 = 20

Atomic number = Mass number - Number of neutrons

= 40 - 20

= 20

Therefore, atomic number is 20 and the element is Calcium with symbol Ca.

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From Hund's rule, we can now see why the two 2p orbital electrons occur singly and are not paired in one orbital.

According to the Hund's rule, we know that before, we can pair the electrons that are present in the atoms of an element, the electrons must first of all occur singly or have the maximum parallel spins before they are pair.

In this case, we have an electron that has six electrons. The electron configuration of the element has been shown in the image attached. we can see that there are two electrons that singly occupy the 2p orbitals.

This serves to validate the Hund's rule.

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Answer:

We have an electron that has six electrons, and there are two electrons that singly occupy the 2p orbitals. According to Hund's rule, electrons arise singly in an atom before pairing occurs.

Explanation:

The evidence which the attorney will most likely use to prove this accusation is Jared’s fingerprints in the car and is denoted as option C.

These refers to the information and happenings which help to prove that something is true and is used in investigations so as to ensure that the culprit is caught.

In this case, Jared’s fingerprints in the car is the most reliable information which puts him at the scene of the crime as it can't be edited and no fear of false witnesses as a result of this thereby making it the correct choice.

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Answer: C

Explanation:

According to the concept of molar mass , in a sample of copper carbonate  there would be 26.47 g and 20 g of copper and oxygen respectively.

Molar mass of a compound or a molecule is defined as the mass of the elements which are present in it.The molar mass is considered to be a bulk quantity not a molecular quantity. It is often an average of the of the masses at many instances.

The molecular mass and formula mass are used as synonym for the molar mass.It does not depend on the amount of substance which is present in the sample.It has units of gram/mole.

Molar masses of an element are given as relative atomic masses while that of compounds is the sum of relative atomic masses which are present in the compound.

In the given problem , sample of copper carbonate has copper, carbon and oxygen in the ratio of 63.54:12:48.Now, for 5 g carbon , amount of copper is calculated as,

5×63.54/12=26.47 g

And amount of oxygen is calculated as,

5×48/12=20 g.

Hence, for 5 g carbon there is 26.47 g copper and 20 g oxygen in copper carbonate sample.

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Potassium iodide (KI) is the limiting reagent in the given chemical reaction. The theoretical yield of PbI₂ is 109.07 grams and the percentage yield of PbI₂  is 81.23 %.

A limiting reagent is that reactant in the chemical reaction which completely consumed from the reaction mixture at the completion of a  reaction. The limiting reagent is the reactant which is used to calculate the theoretical yield of the reaction.

Given, the balanced equation of the chemical reaction is :

Pb(NO₃)₂ (aq) +  2KI (aq)  ⟶  PbI₂ (s)  +  2 KNO₃ (aq)

The molarity and volume of Pb(NO₃)₂ are 791 ml and 0.765 M respectively.

The molarity and volume of KI are 549 ml and 0.861 M respectively.

From the formula of molarity, the number of moles = Molarity × Volume

The number of moles of  Pb(NO₃)₂ = 0.765 × 0.791 = 0.605 mol

The number of moles of KI = 0.861 × 0.549 = 0.473 mol

If one mol of Pb(NO₃)₂ reacts with KI = 2 mol

Then 0.605 mol of  Pb(NO₃)₂  will react with KI = 2 × 0.605 = 1.21 mol.

But we have only 0.473 mol of KI. It means lead iodide will be the limiting reagent for the reaction.

If two moles of the KI form PbI₂  = 1 mol

Then 0.473 mol of KI will form PbI₂ = 0.473/2 = 0.2365 mol

The molecular mass of PbI₂ = 461.2 g.mol

The theoretical yield of PbI₂ = 0.2365 × 461.2 = 109.07 g

Given, the experimental yield of the PbI₂ = 88.6 g

The percent yield of PbI₂  = (88.6/109.07) × 100 = 81.23 %

Therefore, the percent yield of PbI₂ if 88.6 g of PbI₂ is equal to 81.23 %.

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Answer:

it is a high pressure.

Explanation:

im just guessing it

Warning signs are sometimes placed on aerosol cans to prevent people from throwing them into a fire, the contents of the gas in an aerosol can just after it is placed in a fire (c) it has a high temperature is correct option.

When an aerosol can is placed in a fire, the warning signs and precautions are typically in place to prevent potential dangers and hazards that could arise from the contents of the can. The behavior of the contents of an aerosol can in a fire can vary depending on the specific gas or substance contained within. However, some general principles apply:

Pressure Increase: Aerosol cans are often pressurized to allow the contents to be dispensed in a controlled manner. When exposed to heat from a fire, the pressure inside the can can rapidly increase. This pressure buildup can lead to the can potentially rupturing or exploding, which poses a significant danger to anyone nearby.

Potential for Fire Spread: If the contents of the aerosol can are flammable, they can contribute to the spread of the fire. The released flammable gases or liquids can ignite, leading to a more intense and widespread fire.

Toxic Fumes: The contents of some aerosol cans might include toxic or harmful substances. When heated in a fire, these substances can vaporize and release toxic fumes into the air. Inhaling these fumes can be hazardous to health.

Unpredictable Behavior: The behavior of aerosol cans in a fire can be unpredictable. Factors such as the type of propellant, container material, and contents can all influence how the can reacts when exposed to heat.

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Liters of iodine pentafluoride can be formed at STP from the reaction of 0.25L of fluorine gas at STP with excess iodine is 0.1 L

The balanced chemical equation is given as:

I₂(g)   +   5F₂(g)    ------>     2IF₂(g)

1mole       5 mole                2 mole

1 L             5 L                      2 L

here , 1 L of I₂ react with 5 L of F₂ to form 2L IF₂

so, 0.25 L  react with = 0.25 / 5 = 0.05 L F₂

therefore, iodine pentafluoride gas IF₂ formed = 0.05 × 2 L

                                                                              = 0.1 L

Thus, Iodine pentafluoride gas is formed. Liters of iodine pentafluoride can be formed at STP from the reaction of 0.25L of fluorine gas at STP with excess iodine is 0.1 L.

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Answer: every object in the universe with some mass attracts every other object. As the law of gravitation could be applied to all such objects, it is also known as Newton's law of universal gravitation, that is, its application is universal.

Explanation:

The balanced chemical reaction equation as we can see from the question on the left and right hand sides;

[tex]3H_{2} + N_{2} ------- > 2NH_{3}[/tex]

Now we know that we use the chemical reaction equation to show the relationship between the reactants and the products in the system. We know that there is need to balance the chemical reaction equation so that we can be able  to make sense of a given chemical reaction equation.

A chemical reaction equation is said to be balanced when the number of atoms of each of the elements on the reactant side is the same as the number of atoms of each of the elements on the products side. This could also be called the process of making an atom count to show the number of each of the atoms present in the system.

The principle stated above is used to obtain the balanced chemical reaction equation. If we apply it, we would then be able to obtain the equation as have been shown in the answer section above.

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The average atomic mass of the lithium will be 11.00 amu

The average atomic mass of an element is the cumulative sum of the mass of its isotopes multiplied by their respective abundances.

The average atomic mass is mathematically given by the following formula:

Average Atomic Mass = f1M1 + f2M2 + ......fnMn

Where f = abundance and M = mass number.

In this case, lithium has 2 isotopes.

Mass of isotope 1 = 7.0160

The abundance of isotope 1 = 92.5%

Mass of isotope 2 = 6.0151

The abundance of isotope 2 = 7.5%

Average atomic mass of Lithium = 7.0160 x 0.925 + 6.0151 x 0.75

                                             = 6.4898 + 4.511325

                                               = 11.00 amu

Thus, lithium with 2 isotopes has an average atomic mass of 11.00amu.

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8 hours Short Term Exposure Limit (STEL) for 15 minutes is 750 ppm; Weighted Average (TWA) is 500 ppm.

The threshold limit value is thought to be the maximum exposure level that a worker may endure throughout a shift at work without suffering any negative consequences. TLV is technically a term that the American Conference of Governmental Industrial Hygienists reserves.

TLVs are the highest average airborne concentrations of hazardous materials to which healthy adult employees can be exposed over the course of a working lifetime—during an 8-hour workday and a 40-hour workweek—without developing noticeably detrimental health consequences.

The acetone TLV value in parts per million:

The acetone TLVs established by the ACGIH are 750 ppm for an 8-hour TWA and 1000 ppm for a 15-minute STEL.

According to OSHA, the acceptable exposure limit (PEL) for airborne particles is 1,000 ppm when averaged over an 8-hour work shift. The recommended airborne exposure limit (REL) for a 10-hour work shift is 250 ppm, according to NIOSH.

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The possible masses of calcium oxide and carbon dioxide that can form when 400g of calcium carbonate undergoes decomposition is

The correct measurement of the element neon (Ne):

When reactants of a reaction are known, the fact that can always be deduced about the products is:

The correct molar mass correct for carbon dioxide (CO₂) is 44.01 g/mol; option B

The number of moles in 43 g of CO₂ is 0,977 moles.

According to the law of conservation of matter, the statement that best describes a balanced chemical equation:

The number of moles of atoms of each element must be the same in the reactants and in the products.

Based on the law of conservation of mass, the product of the reaction of nitrogen gas and hydrogen is 2 NH₃.

To calculate the number of moles from mass, take the quotient of mass and molar mass; option B

The ratio of components in the reaction of sugar with oxygen gas to produce carbon dioxide and water is:

For every 12 moles of CO₂ produced, 2 moles of C₆H₁₂O₆ is needed; option A

The molar mass of NH₄Cl is 53.5 g/mol; option A.

The molar mass of a substance is the mass of one mole of the substance.

The molar mass of carbon dioxide (CO₂) is calculated below:

molar mass of carbon dioxide, CO₂ = 12 + 16 * 2

molar mass of carbon dioxide, CO₂ = 44.0 g/mol

The moles of CO₂ in 43g of CO₂ is calculated as follows:

moles = mass / molar mass

Moles of CO₂ = 43 / 44 = 0.977 moles

The mass of CaO and CO₂ from the decomposition of 400 g of calcium carbonate is given below:

1 moles of CaCO₃ produces 1 mole of CaO and CO₂

4 moles of CaCO₃ produces 4 moles of CaO and CO₂

Mass of 4 moles of CaO = 4 * 56 = 224 g

Mass of 4 moles of CO₂ = 4 * 44 = 176 g

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On your last visit to the dentist, two cavities were found and the cost of your visit is 250

One who is skilled in and licensed to practice the prevention, diagnosis, and treatment of diseases, injuries, and malformations of the teeth, jaws, and mouth and who makes and inserts false teeth

Here given data is the price of a visit to the dentist is calculated according to the formula 50 + 100n and where n is the number of cavities the dentist find and n = 2 then we have to find cost of your visit = ?

So, 50 + 100n

= 50 + 100(2)

= 50 + 200

= 250

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For an ideal gas behaviour, we know that

PV = nRT

∴ n = PV/RT

• Given T = 25 °C = 273 +25 = 298K

R = 0.0821 atm/mole-k

P = 1 atm

V = 350ml = 350 /1000= 0.35 L

• n = PV /RT

= (1* 0.35) / (0.0821 * 298)

n= 0.0143 moles

• This means that 0.0143 moles of an ideal gas are present in this sample. ,

11.5 ml sample of N₂ gas with 25°C temperature is increases to 75°C  in constant pressure. The volume of N₂ gas at 75°C at constant pressure is 13.4 ml

Given that

V1 = 11.5 ml

T1 = 25°C = 298 K

T2 = 75°C = 348 K

We need to find the volume of gas (V2) at 75°C

We know that,

V1 / T1 = V2 / T2

11.5 / 298 = V2 / 348

V2 = (11.5 × 348) / 298

V2 = 13.4 ml

Thus, the volume of gas (V2) at 75°C = 13.4 ml

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When we have a molecule, we have to identify if it is a charged molecule (ions) or a neutral one. If it doesn't have any sign of + or -, it means that the molecule is neutral, so the charge is going to be zero.

In this particular case, we have the nitrogen gas:

As we can see, it is a neutral molecule, so its charge has to be zero. As it is a molecule composed only of one element, then the oxidation number has to be zero (0).

Plants do not have bones that provide them with structure and support, they have tubes made of cellulose; option A.

The Achilles is a tendon and not a ligament; option D

The type of organism that has an exoskeleton is crustacean; option C.

All organisms have either an endoskeleton or an exoskeleton is False because plants do not have either an endoskeleton or an exoskeleton.

Plants unlike animals do not have skeletons that provide shape and support to them.

Instead, plants have sclerenchyma cell walls which are composed of lignin and extra cellulose. These provide support and shape to plants.

Ligaments are structures found in joints and other parts of the body that provide support to bones, joints, organs, and other structures.

Ligaments in the body include;

Exoskeletons are found in small animals and insects. For example, crustaceans have an exoskeleton.

Other larger organisms such as mammals. have an endoskeleton.

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If you have 8.51x10-3 g of O₂, and excess ZnS, moles of ZnO form is 0.174×10⁻³ moles.

The balanced equation is given as :

2ZnS  +   3O₂    ------>   2ZnO  +  2SO₂

number of moles of O₂ = mass / molar mass

                                       = 8.51 × 10⁻³ g / 31.998 g/mol

                                       = 0.265× 10⁻³ moles

now, 3 moles of O₂ form 2 moles of ZnO

0.265× 10⁻³ moles of O₂  form( 2/3) ×  0.265× 10⁻³ = 0.174×10⁻³ moles

The number of moles of ZnO is 0.174×10⁻³ moles

Thus, If you have 8.51x10-3 g of O₂, and excess ZnS, moles of ZnO form is 0.174×10⁻³ moles.

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In a proton-proton chain, four hydrogen nuclei (protons) are combined to form one helium nucleus; 0.7 percent of the original mass is lost mainly by conversion into heat energy, but some energy escapes in the form of neutrinos (ν).

Explanation:

The  bismuth metal has a percentage yield of  93.4%

We know that the reaction as shown in the question has to do with the reaction of the bismuth oxide  with the excess carbon. this implies that the excess carbon  is the reactant in excess while the bismuth oxide is the limiting reactant.

Number of moles of the bismuth oxide = 3.52 g /465.96 = 0.0076 moles

1 mole of bismuth oxide yields 2 moles of Bi

0.0076 moles of bismuth oxide yields 0.0076 moles * 2/ 1 mole

= 0.00152 moles

Theoretical yield of bismuth = 0.00152 moles * 208.98

= 3.18 g

The percent yield is now obtained from; 2.97 g / 3.18 g * 100/1

=93.4%

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Missing parts;

When  3.98 g  of bismuth oxide (molar mass - 465.96 g/ml) reacts with excess carbon to form  2.97 g of bismuth metal (molar mass-208.98) according to the equation:

Bi2O3(s) + 3C(s) = 2 Bi(s) + 3 CO(g)

What is the percent yield of the reaction?

The volume of the 264 grams of NO gas at STP is 197.12 L

At standard temperature and pressure (STP),

1 mole of a gas = 22.4 L

With the above information, we can determine the volume of 264 grams of NO. Details below.

We'll begin by obtaining the mole of 264 grams of NO. This can be obtained as follow:

Mole = mass / molar mass

Mole of NO = 264 / 30

Mole of NO = 8.8 mole

Finally, we shall determin the volume as follow:

1 mole of NO = 22.4 L

Therefore,

8.8 moles of NO = (8.8 mole × 22.4 L) / 1 mole

8.8 moles of NO = 197.12 L

Thus, 264 grams has a volume of 197.12 L at STP

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A total of 1.104 ml of HCL is required to react with 2.15 g Zn(s).

Aqueous hydrogen chloride solutions are what we refer to as hydrochloric acid or muriatic acid. It has an unmistakable unpleasant fragrance and is colorless. A strong acid is how one would describe it. Most animal species, including humans, have it as a part of the gastric acid in their digestive tracts. There are numerous applications for hydrochloric acid. It is utilized in the manufacture of chlorides, fertilizers, dyes, and electroplating, as well as in the textile, rubber, and photographic industries. The skin, mucous membranes, and eyes are all corrosive to hydrochloric acid. A gas at ordinary temperature and pressure, hydrogen chloride (HCl) is a combination of the elements hydrogen and chlorine. Hydrochloric acid is a gaseous mixture of gas and water. HCl dissociates almost entirely, making it a powerful acid.

A stoichiometrically balanced equation

Zn(s) + 2HCl (a q) ---> ZnCl₂(a q) + H₂ m

Equivalent quantities of metal and hydrochloric acid.

Zinc moles = 2.15/65.39

= 0.032 mol

Moles of HCL = 0.134 mol × 2 / 2.50 × 10³

= 1.072 mol

So total = 0.032 + 1.072

= 1.104 liters

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The number of moles of cobalt (Co) atoms in 9.0 x 10⁹ Co atoms is 1.49 × 10-¹⁴ moles.

The number of moles of a substance can be calculated by dividing the number of atoms of the substance by Avogadro's number as follows:

no of moles = no of atoms ÷ Avogadro's number (6.02 × 10²³)

According to this question, 9.0 x 10⁹ cobalt atoms is given. The number of moles can be calculated as follows:

no of moles = 9.0 x 10⁹ ÷ 6.02 × 10²³

no of moles = 1.49 × 10-¹⁴ moles

Therefore, 1.49 × 10-¹⁴ moles of cobalt are in 9 billion atoms of the element.

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The volume change when all of the reactants combine to form products then the volume increases by a factor of 6/5

Changing the volume occupied by a gas will change its concentration, and therefore, change the rate at which it reacts with other substances called volume in the reaction

Here given reaction is

2CH₄O( g) + 3O₂( g) → 4H₂O( g) + 2CO₂( g)

Then, if the reaction is conducted and maintained at standard temperature and pressure (STP) then all the reactant combine to form product then the volume increases by a factor of 6/5

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Feedback can either cause a change in the system or keep it stable. Melting glaciers are an example of positive feedback.

This is considered a positive feedback because melting of the glaciers would let the air and land of the surrounding get warmer which would cause the glaciers to melt faster.

A positive feedback causes a system to remain stable or causes a change in the system.Global warming is melting ice, thus it amplifies the loss of ice. It is an important feedback called ice albedo feedback.

The increased temperature of ice leads to a positive feedback. It is an increased internal friction heating (strain). This is a positive feedback because it leads to further heating of the ice from the inner side of the ice sheet.

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The correct answer is gold block has the maximum density.

What is the relation between Mass, Volume and Density?
Three of an object's most fundamental characteristics are mass, volume, and density. Volume indicates how large something is, mass indicates how heavy it is, and density is determined by dividing mass by volume. Although you frequently deal with the concepts of mass and volume, the concept of density is less clear-cut and requires careful consideration. Density is useful, though, once you get the hang of it.

Density = mass / volume
So as per given data as the volume is same for all material then we can consider only mass and density
Given, Volume remains constant
So, as mass and density are Directly proportional, it means whose mass is larger than its density will be larger or denser.

From given data Gold has larger mass then its density is larger.

Hence, Gold block has the maximum density

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A function of the plasma membrane includes letting water, certain ions and substrates into the cell (Option 4).

The plasma membrane is the main selective barrier that allows the interchange of nutrients and byproducts of the cell with its surrounding media (i.e., its external environment). The cell membrane allows the passage of substances such as water or ions by using protein channels or also the movement through active transport, which requires energy to proceed.

Therefore, we can conclude that the plasma membrane allows the passage of water and ions inside the cell.

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Al2S3 have higher melting point comparing to BeCl2 because of factual data and also that melting point increases down the group.

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A reaction in which reactants react to form products is called forward reaction. In some reactions, products would change back into reactants which is called backward reaction.

In forward reaction, the reactants react with each other and forms product as a result. The reaction occurs from left to right in an equation.

In backward reaction, the products that was formed would revert back to form reactants due to surrounding conditions. The reaction occurs from right to left in an equation.

The type of reaction where both forward and backward reaction takes place is called reversible reaction. When the rate of the reaction between forward and backward reaction becomes equal, it reaches a state of equilibrium.

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The force that was needed to stretch the spring F = 90 N.

Consistent with Hooke's regulation, when a spring is stretched the applied force is proportional to the increase in duration from its equilibrium duration. The spring consistent may be calculated the usage of the formulation

k = -F/x

In which ok is the spring regular.

F represents the pressure and x represents the change in spring length. Represents the steady of proportionality, additionally known as the spring constant.

The spring steady okay is a measure of the spring stiffness. It relies upon at the feather and material. The higher the spring constant, the stiffer the spring and the much less it stretches. The constant of proportionality ok is known as the spring consistent. it is a degree of spring hardness. as the spring expands and contracts, converting its duration through x from its equilibrium length it exerts a force F = -kx within the course of its equilibrium role.

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