Bubbles that form in boiling water are
air from the surroundings
water particles turning to gas below the surface
water particles moving air into the water
None of the above

Answer:

D. Water vapor in the air condenses to form liquid water or ice

Explanation:

took test on e2020

Answer:

a

3.92

Explanation:

intestinal flora

A modest level of ethanol enters the human circulation naturally from intestinal flora, equivalent to a fraction of a drink per day.

Intestinal microflora primarily serves two purposes:

The immune system's development and balance depend heavily on intestinal microorganisms.

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The 85th percentile of blood pressure readings is approximately 137.64. a. To calculate the z-score for a blood pressure reading of 140, we can use the formula:

z = (x - μ) / σ

where x is the value (140 in this case), μ is the mean (121), and σ is the standard deviation (16).

Substituting the values into the formula:

z = (140 - 121) / 16

z ≈ 1.19 (rounded to two decimal places)

b. To find the proportion of Canadians with high blood pressure, we need to calculate the area under the normal distribution curve for values above 140. This can be done by finding the cumulative probability using the z-score.

Using a standard normal distribution table or a calculator, we can find that the cumulative probability corresponding to a z-score of 1.19 is approximately 0.881.

Therefore, the proportion of Canadians with high blood pressure is approximately 0.881 (rounded to four decimal places).

c. To find the proportion of Canadians with systolic blood pressure in the range from 100 to 140, we need to calculate the area under the normal distribution curve between these two values.

Using the z-scores corresponding to 100 and 140, we can find the cumulative probabilities for each value. The cumulative probability for a z-score of -1.25 (corresponding to 100) is approximately 0.105, and the cumulative probability for a z-score of 1.19 (corresponding to 140) is approximately 0.881 (as calculated in part b).

The proportion with systolic blood pressure between 100 and 140 is the difference between these two probabilities:

Proportion = 0.881 - 0.105 ≈ 0.776 (rounded to four decimal places)

d. The 85th percentile represents the value below which 85% of the blood pressure readings fall. To find the 85th percentile, we need to determine the z-score that corresponds to an area of 0.85 under the normal distribution curve.

Using a standard normal distribution table or a calculator, we can find that the z-score corresponding to an area of 0.85 is approximately 1.04.

To find the actual blood pressure reading at the 85th percentile, we can use the z-score formula:

x = μ + (z * σ)

Substituting the values:

x = 121 + (1.04 * 16)

x ≈ 137.64

Therefore, the 85th percentile of blood pressure readings is approximately 137.64.

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Answer:

Yes

Explanation:

Based on the graph, nuclear energy is one of the least contributors of CO2 emissions.

You would support this source of energy .

The number of protons is 29, the number of neutrons is 36 and the number of electrons is 29 in \(X_{65}^{29}\).

To determine the number of protons, neutrons, and electrons in an atom, you need the atomic number (Z) and the mass number (A) of the element.

In the case of \(X_{65}^{29}\), the atomic number (Z) is 29, which corresponds to the number of protons in the nucleus of the atom. The total of protons and neutrons is represented by the mass number (A), which is 65.

Number of protons = Atomic number (Z) = 29

Number of neutrons
\(= Mass number (A) - Number of protons\)
= 65 - 29 = 36

When an atom is neutral, the number of electrons and protons in the atom are equal. So, in this case, there are 29 electrons.

Therefore, there are 29 protons, 36 neutrons, and 29 electrons in a nucleus.

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The following statements on HPLC modes are true is more polar compounds elute first in normal-phase HPLC (Option E).

The liquid chromatography (HPLC) is a technique in analytical chemistry employed for the separation, identification, and quantification of elements. It is considered a highly sensitive method, and it works by separating the components in a mixture with the assistance of a solvent under high pressure.

There are two modes of HPLC: Reversed-Phase HPLC (RP-HPLC) and Normal-Phase HPLC (NP-HPLC). In RP-HPLC, a nonpolar stationary phase, such as C18, is used, and polar solvents, such as water, are used as mobile phases. Polar stationary phases, such as silica gel, are used in NP-HPLC, while nonpolar solvents, such as hexane, are used as mobile phases.

More polar compounds have a greater affinity for the polar stationary phase than less polar compounds, which have a higher affinity for the nonpolar mobile phase in NP-HPLC. As a result, less polar compounds elute first in normal-phase HPLC.

Thus, the correct option is E.

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Answer: It’s called a alpha particle

Explanation:

Answer:

  85.8 g

Explanation:

The molar mass of BaCl₂ is 208.233 g/mol, so 210.1 g is about ...

  210.1/208.233 ≈ 1.009 mol

The molar mass of K is about 39.089 g/mol, so 45 g is about ...

  45/39.089 ≈ 1.1509 mol

The balanced equation seems to be ...

  BaCl₂ + 2K  ↔ 2KCl + Ba

This reaction requires 2 moles of potassium for each mole of barium chloride, so the available potassium limits the reaction. The result is as many moles of potassium chloride as there are moles of potassium.

The 1.1509 moles of KCl, at 74.551 g/mol will have a mass of about 85.8 g.

The reaction produces 85.8 g of KCl.

Answer:

The dating technique described in your question, which involves counting the frequency of fission tracks in a sample and comparing it to the known rate of fission, is called fission track dating.

This method relies on the decay of uranium-238, which has a half-life of 8.2 x 10¹⁵ years.

When uranium-238 undergoes fission, the resulting fragments are violently repelled from each other, leaving behind track-like scars in materials such as crystalline substances and obsidian.

By measuring the number of fission tracks in a sample and knowing the rate of fission, archaeologists can estimate the age of the sample.

Fission track dating has been used to determine the ages of various geological and archaeological materials.

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The empirical formula of a compound found to contain 26.56% potassium, 35.41% chromium, and the remainder oxygen is K₂Cr₂O₇.

The term an Empirical formula is defined as the chemical formula of a compound that gives the ratios of the elements present in the compound but not the actual numbers or arrangement of atoms.

The number of mole of each element in the compound can be identified by dividing each element's percentage with their respective molar weights:

Potassium K = 26.56%

= 26.56 / 39.1        

= 0.68

Chromium, Cr = 35.41%                

= 35.41/52

= 0.68

Oxygen,

O = 100 - 26.56+35.41                      

= 38.03/16

= 2.38

Divide each number of moles by the smallest.

K = 0.68/0.68  

= 1                                                            

Cr = 0.68/0.68

= 1    

O = 2.38/0.68

= 3.5      

Thus, the empirical formula would be KCrO₃.₅

Multiply all by 2 to remove the fraction:

Then the empirical formula would be K₂Cr₂O₇.

Thus, the empirical formula of a compound found to contain 26.56% potassium, 35.41% chromium, and the remainder oxygen is K₂Cr₂O₇.

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To make an E9 mixture 8657.14 gal of E7 should be mixed with 3000 gal of E10

Given to us is the amount of ethanol in the E10 mixture is 10% of 3000 gallons:

Ethanol in E10 = 10% × 3000 gal = 0.10 × 3000 gal = 300 gal

To solve this problem, we can set up an equation based on the amount of ethanol in each mixture.

Let x represent the amount of E7 mixture (in gallons) that needs to be added to the E10 mixture to obtain the desired E9 mixture.

The amount of ethanol in the E7 mixture is 7% of x gallons:

Ethanol in E7 = 7% ×  gal = 0.07 × gal

The resulting E9 mixture will contain 9% ethanol of the total volume of 3000 + x gallons:

Ethanol in E9 = 9% × (3000 + x) gal = 0.09 × (3000 + x) gal

According to the problem, the resulting E9 mixture contains 906 gallons of ethanol:

Ethanol in E9 = 906 gal

Now we can set up the equation:

Ethanol in E10 + Ethanol in E7 = Ethanol in E9

300 gal + 0.07x gal = 906 gal

Subtracting 300 gal from both sides:

0.07x gal = 606 gal

Dividing both sides by 0.07:

x = 606 gal / 0.07

x = 8657.14

Therefore, approximately 8657.14 gallons of E7 mixture should be mixed with 3000 gallons of E10 to make an E9 mixture.

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Complete question: Ethanol fuel mixtures have "E" numbers that indicate the percentage of ethanol in the mixture by volume. For example, E10 is a mixture of 10% ethanol and 90% gasoline. How much E7 should be mixed with 3000 gal of E10 to make an E9 mixture?

Answer:

Oxygen will have the highest electronegativity

Answer:

The proportionality constant ( Henry’s constant) = 2.32 * 10^-5 M/kPa

Explanation:

Here in this question, we are concerned with calculating the proportionality constant for this gas.

Mathematically, we can get this from Henry law

From Henry law;

Concentration = Henry constant * partial pressure

Thus Henry constant = concentration/partial pressure

Henry constant = 0.00290 M/125 kPa = 2.32 * 10^-5 M/kPa

The empirical formula of a compound that consists of 76.52% Au and 23.48% O is Au2O3.

Here's how to determine it:

The first thing to do is to assume that you have 100g of the compound.76.52% of 100g is 76.52g, and 23.48% of 100g is 23.48g.

To calculate the number of moles of each element, you need to use their molar masses.

The molar mass of Au is 196.967 and that of O is 15.999.

Therefore: moles of Au = 76.52g ÷ 196.967 g/mol

= 0.388 moles

moles of O = 23.48g ÷ 15.999 g/mol

= 1.467 moles

Next, divide the number of moles of each element by the smallest number of moles. In this case, the smallest number of moles is 0.388 (from Au).

Therefore:  moles of Au ÷ 0.388 = 1.00

moles of O ÷ 0.388 = 3.78

Then, round these numbers to the nearest whole number.

In this case: moles of Au ÷ 0.388 = 1

mole of O ÷ 0.388 = 4

Therefore, the empirical formula of the compound is Au1O4, but this formula can be simplified by dividing all the subscripts by the smallest one. This gives the formula Au2O3, which is the empirical formula of the compound.

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The bond angle about the central N in the NO2- ion is approximately 115 degrees. The Lewis structure of NO2- shows that there are two single bonds between the central N atom and the two oxygen atoms, with one lone pair of electrons on the central N atom.

The VSEPR (Valence Shell Electron Pair Repulsion) theory predicts that the lone pair of electrons will repel the bonding pairs, causing a decrease in the bond angle.

In NO2-, the presence of the lone pair of electrons on the central N atom repels the bonding electron pairs, causing the bond angle to be less than the ideal tetrahedral angle of 109.5 degrees. The repulsion from the lone pair pushes the bonding pairs closer together, resulting in a smaller bond angle.

Based on the Lewis structure of NO2- and the principles of VSEPR theory, the most accurate estimate for the bond angle about the central N in NO2- is approximately 115 degrees. The presence of the lone pair on the central N atom causes a decrease in the bond angle compared to the ideal tetrahedral angle.

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Ask your parents or guardian for a tutor.

It's very dangerous to give someone your snap online that you don't know!

Have a nice day <3

Answer:

How do balanced chemical equations show the conservation of mass? They show that the atoms in the products may be different than the reactants as long as the mass does not change. They show that the atoms in the products are the same as in the reactants, but the number of atoms must change.

Explanation:

if it helped u please mark me a brainliest:-))

"the number of ions produced by one formula unit of the electrolyte," refers to the van't Hoff factor (i) in an ideal solution of a strong electrolyte. It represents the extent of dissociation of the electrolyte into ions.

In an ideal solution of a strong electrolyte, the van't Hoff factor (i) represents the number of ions that are produced when one formula unit of the electrolyte dissociates completely in the solution. It is a measure of the extent of dissociation of the electrolyte.

For example, for a strong electrolyte such as sodium chloride (NaCl), when it dissolves in water, it completely dissociates into sodium ions (Na+) and chloride ions (Cl-). In this case, the van't Hoff factor (i) would be 2 because one formula unit of NaCl produces two ions (Na+ and Cl-).

Similarly, for other strong electrolytes, the van't Hoff factor (i) can be determined based on the number of ions produced per formula unit. It is important to note that for non-electrolytes or weak electrolytes, the van't Hoff factor (i) is typically less than 1, indicating partial dissociation or no dissociation in the solution.

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Answer:

valence electrons

Explanation:

Answer:

Ionic bonds result from the transfer of electrons from one atom to another

Explanation:

In covalent bonds, atoms share electrons, whereas in ionic bonds atoms transfer electrons. The reaction components of covalent bonds are electrically neutral, whereas for ionic bonds they are both charged.Covalent bonds are formed between two non-metals, whereas ionic bonds are formed between a metal and non-metal.  

Answer:

Covalent bonds are defined as sharing of electrons, ionic bonds are the result of transferred electrons;

Covalent bonds form between non-metals (elements) and ionic bonds form between metal and non-metals (ions)

The volume of a 15.0% by mass NaOH solution, which has a density of 1.116 g/ml, should be used to make 5.20 l of a NaOH solution with a ph of 10.0 is  3.47 L.

To find the volume of a 15.0% by mass NaOH solution, we need to use the following formula:

mass = volume x density x percentage by mass

We know the density of the solution is 1.116 g/ml and the percentage by mass is 15.0%. Let's assume the mass of the solution we need is x.

x = volume x 1.116 g/ml x 15.0%

Simplifying this equation, we get:

x = 0.1674 volume

Now, let's move on to the second part of the question. We need to make a 5.20 L solution of NaOH with a pH of 10.0. To do this, we need to calculate the concentration of NaOH we need in the final solution.

The pH of a solution can be calculated using the following formula:

pH = -log[H+]

Since we want the pH to be 10.0, we can rearrange this equation to find the concentration of H+ ions we need:

[H+] = 10^-pH

[H+] = 10^-10

[H+] = 1.0 x 10^-10 M

Now, NaOH is a strong base that will dissociate completely in water to form Na+ and OH- ions. The concentration of OH- ions in our final solution will be equal to the concentration of NaOH we add to the solution.

So, to make a 5.20 L solution of NaOH with a pH of 10.0 and a concentration of 1.0 x 10^-10 M, we need to add:

the volume of NaOH = (concentration x volume of solution) / percentage by mass

volume of NaOH = (1.0 x 10^-10 M x 5.20 L) / 15.0%

volume of NaOH = 3.47 L

Therefore, we need to use 3.47 L of the 15.0% by mass NaOH solution to make 5.20 L of a NaOH solution with a pH of 10.0.

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The ratio of the effusion rates of two gases is given by Graham's law, which states that the rate of effusion of a gas is inversely proportional to the square root of its molar mass. We need to determine the identities of the two gases in a mixture where one gas effuses 1.43 times faster than the other. To solve this, we can use Graham's law of effusion.

Graham's law states that the rate of effusion of two gases is inversely proportional to the square root of their molar masses.
Rate1 / Rate2 = (M2 / M1)
Given that one gas effuses 1.43 times faster than the other, we can set up the equation:
1.43 = √(M₂ / M₁)
Now, we need to find two gases that satisfy this equation. To do this, we can use the periodic table to check the molar masses of various gases and find a pair that fits the ratio. For example:
1.43 ≈ √(28.97 g/mol (air) / 20.18 g/mol (Ne))

Thus, the two gases could be air (a mixture of nitrogen, oxygen, and other trace gases) and neon (Ne). In summary, there are many possible combinations of gases that could have effused from the container, but one example is helium and sulfur hexafluoride.

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Answer:

a formula giving the proportions of the elements present in a compound but not the actual numbers or arrangement of atoms.

Hope this helped!!!

Answer:

Empirical formulas show the simplest whole-number ratio of atoms in a compound

Explanation:

Answer:

Because 60 percent of our body weight is made up of water. Our bodies use water in all the cells, organs, and tissues, to help regulate body temperature and maintain other bodily functions.

Explanation:

Our bodies is made out of 60% water and even if the percentage goes down 1% we could faint. 5% and we could die. We wash off with water to clean ourselves. We use water to cook like boiling pasta. Water is a necessity not just humans need it but plants need it to grow and germinate. Hope this helps sorry it took so long. I had a fight with autocorrect.

Answer:

1/8

Explanation:

Use logic,

every one hour, half of a radioactive remains

for the first hour, half remains

for the second hour, half of half remains or quarter remains

for the third hour, 1/2 of 1/2 of 1/2 or 1/8 remains

or use this equation

\(n = r ({ \frac{1}{2} })^{ \frac{f}{t} } \)

where

n = amount after f time

r = amount of the original isotope

f = time

t = half-life

Answer:

Their weight.

Explanation:

Weight is the measurement of gravity pushing you down, so with less gravity there would be less weight.

The astronauts expect their weight to be different on the Moon

Weight is simply defined as the gravitational pull of the earth on an object. It is measured in Newton.

The weight of an object varies with location because of gravity.

The weight of an object is related to it's mass according to the following equation:

Weight = mass × Acceleration due to gravity

Since the gravity of the Moon is lesser than that of the Eearth, the astronauts certainly knew that their weight will be different on the Moon.

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atoms in order of decreasing first ionization energies is given by F>Be>Li>Ba .

Ionization energy can be defined simply as a measurement of how difficult it is to remove an electron from an atom or ion or of an atom's or ion's propensity to give up an electron. Usually, when a chemical species is in its ground state, an electron is lost.

As an alternative, we can say that ionisation or ionisation energy is a measurement of the strength of the attractive forces that hold an electron in a specific location.

ionization energy can be defined more precisely as the least amount of energy that an electron in a gaseous atom or ion must absorb to escape the nucleus's influence. It is typically an endothermic reaction and is also known as the ionisation potential.

Ionization is the process of removing an electron from its orbit and moving it outside of the atom. Ionization energy is equal to the difference in energy between the energy of the electron in the initial orbit and the energy of the electron outside the atom since each orbit of the electron has a distinctive energy (in the infinite orbit from the nucleus).

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