Practice entering numbers that include a power of 10 by entering the diameter of a hydrogen atom in its ground state, dH=1.06×10−10m d H = 1.06 × 10 − 10 m , into the answer box.

Answer:

Explanation:

Three temperature scales are currently in use. Their units are °F (degrees Fahrenheit), °C (degrees Celsius), and K (kelvin). The Fahrenheit scale, which is the most commonly used scale in the United States outside the laboratory, defines the normal freezing and boiling points of water to be exactly 32°F and 212°F, respectively.

The Celsius scale divides the range between the freezing point (0°C) and boiling point (100°C) of water into 100 degrees. The kelvin is the SI base unit of temperature: it is the absolute temperature scale. By absolute we mean that the zero on the Kelvin scale, denoted by 0 K, is the lowest temperature that can be attained theoretically. On the other hand, 0°F and 0°C are based on the behavior of an arbitrarily chosen substance, water.

The size of a degree on the Fahrenheit scale is only 100/180, or 5/9, of a degree on the Celsius scale. To convert degrees Fahrenheit to degrees Celsius, we write:

?ºC = (ºF - 32ºF) * 5ºC/9ºF

The following equation is used to convert degrees Celsius to degrees Fahrenheit:

?ºF = 9ºF/5ºC * (ºC) + 32 ºF

Both the Celsius and the Kelvin scales have units of equal magnitude; that is, one degree Celsius is equivalent to one kelvin. Experimental studies have shown that absolute zero on the Kelvin scale is equivalent to –273.15°C on the Celsius scale.

Thus, we can use the following equation to convert degrees Celsius to kelvin:

?K = (ºC +273.15ºC) * 1K/1ºC

All living organisms are composed of one or more cells. The cell is the basic unit of structure and organization in organisms. Cells arise from pre-existing cells.

Answer:

0.000128 kilometers

Answer:

0.000128 kilometre..

Answer:

The answer to your question is given below.

Explanation:

Sodium (Na) is a group 1 element because it has 1 electron in it's outermost shell.

Sodium ion (Na+) is formed when sodium atom (Na) lose it's outermost electron to attain the octet configuration of the noble gas element.

This can further be seen from the equation given below:

Na —> Na+ + e

Thus, we can represent the above in electronic configuration form as follow:

Na (11) => 1s² 2s²2p⁶ 3s¹

Na+ (10) => 1s² 2s²2p⁶

The three main lines of evidence for revolution is Darwin used multiple lines of evidence to support his theory of evolution by natural selection -- fossil evidence, biogeographical evidence, and anatomical evidence.

The three main lines of evidence for evolution is fossil evidence, biogeographical evidence and anatomical evidence.

In biology evolution is a process in which change in the characterisitics of any species over a several generation on the basis of natural selection method.

The three main lines of evidence for evolution are:

So, three lines of evidences are fossil evidence, biogeographical evidence and anatomical evidence.

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Answer:

B

Explanation:

Sea level changes due to many different  geological events  and can rise or fall over time .

Sea level changes due to global warming , the water being added to the seas as the glaciers melts due to global warming and the expansion of water when it warms.

The sea level also increases due to land processes like soil erosion ,oil and ground water pumping.Changes in land water storage like dams ,changes in global precipitation patterns also make a significant contribution  to change in sea level.

The increased emission of green house gases is a dominant cause  for change in sea level.Fifty percent of sea level rise is due to thermal expansion of seas and the rest is due to the geological activities.

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Answer:

It takes 1,068.76 grams of nitrogen to fill an 855 L tank at STP.

Explanation:

The STP conditions refer to the standard temperature and pressure. Pressure values at 1 atmosphere and temperature at 0 ° C or 273.15 °K are used and are reference values for gases.

On the other side, the pressure, P, the temperature, T, and the volume, V, of an ideal gas, are related by a simple formula called the ideal gas law:  

P*V = n*R*T

where P is the gas pressure, V is the volume that occupies, T is its temperature, R is the ideal gas constant, and n is the number of moles of the gas.

So, in this case:

Replacing:

1 atm* 855 L= n* 0.082 [tex]\frac{atm*L}{mol*K}[/tex] * 273.15 K

Solving:

[tex]n=\frac{1 atm* 855 L}{0.082\frac{atm*L}{mol*K} *273.15 K }[/tex]

n= 38.17 moles

Being the molar mass of nitrogen N2 equal to 28 g / mol, you can apply the following rule of three: if there are 28 grams in 1 mole, how much mass is there in 38.17 moles?

[tex]mass=\frac{38.17 moles*28 grams}{1 mole}[/tex]

mass= 1,068.76 grams

It takes 1,068.76 grams of nitrogen to fill an 855 L tank at STP.

Answer:

H₃O⁺.

Explanation:

Hello,

In this case, ionization of ethanol yields hydrogen cations and ethoxide anions as follows:

[tex]CH_3COOH+H_2O\rightleftharpoons H_3O^++CH_3COO^-[/tex]

Which is at equilibrium as ethanol is a weak acid. Thus, since the conjugate acid is formed by the outgoing H⁺ and the water, we say that the conjugate acid is then the hydroxonium ion, H₃O⁺ whereas the conjugate base is the remaining anion CH₃COO⁻.

Best regards.

Answer:

The temperature is always lower.

Explanation:

The temperature is always lower at the end of the state as compared to beginning of the state. We can see in the given data, the temperature is higher at the beginning i. e. 140 degree Celsius but with the passage of time, the temperature of a state decreases constantly  and the temperature at the end is lower i. e. 20 degree Celsius. So we can conclude that the temperature is always lower.

We want to study how the temperature behaves in a change of phase. Ideally, we would read a graph and use the given information, but we can't see the graph, so for the answer, I will use a general thermodynamics knowledge instead of the missing graph.

We will see that the correct option is: The temperature is always the same

---------------------------------------

Let's start by explaining how temperature manifests in objects.

Assume we have something in solid phase. As we increase the temperature, the particles on the solid increase their kinetic energy, thus, the particles move more.

This causes that the volume of the object increases (for example when we heat up a metal and it dilates). This keeps happening until we reach a critical point, when we are near a change of phase.

At this point the energy given is not used to increase the temperature of the object, but is used to "break" bonds in such a way that the particles are more free than before. When all these bonds are "broken" the change of phase is completed, and in the case of the solid, we go from solid phase to liquid phase.

An example of this is that we can have liquid water and solid water both at 0°C, so if you have a thermometer in your home, an experiment that you can do is:

Put water in the refrigerator.

Note when the liquid water reaches 0°C

As the water starts to solidify, keep recording its temperature, you will see that it does not change (a lot, it may change a little bit) until all the water changes of phase.

So to answer this;

how does the temperature at the beginning of a change of state compare with the temperature at the end of the change?

The temperature is always the same

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Answer:

An increase

Explanation:

The strong southerly winds affect the vapor pressure by increasing it .

When the vapor pressure increases it means an increase in temperature and more evaporation occurs.

A decrease in the vapor pressure means a reduction in temperature with less amount of evaporation being involved

Answer: Copper

Explanation: did it on Edgenuity 2020

Answer:

first is copper

second is gold

Answer:

Strong acids are 100% ionized in water.

Explanation:

A strong acid is any acid that is completely ionized in water (achieves 100% ionization). Weak acids do not ionize completely in water. Many weak acids ionize to a very small extent in pure water.

Examples of strong acids are HCl, H2SO4, HNO3, etc.

Answer:

analyze

Explanation:

After testing is analyzing your data then you compare your data to your hypothesis to see if they match  

Answer:

non polar and neutral polar and neutral acidic and polar basic and polar

Answer:

A-210, n-125

A-207, n-122

A-209, n-124

Explanation:

The mass number is the sum of the number of protons and neutrons in the nucleus of an atom.

Astatine has an atomic number of 85, this is the number of protons in its nucleus. We must subtract the given number of neutrons in each option from the mass number and consider the difference. If the difference between the mass number and number of neutrons is exactly 85, then that option represents one of the isotopes of astatine.

Answer:

287.6g CHCl₃

Explanation:

We can determine the structure of Chloroform, dividing the mass of each element in its molar mass:

C = 12.0g * (1mol /12g) = 1 mol C

H = 1.01g * (1mol / 1.01g) = 1 mol H

Cl = 106.4g * (1mol / 35.45g) = 3 moles Cl

The structure is CHCl₃. And its molar mass is: 12.0g C +1.01g H + 106.4g Cl = 119.41g/mol

Now, the moles of carbon in the second sample = Moles of chloroform are:

28.9g C * (1mol / 12g) = 2.408 moles C = Moles CHCl₃

And its mass is:

2.408 moles CHCl₃ * (119.41g/mol) =

Answer:

The two objects have different volumes.

Explanation:

The density of an object measures how closely packed the mass in the object is. Density of an object is obtained by taking the ratio of the mass of an object and its volume.

Density = mass/volume

The mass present in an object is constant, but the volume may vary with temperature. The volume of substances generally increases with temperature, therefore, density decreases with increase in volume.

Two objects at the same temperature having equal masses may or may not have the same density depending on the volume each object occupy.

If two substances are at the same temperature and have equal masses but different densities, then they must have different volumes.

Answer:

1600

Explanation:

5×10^4÷2.5×10^2

(5×10^4)

(10^4)

(5×40)

(200)

(200÷2.5)

(80)

(80×10^2)

(10^2)

(20)

(80×20)

Answer is 1600.

Sorry if it's not correct.

Answer:

25.0%

A solution of benzene (C6H6) and toluene (C7H8) is 25.0% benzene by mass. At 25 °C the vapor pressures of pure benzene and pure toluene are 94.2 torr and 28.4 torr, respectively.

Answer:

a) pH = 9.44

b) 25mL of HBr are required.

c) pH = 5.37

d) pH = 9.26

Explanation:

The equilibrium of NH₃ in water occurs as follows:

NH₃(aq) + H₂O(l) ⇄ NH₄⁺(aq) + OH⁻(aq)

Kb = 1.8x10⁻⁵ = [NH₄⁺] [OH⁻] / [NH₃]

The reaction of NH₃ with HBr is:

NH₃ + HBr ⇄ NH₄⁺ + Br⁻

That means when you add X moles of HBr before to reach the equivalence point, the moles are:

Moles NH₃ = Initial moles - moles HBr

Moles NH₄⁺ = Moles HBr

Initial moles NH₃ = 0.050L * (0.05mol / L) = 2.5x10⁻³ moles NH₃

Moles HBr = 0.010L * (0.10mol / L) = 1x10⁻³ moles HBr

Thus, after the reaction:

Moles NH₃ = 1.5x10⁻³moles

Moles NH₄⁺ = 1x10⁻³ moles

Using Henderson-Hasselbalch equation, pH of this solution is:

pOH = pKb + log [NH₄⁺] / [NH₃]

Where pKb is -log Kb = 4.74

And [] could be taken as moles of each compound:

pOH = 4.74 + log [1x10⁻³ moles] / [1.5x10⁻³ moles]

pOH = 4.56

And pH = 14 - 4.56

b) To reach equivalence point, we need to add 2.5x10⁻³ moles HBr:

2.5x10⁻³ moles HBr * (1L / 0.10mol) = 0.025L = 25mL of HBr are required

c)At equivalence point, you will have just 2.5x10⁻³ moles of NH₄⁺ in 50.0mL + 25mL = 75mL. The molar mass of NH₄⁺ is:

[NH₄⁺] = 2.5x10⁻³mol / 0.075L = 0.0333M

The equilibrium of NH₄⁺ is:

NH₄⁺ ⇄ NH₃ + H⁺

Ka = [NH₃] [H⁺] / [NH₄⁺] = 5.556x10⁻¹⁰

[NH₃] = [H⁺] because both comes from the same equilibrium and [NH₄⁺] = 0.0333M:

[X] [X] / [0.0333M] = 5.556x10⁻¹⁰

[X]² = 1.85x10⁻¹¹M

[X] = [H⁺] = 4.3x10⁻¹¹M

pH = -log [H⁺] = 5.37

d) At midpoint, [NH₃] = [NH₄⁺]. Using H-H equation:

pOH = 4.74 + log [NH₃] / [NH₄⁺]

pOH = 4.74

And pH = 14 - 4.74

Hello. This question is incomplete. The full question is:

A chemist must prepare 500.0mL of hydrobromic acid solution with a pH of 0.50 at 25°C. He will do this in three steps: Fill a 500.0mL volumetric flask about halfway with distilled water. Measure out a small volume of concentrated (5.0M) stock hydrobromic acid solution and add it to the flask. Fill the flask to the mark with distilled water. Calculate the volume of concentrated hydrobromic acid that the chemist must measure out in the second step. Round your answer to significant digits.

Answer:

31.62 mL

Explanation:

To achieve this result, you must start by calculating the H + concentration. You will do this using the following formula:

pH = -log [H +]

0.50 = -log [H +]

[H +] = 10 ^ -0.50

[H +] = 0.31623 mol / L

After that you must consider that hydrobromic acid will have a weak capacity to disassociate, since it has a strong nature. In this case, we can consider that [HBr] = [H +] = 0.31623 mol / L.

After reaching this reason, it is necessary that you dilute the stock solution, using the formula:

C1V1 = C2V2

5.0 * V1 = 0.31623 * 500.0

V1 = 31.62 mL

And so you finish the answer.

Answer:

Atom is the smallest particle of pure sustance which can take part in a chemical reaction.A chrged atom is called an ion.

A molecule of an element or compound is the smallest particle of it that is stable and capable of independent existence. The molecules of element and compound are different.

Answer:

The solution is not ideal and shows a positive deviation from Raoult’s law since Psolution (experimental) > Psolution (actual).

Explanation:

Number of moles of CS2 = 3.95g/76.13gmol-1 = 0.0519 moles

Number of moles of acetone = 2.43g/58.08gmol-1 = 0.0418 moles

Total number of moles = 0.0937 moles

Mole fraction of CS2 = 0.0519/0.0937 = 0.5538

Mole fraction of acetone = 0.0418/0.0937 = 0.4461

From Raoult’s law;

PCS2 = 0.5538 × 515 torr = 285.207 torr

Pacetone = 0.4461 × 332 torr = 148.1052 torr

Total pressure = 285.207 torr + 148.1052 torr = 433.3 torr

Answer:

See explanation

Explanation:

The shorthand nuclear reaction equations have been given; the first particle in the parentheses is a reactant particle while the second particle is a product particle. These can now be rewritten as the longhand equations as follows;

238/92U + 4/2 He -------> 241/94Pu + 1/0 n

238/92U + 4/2 He ------> 241/94Pu + 1/0 n

14/7N + 4/2 He------> 17/8O + 1/1 p

56/26Fe + 2 4/2 He----> 60/29Cu + 4/2 He

Answer:

This question is incomplete and it lacks options. The complete question is as follows;

In condensation reactions, the atoms that make up a water molecule are from what?

a. oxygen

b. only one of the reactants

c. both of the reactants

d. carbohydrates

e. enzymes

The answer is C. Both of the reactant

Explanation:

In a chemical reaction, two small molecules called monomers combine to form a much larger molecule called polymer in a process called CONDENSATION REACTION. Some condensation reactions is characterized by the release of a water molecule (dehydration).

This water molecule is formed as a result of the active participation of both reactants. During the reaction, hydroxyll group (-OH) from one of the reactants breaks off and combines with hydrogen ion (H+) from the other reactant to form water molecule (H2O).

Hence, the atoms that make up the water molecule come from both of the reactants participating in the condensation reaction.

Answer:

the answer is A

Answer:

Methyl Alcohol.

Acetate

Heptane

Dioxane

Explanation:

The boiling point of liquids are measure by observing the gas pressure or vapors temperature. There are few liquids whose boiling point is difficult to measure. The gas pressure differs for every liquid. It is important to observe the vapor pressure also to identify the boiling point. The most difficult boiling point identification is for Methyl alcohol as it has ability to absorb different level of pressure.

The liquids are Methyl Alcohol, Acetate, Heptane,Dioxane

Information regarding the liquids:

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