Circle the letter of each sentence that is true about what can occur in a chemical change.

a. Compounds may be broken down into elements.

b. Elements may combine to form compounds.

c. Compounds may change from one state to another.

d. Compounds may change into other compounds.

Explanation:

The mechanisms by which amorphous intermediates transform into crystalline materials are poorly understood. Currently, attracting enormous interest is the crystallization of amorphous calcium carbonate, a key intermediary in synthetic, biological, and environmental systems. Here we attempt to unify many contrasting and contradictory studies by investigating this process in detail. We show that amorphous calcium carbonate can dehydrate before crystallizing, both in solution and in air, while thermal analyses and solid-state nuclear magnetic resonance measurements reveal that its water is present in distinct environments. Loss of the final water fraction—comprising less than 15% of the total—then triggers crystallization. The high activation energy of this step suggests that it occurs by partial dissolution/recrystallization, mediated by surface water, and the majority of the particle then crystallizes by a solid-state transformation. Such mechanisms are likely to be widespread in solid-state reactions and their characterization will facilitate greater control over these processes.

The mole ratio of \(NaNO_3\) to \(Na_2O\) is 2:1 in the balanced equation

The reasonable compound condition\(2NaNO_3 + PbO → Pb(NO_3)_2 + Na_2O\) shows that two moles of sodium nitrate\((NaNO_3)\) respond with one mole of lead oxide \((PbO)\)to create one mole of sodium oxide \(Na_2O\) and one mole of lead nitrate\((Pb(NO_3)_2)\) .

In this way, the mole proportion of \(NaNO_3\) to \(Na_2O\)is 2:1. This intends that for each two moles of \(NaNO_3\) utilized, one mole of\(Na_2O\) is delivered.

This mole proportion is significant in deciding how much  \(Na_2O\)delivered when a known measure of \(NaNO_3\) is utilized. For instance, assuming we have 2 moles of \(NaNO_3\), we can establish that we will deliver 1 mole of \(Na_2O\). Assuming that we have 4 moles of\(NaNO_3\) , we will create 2 moles of \(Na_2O\).

Knowing the mole proportion likewise permits us to compute the hypothetical yield of \(Na_2O\) in light of how much \(NaNO_3\)  utilized. In any case, practically speaking, the genuine yield might contrast because of exploratory mistake or different elements.

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Explanation:

it's 2:1 the top person is right and how i know that is because when i was in school i have my notes so the top of me is right!!! :)

polar molecules have an unequal distribution of charges whilst non polar molecules are equally shared between atoms or elements producing no charged end.

Answer:

The answer that completes the question are in BOLD:

At chemical equilibrium, the amount of PRODUCT AND REACTANT REMAIN CONSTANT because the RATES OF THE FORWARD AND REVERSE REACTIONS ARE EQUAL.

Explanation:

In a reversible chemical reaction, an equilibrium is said to be achieved when the rates of the forward reaction is equal to that of the reverse reaction. A reversible reaction is one in which products are formed from reactants simultaneously with the formation of reactants from products.

The combination of two or more substances called REACTANTS gives rise to another substance called PRODUCT, which can in turn give rise to Reactants again. With time, the rate at which the reactants give rise the products, which is called the FORWARD REACTION will be equal to the rate at which the products give rise to the reactants, which is called REVERSE REACTION. At this point, the chemical reaction is said to be in a STATE OF EQUILIBRIUM.

When the rate at which both reaction occurs becomes equal i.e. at an equilibrium state, the concentration of both the reactants and the products becomes constant i.e. no longer changes. Hence, the amount of the reactants forming the products is the same as the amount of products forming the reactants.

N.B: At chemical equilibrium, the amount of the reactants and products does not necessarily equals zero (0). It simply means that there is no net change in the concentration/amount of both reactants and products.

Burning a 54.0-g sample of sodium in the air to produce sodium oxide results in a mass of sodium oxide greater than 54.0 g.This is because, during the burning process, sodium combines with oxygen from the air to form the sodium oxide compound.

Sodium (Na) is a highly reactive metal that readily reacts with oxygen (O2) in the air. When sodium is burned, it undergoes oxidation, where each sodium atom loses one electron to form a sodium ion (Na+). Simultaneously, oxygen molecules gain two electrons each to form oxide ions (O2-). The resulting reaction forms sodium oxide (Na2O) by combining two sodium ions with one oxide ion.

The mass of the sodium oxide formed will be greater than the initial mass of sodium because the reaction involves the addition of oxygen atoms from the air to the sodium atoms. This results in an increase in the total mass of the product. Therefore, the mass of the sodium oxide produced will be greater than 54.0 g, making the correct answer choice "greater than 54.0 g."

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39.20 g of water are theoretically yield produced when 25.34 g of C4H10 are burned.

The highest amount of a product that can be made from a specific quantity of reactants is known as the theoretical yield. Stoichiometry, which involves balancing a chemical equation and calculating the amount of product created using mole ratios, is used to determine it.

Let's start by balancing the provided equation.

C4H10 + 13/2 O2 4 CO2 + 5 H2O.

It is evident that five moles of water react with one mole of C4H10.

Therefore, we can determine the theoretical yield of water using the mole ratio of C4H10 and H2O.

Determine how many moles of C4H10 there are: C4H10 mass and molar mass are used to calculate moles of C4H10.moles of C4H10 are equal to 25.34 g/mol and 58.12 g/mol, respectively.

The mole ratio of C4H10 and H2O is as follows:5 moles of C4H10 equal 1 mole of H2O.moles of water equal 5 0.436 mol2.18 mol = 1 mole of water

Finally, we may use the mole-mass connection to get the mass of water.H2O's molar mass is equal to its molecular mass.mass of H2O = 39.20 g mass of H2O = 2.18 mol 18.02 g/mol

Therefore, 39.20 g of water should theoretically yield be produced when 25.34 g of C4H10 are consumed.

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Answer:

Gas.

Explanation:

Matter can be found in nature in three states: solid, liquid, and gas. The main difference between these three states is the separation of its molecules.

A solid has a definite form, its molecules are closely packed together and there is little to no movement between each molecule. When put in a container, it retains its form.

A liquid does not have a definite form, its molecules can move past another and they are not as close as in a solid, but it is not as loose either. When put in a container, it takes the shape of the container but it has a defined surface.

A gas does not have a definite form, its molecules are totally free from one another and the distance that separates them is much larger than the size they have. When placed in a container, they spread out completely and fill the entire shape of the container.

The triprotic acid among the given options is phosphoric acid.

Acid is a type of chemical substance that gives hydrogen ions when mixed with water. An acid with more than one hydrogen ion that can be released is known as polyprotic acid. Phosphoric acid is a clear, colorless liquid that is extremely viscous and corrosive. It is an odorless and tasteless compound that is used in various industrial applications like fertilizers, detergents, and food products.

Phosphoric acid is a polyprotic acid since it contains three hydrogen ions that can be released. These ions are released in a stepwise manner as the pH level decreases. Phosphoric acid is used in the production of fertilizers and other chemicals.

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Explanation:

Metals and non-metals can be identified either by their position in the periodic table or by their properties.

he metal elements are found on the left hand side of the periodic table, and the non-metal elements are found on the right. You can imagine a zig-zag line, starting at B-Al-Si, separating metals from non-metals.

The nucleus of an atom is small compared to the size of the atom because of Rutherford's nuclear theory. Rutherford's nuclear theory states that most of the mass of an atom and all of its positive charge are contained in a small core called the nucleus.

This statement is consistent with the fact that the nucleus of an atom is small compared to the size of the atom. Rutherford's nuclear theory states that the nucleus of an atom is small compared to the size of the atom, and, therefore, the nucleus has a relatively low mass compared to the mass of an atom.

Rutherford's nuclear theory states that the nucleus is small but contains about half of the mass of an atom. The nuclear theory was discovered by Ernest Rutherford in 1911.

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Enthalpy change (δHrxn) is the amount of heat transferred at constant pressure in a system as a result of a chemical reaction. Equilibrium constant (Kc) is the proportion of concentrations of reactants and products at equilibrium.

Enthalpy change (δHrxn) is the amount of heat transferred at constant pressure in a system as a result of a chemical reaction. Equilibrium constant (Kc) is the proportion of concentrations of reactants and products at equilibrium. The formula used to calculate the equilibrium constant from enthalpy change is:

ΔHrxn = -RTlnKc

where ΔHrxn is the enthalpy change, R is the universal gas constant, T is the temperature in kelvins, and Kc is the equilibrium constant. When you rearrange this equation to isolate Kc, you get:

Kc = e^(-ΔHrxn/RT)

where e is the mathematical constant e (approx. 2.718) and the rest of the variables have the same meaning as before. We can substitute the given values and obtain:

Kc = e^(-(-33.1 kJ/mol)/(8.314 J/mol*K * 298 K))= 1.5 * 10^3

Taking the natural logarithm of both sides of this equation:

ln(Kc) = -ΔHrxn/RTln(1.5 * 10^3) = -(-33.1 kJ/mol)/(8.314 J/mol*K * 298 K)ln(1.5 * 10^3) = 14.306

This means that the enthalpy change for this reaction is exothermic since ΔHrxn is negative. In other words, heat is being released into the surroundings.

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The coefficients needed to balance the chemical equation C2H6(g) + O2(g) → CO2(g) + H2O(g) are 2, 7, 4, 6(c).

The balanced equation must have the same number of atoms of each element on both sides of the arrow. To balance this equation, we start by placing a coefficient of 2 in front of the C2H6, which gives us 4 carbon atoms and 12 hydrogen atoms on the left-hand side.

Next, we need to balance the oxygen atoms, which can be done by placing a coefficient of 7/2 in front of the O2, giving us 7 oxygen atoms on both sides.

Finally, we balance the hydrogen and oxygen atoms in the products by placing coefficients of 4 and 6, respectively, in front of CO2 and H2O. The balanced equation is 2C2H6(g) + 7O2(g) → 4CO2(g) + 6H2O(g). So c option is correct.

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Cross-section of a metal wire wrapped in plastic insulation the metal wire is an element.

An element is a substance or material that cannot be affected by an external substance or cannot be broken down by any reaction.

Metal wire is serving as an element, it should not be easily broken or penetrated as an insulator.

Therefore, Cross-section of a metal wire wrapped in plastic insulation the metal wire is an element.

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Answer:

That means, under 10.0kPa of pressure, 0.4g of gas can be dissolved in 1L

Explanation:

Based on Henry's law, the solubility of the gas is directly proportional to the pressure. The equation is:

P1S2 = P2S1

Where P is pressure and S solubility of 1, initial state and 2, final state of the gas.

Replacing:

P1 = 50.0kPa

S1 = 2.0g/L

P2 = 10.0kPa

S2 = ??

50.0kPa*S2 = 10.0kPa*2.0g/L

S2 = 0.4g/L

That means, under 10.0kPa of pressure, 0.4g of gas can be dissolved in 1L

Answer: 0.4 g/L

Explanation:

S2 = S1 x P2 / P1

S2= 2 g/L x 10 kPa / 50 kPa

CROSS OUT

S2= 2g/L x 10 / 50

S2= 20 g/L/50

S2= .4 g/L

Answer:

Hydrocarbon and oxygen

Explanation:

"a substance reacts with oxygen gas, it must involve O² as one of the reactants."

Using this, we can confirm Hydrocarbon and oxygen is a valid one.

RCA cleaning, SC1/SC2 cleaning, and megasonic cleaning are the three  silicon wafer cleaning methods. Each of them have their advantages and are commonly used in semiconductor manufacturing processes.

There are several methods used to clean silicon wafers in the semiconductor industry.

Here are three common methods along with a comparison of their efficacy:

1) RCA Cleaning (Radio Corporation of America):

RCA cleaning is a widely used method for silicon wafer cleaning. It involves a two-step process:

a. RCA-1: The wafer is immersed in a mixture of deionized water, hydrogen peroxide (H₂O₂), and ammonium hydroxide (NH4OH). This step removes organic contaminants, particles, and some metal ions from the wafer surface.

b. RCA-2: The wafer is then immersed in a mixture of deionized water, hydrogen peroxide, and hydrochloric acid (HCl). This step removes metallic and ionic impurities from the wafer surface.

Efficacy: RCA cleaning is highly effective in removing organic and inorganic contaminants. It provides a good level of cleanliness for most semiconductor fabrication processes.

2) SC1 and SC2 Cleaning (Standard Clean 1 and Standard Clean 2):

SC1 and SC2 cleaning are alternative methods to RCA cleaning and are used for wafer surface preparation. The process involves the following steps:

a. SC1: The wafer is immersed in a mixture of deionized water, hydrogen peroxide, and ammonium hydroxide. This step removes organic and ionic contaminants from the wafer surface.

b. SC2: The wafer is immersed in a mixture of deionized water, hydrogen peroxide, and hydrochloric acid. This step removes metallic and oxide contaminants from the wafer surface.

Efficacy: SC1 and SC2 cleaning methods are effective in removing various types of contaminants from the wafer surface. They provide comparable cleanliness to RCA cleaning.

3) Megasonic Cleaning:

Megasonic cleaning involves the use of high-frequency sound waves (usually in the range of 800 kHz to 2 MHz) to agitate the cleaning solution and remove particles from the wafer surface. It is often used in conjunction with RCA or SC cleaning methods.

Efficacy: Megasonic cleaning is highly effective in removing particles from the wafer surface. It can dislodge and remove smaller particles that may be difficult to remove by chemical cleaning methods alone.

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The correct answer is B) the bright red Balmer alpha emission line.Each transition produces a specific wavelength of light, resulting in different spectral lines. In this particular transition, only one emission line is produced, corresponding to the Balmer alpha line in the red part of the spectrum.

When an electron in a hydrogen atom transitions from a higher energy level to a lower energy level, it releases energy in the form of light. This emitted light corresponds to a specific wavelength or color, creating spectral lines. The Balmer series specifically refers to the spectral lines produced when an electron transitions from higher energy levels (n > 2) to the second energy level (n = 2).

In this case, the transition is from the 2nd (n = 2) to the 1st (n = 1) excited state. This transition is known as the Balmer alpha transition. It results in the emission of light with a specific wavelength corresponding to the red color in the visible spectrum. Hence, the answer is B) the bright red Balmer alpha emission line.

The emission lines observed in hydrogen's atomic spectrum have been extensively studied and categorized based on the different energy level transitions. Each transition produces a specific wavelength of light, resulting in different spectral lines. In this particular transition, only one emission line is produced, corresponding to the Balmer alpha line in the red part of the spectrum.

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Answer: It's 50.69% abundant

Explanation:

Answer:

\(\boxed {\boxed {\sf B. \ -8.9 \ m/s^2}}\)

Explanation:

Acceleration is found by dividing the change in velocity by the change in time.

\(a=\frac {v_f-v_i}{t}\)

The parachute slows from 85 m/s to 45 m/s. Therefore, the final velocity is 45 meters per second and the initial velocity is 85 meters per second. The time is 4.5 seconds.

\(v_f= 45 \ m/s \\v_i= 85 \ m/s \\t= 4.5 \ s\)

Substitute the values into the formula.

\(a= \frac {45 \ m/s- 85 \ m/s}{4.5 \ s}\)

Solve the numerator and subtract.

\(a= \frac {-40 \ m/s}{4.5 \ s}\)

Divide.

\(a=-8.888888889 \ m/s/s\)

If we round this to the nearest tenth, the 8 in the hundredth place tells us to round the 8 up to a 9.

\(a \approx -8.9 \ m/s/s= -8.9 \ m/s^2\)

The acceleration of the parachute is approximately -8.9 meters per square second. The value is negative because the parachute is slowing down.

Answer:

I,II and III

Explanation:

Hope this helps :)

Answer:

l and III is the answer.

hope it hepls

Given data:H2O vapor content: 13 gramsH2O vapor capacity: 52 grams at 25 degrees Celsius 13 grams at 10∘C52 grams at 30∘CFormula used to find the dew point:$$\dfrac{13}{52}=\dfrac{(A*3\pi)/(ln100)}{(17.27-A)}$$$$\frac{1}{4}=\dfrac{(A*3\pi)/(ln100)}{(17.27-A)}$$

Where A is the constantDew Point:It is the temperature at which air becomes saturated with water vapor when the temperature drops to a point where dew, frost or ice forms. To solve this question, substitute the given data into the formula.$$13/52=\dfrac{(A*3\pi)/(ln100)}{(17.27-A)}$$$$13(17.27-A)=3\pi A(ln100)$$By simplifying the above expression, we get$$A^2-17.27A+64.78=0$$Using the quadratic formula, we get$$A=9.9,7.4$$

The dew point is 7.4 since it is less than 10°C.More than 100:The term "More than 100" has not been used in the question provided.

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Five resonance structures are possible for the phosphate ion, PO₄³⁻ and the formal charge are on the each oxygen atom

Resonance structure is the set of Lewis structure that describe the delocalization of electron in a polyatomic ion or a molecule

We can draw five resonance structure for PO₄³⁻ but one of them is  a minor contribution to the resonance hybrid and four oxygen atom single bonded to a phosphorus atom and give every atom an octet and this is not a good structure because it has five atom with formal charges and reduce the number of charges by moving electron to convert a P-O single bond to a P=O double bond and there are four P-O bonds and these are all equivalent and are the major contribution to the resonance hybrid that's why the actual structure is a resonance hybrid of all five structure

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Answer: Significant figures in a measurement are all measured digits, and one estimated digit

Significant figures communicate the level of precision in measurements Significant figures are an indicator of the certainty in measurements.

Explanation:

Significant figures : The figures in a number which express the value or the magnitude of a quantity to a specific degree of accuracy or precision is known as significant digits.

The significant figures of a measured quantity are defined as all the digits known with certainty and the first uncertain or estimated digit.

Rules for significant figures:

1. Digits from 1 to 9 are always significant and have infinite number of significant figures.

2. All non-zero numbers are always significant.

3. All zero’s between integers are always significant.

4. All zero’s preceding the first integers are never significant.

5. All zero’s after the decimal point are always significant.

The true statements are

Significant figures in measurement are all measured digits, and one estimated digit

Significant figures communicate the level of precision in measurements Significant figures are an indicator of the certainty in measurements.

The following information should be considered:

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The complete empirical formula of the organic compound is C₅H₂.

Empirical formula is the simplest formula of an organic compound. The balanced chemical equation of the given organic compound can be determined using the general formula for balancing oxidation reaction of organic compounds as shown below.

\(C_xH_y + (x+ \frac{y}{4} )O_2 = xCO_2 \ + \ \frac{y}{2} H_2O\)

Molecular mass of CO2 = 44 g/mol

mole = reacting mass /molecular mass

mole = 4.4/44 = 0.1

mole = 0.72/18 = 0.04

From the empirical formula, we have \([?]_5H_{[?]} = C_5H_{[?]}\)

\(0.1 \times n = 5\\\\ n = \frac{5}{0.1} = 50\)

From the result above, if we multiply 0.1 by 50 we will have 5 which is already given to us as C₅.

\(x = 0.1 \times 50\\\\x = 5\)

Then multiply 0.04 for y by the same factor.

\(y = 0.04 \times 50\\\\y = 2\)

Thus, the complete empirical formula of the organic compound is C₅H₂.

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Deprotonation of phenol by NaOHPhenol is a weak acid with a pKa value of 10, so it is not very acidic but it can be deprotonated with a strong base like sodium hydroxide (NaOH). The mechanism for this reaction is a simple acid-base reaction where NaOH acts as a base and removes the proton (H+) from phenol.

The curved arrow mechanism is shown below:Here, the Na+ ion comes in and removes the H+ ion from the O-H bond in phenol and forms water as a by-product. The major organic product is phenoxide ion (C6H5O−) which is formed after the deprotonation reaction.SN2 reaction of phenoxide with chloroethane Phenoxide ion is a good nucleophile because it has a negative charge on the oxygen atom which is able to attack the positively charged carbon atom in chloroethane. The mechanism for this reaction is a nucleophilic substitution (SN2) reaction where the phenoxide ion acts as a nucleophile and replaces the chloride ion in chloroethane. The curved arrow mechanism is shown below:Here, the phenoxide ion attacks the carbon atom in chloroethane, and the chloride ion leaves as a leaving group. The major organic product is ethyl phenyl ether (C6H5OC2H5) which is formed after the SN2 reaction.

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The temperature of the gas sample was \(269 Kelvin (K).\)

To solve this problem, we can use the ideal gas law:

\(PV = nRT\)

where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature in Kelvin.

First, we need to rearrange the equation to solve for T:

\(T = PV/nR\)

Now we can plug in the given values and solve for T:

\(T = (0.925 atm)(3.51 L)/(1.350 mol)(0.0821 L·atm/mol·K)T = 269 K\)

Therefore, the temperature of the gas sample was \(269 Kelvin (K).\)

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Answer:

4.Anything that has mass

Explanation:

In order to appreciate what matter is, we must first know that matter is the 'stuff' that makes up the universe. Everything in the universe is composed of matter. Matter in turn is made up of atoms. Intact mass is the quantity of matter in a body.

All matter must have mass and occupy space. Hence all matter must have a measurable mass. This is a fundamental property of all matter. Hence every object in the universe has mass because it is composed of matter. We find matter in our plates, spoons , clothes and indeed everything we see in the universe! For instance, you can measure the mass of a spoon because it is made of matter which has mass and occupy space.

According to Bronsted Lowry definition of acids - base reaction, acids have the ability to donate hydrogen ions and the correct option is option A.

Bronsted acids are those substances that have the ability to donate protons and are called proton donors and Bronsted bases are those substances that have the ability to accept protons and called as proton acceptors.

The Bronsted-Lowry theory of an acid-base reaction involves the transfer of protons or H+ ions between the acid and base.

The conjugate base of a Bronsted-Lowry acid is the species formed after an acid donates a proton. The conjugate acid of a Bronsted-Lowry base is the species formed after a base accepts a proton.

Thus, the ideal selection is option A.

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