the half-life of a radioactive substance is 88 years. if you start with some amount of this substance, what fraction will remain in 139 years?

Reverse osmosis and distillation are methods of making seawater appropriate for drinking.

Two highly effective procedures that can offer optimal purification results when dealing with saline or polluted bodies of water include Reverse Osmosis and Distillation.

The former technique operates by selectively filtering unwanted particles out of solution through an ultrafine mesh material- such as a synthetic membrane and generally removes salt in this way.

Distillation employs heat to vaporize liquids that ultimately leaves contaminants behind. The resulting purified waters produced by each method have widespread use cases across various industries-e.g., Agriculture, Energy and Mining- and can even be directly consumed in households.

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Cu-63 atoms are different from Cu-65 atoms in that they contain 2 or fewer less neutrons. Cu-63 and Cu-65 have 34 and 36 neutrons, respectively, in each atom.

The atomic number of copper is 29, and it has the mass number 63. The mass number is equal to the sum of the protons and neutrons in the nucleus, while the atomic number refers to the quantity of protons in the nucleus. This indicates that the nucleus of the copper atom contains 34 neutrons and 29 protons, for a total of 63 protons. This atom has the mass number 63 because it is a copper-63 atom. The number that corresponds to that element on the predictable serves as the atomic number, which is the same for every atom of a given element.

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Answer:

cubic centimeters is the answer

Answer:Cubic centimeters

Explanation:

Answer:

Building mountains.

Explanation:

Mountains are built by land being pushed over time. Its not made by weathering and erosion!

Hope this helps! :)

The first one appear to be a pan with some liquid heating up.

The beginning state is liquid, the phase change type is a vaporization and its ending state is gas.

The second one seems to be a ice cube melting.

Its beginning phase is solid, the phase change type is fusion, and its ending state is liquid.

The third one is water, or other liquid, making clouds.

The beginning state is liquid, the phase change type is a vaporization and its ending state is gas.

The fourth illustration seems to be an aluminium can. There aren't really a phase change happening, but when we open the aluminium can containing gaseous drink, there are molecules of gas diluted into the liquid and some of it encouter each other to make a bubble of the gas and is released. It is not an actually phase change, it is the reverse process of diluting gas into liquid. Initially it is diluted gas, it gets released and in the end it is in gas phase.

Answer:

volume

Explanation:

things expand when heat is applied taking up more space hence volume

Answer:To determine the number of valence electrons in an atom of a representative element, you can look at its position on the periodic table. Representative elements are also known as the main group elements and are located in groups 1-2 and 13-18 of the periodic table.

The number of valence electrons in an atom of a representative element is equal to the group number. For example, the elements in group 1 (also known as the alkali metals) have 1 valence electron, while the elements in group 2 (the alkaline earth metals) have 2 valence electrons. The elements in group 13 (the boron group) have 3 valence electrons, and so on, up to group 18 (the noble gases), which have a full set of 8 valence electrons (except for helium, which has only 2).

For example, let's consider the element sodium (Na), which is in group 1. Sodium has 1 valence electron because it is in group 1. Similarly, the element carbon (C), which is in group 14, has 4 valence electrons because it is in group 14.

Knowing the number of valence electrons in an atom is important because it helps to determine the chemical properties and reactivity of the element. Atoms with the same number of valence electrons tend to have similar chemical properties and can form similar types of chemical bonds.

Explanation:

Explanation:

Carbon that is a part of rocks and fossil fuels like oil, coal, and natural gas may be held away from the rest of the carbon cycle for a long time. These changes add more greenhouse gases in our atmosphere and this causes climate change.

For the given data , (a) the process cannot reach State 3. Thus, it is impossible to determine the pressure and volume at this state ; (b) Work done is : W1-2 = 0.1005 kJ ; W2-3 = 0.1435 kJ ; W3-1 = 2.019 kJ.

(a) To determine the pressure and volume at State 3 :

For, process 1-2: P1V1 = P2V2

At state 2 :

V2 = 0.004m

P1V1/P2 = V2 = 0.004m

=> P2 = P1V1/V2

=> P2 = 100 kPa * 0.002 m / 0.004 m = 50 kPa

For process 3-1: It is Polytropic compression process

PVn = C where n = 1.4

State 3 = Initial state and State 1 = final state

Let the pressure and volume at state 3 be P3 and V3.

P3V3n = P1V1n

=> P3 = P1(V1/V3)^n= 100 kPa(0.002 m / V3)^1.4

Now, to find V3: V1 = V2 + V3

∴ V3 = V1 − V2

=> V3 = 0.002 m − 0.004 m = -0.002 m (unacceptable)

Volume at state 3 is negative. It is an unacceptable value.

Therefore, the process cannot reach State 3.

Therefore, it is not possible to determine the pressyre and volume at this state.

(b) To determine : work for each process :

We know, Process 1-2: constant pressure process

Q1-2 = ΔH1-2 = H2 − H1

=>  Q1-2 = CpΔT = Cp(T2 − T1)

where Cp = specific heat at constant pressure = 1.005 kJ/kgK

ΔT = T2 − T1

For a constant pressure process, work done, W1-2 = Q1-2 = Cp(T2 − T1)

Now, P1V1 = P2V2 = mRT1

P2/P1 = T2/T1 = V1/V2 = 0.5

At state 2, P2 = 50 kPa

Process 2-3: constant volume process

Work done during a constant volume process is :

W2-3 = Q2-3 = ΔU2-3 =

=> W2-3 = U3 − U2= CvΔT = Cv(T3 − T2)

where Cv = specific heat at constant volume = 0.718 kJ/kgK

ΔT = T3 − T2

Now, Process 3-1: Polytropic compression process

Work done during a polytropic compression process is :

W3-1 = Q3-1 = ΔH3-1

=> W3-1 = H1 − H3 = Cp

ΔT + V(P1 − P3)= Cp(T1 − T3) + V(P1 − P3)

where ΔT = T1 − T3 ;  V = (V1V3)^0.5

State 3 = Initial state and State 1 = final state

As, PVn = CP1V1n = C,

P3V3n = CP3V3n = C

∴ P1V1n = P3V3n

V1/V3 = (P3/P1)^(1/n) = (50 kPa / 100 kPa)^(1/1.4) = 0.883

At state 3, P3V3 = P1V1(V1/V3)^n= 100 kPa * 0.002 m * (0.002 m / 0.004 m)^1.4= 3.925 kJ/kgK

=> W3-1 = Cp(T1 − T3) + V(P1 − P3)

= 1.005 kJ/kgK(T1 − T3) + 0.002 m(100 kPa − 3.925 kPa)

= 2.019 kJ

The pressure and volume at this state is not possible to determine.

Therefore, the work done by all the processes is :

W1-2 = 0.1005 kJ

W2-3 = 0.1435 kJ

W3-1 = 2.019 kJ.

Thus, the required answers are given above.

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Answer:

In the formation of 1 formula unit of Al2O3 in the reaction 4Al + 3O2 → 2Al2O3, a total of 12 electrons are transferred, with each aluminum atom gaining 3 electrons through oxidation and each oxygen molecule gaining 4 electrons through reduction.

Explanation:

In the oxidation-reduction reaction equation: 4Al + 3O2 → 2Al2O3, the reaction involves the oxidation of aluminum (Al) and the reduction of oxygen (O2). The formation of 1 formula unit of the product Al2O3 involves the transfer of a specific number of electrons.

To determine the number of electrons transferred, we need to look at the change in oxidation states of the elements involved. In this case, aluminum (Al) is oxidized from an oxidation state of 0 to +3, while oxygen (O) is reduced from an oxidation state of 0 to -2.

Each aluminum atom gains three electrons during the oxidation process, as its oxidation state increases from 0 to +3. Considering that there are four aluminum atoms in the reaction, a total of 4 × 3 = 12 electrons are transferred due to the oxidation of aluminum.

On the other hand, each oxygen molecule (O2) gains four electrons during the reduction process, as its oxidation state decreases from 0 to -2. Since there are three oxygen molecules in the reaction, a total of 3 × 4 = 12 electrons are transferred due to the reduction of oxygen.

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Answer:

Electrons are the smallest of the particles that make up an atom, and they carry a negative charge.

Answer:

Electrons are the smallest subatomic particles that make up an atom. They have a mass of 1/1836 amu's or 0 amu's (no mass) Electrons are located in the electron cloud and have a negative charge.

Explanation:

Hope that helps

In the subgranular zone

RCA cleaning, SC1/SC2 cleaning, and megasonic cleaning are the three  silicon wafer cleaning methods. Each of them have their advantages and are commonly used in semiconductor manufacturing processes.

There are several methods used to clean silicon wafers in the semiconductor industry.

Here are three common methods along with a comparison of their efficacy:

1) RCA Cleaning (Radio Corporation of America):

RCA cleaning is a widely used method for silicon wafer cleaning. It involves a two-step process:

a. RCA-1: The wafer is immersed in a mixture of deionized water, hydrogen peroxide (H₂O₂), and ammonium hydroxide (NH4OH). This step removes organic contaminants, particles, and some metal ions from the wafer surface.

b. RCA-2: The wafer is then immersed in a mixture of deionized water, hydrogen peroxide, and hydrochloric acid (HCl). This step removes metallic and ionic impurities from the wafer surface.

Efficacy: RCA cleaning is highly effective in removing organic and inorganic contaminants. It provides a good level of cleanliness for most semiconductor fabrication processes.

2) SC1 and SC2 Cleaning (Standard Clean 1 and Standard Clean 2):

SC1 and SC2 cleaning are alternative methods to RCA cleaning and are used for wafer surface preparation. The process involves the following steps:

a. SC1: The wafer is immersed in a mixture of deionized water, hydrogen peroxide, and ammonium hydroxide. This step removes organic and ionic contaminants from the wafer surface.

b. SC2: The wafer is immersed in a mixture of deionized water, hydrogen peroxide, and hydrochloric acid. This step removes metallic and oxide contaminants from the wafer surface.

Efficacy: SC1 and SC2 cleaning methods are effective in removing various types of contaminants from the wafer surface. They provide comparable cleanliness to RCA cleaning.

3) Megasonic Cleaning:

Megasonic cleaning involves the use of high-frequency sound waves (usually in the range of 800 kHz to 2 MHz) to agitate the cleaning solution and remove particles from the wafer surface. It is often used in conjunction with RCA or SC cleaning methods.

Efficacy: Megasonic cleaning is highly effective in removing particles from the wafer surface. It can dislodge and remove smaller particles that may be difficult to remove by chemical cleaning methods alone.

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Answer:

0.2m

Explanation:

I just took the test

Your welcome

Taking into account the definition of molality, the correct answer is the third option: the molality of the solution is 0.2 \(\frac{moles}{kg}\).

Molality is a measure of concentration that indicates the number of moles of solute that are dissolved in 1 kilogram of solvent.

This is, molality is the ratio of the number of moles of any dissolved solute to kilograms of solvent.

The Molality of a solution is determined by the expression:

\(molality=\frac{number of moles of solute}{kilograms of solvent}\)

In this case, you know:

Replacing in the definition of molality:

\(molality=\frac{0.133 moles}{0.725 kg}\)

Solving:

molality= 0.18 \(\frac{moles}{kg}\)≅ 0.2 \(\frac{moles}{kg}\)

Finally, the correct answer is the third option: the molality of the solution is 0.2 \(\frac{moles}{kg}\).

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Answer: PROTON

Explanation:

a stable subatomic particle that has a positive charge equal in magnitude to a unit of electron charge and a rest mass of 1.67262 × 10 −27 kg, which is 1,836 times the mass of an electron. Protons, together with electrically neutral particles called neutrons, make up all atomic nuclei except for the hydrogen nucleus (which consists of a single proton).

Answer:

burrowers

Explanation:

Answer:

Sodium carbonate + Nitric acid → sodium nitrate + water + carbon dioxide.

Explanation:

Answer:

Sodium carbonate + Nitric acid → sodium nitrate + water + carbon dioxide.

Answer:

How do contrasting colors affect the quality of a painting?

Explanation:

Just trust me

What was the medical or physiological cause of the victim’s death? this questions cannot be answered by science. Therefore, option A is correct.

The term "science" is defined as the systematic study of observation, experimentation, and the testing of theories against the evidence obtained and the explanations and predictions about the universe.

The study of science is very important because in day to day life science plays the vital role. It is the process of learning about the natural world by observation and experimentation.

What was the medical or physiological cause of the victim’s death? this questions cannot be answered by science. Because it is related to the physiological study and the other three questions are related to the science.

Thus, option A is correct.

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Your question is incomplete, probably your question was

Which one of the following questions cannot be answered by scientific evidence?

A What was the medical or physiological cause of the victim’s death?

B Why was the victim stabbed many times?

C Is taking cheek scrapings a safe way to collect DNA samples?

D Do all identical twins have exactly the same DNA profile? Option 1​

Answer: HCl

Explanation:

Br₂ is a diatomic molecule meaning that there are no permanent dipole-dipole forces between these two. There are VDW forces between each molecule but these are weak as they are not differing in electronegativities, so this is not the answer.

Ne is a single element, there are no attractive forces.

N₂ is also a diatomic molecule, and for the same reasons as Br₂ it is also not the answer.

Between HCl and HBr, HCl has a greater electronegativity difference.

This is because on the electronegativity scale, H is 2.1, Cl is 3.0, and Br is 2.8. Make sure to refer to the Pauling electronegativity scale for these types of questions - you may be required to just remember that certain values are higher than others (the most electronegative elements on the periodic table are the futherest up and right - so the most electronegative element is fluorine).

As H and Cl have the greatest electronegativity difference, they have the largest dipole-dipole forces.

Answer:

wait what?

Explanation:

brainliest pls

Answer:

Answer:

.

Answer: 5 All of the molecules have the same kinetic energy

since the temperature is kept constant at 298 K

Explanation:

The AVERAGE kinetic energy is directly proportional to the absolute temperature.

All the molecules have the same average kinetic energy as average kinetic energy is directly proportional to the absolute temperature. So, the correct option is 5.

The average kinetic energy (K) is equal to one-half of the mass (m) of each gas molecule times the root mean square speed (Vrms) squared.

We know that the average kinetic energy is directly proportional to the absolute temperature.

All of the molecules have the same kinetic energy since the temperature is kept constant at 298 K.

Therefore, All the molecules have the same average kinetic energy as average kinetic energy is directly proportional to the absolute temperature.

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The concept of conservation of energy, which asserts that the overall amount of energy in a closed system stays constant, can be used to resolve this issue.

The heat absorbed by the water in the styrofoam cup equals the heat lost by the copper cylinder.

We may apply the formula:    Q gain = Q loss

where the subscripts "lost" and "gained" denote the water and the copper cylinder, respectively, and Q represents the heat.

The following equation may be used to determine how much heat the copper cylinder loses:

Q lost = cps * m cylinder * T

where m cylinder is the copper cylinder's mass, cps is copper's specific heat capacity, and T is the copper cylinder's temperature change.

ΔT = (27.9°C) - (-130°C) = 157.9°C

Q lost = cps * m cylinder * T

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Answer:

d

Explanation:

The train will travel for 2 hours to travel a distance of 100 miles with a speed of 50m/h. Therefore, option (C) is correct.

The speed of a body is defined as the rate of change in the position of a body w.r.t. time.

Speed is a scalar parameter with both magnitude and no direction. A simple mathematical formula common way to determine speed.  

S = d / t

where S is the speed, d is the distance moved by a body and t is the time.

Although the SI unit for speed is the same as velocity is m/s and can also be expressed in miles per hour (mph), and kilometers per hour (kph).

Given, the distance traveled by train, d = 100 miles

The time taken by train = 2 hrs

The speed of the train = distance/ time = 100/2 = 50m/h

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Answer:

soluble because all compounds containing K are soluble

Explanation:

Most metal hydroxides are insoluble. However, alkali metal hydroxides (such as KOH and NaOH) are very soluble.

In the case of KOH, the K cation is attracted to the electronegative oxygen on water. The OH anion is capable of hydrogen bonding to the water. (Notice how OH⁻ is simply the deprotonated form of water.)

The compound KOH is soluble insoluble, because all compounds containing K are insoluble insoluble, because all compounds containing OH- are in soluble soluble, because all compounds containing K are soluble soluble, because all compounds containing OH- are soluble insoluble, because KOH is insoluble

Alkalis are bases which are soluble in water. The basic alkalis are as follows:

Mg(OH)2 is insoluble in water.

In conclusion, KOH is a soluble base

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Answer:

rest will do later mom is calling me plz understand promise will do it

Explanation:

Answer:

lol

Explanation:

its 5 points

In the iron oxide compound, the mass percent for iron is approximately 70.05%, and the mass percent for oxygen is approximately 29.95%.

To determine the mass percent for each element in the iron oxide compound, follow these steps:
Step 1: Identify the mass of iron and oxygen in the compound.
You are given that a 14.5 g sample of iron reacts with oxygen to form 20.7 g of iron oxide compound. So, the mass of iron in the compound is 14.5 g.
Step 2: Calculate the mass of oxygen in the compound.
To find the mass of oxygen in the compound, subtract the mass of iron from the total mass of the compound:
Mass of oxygen = Total mass of compound - Mass of iron
Mass of oxygen = 20.7 g - 14.5 g = 6.2 g
Step 3: Calculate the mass percent for each element.
To find the mass percent of each element, divide the mass of the element by the total mass of the compound and multiply by 100.
Mass percent of iron = (Mass of iron / Total mass of compound) x 100
Mass percent of iron = (14.5 g / 20.7 g) x 100 = 70.05 %
Mass percent of oxygen = (Mass of oxygen / Total mass of compound) x 100
Mass percent of oxygen = (6.2 g / 20.7 g) x 100 = 29.95 %

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