25. Which of the following statements concerning atomic structure is/are correct?
1. The nucleus contains most of an atom's mass.
2. The nucleus contains all the positive charge of an atom.
3. Electrons surround the nucleus and account for the majority of an atom's volume.
1 only
2 only
3 only
2 and 3
1, 2, and 3

Answer: Spun yarn is made by twisting staple fibers together

To make a cohesive thread Or “single”. Twisting fibers, into yarn in the process called spinning can be dated back to the upper Paleolithic. Yarn spinning was one of the first processes to be industrialized.

Explanation:

Answer:

opposite

Explanation:

Answer:

opposite

Explanation:

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Answer:

349.22°C

Explanation:

Let the final temperature of the two pieces of metal be x.

Now, the warmer metal which is C u reduces from 475°C to x. Thus Δt for C u is; Δt1 = 475 - x.

The cooler metal Cr increases in temperature from 265°C to x. Thus, it's change in temperature is Δt for Cr is; Δt2 = x - 265.

Now from conservation of energy, the amount of energy leaving the C u metal is equal to the amount of energy entering the Cr metal.

Thus;

q_lost = q_gain

Where;

q_lost = m1•c1•Δt1

q_gained = m2•c2•Δt2

Now, c1 & c2 are the specific heat capacity of C u and Cr respectively.

From online tables, c1 = 0.385 J/g°C and c2 = 0.46 J/g°C

We are given;

m1 = 12g and m2 = 15g

Thus;

12 × 0.385 × (475 - x) = 15 × 0.46 × (x - 265)

2194.5 - 4.62x = 6.9x - 1828.5

6.9x + 4.62x = 2194.5 + 1828.5

11.52x = 4023

x = 4023/11.52

x = 349.22°C

Answer:

It's B

Explanation:

I got it right on edjenuity

The most likely outcome of the retrofitting of a nuclear power plant is that it will be able to reprocess its used uranium fuel. Therefore, option C is correct.

A nuclear power plant is a facility that generates electricity by harnessing the heat produced by nuclear reactions. At the heart of a nuclear power plant is the reactor, where a controlled chain reaction of nuclear fission occurs.

Reprocessing is a process by which the used nuclear fuel is chemically treated to separate out and recover the unused uranium and plutonium, which can then be reused as fuel. This reduces the amount of radioactive waste produced by the plant and also extends the life of the uranium fuel.

The fission reactions to fusion reactions is not currently a viable option for power generation, and the idea that a retrofitting would eliminate radioactive wastes is unlikely, as nuclear power plants will always produce some amount of radioactive waste.

Thus, option C is correct.

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Answer:

B) . six electrons in the triple bond of diatomic nitrogen

Explanation:

The three line in this Lewis dot structure represents the six electrons in the triple bond of diatomic nitrogen.

Nitrogen is made up of 7 electrons with 5 valence ones.

 A lewis structure is made up of the symbol of the element surrounded by dot to represent the valence electrons.

  In this nitrogen molecule, both species share  6 electrons. This makes each nitrogen atom isoelectronic with neon.

Answer:

The answer is true

Explanation: Because The law of multiple proportions states that when two elements react to form more than one compound, a fixed mass of one element will react with masses of the other element in a ratio of small, whole numbers.

Answer:

The flask has to be closed during the hydrochloric acid and sodium carbonate reaction as the resultant gas got trapped inside the closed flask.

Explanation:

The hydrochloric acid and sodium carbonate reaction was exothermic that caused the pressure to decrease. The flask has to be closed during the hydrochloric acid and sodium carbonate reaction as the resultant gas got trapped inside the closed flask.

In exothermic reactions, energy is produced in the form of heat or light.

Answer:

Purple light.

Yellow light.

Explanation:

Answer:

D.All three graph lines peak over the same few weeks of winter.

Explanation:

took the test

Answer:

A) Carbon

Explanation:

the others are wrong its A

Answer:

A) carbon

Explanation:

carbon or simply c has an atomic number of 6 and it has an atomic mass of 12.01 amu. it belongs to group 4a

Answer:

D. Supported by observations

Explanation:

Because theories change over time, they both need to be proven, they do not go off of consensus, but they do need to be supported by observations.

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Answer: The percent yield of the reaction is 77.0 %

Explanation:

[tex]2Pb+O_2\rightarrow 2PbO[/tex]

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]

[tex]\text{Number of moles of lead}=\frac{451.4g}{207.2g/mol}=2.18moles[/tex]

[tex]\text{Number of moles of lead oxide}=\frac{374.7g}{223.2g/mol}=1.68moles[/tex]

According to stoichiometry:

2 moles of [tex]Pb[/tex] produces = 2 moles of [tex]PbO_2[/tex]

2.18 moles of [tex]Pb[/tex] is produced by=[tex]\frac{2}{2}\times 2.18=2.18moles[/tex] of [tex]PbO_2[/tex]

Mass of [tex]PbO_2[/tex] =[tex]moles\times {\text {Molar mass}}=2.18\times 223.2g/mol=486.6[/tex]

percent yield =[tex]\frac{374.7g}{486.6g}\times 100=77.0\%[/tex]

Answer:

liquid

Explanation:

correct answer hope it helps

Answer:

[tex]m_{CO2}=8.33gCO2[/tex]

Explanation:

Hello.

In this case, since the chemical reaction is:

[tex]C_7H_5N_3O_6(s)+\frac{21}{4} O2(g)\rightarrow 7CO_2(g)+\frac{3}{2} N_2(g)+\frac{5}{2} H_2O(l)[/tex]

Thus, since we have the initial moles of TNT:

[tex]n_{TNT}=25.7g*\frac{1mol}{227.13g} =0.113mol[/tex]

And the initial moles of oxygen given the ideal gas equation:

[tex]n_{O_2}=\frac{6.93atm*0.5L}{0.082\frac{atm*L}{mol*K}*298K}=0.142molO_2[/tex]

Given the 1:7 mole ratio between TNT and carbon dioxide and the 21/4:7 mole ratio between oxygen and carbon dioxide, we compute the yielded moles by each reactant:

[tex]n_{CO_2}^{by\ TNT}=0.113molTNT*\frac{7molCO_2}{1molTNT}=0.791molCO_2\\\\ n_{CO_2}^{by\ O_2}=0.142molO_2*\frac{7molCO_2}{21/4molO_2}=0.189molCO_2[/tex]

Thus, since oxygen yields less moles of carbon dioxide than TNT, we infer it is the limiting reactant, therefore, the produced mass of carbon dioxide is:

[tex]m_{CO2}=0.189molCO2*\frac{44.01gCO2}{1molCO2}\\\\m_{CO2}=8.33gCO2[/tex]

Best regards!

Answer:

False

Explanation:

They’re used cause they’re generally harder than pure metals

Alloys are used much more than pure metals because they are generally stronger and less likely to react with air or water...

So I would say false

Answer:

We can see that the atomic radius decreases across every row.

Explanation:

I will comment more below.

The elements that represent the highest points on the graph are all elements of group 1 and occur at the head of the period to which they belong.

The periodic table is an arrangement of elements in groups and periods. The elements in the same group have the same number of valence electrons while the elements in the same period have the same number of shells.

Looking at the graph, we can see that the high points in the graph all correspond to the group 1 elements; sodium, potassium, rubidium and cesium.The have the highest atomic radii in the period. Atomic radii increases down the group but decreases across the period. Remember that these elements are at the head of the period to which they belong hence they have the highest atomic radii.

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Answer:

option is (b)

Explanation:

please mark me as brilliant

This follows a simple conversion technique. Basically what the question is trying to say here is to convert 29.1 inHg to mmHg. 1 inHg is equal to 25.4 mmHg so 29.1 inHg would be equal to [tex]25.4 * 29.1[/tex] which when evaluated turns out to be: [tex]739.14[/tex]. :D

The pressure will be 739.14 mm Hg.

The SI unit measuring pressure would be the pascal, which measures the force of each unit area of the surface.

Calculation of pressure

It is known that 1inHg = 25.4 mm Hg.

Hence, the pressure = 25.4 × 29.1 = 739.14 mm Hg

Therefore, the pressure will be 739.14 mm Hg.

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Answer:

m*s⁻¹.

Explanation:

Hello!

In this case, since the frequency measures how repetitive an event is per unit of time, for instance the laps a car drives every 5 minutes or something similar, we can infer it has units of event/time; in such a way, the unit m*s⁻¹ is not a proper unit of frequency because it is a proper unit of velocity which is the distance traveled per unit of time.

In such a way, Hz (hertz), s⁻¹ and 1/s are possible ways frequency can be represented.

Best regards!

Answer:

one example of chemical weathering is when carbon dioxide mixes with water.

Explanation:

when dioxide mixes with water it creates carbonation.

Answer:

it's answer is

element of an atom ✌️

Answer:

Atomic size is the distance from the nucleus to the valence shell where the valence electrons are located. The separation that occurs because electrons have the same charge. The number of protons in the nucleus. The core electrons in an atom interfere with the attraction of the nucleus for the outermost electrons.

Explanation:

That would be B I believe, but please correct me if I'm wrong.

Answer:

720

Explanation: study island

Answer:

720

Explanation:

If we add water to a concentrated acid, then the solution may boil very violently, splashing concentrated acid. If add acid to water, the solution that forms is very dilute and a small amount of heat is released.

When a strong acid is poured into water, it flows down the flask and mixes much better, so no boiling takes place. The addition of water to acid forms an extremely concentrated solution of acid initially. A large amount of heat is released and the solution may boil very violently, splashing concentrated acid out of the beaker and all this because the reaction is exothermic in nature.

The reason this takes place is due to a large amount of energy liberated in the hydration reaction of concentrated ions. Therefore, we add acid to water dropwise for the dilution with constant stirring and not water to acid directly.

If we add water to acid, then an exothermic reaction occurs and the solution may boil very violently. To form the dilute solution of any strong acid, you should add acid to water and the small amount of heat released is not sufficient to vaporize and spatter it.

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Answer:

This question is incomplete

Explanation:

However, when the carboxylic acids and esters put together are obtained, the procedure below can be followed in drawing and naming them.

For carboxylic acid,

1) it should be noted that the functional group here is -COOH which is drawn as -C = OH

      |

     OH

2) The carbon of the functional group is included among the carbon to be counted when naming the structure. For example, the compound below is propanoic acid.

CH₃CH₂COOH - As you can see that there are 3 carbons linked chain there.

3) As can be seen in (2) above, the suffix "oic" is used to name carboxylic acids

4) The carbon chain here is saturated (meaning there is no double or triple bond within the carbon chain)

Example of a structure of carboxylic acid is

H₃C - CH₂ - CH₂ - C = OH

                              |

                             OH

The structure above is a butanoic acid

For ester

1)The functional group here is -COO- . which can be drawn as

- C = O

   |

  O -

(meaning one oxygen atom is double bonded to the carbon and the other oxygen atom is bonded to another carbon chain)

2) The alkyl group attached to the oxygen atom is first of all mentioned before the carbon chain attached from the left is mentioned. For example, CH₃CH₂CH₂COOCH₂CH₃ is ethyl butanoate

3) As seen from (2) above, the suffix "oate" is used to end the name of esters

4) As also seen from (2) above, the carbon of the functional group is also included while counting the carbon chain of the parent name (butanoate).

5) The carbon chains here are also saturated.

Example of this ester is

CH₃CH₂C = O

              |

             O - CH₂CH₃

The name of this compound is ethyl propanoate