A 100.0 gram sample of Polonium- 210 is contained for 828 days. How many half lives occur during this period of time, if the half live us 138 days?

Items that are less useful, relevant, or efficient are likely to be modified or discarded more frequently than those that are deemed more valuable or necessary.

It is more probable that something will be changed or abandoned when it becomes antiquated, ineffective, or does not satisfy the demands of its users. This could be the result of developments in technology, modifications in society's values or tastes, or just the passage of time. Less value or required things or ideas will probably be changed or rejected more frequently since they are not as crucial to success in general or day-to-day life. To ensure their future relevance and usefulness, those that are highly appreciated or thought necessary will probably be kept or improved upon. This idea may be applied to a variety of things, including corporate procedures, cultural customs, and home appliances.

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Answer:

yes it right. well done try more questions.

Explanation:

To identify the contents of the three unlabelled test tubes, you could carry out the following test-tube reactions:

To identify the alkene:

Add bromine water (dilute aqueous solution of bromine) dropwise to each test tube. The alkene will react with the bromine water and decolourize it, giving a clear solution. The alkane and water test tubes will not show any reaction.

To identify the alkane:

Add a few drops of a concentrated sulfuric acid to each test tube. The alkane will not react with the sulfuric acid, and there will be no observable reaction. The alkene and water test tubes will show no reaction or some reaction, but not as significant as the alkane test tube.

To identify water:

Add a few drops of anhydrous copper (II) sulfate to each test tube. The anhydrous copper (II) sulfate will react with any water present in the test tube and turn blue. The alkane and alkene test tubes will not show any reaction with copper (II) sulfate.

By performing these test-tube reactions, you should be able to identify which test tube contains an alkene, an alkane, and water.

A 9.03 g sample of unknown alkali metal chloride, MCI , is dissolved into 55.00 g of water. the freezing point of the solution is "-10.45" C. Calculate the molar mass of the solute74.1 g/mol .

Water is a chemical compound made up of two hydrogen atoms and one oxygen atom (H2O). It is a natural compound that is essential for all known forms of life. Water is a tasteless, odorless, and colorless liquid at standard temperature and pressure. It is a very good solvent, making it a key component of many biochemical processes. Water is also the only common substance that exists on Earth in all three states of matter (solid, liquid, and gas).

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Answer:

2.7mol

Explanation:

Concentration = amount of substance (n)/Volume

n = C × V

n = 2.7M × 1L

n = 2.7mol

The birth rate is obtained to be 1.36 births per year

The birth rate is typically calculated as the number of births per 1,000 people in a given population over a specific period of time.

The formula that we can use so as to obtain the birth rate can be given as;

Birth rate = (Number of births / Population) x 1,000

We can find the birth rate from;

5.7 x 10^3 / 4.2 x10^6  x 1,000

1.36 births per year

This calculation provides an estimate of the number of births per 1,000 people in the population over a specific time period.

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The combined gas law, which relates the initial and final conditions of pressure, volume, and temperature of a gas, can be used to solve this issue.

(P1V1) / (T1) equals (P2V2) / (T2) where: The initial pressure and temperature at STP are, respectively, P1 and T1 (1 atm and 273 K) The initial volume, or V1, is specified as 2 mL. P2 and T2 represent the final pressure and temperature in the new conditions, respectively, and V2 represents the volume we need to calculate. The given pressure can first be converted to atm: P2 = 460 mm Hg is equal to 460/760 atm, or 0.6053 atm. Additionally, we can change the stated temperature to Kelvin: T₂ = 193 K. Now that the values have been entered, we can solve for V2 using the combined gas law: (0.6053 atm)(V2) / (1 atm)(2 mL)/273 K (193 K), ((1 atm)(2 mL)(193 K)] = V2. / [(273 K)(0.6053 atm)] V₂ ≈ 1.14 mL. As a result, the gas's final volume under the new circumstances is roughly 1.14 mL.

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Answer:

28 liters of O2

Explanation:

A marvelous byproduct of establishing a STP (Standard Temperature and Pressure) is a conversion factor that 1) seems impossible, and 2) saves a lot of time.  That factor is 22.4 Liters/mole gas.  At STP ALL gases occupy 22.4 liters per mole of that gas.  Hydrogen, argon, methane, etc. all will occupy 22.4 liters at 1 atm pressure and 0°C.

That made no sense to me, but after realizing the amount of time it can save answering question as this, I'm a firm believer.

Without this conversion factor, the way to answer the question is to use the ideal gas law:  PV=nRT, where n is the number of moles and R is the universal gas constant.   Not a super difficult equation, but looking up the gas constant and making sure all the units match and cancel can take time and requires focus.

But the conversion factor is straightforward.  We are given 40 g of O2.  Let's coivert the 40g into moles O2.  Divide the mass by the molar mass of O2 (32 g/mole):

(40g O2)/(32 g/mole O2) = 1.25 moles of O2

Now is when the ideal gas law might be employed.  We have P, T, n, and R, so plug them is and calculate volume.  This is done below, just as an illustration.

But since we are at STP, we can use the handy coversion factor to determine the volume of O2:

      (1.25 moles O2)*(22.4L/mole O2) = 28.0 liters of O2

In contrast, the ideal gas law calculation would look like this:

Rearrange to isolate V, the unknown:

V = (nRT)/P

Enter the data, ensuring the correct gas constant is used for the units provided:

V = [(1.25 moles)*(0.0820575L⋅atm⋅K^1⋅mol^1)(273.15K)]/(1atm)

Ouch

V = 28.0 liters

Same answer, more effort.

The tubules in the kidney that transport urine from the nephrons to the ureter are called renal tubules.  The negatively charged ion that is reabsorbed by renal tubules is HCO3-.

The renal tubule is comprised of the proximal convoluted tubule, loop of Henle, and distal convoluted tubule. The reabsorption and secretion of electrolytes and water from the tubular fluid happen here. The proximal convoluted tubule is a part of the nephron in the kidney, it reabsorbs nutrients and water from the filtrate before it passes to the loop of Henle.

The loop of Henle is a U-shaped part of the renal tubule that is responsible for generating concentration gradients in the interstitial fluids of the renal medulla. Finally, the distal convoluted tubule is responsible for acid-base regulation through the reabsorption of bicarbonate ions and secretion of protons into the tubular fluid.

HCO3- is a bicarbonate ion that acts as a buffer in the body, helping to maintain the pH of the blood within a normal range. It is reabsorbed in the proximal tubule and secreted in the distal tubule, depending on the pH of the urine.

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Answer: 16.25

Explanation:

The molar mass of helium (He) is approximately 4 g/mol.

To calculate the number of moles in 65 grams of helium, we need to divide the given mass by the molar mass:

Number of moles = mass ÷ molar mass

Number of moles = 65 g ÷ 4 g/mol

Number of moles = 16.25 mol

Therefore, there are 16.25 moles of helium in 65 grams of helium.

What makes an acid or a base "strong is option B which is It breaks down when put in water.

Not all acids and bases are considered strong. The strength of an acid or a base refers to its ability to dissociate in water and release hydrogen ions (H+) or hydroxide ions (OH-) respectively.

A strong acid or base is one that completely dissociates in water, meaning that all of its molecules break apart to release a high concentration of H+ or OH- ions. Examples of strong acids include hydrochloric acid (HCl) and sulfuric acid (H2SO4), while examples of strong bases include sodium hydroxide (NaOH) and potassium hydroxide (KOH).

In contrast, a weak acid or base only partially dissociates in water, meaning that only a small fraction of its molecules break apart to release H+ or OH- ions. Examples of weak acids include acetic acid (CH3COOH) and carbonic acid (H2CO3), while examples of weak bases include ammonia (NH3) and aluminum hydroxide (Al(OH)3).

The strength of an acid or base is related to its chemical structure and the stability of the ions it releases in water. Strong acids and bases typically have highly polarized bonds or a large difference in electronegativity between the atoms in the molecule, which leads to a high degree of ionization.

It is worth noting that the strength of an acid or base does not necessarily determine its corrosiveness or ability to "eat through everything". Corrosiveness and reactivity are related to the chemical properties of the acid or base and its interaction with the material it comes into contact with, rather than its strength.

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To create a model for a repeating group of atoms that could make up sample 2, is made up of hydrogen and carbon atoms, and it looks like a colorless liquid with a smell similar to gasoline. It has a low boiling point of 36°C.

One possible repeating group of atoms for Sample 2 is a chain of carbon atoms bonded together with hydrogen atoms attached to the carbon atoms. This is called a hydrocarbon chain. The hydrocarbon chain can be represented as follows:

H H H H H H H H H H H H H H H H | | | | | | | | | | | | | | | | C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C

This repeating group of atoms is called a "linear alkane". The alkane has the chemical formula CnH2n+2, where n is the number of carbon atoms in the chain. For example, if there are 4 carbon atoms in the chain, the formula would be C4H10.

This model is consistent with the properties of Sample 2, as hydrocarbons are commonly used as fuels due to their flammability and low boiling points. The smell of hydrocarbons can vary, but some have a similar odor to gasoline. The low boiling point of hydrocarbons means they can exist as liquids at room temperature, which matches the description of Sample 2.

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To make a buffer of pH 8.50 with 1.00 L of 0.200 M ammonia, you need to dissolve 5.6 g of solid ammonium chloride.

This can be calculated using the Henderson-Hasselbalch equation:

pH = pKa + log ( [salt]/[acid] )

8.50 = 9.25 + log ( [NH4Cl]/[NH3] )

[NH4Cl]/[NH3] = 10^(pH-pKa)

[NH4Cl]/[NH3] = 10^(8.50-9.25)

[NH4Cl]/[NH3] = 10^(-0.75)

[NH4Cl] = [NH3] * 10^(-0.75)

[NH4Cl] = 0.200 M * 1.00 L * 10^(-0.75)

[NH4Cl] = 0.158 M

Mass of NH4Cl = 0.158 M * (5.6 g/mol) * 1.00 L

Mass of NH4Cl = 5.6 g

Hence, To make a buffer of pH 8.50 with 1.00 L of 0.200 M ammonia, you need to dissolve 5.6 g of solid ammonium chloride.

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The enthalpy change of the reaction is 148.4 kJ/mol.  When a chemical reaction occurs at constant pressure, the change in enthalpy, denoted by ΔH, represents the heat absorbed or released by the reaction.

What is Enthalpy ?

Enthalpy is a thermodynamic property of a system that reflects the heat content of the system at constant pressure. It is denoted by the symbol H and has units of joules (J) or kilojoules (kJ). Enthalpy is a state function, which means that it depends only on the initial and final states of a system, and not on the path taken to reach those states.

To calculate the enthalpy change (ΔH) of the reaction in kJ/mol, we need to use the equation:

ΔH = q / n

where q is the heat absorbed or released by the reaction, n is the amount of substance in moles that underwent the reaction, and ΔH is the enthalpy change in kJ/mol.

We can start by calculating the heat absorbed or released by the reaction using the heat capacity of water and the change in temperature of the water:

q = m × C × ΔT

where m is the mass of water, C is the specific heat capacity of water (4.184 J/g°C), and ΔT is the change in temperature of the water.

Substituting the given values, we get:

q = (109 g) × (4.184 J/g°C) × (25.7°C - 13.2°C) = 5619.9 J

We can convert this to kilojoules (kJ) by dividing by 1000:

q = 5.62 kJ

Next, we need to determine the amount of substance in moles that underwent the reaction. From the given information, we know that 0.038 mol of the unknown substance was consumed.

Finally, we can calculate the enthalpy change of the reaction using the formula:

ΔH = q / n = (5.62 kJ) / (0.038 mol) = 148.4 kJ/mol

Therefore, the enthalpy change of the reaction is 148.4 kJ/mol.

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The mixture that exhibits the Tyndall effect is fog. The Tyndall effect is the scattering of light by particles in a medium.

What is Tyndall Effect?

The Tyndall effect is the scattering of light by particles in a medium. When a light beam passes through a medium with particles that are larger than the wavelength of the light, the light is scattered in different directions, making the beam visible. This effect is observed in mixtures such as fog, smoke, and dust.

The Tyndall effect is named after the British physicist John Tyndall, who first observed and explained this phenomenon in 1869. Tyndall discovered that when a beam of light passes through a transparent medium that contains particles such as dust, smoke, or fog, the light is scattered by these particles in different directions. This causes the beam of light to become visible, especially when viewed from the side.

Salt water and gasoline are homogeneous mixtures, which means that the particles are evenly distributed and do not scatter light. Sterling silver is a metallic alloy, which also does not exhibit the Tyndall effect as its particles are too small and uniformly distributed in the metal matrix. Therefore, the correct answer is fog.

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Answer:

Explanation:

The formula for lead (IV) oxide is PbO2

The volume of the second vessel is approximately 322.7 mL.

To solve this problem, we can use the combined gas law, which relates the pressure, volume, and temperature of a gas:

(P₁ × V₁)/T₁ = (P₂ × V₂)/T₂

where P₁, V₁, and T₁ are the initial pressure, volume, and temperature, respectively, and P₂ and V₂ are the final pressure and volume, respectively.

First, we need to convert the temperatures to Kelvin, which is done by adding 273.15 to the Celsius temperature:

T₁ = 40.0 + 273.15 = 313.15 K

T₂ = 0.0 + 273.15 = 273.15 K

Next, we can plug in the given values and solve for V₂:

(P₁ × V₁)/T₁ = (P₂ × V₂)/T₂

(895 torr × 550.0 mL)/313.15 K = (745 torr × V₂)/273.15 K

Simplifying and solving for V₂, we get:

V₂ = (745 torr × 550.0 mL × 313.15 K) / (895 torr × 273.15 K)

≈ 322.7 mL

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Answer:

To solve this problem and calculate the grams of Ni, we need to use the molar mass of Ni₂0₃ and the stoichiometry of the reaction.

The balanced chemical equation for the reaction between Ni₂0₃ and H₂ is:

Ni₂0₃ + 2H₂ → 2Ni + 3H₂0

From this equation, we can see that 1 mole of Ni₂0₃ reacts to produce 2 moles of Ni. Therefore, we can use the following conversion factor:

1 mole Ni₂0₃ = 2 moles Ni

We can also use the molar mass of Ni₂0₃ to convert grams of Ni₂0₃ to moles of Ni₂0₃:

54.3 g Ni₂0₃ x (1 mole Ni₂0₃ / 165.38 g Ni₂0₃) = 0.3284 moles Ni₂0₃

Now, we can use the conversion factor to find moles of Ni:

0.3284 moles Ni₂0₃ x (2 moles Ni / 1 mole Ni₂0₃) = 0.6568 moles Ni

Finally, we can use the molar mass of Ni to convert moles of Ni to grams of Ni:

0.6568 moles Ni x (58.69 g Ni / 1 mole Ni) = 38.53 g Ni

Therefore, the grams of Ni in 54.3 g Ni₂0₃ is 38.53 g Ni.

Explanation:

Ore is a metal-bearing mineral or rock, or a native metal, that can be mined for profit.

The mass of sodium Tetraoxosulphate formed when 0.5 mole of sodium hydroxide react with Tetraoxosulphate acid is 35.5 grams.

0.5 m of NaOH denotes the amount of the solvent that is dissolved in 0.5 mole (20.0 g) of NaOH. 0.5 moles of NaOH (20.0 g) are dissolved in 1000 millilitres of the solution, or 0.5 M of NaOH.

Tetraoxosulphate VI acid is produced commercially using the Contact process. The Contact procedure entails the following steps. In order to purge the sulphur (IV) oxide generated of contaminants and dust that can poison the catalyst, it is combined with extra air and sent through an electric chamber.

Strong acid known as tetraoxosulphate may be used to produce synthetic colours, extract metals, serve as the electrolyte in lead-acid storage batteries, and produce synthetic and natural fibres.

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Complete question:

Calculate the mass of sodium tetraoxosulphate (vi) formed when 0.5 mole of sodium hydroxide react with tetraoxosulphate (vi) acid. (Na=23, O=16, S=32, H=1

One material that can produce sound and be converted into another form of energy is piezoelectric material. Piezoelectric materials have an electrical charge when subjected to mechanical stress.

Piezoelectric material produces an electrical charge when subjected to mechanical stress, such as vibrations or pressure. This means that they can convert sound waves into electrical energy, which can then be used to power other devices.

One potential application of this technology is in developing piezoelectric generators that can be installed in public spaces, such as parks or city streets, to capture the energy from ambient sound waves and convert it into electricity. The electricity generated by these devices could be used to power streetlights, charging stations for mobile devices, or other public amenities.

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Answer:

A) The salt lowers the freezing point of the ice-water mixture.

Explanation:

Ice cream freezes at a lower temperature than water because the presence of sugar and fat prevents the formation of ice crystals, necessitating a lower temperature to achieve freezing. Ice by itself cannot adequately chill the ice cream base because it will melt before the base has cooled enough. Water's freezing/melting point can be lowered with the use of salt. Just consider the effects salt has on the roadways when it melts ice. Similar to the last example, adding salt to the ice that surrounds the ice cream base creates a temperature that is chilly enough to prevent the ice cream within from melting completely before it has a chance to thicken and freeze.

Thanks,

Eddie.

Conventional direction is from positive terminal to negative terminal and this is the direction of the electric field within the wire.

Single cell or other power source is represented by long and short parallel line. Collection of cells or battery is represented by collection of long and short parallel lines.

In electrochemical cell, higher positive potential is cathode, therefore conventional current direction is from cathode to anode through conductor (metallic path) and from anode to the cathode in electrolyte

In an electric circuit, battery is charge pump which pumps charge through battery from location of low electric potential energy (the - terminal) to location of high electric potential energy (the + terminal). The battery does not supply electric charge as the charge is already in the wire.

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Answer: First we need to balance the elements other than oxygen and hydrogen on both sides. C3​H8​+O2​→3CO2​+H2​O Now, balance the number of hydrogens on both sides:.

Explanation:

Answer:To calculate the reacting mass of propane (C₃H₈) when it is completely burnt in the given reaction, we need to use the balanced chemical equation and the molar masses of the reactants and products.

The balanced chemical equation for the combustion of propane is:

C₃H₈ + 5O₂ → 3CO₂ + 4H₂O

From the equation, we can see that one mole of propane (C₃H₈) reacts with five moles of oxygen (O₂) to produce three moles of carbon dioxide (CO₂) and four moles of water (H₂O). The molar masses of the compounds involved in the reaction are:

Propane (C₃H₈): 44.1 g/mol

Oxygen (O₂): 32.0 g/mol

Carbon dioxide (CO₂): 44.0 g/mol

Water (H₂O): 18.0 g/mol

To calculate the reacting mass of propane, we need to know the mass of oxygen required to react completely with one mole of propane. From the balanced chemical equation, we can see that 5 moles of O₂ are required to react with 1 mole of C₃H₈. Therefore, the mass of oxygen required is:

mass of O₂ = 5 × molar mass of O₂ = 5 × 32.0 g/mol = 160.0 g/mol

Now, we can use the mass of oxygen required to calculate the reacting mass of propane. If 160.0 g of oxygen reacts with one mole of propane, then the mass of propane that would react completely with 160.0 g of oxygen is:

reacting mass of C₃H₈ = (1 mole of C₃H₈ × 44.1 g/mol) / (5 moles of O₂ × 32.0 g/mol) = 0.275 g

Therefore, the reacting mass of propane (C₃H₈) when it is completely burnt in the given reaction is 0.275 g.

Explanation:   May i get brainliest :D

When calcium and oxygen interact, calcium oxide is created. Calcium oxide has the chemical formula CaO. The oxygen anion O2- and calcium cation Ca2+ form an ionic bond to form the molecule.

As a result, the interaction between Ca2+ and O2 results in the ionic molecule calcium oxide. The chemical name is CaO.

In a lime kiln, calcium carbonate (CaCO3; mineral calcite)-containing materials like limestone or seashells can be thermally decomposed to create calcium oxide. Calcination is the name of the method used to manufacture burnt lime.

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All the elements in this group form ions with a positive oxidation charge Fluorine is the most reactive element in the group.

Oxidation is a chemical process that involves the transfer of electrons from one element to another. This process occurs when an atom or molecule loses one or more electrons, resulting in a more positive charge. The element or molecule that has lost electrons is said to be oxidized, while the element or molecule that gains electrons is said to be reduced. Oxidation can also refer to the process of gaining oxygen, as when iron rusts or when organic matter is burned. Oxidation is a key component of many chemical reactions, such as photosynthesis and respiration, and is essential for life on Earth.

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Explanation:

could you post the text? its inconvenient to go back and forth to the picture.

the Celsius temperature of 1.50 moles of ammonia contained in a 10.0 L vessel under a pressure of 2.0 atm is approximately -56.15 C. The closest answer choice to this value is -50 C.

To determine the Celsius temperature of 1.50 moles of ammonia contained in a 10.0 L vessel under a pressure of 2.0 atm, we can use the Ideal Gas Law equation:

PV = nRT

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

T = PV/nR

T = (2.0 atm) x (10.0 L) / (1.50 moles x 0.08206 L atm/K mol)

T = 217 K

To convert this temperature to Celsius, we can simply subtract 273.15 K:

T(Celsius) = 217 K - 273.15

T(Celsius) = -56.15 C

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The percent yield of [tex]ClF_3[/tex] was obtained is 39.97% when the reaction of 7.1 grams of chlorine with excess fluorine produced 7.4 grams of [tex]ClF_3[/tex].

Given the mass of chlorine = 7.1g

The mass of chlorine trifluoride produced = 7.4g

Molar mass of chlorine used = 70.906g/mole

Molar mass of [tex]ClF_3[/tex] used = 92.448g/mole

The reaction of chlorine with fluorine to produce chlorine tri fluoride is as:

[tex]Cl_2 + 3F_2 -- > 2ClF_3[/tex]

1 mole of [tex]Cl_2[/tex] is used to produce 2 moles of [tex]ClF_3[/tex]

mass of [tex]Cl_2[/tex] used = number of moles x molar mass = 1 * 70.906= 70.906g

Mass of [tex]ClF_3[/tex] used = 2 * 92.448 = 184.896g

Here for 70.906g of  [tex]Cl_2[/tex], 184.896g of [tex]ClF_3[/tex] is produced.

Then for 7.1g of [tex]Cl_2[/tex] = 184.896 * 7.1/70.906 = 18.51g of  is produced.

Theoretical Yield of [tex]ClF_3[/tex] = 18.51g

Actual Yield = 7.4g of [tex]ClF_3[/tex]

Percent Yield =[tex](7.4/18.51 )*100 = 39.97[/tex]% yield of [tex]ClF_3[/tex]

Therefore, 39.97% yield of [tex]ClF_3[/tex] was obtained.

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