An amount equaling 28 kilograms of a radioactive substance has a half-life of 10 years. How many years will it take the substance to decay naturally to only 7 kilograms

When the volume of a gas is changed from 3.75 L to 6.52 L, the temperature will change from 100. 0 K to 173.86 K.

Temperature of the given gas will be calculated by rearranging the ideal gas equation as:

V₁/T₁ = V₂/T₂, where

V₁ = initial volume of gas = 3.75L

T₁ = initial temperature of gas = 100K

V₂ = final volume of gas = 6.52L

T₂ = final temperature of gas = to find?

Putting all these values on the above equation and calculate for the value of T₂ as:

T₂ = (6.52 × 100) / 3.75 = 173.86 K

Hence, 173.86 K is the required temperature.

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The mass of P4 needed to completely react with 47.61 L of fluorine gas at STP is 43.88 g. The answer is 1. 43.88 g P4.

We can use the ideal gas law to calculate the number of moles of fluorine gas at STP, and then use the stoichiometry of the balanced chemical equation to determine the number of moles of phosphorus required to react completely with that amount of fluorine.

At STP (standard temperature and pressure), one mole of any gas occupies 22.4 L of volume. Therefore, the number of moles of fluorine gas in 47.61 L of fluorine gas at STP can be calculated as follows:

n = V/VM

n = 47.61 L / 22.4 L/mol

n = 2.125 mol F2

According to the balanced chemical equation, 1 mole of P4 reacts with 6 moles of F2 to produce 4 moles of PF3. Therefore, the number of moles of P4 required to react completely with 2.125 mol of F2 can be calculated as follows:

n(P4) = n(F2) / 6

n(P4) = 2.125 mol / 6

n(P4) = 0.3542 mol

Finally, we can use the molar mass of P4 to convert the number of moles of P4 to its mass:

mass(P4) = n(P4) x M(P4)

mass(P4) = 0.3542 mol x 123.9 g/mol

mass(P4) = 43.88 g

Therefore, the mass of P4 needed to completely react with 47.61 L of fluorine gas at STP is 43.88 g. The answer is 1. 43.88 g P4.

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A one-carbon alkyl substituent is called a methyl group, which is represented by the symbol CH3.

The name for a one-carbon alkyl substituent is a methyl group. A methyl group is the smallest alkyl group consisting of a carbon atom and three hydrogen atoms. It is represented by the symbol CH3 and is attached to a carbon chain by a single covalent bond.

The term alkyl refers to a type of organic molecule consisting of a hydrocarbon chain with one less hydrogen atom than its parent molecule. Therefore, the term "alkyl substituent" refers to a part of a molecule where one or more hydrogen atoms are replaced by an alkyl group.

Methyl groups are widely used in organic chemistry, biochemistry, and pharmacology. For example, they are found in many important molecules such as methane, methanol, and acetic acid. They can also be used to modify the properties of other molecules, such as in the synthesis of drugs and polymers.

In conclusion, a one-carbon alkyl substituent is called a methyl group, which is represented by the symbol CH3.

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The original size of the carbon-14 sample was 560 grams if the sample of carbon-14 has been decaying for 22,920 years and it is now 35. 0 grams.

The given data is as follows:

Material given = carbon -14

Time period = 22,,920 years

weight = 35 grams

To calculate the original sample size, we need to use the formula,

N = M (1/2)^(t/T)

35.0 g = M (1/2)^(22,920/5730)

35.0 g = M (1/2)^4

35.0 g = M (1/16)

For simplification, we need to multiply both sides by 16 to balance the value on the right side.

M = 16 * 35.0g

M = 560g

Therefore, we can conclude that the original size of the carbon-14 sample was 560 grams.

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Finding molar mass of NaOH

We know that

Molar mass of Sodium (Na) = 23 g/mol

Molar mass of Oxygen (O) = 32 g/mol

Molar mass of Hydrogen (H) = 2 g/mol

So,

Mass of 1 mole of NaOH

=> 1 × 23 + 1 × 16 + 1 × 1

=> 23 + 16 + 1

=> 40 g/mol

Now,

Mass = 40 × 0.25

Mass = 10 g

It will take 1.51 billion years for an amount of U-235  with a half-life of 703 million years to reach 13.0% of its initial amount.

To calculate the time it takes for an amount of U-235 to reach 13.0% of its initial amount, we can use the formula for radioactive decay:
\(N_{t}\)  =  \(N_{0}\)  * \(1/2^{t/T}\)


We want to find the time t when    \(N_{t}\)  = 0.13 * \(N_{0}\), or when the amount of U-235 remaining is 13.0% of its initial amount.

0.13 * \(N_{0}\) = \(N_{0}\)  * \(1/2^{t/T}\)

Taking the natural logarithm of both sides, we get:
ln(0.13) = ㏑ \(1/2^{t/T}\)
Simplifying, we get:
t = -T * ㏑(0.13) / ln(1/2)

Plugging in the values for T (703 million years), we get:
t = -703 million years *  ㏑(0.13) / ln(1/2) = 1.51 billion years

Therefore, it will take 1.51 billion years for an amount of U-235 to reach 13.0% of its initial amount.

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Answer:

The pool float looked would have looked deflated the next morning.

Explanation:

When temperature decreases the volume decreases

Answer:

The pool float most likely looked a little deflated or pushed in

Explanation:

The pool float most likely looked a little deflated or pushed in. This is because during the night temperatures most likely dropped. These cold temperatures during the night would have caused the air molecules inside the pool float to come closer together which would cause there to be more excess space inside the pool float. Therefore, allowing it to collapse into itself. This would be far worse if the float was filled with helium or another gas other than O2.

Answer: A) 3 / C) all objects / D) reference point / C) velocity

Explanation: I did some research before answering, I hope this helps.

Answer:

Both observe little creature.

Explanation:

Leeuwenhoek's observations of animalcules is similar to Hooke's observations of cells in the cork because both used microscope to see little creature. There is also a difference between both scientist's observation because one observe living creature and the other observe non-living thing. Leeuwenhoek observe protists in the pond which he named animalcules while on the other hand,  Hooke observe the cell wall in cork tissue.

The electron domain geometry is trigonal bipyramidal while the molecular geometry of the compound is seesaw.

The shapes of molecules is determined by the number of electron pairs on the valence shell of the central atom in the molecule. These electron domains include lone pairs and bond pairs.

The lone pairs only contribute towards the electron domain geometry and not the molecular geometry. SCl4 has five electron domains hence its electron domain geometry is trigonal bipyramidal. The molecular geometry of the compound is seesaw.

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The pH scale is a way to measure the acidity or basicity of a solution. pH is defined as the negative logarithm (base 10) of the hydrogen ion concentration, [H+], in moles per liter.

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The composition of the sigma bonds in methane i.e. the atomic orbits comprise the molecular orbit is σsp³-sp³

Methane is a one-carbon compound in which carbon is attached to four hydrogen atoms by single bonds. It is colorless, odorless, non-toxic, but a flammable gas (bp -161°C). It serves as a fossil fuel, a member of greenhouse gases, and a bacterial metabolite. In the methane molecule, a carbon atom forms covalent bonds with four different hydrogen atoms. There are no lone pairs of electrons in carbon atoms. So the 4 hydrogen atoms are at the 4 corners of the tetrahedron and the carbon is at the center of the tetrahedron. Hybridization in the methane molecule occurs by mixing one orbital with three p-orbitals. Each orbital consists of an unpaired electron. Carbon's s orbital and three p orbitals overlap with her 1s orbital of hydrogen to form a bond. Therefore, methane hybridizes to sp3 resulting in tetrahedral geometry. The methane molecule is non-polar. In particular, the dipole moment of methane is zero. A dipole moment of zero means that the "center of negative charge" in the molecule corresponds to the "center of positive charge".

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At a high altitude, water boils at a lower temperature than at sea level because the atmospheric pressure is lower. Option B

The atmospheric pressure decreases with increasing altitude because there is less air pressing against the water's surface.

When a liquid's vapor pressure reaches the same level as air pressure, boiling takes place. At sea level, the atmospheric pressure is 1 atm, hence for water to boil at 100°C, the vapor pressure must also be 1 atm. In contrast, the vapor pressure of water exceeds atmospheric pressure at lower temperatures at high elevations when the atmospheric pressure is lower.

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Answer: Caesium

Explanation:

Caesium has the lowest ionization energy. With the lowest ionization energy, it is the one that will most easily give up electrons.

Answer: cesium

Explanation:(cs)

Answer:

I think it is D, a hydrogen ion.

Explanation:

The difference between a conjugate acid and a base is the presence of an extra proton in the acid, which can be written as HA, compared the base, which can be written as A-.

An example is carboxylic acid, which is COOH, and the conjugate base, COO-, where the difference is a hydrogen ion.

Explanation:

A. Exothermic .... the Enthalpy of products is less than Enthalpy of reactants

B. For the forward reaction,

A + B --> C + D

∆H(A+B) = 200Kj/mol

∆H(C+D) = 100Kj/mol

∆H = ∆P - ∆R = 100 - 200 = -100KJ/mol

For backward reaction,

C + D ---> A+B

∆H(A+B) = 200Kj/mol

∆H(C+D) = 100Kj/mol

∆H = ∆P - ∆R = 200 - 100 = 100KJ/mol [ Forward is exothermic, backward is endothermic]

C. ... Activated complex should be the peak---that 600kj/mol

D. Activation energies -->

For forward reaction,

Activation energy = (600 - 200) = 400Kj/mol [That's the energy required for the reaction to occur]

For backward reaction, [here, C + D are the reactants ]

Activation energy = (600 - 100) = 500KJ/mol

The forward reaction is to proceed faster because it requires less energy to be overcome, I think.

Answer:

A. Barium

Explanation:

hope this helps! :)

Answer:

OB- one or more cells

Explanation:

hope this helps :)

True. Volatile solvents that act as CNS depressants, such as inhalants, can be found in a wide variety of household products.

Volatile solvents are chemicals that vaporize at room temperature and can be inhaled to produce intoxicating effects. These solvents are commonly found in various household products, including cleaning agents, paint thinners, adhesives, aerosol sprays, and certain fuels. Examples of volatile solvents include toluene, xylene, benzene, and trichloroethylene.

When these volatile solvents are inhaled, they enter the bloodstream through the lungs and quickly reach the central nervous system (CNS). In the CNS, they act as depressants, slowing down the activity of the brain and nerve cells. The effects can include dizziness, disorientation, euphoria, hallucinations, and in severe cases, loss of consciousness or even death.

It is important to note that inhalant abuse, particularly among adolescents and young adults, poses serious health risks and can lead to addiction, organ damage, cognitive impairment, and other long-term consequences. Proper usage and storage of household products containing volatile solvents are crucial to prevent unintended inhalation and protect individuals from the harmful effects associated with their misuse.

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Answer:

Fossil fuels release greenhouse gases and are non renewable

Answer:

8.90

Explanation:

Density = mass ÷ volume

D = 222.50 g ÷ 25.00

= 8.9

The density of the unknown metal is 8.90.

Hope that helps.

Answer:

C: 8.90

Explanation:

Answer:

50.6

Explanation

using the furmla

mole=mass/mole mass

1012/20=50.6

Section I: Experimental Overview

1. What is the question that you are trying to answer?

2. What is the background information related to this question?

3. What is your hypothesis?

4. What was the procedure that you used to test your hypothesis?

Section II: Data & Analysis

5. What data did you collect during the experiment?

6. What trends or patterns did you observe in the data?

7. How do the trends in the data support or refute your hypothesis?

Section III: Conclusions

8. Based on the data and analysis, what conclusions can you draw about the question you were trying to answer? How could the experiment be improved for future studies?

Option (d) is correct. A magnetic field is produced by a stream of electrons flowing through a wire that is coiled around an iron core.

Magnetic field is defined as a vector field that describes the magnetic influence on moving electric charges, electric currents and magnetic materials. It is said that a moving charge in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field. It is the portion of space near a magnetic body or a body carrying an electric current within which magnetic forces due to the body or current can be detected. It is a vector field in the electric current or changing electric field in which magnetic forces are observable. It force moving electrically charged particles in a circular or helical path.

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Answer:

Save earth, and universe

If the net force on the object along the vertical plane is zero, the statement which is correct is that: F equals 3 N and the object remains stationary.

A net force simply refers to the vector sum of all the forces that are exerted on a physical object. This ultimately implies that, a net force is a single force that substitutes the effect of all the forces acting on a physical object.

Generally speaking, the amount of net force that keeps a physical object moving at constant speed and in the same direction is always equal to zero (0) Newton in accordance with Newton's First Law of Motion.

In this context, we can reasonably infer and logically deduce that the net force acting on this physical object would cause it to remain static or stationary because the vertical component of the force is zero (0) and there is no acceleration.

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Answer:

50°F,  70°F

Explanation:

Answer:

50 and 70 degrees F

Explanation:

got it right on the quiz on edge

The empitical formula shows the simplest ratio of elements in a compound (not the total number of atoms in the molecule).

So to find the empirical formula we need to calculate how many moles of each atom we have in this sample. Then we will see the ratio of each element.

We are given the mass, so to convert it to moles we use the molar mass. For this we go to the periodic table and see that the values for each element are:

Na (sodium): 22,99 g/mol

H (hydrogen): 1 g/mol

P (phosphorus): 25,81 g/mol

So we calculate the moles of each element as follows:

And as we see, for every 0.833 moles of Na we have the same number of moles of P, so the ratio of these elements in the molecule is 1 to 1.

As for the hydrogen:

So the ratio Na to H is 1 to 2.

Now we can write the empirical formula as follows=