What was Johann Dobereiner's contribution to the development of the periodic table?

Answer:

If you cannot get a chair to move across the floor, it is because ___ friction opposes your push.

Static friction.

Explanation:

Fluid friction is the resistance an object encounters in the water surface so in our case it's incorrect because we can't see any water in our scenario.

Rolling friction is the friction a wheel or sphere finds as resistance in the surface. In our scenario, we are talking about a wheelchair or a chair with small wheels like the office ones. So it is incorrect.

Sliding friction is the friction that an object encounters when it is pushed to move in a surface that slides against the direction of the object. Or that opposes gravitational resistance against the object direction because it is in a certain degree of elevation. Meaning that the surface is perpendicularly pointing the sky.

Static friction is the type of resistance an object finds when it is moved after being static. And this is our answer because the chair was static without wheels.

Final answer:

To determine the moles of sucrose available, the molar mass of sucrose is calculated and used to convert the given mass of sucrose to moles, resulting in approximately 0.0292 moles.

Explanation:

To calculate the number of moles of sucrose available for the combustion reaction, first, we need to find the molar mass of sucrose (C₁₂H₂₂O₁₁). By adding the atomic masses of carbon (12 atoms × 12.01 g/mol), hydrogen (22 atoms × 1.008 g/mol), and oxygen (11 atoms × 16.00 g/mol), we can determine the molar mass of sucrose to be approximately 342.3 g/mol. Using the mass of sucrose given, we can calculate the number of moles of sucrose as follows:

Therefore, there are approximately 0.0292 moles of sucrose available for the reaction.

Studies involving humans or animals are conducted under strict policies and procedures, and this solution addresses the ethical concerns as the animals and humans should not be harmed in such processes.

In general, animals such as mice, pigs, and other animals are used in scientific experiments for clinical tests such as vaccine tests, drug tests, and so on for safety reasons, and as a result, the animals' health suffers and they may die. So there are always ethical concerns in scientific research when there is the involvement of animals and humans, and that should be replaced with safe and secure research.

Hence, studies involving humans or animals are conducted under strict policies and procedures, and this solution addresses the ethical concerns as the animals and humans should not be harmed in such processes.

Learn more about the ethical concerns in the scientific experiment here.

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The question is incomplete, the complete question is here

Studies involving humans or animals are conducted under strict policies and procedures. This solution addresses which limitation?

A) Lack of proper equipment

B) Size of the system

C) Limited amount of time

D) Ethical Concerns

Hello!

The scientific study of the behavior of matter near 0K is called cryogenics

The word "cryogenics" comes from the greek kyros (cold) and geneia (generation). It describes the techniques used to reach very low temperatures to study the behavior of matter.

The ways to achieve these low temperatures are various, but here are the most common:

Have a nice day!

To estimate the value of a large coffee can of pennies, draw out a sample. Count it and weigh it, obtaining an average weight per penny. Weigh the all the coins in the can, subtracting the weight of the empty can. By dividing the weight of all coins by the weight of one penny, you can estimate the total amount.

To estimate the amount of money a large coffee can full of pennies contains without counting all the coins, you can use a method known as sampling. Start by selecting a small, manageable number of pennies from the can. For instance, you could take out 20. Count the value of the pennies you've selected, using the knowledge that each penny, in U.S currency, is worth 1 cent. This will give you an average value. Then weigh the pennies. This will give you the average weight of 1 cent. Next, weigh the entire can and subtract the weight of the can itself. This gives you the weight of all the pennies. Divide the weight of all coins by the average weight of 1 cent. You now have an estimate of the total amount of money in the can.

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An ion is an atom or molecule with a net electrical charge due to the loss or gain of electrons. Out of the options provided (Ca, Na^+, Mg, ^4He), only Na^+ is an ion, representing a sodium atom which has lost one electron.

An ion is an atom or molecule that has gained or lost one or more electrons, giving it a net electrical charge. From the provided options, only Na^+ is an ion. It represents a sodium atom that has lost one electron, resulting in a positive charge.

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The answer would be neutron. This is 100% correct, because I got it right on my lesson.

The question does not provide specific data for different sites or collection days to determine where swimming would be unsafe. However, if E. coli concentration exceeds 200 colonies per 100 mL water, it's unsafe. Regular sampling and testing is crucial to ensure water safety for recreational activities.

The information provided does not include specific data on the concentration of E. coli colonies at different sites or at different collection days, which makes it impossible to identify the days or sites where it would have been unsafe to swim, tube, or raft. However, the concept of unsafe concentrations of E. coli in water can be discussed. The U.S. Environmental Protection Agency (EPA) sets enforceable concentration values for primary contaminants, and these are known as Maximum Contaminant Levels (MCLs). For E. coli, a concentration exceeding 200 colonies per 100 mL is deemed unsafe.

Water sampling and testing for the presence of E. coli is a common microbial testing procedure. In a simplified process, the sample is diluted in lactose broth tubes at different volumes and then incubated. If E. coli is present, it ferments the lactose, causing a color change in the broth. This method helps to estimate the probable number of bacteria per 100 mL of water.

Maintaining good personal hygiene and avoiding untreated water in developing nations is crucial to preventing E. coli infections. Ensuring the safety of recreational water activities involves continuous monitoring and testing of water samples to prevent potential health hazards related to excessive E. coli concentration in the water. In the absence of monitoring and testing, any water body could potentially be unsafe for swimming, tubing, and rafting.

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At a consistent leakage rate of 1.2 mL/hour, a container will lose 0.2016 liters of water over the span of a week.

If water is leaking from a container at a rate of 1.2 mL/hour, we can calculate the total amount of water lost in a week by first understanding the total hours in a week and then multiplying this by the rate of leakage.

A week consists of 7 days, and each day has 24 hours, making the total hours in a week 168 hours. Given the rate of 1.2 mL/hour, we multiply this rate by the total hours to find the total volume of water lost over the week:

1.2 mL/hour * 168 hours = 201.6 mL

To convert this volume into liters, we remember that 1000 mL equals one liter. Therefore, dividing 201.6 mL by 1000 gives us the volume in liters:

201.6 mL / 1000 = 0.2016 liters

Thus, at a rate of 1.2 mL/hour, a total of 0.2016 liters of water will be lost in a week.

Answer:  the correct choice is d) 100000 organisms in 0.5 miles.

Explanation: Population density is directly proportional to the number of species(organisms) and inversely proportional to the land area.

population density = number of organisms/land area

Let's plug in the values for all the choices and see which one gives greatest population density.

a) population density = [tex]\frac{125000}{2.5}[/tex]  = 50000

b) population density = [tex]\frac{13000}{1.0}[/tex]  = 13000

c) population density = [tex]\frac{150000}{4.0}[/tex]  = 37500

d) population density = [tex]\frac{100000}{0.5}[/tex]  = 200000

From above calculations, the greatest population density(200000 organism per mile) is for the last choice.

So, the correct choice is d) 100000 organisms in 0.5 miles.

Answer: True

Explanation: The Periodic Table is an orderly grouping chemical elements known to scientists. This table includes the name of each element, its symbol, atomic mass (weight), and electron distribution. The first letter of each chemical symbol is capitalized.

The functional group of the aspirin in which causes this compound to cause a person’s stomach to be irritated is most likely because of the acetyl salicylic acid in which its acid portion of this drug causes the person’s stomach to feel stomach irritation.

Answer:

The acid (-COOH) functional group of aspirin causes it to irritate the stomach

Explanation:

Aspirin is acetylsalicylic acid with a molecular formula C₉H₈O₈.

It is a cyclic compound composed of a benzene ring along with 2 functional groups: the carboxylic acid (-COOH) and acetyl group (-OCOCH3)

The most common side effect of consuming aspirin is an upset stomach. This is due to the acid functional group which can irritate the stomach lining.

Answer is: B. beta particles.

Nuclear reaction: ¹⁴C → ¹⁴N + e⁻ + νe (electron antineutrino).

In beta minus decay (atomic number Z is increased by one, from 6 in carbon to 7 in nitrogen) neutron is converted to a proton and an electron and an electron antineutrino.

Beta decay is radioactive decay in which a beta ray and a neutrino are emitted from an atomic nucleus.

Answer:

+1

Explanation:

Final answer:

The correct answer "atom". The smallest unit that can maintain the properties of an element is an atom. Atoms are composed of electrons, protons, and neutrons, with the number of protons determining the element type. Atoms are the key to understanding elemental properties.

Explanation:

The smallest unit that can exist as an element and still maintain the properties of that element is a(n) atom. An atom is the foundational building block of all matter, and it retains all the characteristics of the element. By definition, atoms are composed of subatomic particles: electrons (negative charge), protons (positive charge), and neutrons (neutral). These particles are what give the atom its properties. The number of protons in an atom’s nucleus specifically determines the type of element it is.

Atoms are extremely small, typically around 100 picometers in size, and their behavior is heavily influenced by quantum mechanics. This means that classical physics, which might treat particles like billiard balls, does not accurately predict atomic behavior. Atoms are the smallest units that maintain the properties of an element, making it the correct answer (D).

Many toxic manufacturing compounds are securely disposed of through the means of high-temperature combustion. However mercury is not "annihilated" when coal comprising mercury impurities is scorched. This is happening because when the mercury in the carbon (coal Hg) is burned it changes into a gas which is emitted into the atmosphere.

Answer: Option (B) is the correct answer.

Explanation:

When we heat food in a microwave then the electrical energy of microwave produces microwaves which are also part of electromagnetic spectrum.

These microwaves are absorbed by food and as a result microwaves change into heat energy. Therefore, food becomes hot.

Thus, we can conclude that to cook food, a microwave oven converts electrical energy into heat energy.

Answer:

The answer is A

Explanation:

Answer:

Energy can be exchanged between the system and surroundings, but matter cannot.

Explanation:

In thermodynamics a closed does not allow the exchange of matter but allows the exchange of energy. Thus option C is correct and option B is incorrect.  

Open system allows both the transfer of mass and energy. Thus option A is incorrect.  

Isolated system does not allow the transfer of mass nor energy. Option D is incorrect.

Using Boyle's Law, which states that the pressure and volume of a gas at constant temperature are inversely proportional, we can calculate that a tank of about 1920 liters would be needed to contain the same amount of helium at atmospheric pressure.

The application of Boyle's law, which describes the inverse relationship between the pressure and volume of a gas at a constant temperature, can assist in determining the size of the tank needed to contain the same amount of helium at atmospheric pressure. This relationship is expressed by the formula P₁V₁ = P₂V₂, where P₁ and V₁ are the initial pressure and volume, and P₂ and V₂ are the final pressure and volume.

Here, the initial pressure (P₁) is 160 atm, the initial volume (V₁) is 12 L, and we want to find the final volume (V₂) at atmospheric pressure (P₂) of 1 atm. By substituting these values into the formula, we have 160 atm * 12 L = 1 atm * V₂. The calculation leads to V₂ = 1920 L.

So, a tank of approximately 1920 liters would be needed to contain the same amount of helium at atmospheric pressure according to Boyle's Law.

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