Which is an example of a physical change?

A) Mixing blue and yellow paint to create green paint

B) Adding water and yeast to bread dough in order to make it raise.

C) Mixing two liquids together in a test tube and the tube becoming warm.

D) Adding a piece of chalk containing calcium carbonate to a glass of mild acid causing the information of a foam of bubbles. ​

Answer:

0.57 molecules

Explanation:

Answer:

First shell is lower

Explanation:

The electron has to absorb energy to excite and go to higher energy levels/ shells and should release energy to go to lower energy levels/ shells. This means higher the shell , more energy is required and vice versa

The energy of the photon with a frequency of 9.50×10¹³ Hz is 6.29×10¯²⁰ J

From the question given above, the following data were obtained:

Frequency (f) = 9.50×10¹³ Hz

Planck's constant (h) = 6.626×10¯³⁴ Js

The energy of the photon can be obtained as follow:

E = hf

E = 6.626×10¯³⁴ × 9.50×10¹³

Therefore, the energy of the photon is 6.29×10¯²⁰ J

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Bond number

The characteristic of reactions that depends on valence electrons is the bond type.

In chemistry, a chemical bond could be;

Ionic

Covalent

The type of bond formed depends on the number of valence electrons present. When there are few valence electrons on an atom, it mostly forms ionic bonds.

When there are more electrons on an atoms, it mostly forms covalent bonds and the electrons between the atoms are shared.

Answer:

Ionic bonds result from the transfer of electrons from one atom to another

Explanation:

In covalent bonds, atoms share electrons, whereas in ionic bonds atoms transfer electrons. The reaction components of covalent bonds are electrically neutral, whereas for ionic bonds they are both charged.Covalent bonds are formed between two non-metals, whereas ionic bonds are formed between a metal and non-metal.  

Answer:

Covalent bonds are defined as sharing of electrons, ionic bonds are the result of transferred electrons;

Covalent bonds form between non-metals (elements) and ionic bonds form between metal and non-metals (ions)

Answer: 3-nitropyridine

Explanation:

Answer:

b

Explanation:

When the compound shown is treated CH3MgI followed by water, 1,3 - cyclohexadienol is formed.

Grignard reagent is an alkylmagnesium halide. Grignard reagents are important synthetic tools in chemistry. They are used to synthesize and number of compounds in the laboratory.

When the Grignard reagent, CH3MgI is reacted with compound shown followed by treatment with water, the product of the reaction is 1,3 - cyclohexadienol whose structure is shown in the second image attached to this answer.

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Answer:

Physical changes can be classified as reversible or irreversible. Melting is an example of a reversible physical change.

Explanation:

Answer:

Freeze wedging is caused by the repeated freeze-thaw. Frost wedging occurs as the result of 9% expansion of water when it is converted to ice. Cracks filled with water are forced further apart when it freezes.

Answer:

c the answer is c that is the answer

This problem is giving information about the proton concentrations of three solutions at 25 °C. Despite they are not numerically given, we can propose three scenarios to see how to approach the question.

Let the following solutions to come up:

[H⁺] = 2.63x10⁻³ M

[H⁺] = 1.00x10⁻⁷ M

[H⁺] = 4.511x10⁻⁹ M

The first step, will be the calculation of the pH for each solution via:

pH = -log([H⁺])

So that they turn out to be:

pH = -log(2.63x10⁻³ M) = 2.580

pH = -log(1.00x10⁻⁷ M) = 7.000

pH = -log(4.511x10⁻⁹ M) = 8.3457

In such a way, since acidic solutions have a pH below 7, neutral have a pH equal to 7 and basic have it above 7, we infer the first one is acidic, second one is neutral and third one is basic.

Thus, you can reproduce this methodology with the proton concentrations you are given.

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Explanation:

The burning of fossil fuels contributes to the addition of greenhouse gases to the atmosphere. These gases trap thermal energy in the Earth's atmosphere.

The materials which contain hydrocarbons which are generated from the remains of decay of plants and animals that are buried underground for many years are called fossil fuels.

The burning of fossil fuels can affect the environment, climatic conditions and human health. The burning of fossil fuels produces large amount of green house gases like CO₂, CH₄, etc. The increase in the amount of green house gases increases the heat and temperature of the earth's surface which leads to global warming.

The increase of temperature due to global warming can cause rise in the sea level, the glaciers of the earth will melt and coastal areas will be submerged under water due to this.

The burning of fossil fuels also releases toxic gases like SO₂, NO₂ which can cause acid rain and the emission these gases causes air pollution.

Thus the burning of fossil fuels has adverse effects.

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Answer: Place a piece of white paper under the analyte flask throughout the titration

Explanation:

The end point of titration can be made easy by the use of indicators. But we have to be keenly observe for each drop from the burette because, the colour change will be sudden for a drop.

Titration is an analytical technique used to determine the unknown concentration using a standard reagent of known concentration. The standard reagent of known concentration is called titrant and the  one to be determined is called analyte.

Usually analyte is taken in a conical flask and titrant in a burette. The end point of titration is the point at which the reaction is completed in perfect stoichiometry.

In acid-base titrations, the indicators used having different colors in different pH. Hence, the indicator in the analyte will change in color when the acidity of the medium changes. We have to observe keenly for the color change because it happens for any drop.

The adding of titrant from the burette must be dropwise and thus we can get a time to notice the sudden colour change of indicator.

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In this exercise we want to calculate the amount of moles, so this is going to be:

[tex](4.6)(10^{-3}) \ mols \ CO_2[/tex]

Knowing that Henry's law is given by:

[tex]C = KHP[/tex]

Where constants are given by:

Before we can find the concentration of CO2 (and hence the moles of CO2), we first need to find its partial pressure.  We look up the vapor pressure of water at 25º and find it to be 0.03 atm.  Since the total pressure is equal to 0.1 atm, this mean the partial pressure of:

[tex]CO_2 = 0.1 \ atm - 0.03 \ atm = 0.07 \ atm[/tex]

Now using Henry's law, we find the concentration:

[tex]C = (0.033)*( 0.07) = (2.31)*(10^{-3})[/tex]

Converting to moles of CO2, we have:

[tex](2.31)*(10^{-3})*( 2) = (4.6)*(10^{-3})[/tex]

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Answer:

you did not give the specific heat like formula like it takes 1kj to raise 28grams of water by 10 grams

Answer:

The two main classes of molecules are polar molecules and nonpolar molecules. Some molecules are clearly polar or nonpolar, while others fall somewhere on the spectrum between two classes. Here's a look at what polar and nonpolar mean, how to predict whether a molecule will be one or the other, and examples of representative compounds.

Explanation:

so its c

An example of polar molecule is a molecule made of covalent bonds that has partial positive and partial negative charges in different areas of the atom.

Covalent bond is defined as a type of bond which is formed by the mutual sharing of electrons to form electron pairs between the two atoms.These electron pairs are called as bonding pairs or shared pair of electrons.

Due to the sharing of valence electrons , the atoms are able to achieve a stable electronic configuration . Covalent bonding involves many types of interactions like σ bonding,π bonding ,metal-to-metal bonding ,etc.

Sigma bonds are the strongest covalent bonds while the pi bonds are weaker covalent bonds .Covalent bonds are affected by electronegativities of the atoms present in the molecules.Compounds having covalent bonds have lower melting points as compared to those with ionic bonds.

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Answer:

Explanation:

1) Organic compounds always contain only p-block elements (Groups III-VII), at least one of which must be carbon. 2) Organic compounds almost always contain one or more C-H bonds. ... Thus, all bonds are typically covalent in organic compounds. Methane (CH4) is the prototypical organic molecule.

Methane contains carbon, forming covalent bonds, and is found in living organisms, making it an organic compound.

Methane (CH₄) is considered an organic compound due to its molecular structure and occurrence in living organisms. Organic compounds are primarily composed of carbon atoms covalently bonded to hydrogen and often other elements like oxygen, nitrogen, sulfur, and more.

Methane consists of one carbon atom bonded to four hydrogen atoms through covalent bonds. Carbon's unique ability to form stable covalent bonds with other elements, including itself, leads to the vast diversity of organic molecules found in living organisms.

Methane is a crucial component of natural gas and is produced by various biological and geological processes. It is present in the digestive systems of animals, formed during decomposition, and plays a role in carbon and energy cycles.

Its prevalence in living systems and its molecular structure classify methane as an organic compound, reflecting the foundational principles of organic chemistry.

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The complete question is :

Methane is called an organic compound why​?

Answer:

Explanation:

The new pressure can be found by using the formula for Boyle's law which is

[tex]P_2 = \frac{P_1V_1}{V_2} \\[/tex]

where

P1 is the initial pressure

P2 is the final pressure

V1 is the initial volume

V2 is the final volume

From the question we have

[tex]P_2 = \frac{125\times3.50 }{2.75} = \frac{437.5}{2.75} \\ = 159.090909...[/tex]

We have the final answer as

Hope this helps you

Answer:

Nuclear fusion of hydrogen to form helium occurs naturally in the sun and other stars. It takes place only at extremely high temperatures. That's because a great deal of energy is needed to overcome the force of repulsion between the positively charged nuclei.

Explanation:

hope it helps

Answer:

Test for carbon dioxide gas.

The reaction between baking soda and citric acid will form sodium ions, citric acid ions, carbon dioxide gas, and water. So all you have to do is add the gas produced (by gas displacement method or something) and test whether the gas is carbon dioxide, with lime water or other methods like hydrogencarbonate indicator. Hope this helped!

Explanation:

Answer:

depends on amount, but the reaction's endothermic (meaning its cold, absorbs heat from surroundings)

I hope it helps.

The frequency of the infrared wave at the given speed and wavelength is [tex]5.5 \times 10^{13} \ Hz[/tex].

The given parameters;

The frequency of the infrared wave is calculated by using wave equation as shown below;

v = fλ

where;

[tex]f = \frac{v}{\lambda} \\\\f = \frac{3\times 10^8}{5.5 \times 10^{-6}} \\\\f = 5.5 \times 10^{13} \ Hz[/tex]

Thus, the frequency of the infrared wave at the given speed and wavelength is [tex]5.5 \times 10^{13} \ Hz[/tex].

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Answer:

Similar: both processes of cell division; both processes take place in the nucleus of the cell

Different: mitosis divides into 2, meiosis divides into 4; one is the division of body cells and the other is of specifically sex cells

Explanation:

https://byjus.com/biology/mitosis-and-meiosis/

^ this has more info!

Answer:

[tex] \huge \color{indigo} \boxed{a. \: aldehyde}[/tex]

Explanation:

Pentanal is considered to be a fatty aldehyde lipid molecule. These are compounds containing more than one aldehyde group. Pentanal is a very hydrophobic molecule, practically insoluble in water, and relatively neutral.

Por definición de enlace iónico, covalente y regla del octeto, la relación existente entre la teoría del octeto de Lewis con los enlaces iónicos y  covalentes es que dichos enlaces se producen con el objetivo de completar la última capa de electrones y adquirir estabilidad.

Por un lado, se produce un enlace iónico entre átomos metálicos y no metálicos, donde los electrones se transfieren completamente de un átomo a otro. Durante este proceso, un átomo pierde electrones y otro los gana, formando iones. Por lo general, el metal cede sus electrones formando un catión al elemento no metálico, que forma un anión.

Por otro lado, el enlace covalente es el enlace químico entre átomos donde los electrones se comparten, formando una molécula. Se establecen enlaces covalentes entre elementos no metálicos. El par de electrones compartidos es común a los dos átomos y los mantiene unidos.

En ambos casos se cumple con la regla del octeto, que establece que los átomos de los elementos se enlazan unos a otros en el intento de completar su capa de valencia con ocho electrones. Es decir que los átomos van a tender a ceder o compartir electrones para completar ocho electrones en la capa de valencia mediante un enlace iónico, covalente o metálico.

En otras palabras, el objetivo es tener la configuración electrónica del gas noble más cercano, teniendo así la última capa de electrones completa y adquiriendo estabilidad.

En resumen, la relación existente entre la teoría del octeto de Lewis con los enlaces iónicos y  covalentes es que dichos enlaces se producen con el objetivo de completar la última capa de electrones y adquirir estabilidad.

Aprende más:

Answer:

see answer

Explanation:

DO the postulates of Daltons atomic theory explain the law of conservation of mass and the law of constant composition.

1. Everything is composed of atoms, which are the indivisible building blocks of matter and cannot be destroyed or divided any further.

2. All atoms of a single pure element are the same in size and mass

3. Atoms of different elements vary from each other in size and mass.

4. Compounds are produced through different simple whole-number combinations of atoms to produce molecules.  

5. Anywhere a compound exists, it will have the same atoms in the same ratio.

6. A chemical reaction between compounds is a re-arrangement of atoms

The law of conservation of mass is shown in 2, 4. and 5.

The law of constant co,position is shown in 2, 4, 5, and 6

When a substance dissolves, it looks like it disappears. But in fact it has just mixed with the water to make a transparent (see-through) liquid called a solution. A solution has two parts. The solute is the solid that gets dissolved.

Answer:

it really depends what they are

Explanation:

Mr. garcia uses magnets to hold a poster on a steel filing cabinet because a main component of steel is iron.

The chemical element iron has the atomic number 26 and the symbol Fe. It is a metal that is found in group 8 of a periodic table and the first transition series. It makes up a large portion of the planet's outer or inner core and is the most prevalent element on Earth by mass, just ahead of oxygen.

It is the fourth most prevalent element in the crust of the Earth, having been mostly deposited by meteorites inside its metallic state, along with its ores. Iron ores must be processed in kilns or furnaces that may reach 5000 °C (2,730 °F) and higher, which is approximately 500 °C (932 °F) greater than the temperature needed to smelt copper. Mr. garcia uses magnets to hold a poster on a steel filing cabinet because a main component of steel is iron.

Therefore, mr. garcia uses magnets to hold a poster on a steel filing cabinet because a main component of steel is iron.

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