7
What might cause a theory to change over time?
A
New laws passed by the government
B
New but untestable Ideas
C Changes in public opinion
D
The discovery of new evidence

a) The mole ratio is 2/1

b) The mole ratio is 4/6

c) The mole ratio is 2/3

We have to note that the mole ratio is the ratio of the stoichiometric coefficient that we have between two reactants that can be found in an equation. In the case of the reaction equations that we have, we must look closely at each equation.

As we can see, each of the reaction equations is balanced and we can now be able to obtain the mole ratio of each of the reaction as shown in the answer above.

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Answer:

Carbon moves from the atmosphere to the land, ocean, and life through biological, chemical, geological and physical processes in a cycle called the carbon cycle. Because some carbon gases are greenhouse gases, changes in the carbon cycle that put more carbon in the atmosphere also warm Earth’s climate.

Mole measure the number of elementary entities of a given substance that are present in a given sample. Therefore,  the volume of oxygen needed to completely react with 171.9 g of S8 at STP is 180.09L.

The SI unit of amount of substance in chemistry is mole. The mole is used to measure the quantity or amount of substance. We know one mole of any element contains 6.022×10²³ atoms which is also called Avogadro number.

S[tex]_8[/tex](s) +12O[tex]_2[/tex](g) →8SO[tex]_3[/tex](l)

171.9 g of S8

mole of  S[tex]_8[/tex]=  171.9 g/ 256.52g/mol

                 =0.67mol

The mole of oxygen = 12×0.67

                                = 8.04mol

volume of oxygen= 22.4× 8.04

                            =180.09L

Therefore,  the volume of oxygen needed to completely react with 171.9 g of S8 at STP is 180.09L.

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When a 211-mL sample of a 0.285 M CaCl₂ solution is left on a hot plate overnight and the following morning, the solution is 1.25 M, the volume of water evaporated from the 0.285 M CaCl₂ solution is 48.108 ml.

Molarity (M) is defined as the ratio of the number of moles of solute present in a solution to the volume of the solution in litres.

given here,

Molarity of the original solution(M₁) = 0.285M

Volume of the original solution(V₁) = 211 ml

Molarity of  the solution in the morning (M₂) = 1.25 M

Volume of the solution in the morning (V₂) = ?

We will calculate the volume of the solution in the morning by using the formula:

M₁ × V₁ = M₂ × V₂

⇒0.285 M× 211 ml = 1.25 M × V₂

⇒V₂ = 0.285 M× 211 ml / 1.25 M

⇒V₂= 48.108ml

The volume of water evaporated from the 0.285M CaCl₂ solution is 48.108 ml.

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The dominant phenotype for sheep color is wool because it is the most common color seen in sheep.

What do you mean by Phenotype?

Phenotype is the physical, biochemical, and physiological characteristics of an organism, as determined by both genetic makeup and environmental influences. It is the physical expression of an organism's genes, and can be seen in its morphology, development, and behavior.

Wool is usually white or off-white in color and is the result of a dominant gene. The recessive phenotype for sheep color is non-wool, which is usually a darker color, such as black, brown, or gray. This is the result of a recessive gene and is less common than the dominant gene.

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The empirical formula of this compound is Ca3(PO4)2.

What is an Empirical formula?

An empirical formula is a type of chemical formula that shows the simplest ratio of atoms in a molecule, rather than the total number of atoms. It is the simplest possible chemical formula that shows the relative numbers of each type of atom in a molecule.

The molecular formula is Ca3(PO4)2•H2O, which indicates that the compound is composed of three calcium atoms, two phosphate atoms, and two water molecules. The molar mass of this compound is 1004 g/mol, which is two times the molar mass of the empirical formula (502 g/mol). Therefore, the molecular formula of this compound is Ca3(PO4)2•H2O.

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An alpha particle bombardment of aluminum with an atomic number of 27 results in the production of a neutron and phosphorus 15. The particular isotope formed is aluminum-28.

Fundamental alterations take place at the level of the atomic nucleus during nuclear reactions. Analyze the properties of the neutron, which has a mass similar to that of a proton but no electric charge. As a result, when it interacts with the aluminum core, the atomic number should remain constant but the atomic mass should rise by one unit. The newly produced atom is in an excited state when it transitions to the base state with the emission of a high-energy radiation called a gamma ray. Aluminum-28 isotope is formed.   ⁷A₂₇ + ⁰n₁ → ⁷Al₂₈ˣ

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The reaction occurs via a nucleophilic substitution mechanism. The D_2O molecule acts as the nucleophile, attacking the carbon atom of the CH_3CH_2OBH_3 molecule.

Step 1:

NaBH_4 + CH_3CH_2OH → CH_3CH_2OBH_3 + NaOH

Step 2:

CH_3CH_2OBH_3 + D_2O → CH_3CH_2OD + BH_3OH

Step by explanation in  detail

Step 1:

NaBH_4 + CH_3CH_2OH → CH_3CH_2OBH_3 + NaOH

The reaction occurs via a nucleophilic substitution mechanism. The Na^+ cation acts as a spectator ion and does not take part in the reaction. The BH_4- anion acts as the nucleophile, attacking the carbon atom of the CH_3CH_2OH molecule. This causes the C-O bond to break and the BH_3 group to form a bond with the carbon atom. This results in the formation of the CH_3CH_2OBH_3 molecule and the NaOH molecule.

Step 2:

CH_3CH_2OBH_3 + D_2O → CH_3CH_2OD + BH_3OH

The reaction occurs via a nucleophilic substitution mechanism. The D_2O molecule acts as the nucleophile, attacking the carbon atom of the CH_3CH_2OBH_3 molecule. This causes the C-B bond to break and the D atom to form a bond with the carbon atom. This results in the formation of the CH_3CH_2OD molecule and the BH_3OH molecule.

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The relative acidity of orange juice compared to pure water is 1000times. The relationship between acid strength and pH is inverse.

A scale that historically denoted "potential of hydrogen" was used to describe how basic or acidic an aqueous solution was. The pH values of acidic solutions are typically lower than those of basic or alkaline solutions. The pH scale can be used to gauge how strong an acid is. Higher pH values result in weaker acids, while lower pH values result in stronger acids. Therefore, we may conclude that the relationship between acid strength and pH is inverse.

Given the pH of orange juice = 4

Then concentration of orange juice (M1) = 10^-4M

pH of pure water = 7

The concentration of [H+] in water (M2) = 10^-7M

The relative pH = 10^-4/10^-7 = 10^3

Hence  its relative acidity compared to pure water is 1000 times.

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The freezing point of the solution after you add an additional 1.34 g is -0.808°C.

A solution's freezing point is lower than the pure solvent's freezing point. This means that for freezing to happen, a solution needs to be cooled to a lower temperature than the pure solvent.

We use the equation: to determine the mass of the solution

Density = mass/volume

1.05 g/ml = mass/ 50ml

mass = 1.05×50

mass = 52.5g.

Percentage of magnesium chloride in the solution is 1.52%

Mass of magnesium chloride in the solution = 1.52 % of 52.5 g

Mass of magnesium chloride in the solution = 1.52/100×52.5

Mass of magnesium chloride in the solution = 0.798g

The following equation is used to determine depression in freezing point:

ΔTf = Freezing point of pure solution - Freezing point of solution

ΔTf = i Kf m

Freezing point of pure solution - Freezing point of solution = i Kf m

m =  m solute × 100/M solute × W solvent

Given values,

Freezing point of pure solution (water) is 0°C

i is Vant hoff factor = 2.5

Kf molal freezing point elevation constant = 1.86°C/m

m solute given mass of solute (magnesium chloride) = [0.798 + 1.34] g

m solute = 2.138 g

M solute molar mass of solute (magnesium chloride) = 95.2 g/mol

W solvent mass of solvent (water) = [52.5 - 0.798] g = 51.702 g

substitute the given values,

0 - Freezing point of solution = 1×1.86×2.138×1000/95.2×51.702

Freezing point of solution = -0.808°C.

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Complete question is " A 50 mL solution is initially 1.52% MgCl₂ by mass and has a density of 1.05 g/ml

What is the freezing point of the solution after you add an additional 1.34 g MgCl₂? (Use i = 2.5 for MgCl₂)."

Titration is a quantitative analysis method for determining the concentration of a substance from a measured titrant. According to the equation, if the reactants are halved, the amount of H2O produced will be halved.

The molecular equations for sodium hydroxide, hydrochloric acid, sodium chloride, and water can be expressed as:

 HCl + NaOH ⇒ NaCl + [tex]H_{2}[/tex]O

In the given equations, the spectator ions and the ionic equation can be distinguished as follows:

H⁺ + Cl⁻ Na⁺ + OH⁻ ⇒ Na⁺ + Cl⁻ + 2H⁺ + O⁻²

The net ionic equation is:

 H⁺ + OH⁻ ⇒ [tex]H_{2}[/tex]O

From the above equation, we can see that the production of water molecules depends on the number of reactants. The reactants are,

H⁺ and OH⁻.

Therefore, when the number of reactants is halved, the resulting water molecules are halved.

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Answer:

added to what? base? if its added to base then it will increase in pH. H2S04(sulphuric acid is strong) so the pH is ard 3

Answer:

20 meters

Explanation:

The bike is moving at a rate of 4 meters per second. In 5 seconds, the bike would have gone 20 meters

4 m/s x 5s = 20 m

Answer:

20 miles

Explanation:

Answer:

true hope it helps

Explanation:

have a nice day

Answer:

Molarity of a solution is defined as

the amount of a substance in a certain volume of solution or the moles of a solute per liters of a solution and also known as the molar concentration of a solution.

The units of molarity are M or mol/L

Define molarity of a solution.

Molar concentration or Molarity is a measure of the concentration of a chemical species, in particular of a solute in a solution, in terms of amount of substance per unit volume of solution.

_____

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1.50g of hydrofluoric acid is produced if 3.00 g of hydrogen reacts with excess fluorine with a 25 percent yield.

The balanced equation for the reaction of hydrogen (H2) and fluorine (F2) to form hydrofluoric acid (HF) is:

H2 + F2 -> 2HF

To calculate the amount of HF produced, we'll use the concept of theoretical yield and percent yield.

The theoretical yield is the maximum amount of product that can be formed based on the amount of reactants used.

Here, we're given that 3.00 g of hydrogen is used, so to find the theoretical yield of HF, we'll use the molar ratio of hydrogen to hydrofluoric acid in the balanced equation.

1 mol of H2 produces 2 mol of HF

So, 3.00 g of H2 produces 2*3.00g = 6.00g of HF

Percent yield is the ratio of the actual yield to the theoretical yield multiplied by 100%.

It's given that the yield is 25%.

So the actual yield of hydrofluoric acid will be:

Actual yield = (Theoretical yield) x (percent yield/100)

Actual yield = 6.00g x (25/100)

Actual yield = 1.50g

So, 1.50g of hydrofluoric acid is produced if 3.00 g of hydrogen reacts with excess fluorine with a 25 percent yield.

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Answer:

Which one do you need the answer to?

Explanation:

When the arrangement of atoms changes in a substance, the properties of the substance can change as well. The different arrangements of atoms can lead to different chemical and physical properties.

For example, if the atoms of a substance are rearranged to form a new compound, the new compound will have different chemical properties than the original substance. A new compound may have a different color, odor, reactivity, or melting point than the original substance.

Changing the arrangement of atoms without changing the chemical composition can change the physical properties. For example, a crystalline solid has atoms or molecules arranged in a regular, repeating pattern. This arrangement gives the material unique properties such as density, melting point, and hardness. If the arrangement of atoms and molecules changes, the properties of solids can also change.

In summary, when the arrangement of atoms in a substance changes, the properties of the substance can also change. Different arrangements of atoms have different chemical and physical properties.

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Answer:

1) in excess

Explanation:

Copper oxide is insoluble in water, while acid is soluble in water

Answer:

a) red, blue, and violet

b) orange, yellow, and green

C) red, orange, and yellow

D) blue, indigo, and violet​

The life cycle of a star the size of our sun starts with a nebula, a huge cloud of dust and gas. The gravity of the nebula compresses the cloud until the atoms fuse together, creating a star. This stage is known as pre-birth.

Next, the star enters a main sequence phase, where it shines brightly for millions of years, powered by nuclear fusion.

Eventually the star will slowly run out of hydrogen and the fusion process will become less and less efficient. The star will expand and become what is known as a red giant. This marks the end of the main sequence phase.

After this point, the star expels its outer layers, leaving behind a small, hot core called a white dwarf. It will continue to cool down until it becomes a black dwarf.

If the star is at least 5 times bigger than our sun, it will enter a different life cycle. After the red giant phase, the star will undergo a supernova explosion, which will spew dust and gas into the surrounding areas. These remainders will later form new stars, planets, and other cosmic bodies. What's left of the star will become a neutron star or a black hole.

Answer:

Separation by density

Hope this helps

Answer & Explanation:

It is NOT POSSIBLE to determine a person's genotype if that person presents the dominant trait

In the box on a periodic table  we can find its atomic number, symbol, average atomic mass, and (sometimes) name of the element.

By the 20th century, it was clear that atomic numbers, not atomic masses, were involved in the periodic relationship. The periodic law, a more recent formulation of this relationship, states that an element's properties are a periodic function of its atomic number.

The elements are arranged in a modern periodic table in increasing order of their atomic numbers, and atoms with comparable properties are grouped in the same vertical column (Figure below). With its atomic number, symbol, average atomic mass, and (sometimes) name, each box represents an element. The elements are grouped in 18 vertical columns called groups and seven horizontal rows known as periods or series.

Each column's header lists the names of its groups. Roman numerals and capital letters have traditionally been used on labels in the United States. The IUPAC advises using the digits 1 through 18, and these labels are more widely used. Parts of two of the rows, totaling 14 columns, are typically written below the table's main body in order for it to fit on a single page.

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After 4 minutes, 400 g of the sample would have decayed to 400 g -  (200 g x 4) = 396.2 g.

Protactinium (symbol Pa) is a rare, radioactive, metallic element in the actinide series of the periodic table. It has an atomic number of 91 and an atomic mass of 231. It is found in trace amounts in nature, but can be artificially produced in a nuclear reactor. Protactinium is a soft, silvery-gray metal that is soluble in acids and insoluble in bases. It has a high melting point and is moderately toxic. It has a variety of uses, including as a fuel source in nuclear reactors and in medical research.

After 4 minutes, 400 g of protactinium-234 would have decayed to approximately 396.2 g.
This is because the half-life of protactinium-234 is 1 minute, meaning that in one minute, half of the original amount (200 g) of the sample will decay.

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The expression is  [tex]\frac{(h+2)}{4}[/tex] which can be solved by BODMAS rule

The abbreviation BODMAS, which stands for "Brackets, Order of powers or roots, Division, and Multiplication," is followed by the BODMAS rule. A stands for addition and S for subtraction. According to the BODMAS rule, multi-step mathematical statements must be solved in the BODMAS order from left to right. Similar to how Addition and Subtraction depend on which comes first in the sentence, Division and Multiplication are thought of as interchangeable operations.

The expression can be written as follows WE have 2 quantities h and 2

Their sum can be written as h+2 Now We have the sum divided by 4 so it can be written as : [tex]\frac{(h+2)}{4}[/tex]

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Answer:

Explanation: 8.43

For a team of scientists to claim that they have discovered a new experimental method for determining atomic mass, their claim is to be considered valid only if another team of scientists is able to replicate the results of the experiment.

In order for a scientific claim to be considered valid, it is important that the results of the experiment can be replicated by other researchers.

Replication means that other scientists should be able to obtain the same results using the same methods. This helps to ensure that the results are accurate and reliable, rather than being a fluke or an error.

Without the ability to replicate the results, it is difficult to have confidence in the validity of the claim, as it may be due to uncontrolled variables or other factors that cannot be reproduced. Ensuring that results are replicable is an important part of the scientific process and helps to build a strong foundation of knowledge.

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