This element has two electrons in its outer orbit, and it belongs to the third period.

Explanation:

what is your Question plese

Answer:

3.125%

Explanation:

After 1 half life it remains 50%

After 2 half lines it remains 25%

After 3 half lines it remains 12.5 %

After 4th half life it remains 6.25%

After 5th half life it remains 3.125%

Mole measure the number of elementary entities of a given substance that are present in a given sample. Therefore, the mass of every substance can be calculated as below.

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.

HNO\(_2\) + KOH  \(\rightarrow\) KNO\(_2\)+ H\(_2\)O

The mole ratio among HNO\(_2\), KOH, KNO\(_2\) and H\(_2\)O is 1:1:1:1.

number of moles of HNO\(_2\)= given mass of HNO\(_2\)/ molar mass of HNO\(_2\)

number of moles of HNO\(_2\)= 0.87 / 31.01

                                          = 0.028 moles

moles of HNO\(_2\), KOH, KNO\(_2\) and H\(_2\)O is  0.028 moles

mass of KOH= moles of KOH× Molar mass of KOH

                     =  0.02× 56.11

                     =1.12g

mass of  KNO\(_2\)=  0.02× 85.1

                        = 1.70g

mass of  H\(_2\)O =0.02× 18

                     = 0.36g

Therefore, the mass of every substance can be calculated as above.

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Answer: 17.91 grams of CO2 will be produced

Explanation:

The balanced chemical equation for the combustion of pentane is:

C5H12(l) + 8 O2(g) → 5 CO2(g) + 6 H2O(g)

From the equation, we can see that for every 1 mole of C5H12 that reacts, 5 moles of CO2 are produced. Therefore, to determine the mass of CO2 produced, we need to first calculate the number of moles of CO2 produced by 0.08142 moles of C5H12:

0.08142 moles C5H12 x (5 moles CO2 / 1 mole C5H12) = 0.4071 moles CO2

Now we can use the molar mass of CO2 (44.01 g/mol) to calculate the mass of CO2 produced:

0.4071 moles CO2 x 44.01 g/mol = 17.91 g CO2

Therefore, the mass of CO2 produced by the complete combustion of 0.08142 moles of pentane is 17.91 g.

Answer: 17.912 gm

Explanation: C5H12 + 8O2 ------- 5CO2 +6H2O

IF ONE MOLE OF C5H12 produces 5 moles of CO2 then 0.08142 produces x mole

then x = 5 X 0.08142

X = 0.4071

NO. OF MOLES = given mass/ molecular mass of CO2

0.4071= mass/44

Mass= 0.4071 X 44

mass = 17.912

therefore mass of CO2 produced is 17.912

The mass of HBr that would be needed to dissolve the 3.0 g pure iron bar is 11 g

3.0 g is the mass of pure iron (Fe).

HBr mass required to dissolve the aforementioned iron

Explanation:

HBr and Fe react, and the result is

FeBr2 + H2 = Fe + 2HBr

Based on the stoichiometry of the reaction,

2 moles of HBr and 1 mole of Fe react.

Mass of Fe/atomic mass of Fe = 3.0/56 g.mol.1 = 0.0607 moles of Fe.

As a result, the number of moles of HBr is equal to 2*0.0607 moles.

HBr's molar mass is 81 g/mole.

HBr mass equals 0.1214 moles times 81 g/mole, or 11 g.

11 gram of HBR are needed.

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The mass of hydrogen needed to produce 51.0 grams of ammonia is  ≈ 9.07 grams.

To determine the mass of hydrogen required to produce 51.0 grams of ammonia (NH3) using the Haber process, we need to calculate the stoichiometric ratio between hydrogen and ammonia.

From the balanced chemical equation:

3 H₂(g) + N₂(g) → 2 NH₃(g)

We can see that for every 3 moles of hydrogen (H₂), we obtain 2 moles of ammonia (NH₃).

First, we need to convert the given mass of ammonia (51.0 grams) to moles. The molar mass of NH₃ is 17.03 g/mol.

Number of moles of NH₃ = Mass / Molar mass

                     = 51.0 g / 17.03 g/mol

                     ≈ 2.995 moles

Next, using the stoichiometric ratio, we can calculate the moles of hydrogen required.

Moles of H₂ = (Moles of NH₃ × Coefficient of H₂) / Coefficient of NH₃

           = (2.995 moles × 3) / 2

           ≈ 4.493 moles

Finally, we can convert the moles of hydrogen to mass using the molar mass of hydrogen (2.02 g/mol).

Mass of H₂ = Moles × Molar mass

          = 4.493 moles × 2.02 g/mol

          ≈ 9.07 grams

Therefore, approximately 9.07 grams of hydrogen is needed to produce 51.0 grams of ammonia in the Haber process.

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Answer:

A a chemical change

Explanation:

because a chemical change is when you mix tow substance together and they creat a new substance

Answer:

The pH does not decrease drastically because the HCl reacts with the sodium azide (NaN₃) present in the buffer solution.

Explanation:

The buffer solution is formed by 0.26 moles of the weak acid, hydrazoic acid (HN₃), and by 0.26 moles of sodium azide (NaN₃). The equilibrium reaction of this buffer solution is the following:

HN₃(aq) + H₂O(l)  ⇄ N₃⁻(aq) + H₃O⁺(aq)          

The pH of this solution is:

\( pH = pka + log(\frac{[N_{3}^{-}]}{[HN_{3}]}) = -log(2.5 \cdot 10^{-5}) + log(\frac{0.26 mol/1 L}{0.26 mol/1 L}) = 4.60 \)

When 0.05 moles of HCl is added to the buffer solution, the following reaction takes place:

H₃O⁺(aq) + N₃⁻(aq)  ⇄  HN₃(aq) + H₂O(l)

The number of moles of NaN₃ after the reaction with HCl is:

\( \eta_{NaN_{3}} = \eta_{i} - \eta_{HCl} = 0.26 moles - 0.05 moles = 0.21 moles \)

Now, the number of moles of HN₃ is:

\( \eta_{HN_{3}} = \eta_{i} + \eta_{HCl} = 0.26 moles + 0.05 moles = 0.31 moles \)

Then, the pH of the buffer solution after the addition of HCl is:

\( pH = pka + log(\frac{[N_{3}^{-}]}{[HN_{3}]}) = -log(2.5 \cdot 10^{-5}) + log(\frac{0.21 mol/V_{T}}{0.31 mol/V_{T}}) = 4.43 \)

The pH of the buffer solution does not decrease drastically, it is 4.60 before the addition of HCl and 4.43 after the addition of HCl.    

Therefore, the pH does not decrease drastically because the HCl reacts with the sodium azide (NaN₃) present in the buffer solution.

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a) The three solvents suitable for solvent extraction in combination with water are 2-butanone, acetone, and 1-propanol. These solvents are suitable because they are all miscible with water, meaning they can dissolve in water to form a homogeneous solution.

b) Solvent 1 is 2-butanone and the organic layer is the upper layer because the density of 2-butanone (0.805 g/mL) is lower than the density of water (1.000 g/mL).

Solvent 2 is acetone and the organic layer is the upper layer because the density of acetone (0.7845 g/mL) is lower than the density of water (1.000 g/mL).

Solvent 3 is 1-propanol and the organic layer is the upper layer because the density of 1-propanol (0.803 g/mL) is lower than the density of water (1.000 g/mL).

In solvent extraction, the organic layer will be on top if the density of the solvent is lower than the density of water, and the organic layer will be on the bottom if the density of the solvent is higher than the density of water.

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The number of CFU's in the original sample is 540000000.

The colony forming unit stands for (CFU) is a measure of viable colonogenic cell numbers in CFU/mL. CFU's are an indication of the number of cells that remain viable enough to proliferate and form small colonies.

CFU/ml = [Number of colonies ][Dilution factor]/Volume of cultre plate

In the question , Volume of cultre sample=0.1 ml

Dilution factor = Final volume/Sample volume

                        = 0.1 ml/1 ml

                        = 0.1 ml

Let x be the number of colonies,

CFU =[x 1/10] /0.1 =540000000

x = 540000000 × 0.1 × 10

  = 540000000

Therefore CFU in the original sample = [540000000 × 1/10 ] /0.1

                                                               = 540000000

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Explanation

Given:

Mass of the solute = 60 g

Volume of the solution = 270 mL

Required: mass/volume %

Solution

To solve this problem: Percent (m/v) is the mass of solute divided by the volume of the solution, multiplied by 100 %.

Percent (m/v) = mass of solute volume of solution × 100 %

Percentage (m/v) = (60g/270 mL) x 100

Percentage (m/v) = 22.2%

Answer

% (m/v) = 22.2%

2.5 moles of NaCl can be produced from 2.5 moles of BaCl\(_2\). Mole, often known as mol, is a commonly used unit of measurement.

Mole, often known as mol, is a commonly used unit of measurement in chemistry for vast amounts of tiny objects such molecules, atoms, or other specific particles.

In addition, starting on May 20, 2019, the General Conference upon Weights and Measures declared the mole as the quantity of the International System of Units.

Na\(_2\)SO\(_4\) + BaCl\(_2\) → BaSO\(_4\) + NaCl

moles of BaCl\(_2\) =2.5 moles

the mole ratio between BaCl\(_2\) and NaCl is 1:1

mole of NaCl =2.5 moles

Therefore, 2.5 moles of NaCl can be produced from 2.5 moles of BaCl\(_2\).

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Answer:

0.551 moles

Explanation:

To calculate the number of moles in 22 grams of argon, divide the mass by the molar mass:

Number of moles = Mass / Molar mass

Number of moles = 22 g / 39.95 g/mol

Number of moles ≈ 0.551 moles

Therefore, there are approximately 0.551 moles of argon in 22 grams of argon.

Answer:

Reduction reaction

This is so because considering the reaction Cu 2+ has been reduced to Cu(s) by losing two electrons , and any other element that undergoes this stage is termed as a reduction reaction.

Hope this helps

Answer:

c) oil and vinegar

Explanation:

A heterogeneous mixture is a mixture that does not have a "uniform composition" (meaning that the entire mixture is not thoroughly mixed to be the exact same. In different parts of the mixture, there is a              non-consistent / differing composition.)

Oil and vinegar, as you may know, do not thoroughly mix when put together--different parts of the mixture are made of different compositions. Some parts are made of oil, and some are a concentration of vinegar, but because they are not able to be mixed entirely, the mixture is considered a heterogeneous mixture. If you were to take different samples of different parts of the liquid, you would have a clear separation of oil and vinegar.

Milk is thoroughly milk--if you take out a tablespoon, it will be milk entirely--and it will have the same composition as all of the other milk in the bottle.

Air is complicated--and it can be described as either, but the question was likely intending the answer of oil and vinegar.

Vinegar and water do thoroughly mix. Vinegar absorbs water on a molecular level, so the mixture is thoroughly mixed when put together.

(Hope this helps!)

The mass of the asteroid is C. 1.2 x \(10^{12}\) Kg

To find the mass of the other asteroid, we can rearrange the equation for the gravitational force between two objects:

F = (G * m1 * m2) / \(r^{2}\)

where F is the force of gravity, G is the gravitational constant, m1 and m2 are the masses of the two asteroids, and r is the distance between them.

Given that the distance between the asteroids is 75000 m, the force of gravity between them is 1.14 N, and one asteroid has a mass of 8 x \(10^{7}\) kg, we can substitute these values into the equation and solve for the mass of the other asteroid (m2):

1.14 N = (6.67430 × \(10^{-11}\) N \(m^{2}\)/\(Kg^{2}\) * 8 x \(10^{7}\) kg * \(m2\)) / \((75000 m)^{2}\)

Simplifying and solving the equation, we find that the mass of the other asteroid (m2) is approximately 1.2 x \(10^{12}\) kg. Therefore, Option C is correct.

The question was incomplete. find the full content below:

Two asteroids are 75000 m apart one has a mass of 8 x \(10^{7}\) kg if the force of gravity between them is 1.14 what is the mass of the asteroid

A. 3.4 x \(10^{11}\) kg

B. 8.3 x \(10^{12}\) kg

C. 1.2 x \(10^{12}\) kg

D. 1.2 x \(10^{10}\) kg

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The volume of the gas at 101.3 kPa and 24°C will be 24.58 L.

Gas law is a set of empirical laws that describe the physical behavior of a gas. They are derived from experiments on gases, and they relate the pressure, volume, and temperature of a gas. The most famous gas law is the Ideal Gas Law, which states that the pressure, volume, and temperature of an ideal gas are related by the equation PV=nRT, where P is the pressure, V is the volume, n is the amount of gas, R is the gas constant, and T is the temperature.

At constant pressure, the volume of a gas will increase as its temperature increases. This is because the molecules are moving faster, so they take up more space. Therefore, the volume of the gas at 101.3 kPa and 24°C will be greater than 0.8 L. To calculate the exact volume, you would need to use the ideal gas law:
PV = nRT
where P is pressure,
V is volume,
n is the number of moles of gas,
R is the ideal gas constant, and
T is temperature in Kelvin.
Solving for V, we get:
V = (nRT) / P
Plugging in the given values, we get:
V = (n * 8.314 * 297.15) / 101.3
V = 24.58 L
Therefore, the volume of the gas at 101.3 kPa and 24°C will be 24.58 L.

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Answer:

Answer:

Silicon dioxide 

Explanation:

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Answer:

32,8mL

Explanation:

1lb=2.2kg

18lb= 8.2 kg  

100mg/5mL=20mg/1mL

164mg=32.8mL

Taking into account the reaction stoichiometry and molarity, 10.17 mL of 0.32 M H₂C₂O₄ is required to titrate 15.50 mL of 0.21 M Mg(OH)₂.

In first place, the balanced reaction is:

H₂C₂O₄ + Mg(OH)₂ → MgC₂O₄ + 2 H₂O

By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:

Molar concentration or molarity is a measure of the concentration of a solute in a solution and indicates the number of moles of solute that are dissolved in a given volume.

The molarity of a solution is calculated by dividing the moles of solute by the volume of the solution:

\(Molarity=\frac{number of moles}{volume}\)

Molarity is expressed in units \(\frac{moles}{liter}\).

In this case, you know:

Replacing in the definition of molarity:

\(0.21 M=\frac{number of moles}{0.0155 L}\)

Solving:

number of moles= 0.21 M× 0.0155 L

number of moles= 0.003255 moles

So, you must titrate 0.003255 moles of Mg(OH)₂.

The following rule of three can be applied: If by reaction stoichiometry 1 mole of Mg(OH)₂ react with 1 mole of H₂C₂O₄, 0.003255 moles of Mg(OH)₂ react with how many moles of H₂C₂O₄?

\(amount of moles of H_{2} C_{2} O_{4} =\frac{0.003255 moles of Mg(OH)_{2} x1 mole of H_{2} C_{2} O_{4}}{1mole of Mg(OH)_{2}}\)

amount of moles of H₂C₂O₄= 0.003255 moles

0.003255 moles of H₂C₂O₄ is required to titrate 15.50 mL of 0.21 M Mg(OH)₂.

In this case, you know:

Replacing in the definition of molarity:

\(0.32 M=\frac{0.003255 M}{volume}\)

Solving:

0.32 M× volume= 0.003255 moles

volume= 0.003255 moles÷ 0.32 M

volume= 0.01017 L= 10.17 mL (being 1 L= 1000 mL)

Finally, 10.17 mL of 0.32 M H₂C₂O₄ is required to titrate 15.50 mL of 0.21 M Mg(OH)₂.

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The equilibrium constant of the reaction at the given temperature is obtained as 336.

Synthesis gas, also known as syngas, is a mixture of hydrogen gas (H2) and carbon monoxide gas (CO) that is produced from a variety of feedstocks, including coal, natural gas, biomass, and waste materials.

Gladly what we have here are the concentration of each of the species at the point of equilibrium and so we can plug them in to get the equilibrium constant are required.

The reaction equation is;

CO(g)+2H2(g)⟶CH3OH(l)

Thus;

K = [CH3OH]/[CO] [H2]^2

K = (0.0401 )/(0.02320) (0.07107)^2

K = 336

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Answer:

The number of these organisms in the soil would decrease.

Explanation:

The mass in grams of 4.60 x 10^23 atoms is approximately 9.17 g.

To find the mass in grams of 4.60 x 10^23 atoms, we need to consider the molar mass and Avogadro's number. Avogadro's number (6.022 x 10^23) represents the number of atoms or molecules in one mole of a substance.

First, we need to determine the molar mass of the substance in question. Let's assume we are dealing with a specific element, such as carbon (C), which has a molar mass of approximately 12.01 g/mol.

To calculate the mass in grams, we can use the following formula:

Mass (in grams) = (Number of atoms / Avogadro's number) x Molar mass

Substituting the given values:

Mass (in grams) = (4.60 x 10^23 atoms / 6.022 x 10^23) x 12.01 g/mol

Calculating the expression:

Mass (in grams) = (0.763 mol) x 12.01 g/mol

Mass (in grams) = 9.17 g

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The molarity of the ammonium nitrate solution is 2281 M.

Molarity is defined as the number of moles of solute per liter of solution. It is also known as molar concentration of the solution and is used to calculate amount of substances in the solution.

Molarity = n/M

n = m / MW

m = 2 lbs = 1000/2.2 = 909 g

V = 53 x 3.79/1 = 200.9

MW = 80.04 g

M = m/Mw / V

M = 909/80.04 /200.9

M = 2281 M

Thus, the molarity of the ammonium nitrate solution is 2281 M.

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Answer:

Explanation:

i) in keeping industrial machine cool

ii) in textile inustries for dying clothes

Aloud is trying to find evidence that a galaxy has supermassive black hole at its center. He should look for the black matter in the center of the Earth. Thus, the correct option is D.

Black matter or dark matter is composed of the particles which do not absorb, reflect, or emit light rays, so they cannot be detected by observing electromagnetic radiations. Dark matter is the material which cannot be seen directly through the eyes.

Dark matter play an important role in the formation of galaxies. Many researchers use the astronomical surveys to build maps of the location where dark matter in the universe is found based on how the light from the distant galaxies bends as it travels to us.

Thus, the matter which fall into a black hole arranges itself in the shape of a disk which is thick at the outer edge, while it is thin along the inner ring of the disk.

Therefore, the correct option is D.

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The amount of \(HNO_3\) that can be made from 25.0 g of \(NO_2\) according to the reaction would be 22.68 grams.

From the balanced equation of the reaction:

\(3 NO_2 + H_2O -- > 2 HNO_3 + NO\)

The mole ratio of \(NO_2\) and  \(HNO_3\) is 3:2. In other words, for every 3 moles of \(NO_2\) that react, 2 moles of \(HNO_3\) are produced.

If mole = mass/molar mass

25.0 g of \(NO_2\) will be equivalent to (the molar mass of \(NO_2\) is 46 g/mol):

                   25/46 = 0.54 moles

From, the mole ratio of 3:2, 0.54 moles of \(NO_2\) will require:

    2/3 x 0.54 = 0.36 moles of  \(HNO_3\)

The molar mass of  \(HNO_3\) is 63.01 g/mol.

Mass of 0.36 moles of  \(HNO_3\) = 0.36 x 63.01

                                                  = 22.68 g

Thus, the mass of \(HNO_3\) that can be made from the reaction is 22.68 grams.

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