Avogadro's number is the number of

The  observation of this process that  provides evidence of a chemical reaction is "The liquid solution changed color" Option B

This is further explained below.

Generally, A chemical reaction is a process in which one or more compounds, referred to as the reactants, are changed into one or more new substances, referred to as the products.

Either the chemical components or the chemical compounds make up a substance.

During a chemical reaction, the individual atoms that make up the reactants are rearranged, which results in the production of new substances.

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CQ

A silver ring reacts with compounds containing sulfur in the air to form silver sulfide, a black substance that makes up the tarnish on the surface of silver objects. To remove that tarnish from the ring, students placed it in a pan lined with aluminum foil and added hot water. Baking soda was added to the hot water and stirred. Students made observations about the process. Which observation of this process provides evidence of a chemical reaction? *

A- Hot water heated the aluminum foil

B- The liquid solution changed color

C- The pan was lined with aluminum foil

D- The hot water cooled

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:

INFORMATION:

We know that:

- the diagram represents a chemical cell at 298 K

And we must determine how is the flow of electrons when the switch is closed

STEP BY STEP EXPLANATION:

To determine it, we need to know that the flow of electron will be from the particles undergo oxidation to particles undergo reduction.

Analyzing the equation, we can see that Al particles undergo oxidation and Ni particles undergo reduction

Then, electrons will flow from Al(s) to Ni(s)

ANSWER:

(3) Al(s) to Ni(s)

According to the given statement The empirical formula of the oxide is YO3.

Chemical formulae for compounds that simply specify the proportions of the elements they include rather than the exact number or arrangement of atoms are known as empirical formulas. The component in the compound with the lowest whole lot would be this one.

By: Calculating the number of moles of each element from its mass, empirical formulas are generated using empirically measured element masses. Obtaining subscripts for a possible empirical formula by dividing the molar amount of each element by its smallest molar amount.

Since volume is represented as moles

Y 0

1 1.5

Y+1.5O2 = YO3.

YO3 - the empirical formula.

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Answer:Ca(No3)2

Explanation:

The reaction that is chemically balanced and shows complete combustion is [tex]C_3 H_8 + 5 O_2 -- > 3 CO_2 + 4 H_2 O[/tex], Option B.

A balanced equation is an equation that obeys the law of conservation of atoms.

According to this law, atoms cannot be created and cannot be destroyed during the course of chemical reactions. The atoms can, however, be converted into different forms.

Thus, a balanced equation must have an equal number of participating atoms on both the reactant and product sides of the equation.

Also, a complete combustion reaction must produce carbon dioxide and water. Not carbon monoxide.

Therefore, the equation that fulfills the two conditions is[tex]C_3 H_8 + 5 O_2 -- > 3 CO_2 + 4 H_2 O[/tex]

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Answer:

C

Explanation:

I got it right

The characteristic of group 14 elements is that they have four valence electrons in their outermost shell.

This is referred to as a substance which can't be broken down into simpler substances through as chemical reaction and examples include hydrogen, calcium etc.

These elements are arranged into different groups and periods on a periodic table according to their similarities. For example group 14 elements have four valence electrons which they need to complete in other to achieve a stable configuration.

Example of group 14 elements are carbon,silicon, tin etc which form covalent bonds with other elements in a reaction so as to ensure that that both become stable and is therefore the reason why it was chosen as the most appropriate choice.

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I believe the answer is B, neutrons

Mass of dichloromethane is  324.9g

We can define mass as the measure of the amount of matter in a body

Here given reaction is

CH₄ + CCl₄ → 2CH₂Cl₂

So the limiting reactant is the reactant that produced the leadt amount of product and the molar mass of methane is 16.042g/mol and the number of mole of methane is

n = 30.7/16.042

n = 1.913 mol

And the amount of dichloromethane that can be produced is

n = 1.913 mol ×2/1 = 3.826 mol

So, molar mass of dichloromethane is 84.9325

3.826 mol × 84.9325 = 324.9g

So, mass of dichloromethane is  324.9g

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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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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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2509 in 3 significant figures is 2510.

Significant figures is a digit that is meaningful with respect to the precision of a measurement.

Significant figures are the number of digits in a value, often a measurement, that contribute to the degree of accuracy of the value.

We can identify the number of significant digits by counting all the values starting from the 1st non-zero digit located on the left. For example, 12.45 has four significant digits.

According to this question, 2509 contains 4 significant figures.

2509 is rounded to significant figures as follows:

To count the number of sig figs in 2509, count all 4 digits since it has no insignificant digits.

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Answer: 1.27 mol Sulfur

Explanation: For every element, one mole of it contains 6.02x10^22 atoms (Avogradro's Number). So you just divide the original amount by Avogadro's Number to get 1.27 moles.

Considering the definition of atomic mass, isotopes and atomic mass of an element, the relative atomic mass for pivotium is 418.32 amu.

The isotopes of an element are those different atoms that make up an element, that is, their atomic numbers are the same, but the number of neutrons is different.

The atomic mass of an element is the weighted average mass of its natural isotopes, taking into account the relative abundance of each of them.

In this case, you know:

The average mass of pivotium can be calculated as:

average mass of pivotium= 423 amu×0.22 + 417 amu×0.78

average mass of pivotium= 418.32 amu

Finally, the atomic mass of the pivotium is 418.32 amu.

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Answer: Potential energy.

Explanation: Potential energy is stored energy and the energy of position.

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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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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The balanced equation is:

Zn + 2HCl ---> ZnCl2 + H2

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?

Answer:

look that might be answer

Explanation:

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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The relative atomic mass of the rubidium atom could be calculated from the data provided as 85.46.

When we talk about an isotope, we are referring to the idea that we could have tow or more atoms of the same element that have the same atomic number but do not have the same mass number. Given that the atomic number is the number of protons, it then follows that the two elements as we know them does differ only in the number of the neutrons that they have. The atoms that we have thus described in the several lines above are other wise called the isotopes of the element. We have in the image of the question a clear example of what an isotope is and we now want to find the relative atomic mass of Rubidium.

The relative atomic mass can be obtained from the use of the formula;

(84.9118 * 72.2/100) + (86.9092 * 27.8/100)

= (61.30 + 24.16)

= 85.46

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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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Answer: O2 is the reducing agent

Explanation: When you are adding oxygen, you are oxidizing.  So O2 is the reducing agent because Aluminum  loses electrons and becomes positive in charge and O2 gains electrons and becomes negative in charge.  Aluminum is oxidized and oxygen is reduced, therefore the oxygen is the reducing agent.  Remember oxidation cannot occur in isolation.  There is another process going on when something is oxidized and that process is reduction.    

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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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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The difference as required in the question to the correct number of significant figures is 147 in units of millimeter.

Let us take note of the fact that the term significant figures has to do with the number of figures that could be assigned a place value. This is the number of figures that we could be able to give the corresponding value.

Now we can see that one of the numbers have four significant figures and the other number has only about three significant figures. The result that we obtain must be such that has three significant figures.

It the follows that the result of the computation is; 147.6 - 0.82 = 147 in units of millimeter.

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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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