What is the "magic number' of valence electrons? How does this influence the type of bonds formed by various combinations of
elements

Answer:

c

Explanation:

heatmass*density*temp. difference=

In the sample, the mass of water is "225 g".

Given:

Heat energy,

Specific heat,

The change in temperature,

              [tex]= 100-88[/tex]

              [tex]= 12 ^{\circ} C[/tex]

As we know,

→             [tex]Q = mc \Delta T[/tex]

→ [tex]1.13\times 10^4=m\times 4.186\times 12[/tex]        

→              [tex]m = \frac{1.13\times 10^4}{4.186\times 12}[/tex]

→                   [tex]= 224.956 \ g[/tex]

or,

→                   [tex]= 225 \ g[/tex]

Thus the answer above is appropriate.

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Answer:

ok so you take the volume then divide it by the pressure, and subtract the area to find the rough estimate. but your probably looking for an exact answer so you take that and then do that when you get that thatll be that.

Explanation:

Decreasing the pressure on the gas will  most likely result in an increase in the volume of a gas.

Pressure is defined as the force applied on an object perpendicular to it's surface per unit area over which it is distributed.Gauge pressure is a pressure which is related with the ambient pressure.

There are various units by which pressure is expressed most of which are derived units which are obtained from unit of force divided by unit of area . The SI unit of pressure is pascal .

It is a scalar quantity which is related to the vector area element with a normal force acting on it.It is distributed over solid boundaries and across arbitary sections of fluid normal to the boundaries at every point.

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Answer:

Moles of NaCl formed is 6.0 moles

Explanation:

We are given the equation;

2 Na(s) + Cl₂(g) → 2 NaCl(s)

From the reaction;

2 moles of sodium reacts with 1 mole of chlorine gas to form 2 moles of NaCl

In this case;

6 moles of Na would require 3 moles of Cl₂, this means that chlorine gas is in excess.

Thus, the rate limiting reagent is sodium.

But, 2 moles of sodium reacts to form 2 moles of NaCl

Therefore;

Moles of NaCl = Moles of Na

                      = 6.0 moles

Thus, moles of sodium chloride produced is 6.0 moles

Molecules are combinations of two or more atoms.

The relationship between molecules and atoms is molecules are combination of two or more atoms (1st option)

To obtain the relationship between atoms and molecules, we must know the definition of atom and molecule. This is given below:

Atoms are smallest particles of an element that can partake in a chemical reaction.

Molecules are combination of two or more atoms that can exist free in natural state

From the above definition, we can see that molecules contains atoms.

Thus, we can conclude that from the above definition that the correct answer to the question is molecules contains two or more atoms (1st option)

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Answer:

The periodic table

Explanation:

The periodic table can show the atomic number and atomic mass of any atoms easily. To convert grams of water to moles of water, you need to know the atoms that made up water molecules then find out their molecular mass. Water is made of two hydrogens and one oxygen atoms. Then you can find the atomic mass of hydrogens is 1 while oxygen is 16. The molecular mass of water will be 2*1 + 16= 18g/mol.

Use the molecular weight of water as a conversion factor to convert grams to moles. Then, use the number of moles and the mass of solvent to determine the molality of the solution.

The most useful scientific tool when trying to convert a known amount of grams of water to moles of water is the molecular weight of water, which is used as a conversion factor. The process involves converting from grams to moles using the molecular weight of water (18.01528 g/mol).

In general, a mole of any substance has a mass in grams numerically equal to its molecular mass. So the molecular weight is a very convenient conversion factor for such calculations.

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Answer:

84.96K

Explanation:

The following were obtained from the question:

n = 1.5 mole

V = 5.5L

P = 192.4 kPa = 192400Pa

Recall

101325Pa = 1atm

192400Pa = 192400/101325 = 1.9atm

R = 0.082atm.L/K /mol

T=?

We can obtain the temperature by applying the following:

PV = nRT

T = PV / nR

T = (1.9 x 5.5)/(1.5 x 0.082)

T = 84.96K

Answer:

Cr

Explanation:

Cr will displace Sn from compound because Cr is higher than Sn in the electrochemical series of metals

Answer:

Cr

Explanation:

Answer:

Explanation:

Alchemy is the forerunner of modern chemistry practiced during the medieval times. Chemists of those times were known and called alchemists.

These chemists had a very shallow knowledge of chemistry but were able to produce a wide range of chemicals.

Answer:

dioxide

Explanation:

Answer:

Why would it be false? That would be a great magic act.

Explanation:

The below is about the energy exchanges in earth systems.                                                                                                          

Explanation:

Energy exchanges in Earth's system revolves around Earth's main energy outputs which are visible and infrared radiation, reflected light and thermal infrared radiation. ultraviolet radiation and visible radiation,  gamma rays, X-rays and ultraviolet radiation.

Explanation:

Answer:

The Correct Answer is C

Fossil A is younger than the index fossil.

Explanation:

Fossil A is younger than the index fossil is correct statement. Hence option 3 is correct.

Fossils are defined as an animal or plant relic, impression, or trace that has survived in the Earth's crust over time. A living object, such an animal or plant, dies and is quickly buried by debris, like mud, sand, or volcanic ash, which results in the creation of fossils.  Important evidence for evolution and the environmental adaptation of plants and animals can be found in fossils.

Index fossils are fossils that are common yet were only present for a brief time. By comparing a rock layer to other rock layers, index fossils enable scientists to determine the relative age of a rock layer. Organisms that are still alive today yet have undergone little alteration over millions of years are known as living fossils.

Thus, fossil A is younger than the index fossil is correct statement. Hence option 3 is correct.

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Answer:

The mass percent of a solution of 7.6 grams sucrose in 83.4 grams of water is 8.351 %.

Explanation:

Given,

Mass of Sucrose = 7.6 grams

Mass of Water = 83.4 grams

In this solution, Sucrose is solute and water is the solvent.

Mass percent of a solution can be calculated using the formula,

Mass percent =  (Mass of Solute/Mass of Solution)(100)

As sucrose is solute, mass of solute = 7.6 grams

As the solution contains both Sucrose and Water,

Mass of solution = 7.6 grams + 83.4 grams = 91 grams

Substituting the values, Mass percent = (7.6/91)(100) = 8.351 %.

Taking into account the definition of percentage by mass, the mass percent of a solution of 7.6 grams sucrose in 83.4 grams of water is 8.35 %.

The percentage by mass expresses the concentration and is defined as the ratio of the mass of the solute to the mass of the solution, expressed as a percentage.

The percentage by mass is calculated as the mass of the solute divided by the mass of the solution and multiplied by 100 to give a percentage. This is:

[tex]percent by mass= \frac{mass of solute}{mass of solution}x100[/tex]

In this case, you know:

Replacing:

[tex]percent by mass= \frac{7.6 grams}{91 grams}x100[/tex]

Solving:

percent by mass= 0.0835

percent by mass= 8.35 %

Finally, the mass percent of a solution of 7.6 grams sucrose in 83.4 grams of water is 8.35 %.

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The volume of gas under STP is 0.512 liters.

Explanation:

At STP (Standaed Temperature and Pressure)

T =  0°C

P = 1 atm = 760 mmHg

Given

P1 = 756 mmHg

T1 = -21.5°C = -21.5 + 273 = 251.5 K

V1 = 475 mL = 0.475 L

P2 = 760 mmHg

T1 = 0°C = 0 + 273 = 273 K

We know that

[tex]\frac{P1 \times V1}{T1} = \frac{P2 \times V2 }{T2}\\\\\frac{756 \times 0.475}{251.5} = \frac{760 \times V2}{273}\\[/tex]

[tex]V2 = \frac{273 \times 756 \times 0.475}{251.5 \times 760} \\V2 = \frac{98034.3}{191140}[/tex]

V2 = 0.512 L

217 ml of 0.05 M HCl will be required to react with 5 gm of MnO2 according to the equation given.

Explanation:

The balanced chemical equation is given as:

4HCl(aq) + MnO2(s) → 2H2O(l) + MnCl2(aq) + Cl2(g)

This shows that 4 moles of HCl reacts with 1 mole of MnO2

the mass of Manganese oxide is given as 5 grams

molar mass of MnO2 = 86.93 grams/mole

number of moles of MnO2 is given by

number of moles = [tex]\frac{mass}{atomic mass of one mole}[/tex]

number of moles= [tex]\frac{5}{86.93}[/tex]

                            = 0.0575 moles of MnO2

From the equation:

4 moles of HCl reacts with 1 mole of MnO2

x moles of HCl reacts with [tex]\frac{0.0575}{x}[/tex] moles of MnO2

[tex]\frac{1}{4}[/tex] = [tex]\frac{0.0575}{x}[/tex]

= 0.23 moles of HCl will react

atomic mass of HCl = 36.46 Grams/mole

mass = 0.23 x 36.46

         = 8.3858 grams.of HCl

molarity of HCl = [tex]\frac{number of moles}{volume in liters}[/tex]

volume is 1 litre

so molarity is 0.23 M

Using the formula

M1V1 = M2V2

0.05 x 1 = 0.23 X x

x = 0.217 litre

so 217 ml of 0.05 M HCl will be required to react with 5 gm of MnO2.

To find the initial concentration of A in a first-order reaction, we can use the integrated rate law.

In a first-order reaction, the rate of the reaction is directly proportional to the concentration of the reactant. The rate constant for the given first-order reaction is 0.291 s-1. To find the initial concentration of A, we can use the integrated rate law for first-order reactions:

[A]t = [A]0 * e-kt

Where [A]t is the concentration of A at time t, [A]0 is the initial concentration of A, k is the rate constant, and e is the base of natural logarithms. Putting in the given values, we get:

0.081 mol/L = [A]0 * e-(0.291 s-1)(5 s)

Solving for [A]0, we find that the initial concentration of A is approximately 0.232 mol/L.

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Answer:

4 moles

Explanation:

N is 1 atom and H has a subscript of 3 meaning there are 3 hydrogen atoms. (3+1=4). We know that N is a separate element of H, because they are both uppercase.

Moles are defined as the smallest base unit that is equivalent to [tex]6 .02214 \times 10^{23}[/tex] units.

In the given molecule of NH[tex]_4[/tex], there will be 4 moles of each atom.

NH[tex]_4[/tex] consists of 1 mole of the Nitrogen atom and 3 moles of the Hydrogen atom, which is then equivalent to the 4 moles of each atom in the molecule of NH[tex]_4[/tex].

Moles are chemical entities, which are used to measure the mass or molecular mass of the compound, molecule, or atom. The moles are, for example can be explained as equal to the mass of the atom. For example, there is one mole in 12 grams of carbon.

Thus, the correct answer is Option D.

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Answer:

Nickel is extracted from nickel oxide by reduction with carbon. Nickel is a metal which react with atmospheric oxygen which is very reactive in order to protect the inner surface of metal. Carbon extract oxygen which is attached to the nickel in the form of nickel oxide because carbon is more reactive so it made a chemical bonds with oxygen and nickel oxide is converted into a pure nickel.

Carbon is used to extract nickel from nickel oxide because carbon acts as a reducing agent. During the reduction reaction, carbon reacts with nickel oxide to form nickel and carbon dioxide. Carbon's greater affinity for oxygen allows it to remove oxygen from nickel oxide, leaving nickel.

Carbon can be used to extract nickel from nickel oxide because of its ability to act as a reducing agent. In this context, a reducing agent is a substance that donates electrons to another substance, in this case, nickel oxide. This reduction reaction involves carbon reacting with nickel oxide to form nickel and carbon dioxide. Carbon, having a greater affinity for oxygen than nickel, binds with the oxygen in the nickel oxide forming carbon dioxide and leaving the nickel behind. This process is commonly used in metal extraction from their oxides, especially those of less reactive metals like nickel.

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Answer: I don’t have much of a clue as to what you did; I wasn’t there . In gas theories however, the heated gas into a balloon will expand, and gases when under pressure can liquify. It is easy to see which molecules were popped around the most! Read that chapter and work all of the problems.

Explanation:

Answer:

1.52g

Explanation:

First, let us calculate the number of mole of CO2 present. This is illustrated below:

V = 800mL

Recall: 1000mL = 1L

800mL = 800/1000 = 0.8L

P = 94.5 KPa = 94500Pa

Recall: 101325Pa = 1atm

94500Pa = 94500/101325 = 0.93atm

T = -10°C = -10 + 273 = 263K

R = 0.082atm.L/Kmol

n =?

PV = nRT

n = PV/RT

n = (0.8x0.93)/(0.082x263)

n = 0.0345mol

Now, we can obtain the mass of CO2 as follows:

Molar Mass of CO2 = 12 + (2x16) = 12 + 32 = 44g/mol

Number of mole of CO2 = 0.0345mol

Mass of CO2 = number of mole x molar Mass

Mass of CO2 = 0.0345 x 44 = 1.52g

Answer:

you ask  them a couple of questions like what would u do in this problem and see their answer

Explanation:

Honestly I'm going through a lot of fake friends right now and I don't have the guts to tell them off cause I feel bad. But a way to see if there fake is if they usually don't want to hang out with you or always change the plans, or just act like your friends when they want something such as buying them stuff, giving them money, or just wanting something. Another way to test is if they do everything they can to give you as little as possible. If they do stuff like this just stop talking to them or try to get away from what they want or ditch them and tell them their fake.

The net force on the cube in Diagram A is 3 N to the right. The net force on the cube in Diagram B is 47 N downwards.

Diagram A

This diagram shows a cube with two forces acting on it: a 5 N force to the left and an 8 N force to the right. To calculate the net force, we need to subtract the smaller force from the larger force.

Net force = 8 N - 5 N = 3 N to the right

Diagram B

This diagram shows a cube with two forces acting on it: a 128 N force upwards and a 175 N force downwards. To calculate the net force, we need to subtract the smaller force from the larger force.

Net force = 175 N - 128 N = 47 N downwards

The net force on an object is the sum of all the forces acting on it. If the net force is zero, then the object is in equilibrium. If the net force is not zero, then the object will accelerate in the direction of the net force.

To calculate the net force on an object, we need to add up all the forces acting on it, taking into account their magnitudes and directions. We can use the following formula:

Net force = F1 + F2 + F3 + ...

Where F1, F2, F3, etc. are the magnitudes of the forces acting on the object.

In the case of Diagram A, we have two forces acting on the cube: a 5 N force to the left and an 8 N force to the right. To calculate the net force, we need to subtract the smaller force from the larger force:

Net force = 8 N - 5 N = 3 N to the right

This means that the cube will accelerate to the right.

In the case of Diagram B, we have two forces acting on the cube: a 128 N force upwards and a 175 N force downwards. To calculate the net force, we need to subtract the smaller force from the larger force:

Net force = 175 N - 128 N = 47 N downwards

This means that the cube will accelerate downwards.

Answer:

c

Explanation:

Answer:

option 2

Explanation:

temperature decreases as you are further away from the sun and less thermak energy is reaching you. the pressure increases as more water is above you.

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The amount of ink leaking out of the pen when the pressure decreases from 780 mm Hg to 520 mm Hg is 0.6 cm3, calculated using Boyle's Law.

The question involves principles of physics, particularly the behavior of gases under changes in pressure, represented by Boyle's Law, which states that the volume of a gas is inversely proportional to its pressure. This means that when the pressure decreases, the volume of a gas (or ink in this case) increases. The fountain pen was filled at a pressure of 780.0 mm Hg, and the new pressure at the pilot's altitude is 520.0 mm Hg. We can use Boyle's Law to calculate the new volume of ink.

Here's how:

Since the pen can only hold 2.4 cm3, the excess volume of ink that is 1.8 cm3 - 2.4 cm3 = -0.6 cm3 will leak out. Note that the negative sign just implies leakage or reduction in volume.

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Answer: gas dissolved in liquid

Explanation:

The different atoms lead to the formation of living and nonliving things then  

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Electromagnetic wave travels faster through air than metal.

Option A

Explanation:

There are different kinds of wave energy. The most significant are electromagnetic and mechanical waves. The mechanical waves propagate through the medium by transfer of energy by vibrating of particles in medium.

So, the more number of particles present in the medium, the more fast the mechanical wave can propagate. So the mechanical waves travel faster in metals consisting of more number of free charge carriers. But electromagnetic waves does not need any of the medium to propagate. So it can travel faster in air than in metals.

Answer: A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another.[1] Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei (no change to the elements present), and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur.

The substance (or substances) initially involved in a chemical reaction are called reactants or reagents. Chemical reactions are usually characterized by a chemical change, and they yield one or more products, which usually have properties different from the reactants. Reactions often consist of a sequence of individual sub-steps, the so-called elementary reactions, and the information on the precise course of action is part of the reaction mechanism. Chemical reactions are described with chemical equations, which symbolically present the starting materials, end products, and sometimes intermediate products and reaction conditions.

Chemical reactions happen at a characteristic reaction rate at a given temperature and chemical concentration. Typically, reaction rates increase with increasing temperature because there is more thermal energy available to reach the activation energy necessary for breaking bonds between atoms.

Reactions may proceed in the forward or reverse direction until they go to completion or reach equilibrium. Reactions that proceed in the forward direction to approach equilibrium are often described as spontaneous, requiring no input of free energy to go forward. Non-spontaneous reactions require input of free energy to go forward (examples include charging a battery by applying an external electrical power source, or photosynthesis driven by absorption of electromagnetic radiation in the form of sunlight).

Different chemical reactions are used in combinations during chemical synthesis in order to obtain a desired product. In biochemistry, a consecutive series of chemical reactions (where the product of one reaction is the reactant of the next reaction) form metabolic pathways. These reactions are often catalyzed by protein enzymes. Enzymes increase the rates of biochemical reactions, so that metabolic syntheses and decompositions impossible under ordinary conditions can occur at the temperatures and concentrations present within a cell.

The general concept of a chemical reaction has been extended to reactions between entities smaller than atoms, including nuclear reactions, radioactive decays, and reactions between elementary particles, as described by quantum field theory.

When pure water is consumed in a chemical reaction, it undergoes a chemical change and forms new substances.

The type of change that occurs when pure water is consumed in a chemical reaction, resulting in the formation of a new product, is B. A chemical change.

In a chemical change, the substances involved undergo a chemical reaction and form new substances with different properties. In this case, when water is consumed, it is chemically broken down and transformed into other compounds and molecules that are used by our bodies.

An example of a chemical change involving water is the process of digestion. When we consume food, it goes through various chemical reactions in our body, breaking down into smaller molecules that our cells can utilize.

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Answer:

It is a homogeneous mixture

Answer:

None of the options are correct. The answer to the question is 353.2g

Explanation:

The equation for the reaction between is given below:

KI + AgNO3 —> KNO3 + AgI

Molar Mass of KI = 39 + 127 = 166g/mol

Molar Mass of AgI = 108 + 127 = 235g/mol

From the equation,

166g of KI produced 235g of AgI.

Therefore, Xg of KI will produce 500g of AgI i.e

Xg of KI = (166 x 500)/235 = 353.2g

Answer:

Explanation:

The white precipiate that is formed when sodium sulfate, Na₂SO₄, reacts with barium ions in solution, Ba²⁺, is barium sulfate, BaSO₄.

The molar mass of BaSO₄ is 233.38 g/mol. Thus, the number of moles of BaSO₄ is:

Since 1 mole of BaSO₄ contains 1 mole of Ba, there are 0.00110549 mol of Ba²⁺ ions.

Use the atomic mass of Ba to calculate the mass in grams in the original solution:

Then, with 3 significant figures, there were 152mg of barium in the original solution.