I need help, plz and thank you.

Answer:

1.1 x [tex]10^{9}[/tex] km/h

Explanation:

Here we need to do two conversions- one from centimetres to kilometres and one from seconds to hours.

To get from cm to km- we divide by 100 000 since there are 100 000 cm in a km.

To get from seconds to hours we divide by 3600 since there are 3600 seconds in an hour

[tex]\frac{3*10^{10}cm/100000 }{1second/3600} =1.1*10^{9} km/h[/tex]

Answer:

Explanation:The scientific method is an empirical method of acquiring knowledge that has characterized the development of science since at least the 17th century. It involves careful observation, applying rigorous skepticism about what is observed, given that cognitive assumptions can distort how one interprets the observation. It involves formulating hypotheses, via induction, based on such observations; experimental and measurement-based testing of deductions drawn from the hypotheses; and refinement (or elimination) of the hypotheses based on the experimental findings. These are principles of the scientific method, as distinguished from a definitive series of steps applicable to all scientific enterprises.[1][2][3]

Though diverse models for the scientific method are available, there is in general a continuous process that includes observations about the natural world. People are naturally inquisitive, so they often come up with questions about things they see or hear, and they often develop ideas or hypotheses about why things are the way they are. The best hypotheses lead to predictions that can be tested in various ways. The most conclusive testing of hypotheses comes from reasoning based on carefully controlled experimental data. Depending on how well additional tests match the predictions, the original hypothesis may require refinement, alteration, expansion or even rejection. If a particular hypothesis becomes very well supported, a general theory may be develope

Answer:

Explanation:

Beta radiations:

mass 1/200 , charge -1, medium penetration

Beta radiations are result from the beta decay in which electron is ejected.

The mass of beta particle is smaller than the alpha particles.

They can travel in air in few meter distance.

These radiations can penetrate into the human skin.

The sheet of aluminum is used to block the beta radiation

Properties of alpha radiation:

mass 4 amu, charge +2, least penetration

Alpha radiations are emitted as a result of radioactive decay. The atom emit the alpha particles consist of two proton and two neutrons. Which is also called helium nuclei. When atom undergoes the alpha emission the original atom convert into the atom having mass number less than 4  and atomic number less than 2 as compared to parent atom the starting atom.

Alpha radiations can travel in a short distance.

These radiations can not penetrate into the skin or clothes.

These radiations can be harmful for the human if these are inhaled.

These radiations can be stopped by a piece of paper.

Gamma radiations:

mass 0, charge 0, deepest penetration

Gamma radiations are high energy radiations having no mass.

These radiations are travel at the speed of light.

Gamma radiations can penetrate into the many materials.

These radiations are also used to treat the cancer.

Lead is used for the protection  against gamma radiations because of its high molecular density.

The lead apron are used by the person when treated with gamma radiations.

Answer:

attached below is the detailed solution

answer : value of constant = 2.18 * 10^-18 J

Explanation:

Express the constant in terms of h and c and RH

attached below is the detailed solution

Constant = [tex]h_{C} R_{H}[/tex]

               = ( 6.626 * 10^-34 ) * ( 3 * 10^8 ) * ( 1.097 * 10^7 )

               = 2.18 * 10^-18 J

The Planck equation and the light speed  allow us to find the results for the transformation of the Rydberg equation are:

   [tex]E = A ( \frac{1}{n_1^2}\frac{x}{y} - \frac{1}{n_2^2} )\\A= R_H \ h \ c \\A = 2.18 \ 10^{-18} j[/tex]

The Rydberg equation is an empirical expression that explains the wavelength of the emissions.

          [tex]\frac{1}{\lambda } = R_H ( \frac{1}{n_1^2} - \frac{1}{n_2^2} )[/tex]  

Where λ is the wavelength of the emitted radiation, is the Rydberg constant, n₁ and n₂ are integers with n₁ <n₂

It is asked to write the Rydberg equation  for the energy.

Let's use the Planck relation.

           E = h f

The light speed is related to the wavelength and frequency of radiation.

           c = λ f

Where E is the energy, h the Planck constant, c the speed of light, λ the wavelength and f the frequency.

Let's  substitute.

           E = [tex]\frac{hc}{\lambda}[/tex]  

           [tex]\frac{1}{\lambda} = \frac{E}{hc}[/tex]  

Let's substitute in the Rydberg equation.

          [tex]\frac{E}{hc} = R_H ( \frac{1}{n_1^2} - \frac{1}{n_2^2}) \\E = R_H \ h \ c \ ( \frac{1}{n_1^2} - \frac{1}{n_2^2} )[/tex]

We can write is an constant of the form.

          A = [tex]R_H h c[/tex]

The value of the constant is :          

          A = 1,097 10⁷ 6,626 10⁻³⁴ 3 10⁸

          A = 2.18 10⁻¹⁸ J

In conclusion, using the Planck equation and the light speed we can find the results for the transformation of the Rydberg equation are

        [tex]E = A ( \frac{1}{n_1^2} - \frac{1}{n_2^2} )\\ A = R_H h c\\[/tex]

       A = 2.18 10⁻¹⁸ J

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Answer:

B.  thermal conductivity

Explanation:

They physical property being tested during the fourth step is the thermal conductivity of the materials.

Thermal conductivity is the ability of a body to transmit heat energy from one place to another.

Answer:

A force is described as any influence that causes an object to undergo a change. Distance refers to how far an object travels over a period of time. The greater the force that is applied on an object the further distance that object will travel.

Answer:

I think there would be no differences

Answer:

.9375 x 10⁻³ moles .

Explanation:

2.5 mEq / L of Magnesium ion

2.5 x 10⁻³ Eq / L

= 2.5 x 10⁻³ / 2 mole / L    [  1 mole = 2 Eq ]

= 1.25 x 10⁻³ mole / L

1 L contains 1.25 x 10⁻³ mole

750 mL = .75 x 1.25 x 10⁻³ mole

= .9375 x 10⁻³ mole .

So 750 mL contains .9375 x 10⁻³ moles .

Answer:

The answer is the second picture.

Explanation:

When you perceive a sound lower than its actual pitch, then you must have been further from the actual position.

The pitch of a sound is a perceptual property of sounds that allows sound of similar frequencies to be distinguished.

Pitch is the quality of sound, that makes it possible to judge sounds as "higher" and "lower" in the sense associated with musical notes.

Thus, when you perceive a sound lower than its actual pitch, then you must have been further from the actual position.

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Answer:

What's the problem???

Answer:500

Explanation:

Answer:

3

Explanation:

Step 1: RxN

Rb + P → Rb₃P

Step 2: Balance RxN

We will need 3 Rb's on both sides.

3Rb + P → Rb₃P

Answer:

C₂H₃O₂

Explanation:

Given the relative formula mass = 59g/mol

Unknown:

Molecular formula of the compound

Solution:

To identify this compound, let us find the molecular mass of the choices given.

The one that tallies with the number 59 is the solution:

For;

  C₂H₃O₂;

 Atomic mass of C = 12

 Atomic mass of H  = 1

  Atomic mass of O = 16

Insert the parameters and solve;

  Relative molecular formula = 2(12) + 3(1) + 2(16) = 59g/mol

So, the first choice is the compound.

Answer:

B.Michanine

Explanation:

Answer: The answer is a college professor since people in the fourth level of industry create, share, and store information. They do research, give advice, report on events, and keep records. Furthermore, workers in the quaternary include teachers, librarians, accountants, scientists, and reporters, nor do the traits describe coal miners, car machines, and a car factory worker as these are the secondary level since their work involves manufacturing, make sure to study! You got this have a g’day. Again, the answer is C: A college professor.

Explanation:

Answer:

it blows up very lighty

Explanation:

Answer: I looked at the periodic table and the element that lines up between the two is F which is Fluorine.

Explanation: I hope this helps!

The element in period 2 of group 17 is fluorine.

Fluorine is the most chemically reactive and electronegative of all the elements. It is a single-valent toxic gaseous halogen that is pale yellow-green in color. Even with the noble gases krypton, xenon, and radon, fluorine easily combines with the majority of other elements to generate new compounds.

Glass, metals, and even water, as well as other materials, burn with a brilliant flame in a jet of fluorine gas because it is so reactive. The fluoride ion F- is the most frequent form of fluorine in aqueous solutions. Fluorides are substances that contain fluoride along with a positively charged partner.

Fluorine is indirectly utilized in the manufacturing of uranium, low friction polymers like teflon, and halons like freon. Fluorochlorohydrocarbons are widely utilized in refrigeration and air conditioning.

Therefore, the name of the element is fluorine.

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Answer: ik im late but I got b

Explanation:

A homogeneous mixture can be described as the solute uniformly dissolving in a solvent to make a solution. Therefore, option (B) is correct.

A mixture can be described as a combination of two or more substances that are not chemically combined with each other. Mixtures can be categorized into two kinds homogeneous mixtures and heterogeneous mixtures.

A homogeneous mixture can be defined as one whose whole composition is uniform throughout the entire mixture. It can be the type of mixture where the entire composition is constant throughout that make up the mixture and is distributed uniformly.

A homogeneous mixture can be described as a gaseous, liquid, or solid mixture that has equal proportions of its components throughout the sample. In a homogeneous mixture, there is only one phase of matter observed.

Some examples of Homogeneous Mixtures are Air Rainwater, Vinegar, Dishwashing detergent, Steel, Sugar water, a Cup of Coffee, etc.

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Answer:

No

Explanation:

Fortunately, in this scenario, you are not out of luck. Each of these components has a unique trait that would allow you to easily separate them. For starters, you can separate all of the Iron with a strong magnet since iron has a magnetic field while sand and salt do not. Next, you can separate the salt and sand by adding water since salt will dissolve in the water leaving only the sand which is not soluble. Once the sand is removed you would simply need to distill the water/salt mixture which would separate the salt from the water. Now you have all three components separated and can get your wish.

Answer:

ORANGE WAIT NO IM COLOR BLIND

Explanation:

Answer:

Between oxygen and selenium, oxygen is more electronegative because of more ionisation energy and small size

Explanation:

Answer:

B is the correct answer because bubbling is a sign of chemical reaction and production of a new substance

Answer:

Double Displacement Reaction

Explanation:

A double displacement reaction is a type of chemical reaction in which the reactant ions exchange places to form new products. Usually, a double displacement reaction results in precipitate formation.

Answer:

D (32.7%)

Explanation:

Answer:D (32.7%)

Explanation:

Answer:

The amount of energy absorbed when 10 g water at 86 C turns completely to steam vapor at 100 C is 584.76 J

The amount of energy released when 10 g water at 72 C freezes completely at 0 C is 3,012.48 J

Explanation:

Sensible heat is the amount of heat that a body can receive without affecting its molecular structure. If the molecular structure does not change, the state (solid, liquid, gas) does not change. Since the molecular structure does not change, a change in temperature is observed.

In other words, the heat that produces a change in the temperature of a substance without any changes in its physical state (phase change) is called sensible heat.

The equation that allows calculating this type of heat exchange is:

Q = c * m * ΔT

where Q is the heat exchanged by a body of mass m, constituted by a substance of specific heat c and where ΔT is the change in temperature.

1. In this case, you know:

Replacing:

Q= 4.184 [tex]\frac{J}{C*g}[/tex] *10 g*14 C

Solving:

Q= 584.76 J

The amount of energy absorbed when 10 g water at 86 C turns completely to steam vapor at 100 C is 584.76 J

2. In this case, you know:

Replacing:

Q= 4.184 [tex]\frac{J}{C*g}[/tex] *10 g*(-72) C

Solving:

Q= -3,012.48 J

The amount of energy released when 10 g water at 72 C freezes completely at 0 C is 3,012.48 J

Answer:

It's Anglo Saxon.

Explanation:

From the Latin aurum, which stands for Aurora, the dawn goddess, comes the symbol Au. Early humans were aware of and highly valued gold. Gold is a beautiful and valuable metal that has been used for at least 5500 years. The original name for gold is Anglo-Saxon.

The element number 79 for gold is Au. Gold's Latin name, Aurum, or shining morning, and its earlier Greek origins predate the Anglo-Saxon term for it. It is one of the more abundant elements with a higher atomic number and exhibits very little reactivity towards the majority of atmospheric conditions, such as water and air.

Although gold is typically inert, it can react with a substance called aqua-regia. A substance called aqua regia is used to dissolve gold. Nitric and hydrochloric acids are combined to make them. The oxidizing agent will be nitric acid, which will result in the creation of gold ions.

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Answer:

the answer is B

Explanation:

because its asking you the frequent summertime storms

hope it helps you

Answer:

b is your answer i'm sure of it :)

Explanation:

have great day :)

Answer: The first picture

Explanation:

The structure of hydronium ion is correctly represented in  the first structure where there are three hydrogen atoms and one oxygen atom.

An ion is defined as an atom or a molecule which has a net electrical charge. There are 2 types of ions :1) cation 2) anion . The cation is the positively charged ion and anion is the negatively charged ion . As they are oppositely charged they attract each other resulting in the formation of ionic bond.

Ions consisting of single atom are mono-atomic ions while which consists of two or more ions are called as poly-atomic ions . They are created by chemical interactions . They are very reactive in their gaseous state and rapidly react with oppositely charged ions resulting in neutral molecules.

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Chopping a piece of wood

Physical changes are changes affecting the form of a chemical substance but not it's chemical composition.

Answer:

rusting nail: Rusting would only be a physical change if iron molecules remained pure iron throughout the process. Yeah your correct a physical change is anything seen or felt like changing the temperature of water a chemical change can also be seen also like if a iron nail rusts the nails iron atoms were chemically changed by oxygen.

lighting a match: Breaking a match in two pieces is an example of a physical change. Lighting a match and letting is burn is an example of a chemical change. Chemical reactions cause chemical changes. In a chemical reaction two or more substances, called the reactants, form different substances called products.

burning a piece of paper: Burning of paper is not a physical change. It is chemical change as ash is formed in the process which is new compound and oxides of carbon are also released during the process. By the definition of chemical change, we come to know that during chemical change a new substance must form. These changes are irreversible in nature.

chopping a piece of wood: The chopping of wood is a physical change because as stated previously, any physical change can include cutting, bending, sharpening, etc. When a piece of wood is being cut, it undergoes one of these processes. The chopping of wood doesn't alter the chemical structure of the actual wood.

So Its chopping piece of wood!