Which observation most likely indicates that only a chemical change has taken place?(1 point)



The change cannot be reversed.

The shape changes



States of matter changes.

A reaction occurs.

If the dissolution of borax in water is spontaneous, the change in enthalpy will be both positive and negative. It can be predicted by the sign of the enthalpy change depending on the temperature.

Borax is a hydrated borate of sodium. It is a salt. When borax is mixed in water, it is converted into boric acid and the pH will be 9.13.

Enthalpy is a total heat energy present in a closed system, also called a thermodynamic system.

Thus, the change in enthalpy will be of both signs. Predicted by the sign of the change in temperature.

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Answer: See below.

Explanation: An atom is made up of protons, neutrons and electrons.

A water-cooled condenser must have the water flowing over it continuously to function. The water must enter through the bottom port and exit through the top port for this to occur.

What is condenser?

A device or component used to condense vapor into liquid is a condenser (heat transfer). HVAC air coils are an example of specific sorts. Condenser (laboratory), a group of glassware used in laboratories to cool fluids.

The condenser's job is to take the high-pressure gas coming from the compressor and turn it into a liquid. By using the idea that heat will always travel from a warmer to a cooler substance, it accomplishes this.

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The correct matches for changes of state are:

Change of state is the process whereby matter in one physical state is converted to matter in another state by the addition or removal of heat.

The process of change of state are:

Considering the given diagram, the correct matches are:

In conclusion, change of state of matter occurs due to heat changes.

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The balanced chemical equation for the reaction occurs when dimethyl ether, ch3och3(g), is combusted in air.

CH3OCH3(g) + 3O2(g) ----> 2CO2(g) + 3H2O(l)

A chemical is a substance with a defined composition. That is, chemicals are always made up of the same "things". Some chemicals are found in nature, such as water. Other chemicals are also manufactured, such as chlorine (used in bleaching fabrics and in swimming pools).

There are four main types of compounds, distinguished by how the atoms are bonded together. Molecular compounds are bound by covalent bonds. Ionic compounds are held together by ionic bonds. Intermetallic compounds are held together by metallic bonds. Coordination complexes are held together by coordinate covalent bonds. Non-stoichiometric compounds form a controversial edge case.

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Before to exposed to heat stearic acid is a colorless solid, which gets converted to a clear liquid under the influence of heat.

Stearic acid is a colorless or white, waxy solid, which slightly dissolves in water but is soluble in oil, Stearic Acid is a fatty acid due to the presence of an 18-carbon chain, it also knows as Octadecanoic Acid. When the stearic acid is exposed to heat it gets converted to a clear liquid which was supposed to be a white solid in nature.As we know that the law of conservation of matter defines that matter is conserved,  the matter can change form through chemical and physical changes, but the amount of matter before the changes remains the same, which means it can't be destroyed or created.

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A chemical reaction in which bonds are created is usually associated with The consumption of energy

Consumption method using, shopping for, or consuming something. If we do not lessen our power intake, we are able to run out of fuel. Conspicuous intake is shopping for something to expose off. Consumption is associated with the verb consume, which means to eat, use, or buy.

There are four Consumption kinds of client goods. They are comfort goods, distinctiveness goods, purchasing goods, and unsought goods.

Consumption of Food intake is a periodic behavior. It is brought on at diverse moments of the day through some converging factors (time of day, want a state, sensory stimulation, social context, etc.).

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According to the bohr model, the energy change in joules that occurs E=−1.36×10∧−19J, when an electron falls from the n = 4 to the n = 2 energy level in a hydrogen atom.

The Bohr model, also known as the Rutherford-Bohr model, was first proposed by Niels Bohr and Ernest Rutherford in 1913 and describes an atomic system with an orbiting system of electrons and a small, dense nucleus that is similar to the Solar System in structure but is attracted by electrostatic forces rather than gravity.

1) The orbits of the electrons surrounding the nucleus are circular and have a constant energy.

2) The electron only rotates in orbits with angular momentum greater than or equal to nhi/2π³.

Only when an electron transitions from one orbit to another can energy become realised or absorbed in the form of a photon.

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Valine-valine and valine-leucine would be formed by heating a mixture of valine and N-protected leucine.

Amino acid leucine is protected at the N-terminal end, so it is not available to form a polypeptide at that end.

Peptide bond is a covalent chemical bond linking two consecutive alpha-amino acids from C1 (carbon number one) of one alpha-amino acid and N2 (nitrogen number two) of another along a peptide or protein chain.

Valine and leucine can react and form dipeptide valylleucine (valine-leucine), see picture below.

When two valine amino acids react, dipeptide valylvaline (valine-valine) is formed.

Polypeptide is a long and unbranched peptide chain with more than ten amino acids.

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Answer:

29.25g

Explanation:

Number of moles = Mass / Molar mass

Number of moles of NaOH = 20g/(23 + 16 + 1)

= 0.5mol

1 mol of NaOH = 1 mol of NaCl

Therefore, 0.5mol of NaOH = 0.5mol of NaCl

0.5mol = Mass of NaCl / (23 + 35.5)

Mass = 0.5 × 58.5

= 29.25g

I hope this helps! ^^

The molarity of a solution of KIO3 is dissolved in enough water to make 250.0 ml of solution is 0.1595.

Molarity is the measure of the concentration of any solute per unit volume of the solution.

M = {n}{V}

The molar mass of KIO3 is  214.001

Given the mass is 853.5 mg

First, we calculate the number of moles

moles = mass / molar mass

853.5 / 214.001 = 3.988

Now, molarity can be calculated

The number of moles is 3.988

The volume is 250.0 ml

Putting the values in the formula

M =  3.988  / 250.0 = 0.1595

Thus, the molarity is 0.1595.

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Water is called Solvent ,When salt dissolves completely into water.

Solvents are substances, usually liquids, that help other substances dissolve and mix together to form solutions. Nonpolar solvents, such as hydrocarbons, do not support ion production; polar solvents do (for example, water). Acidic, basic, amphoteric (both), or aprotic solvents are the four most common types (neither).

Alcohols, esters, ethers, ketones, amines, nitrated and halogenated hydrocarbons are a few examples of organic substances that are utilized as solvents, along with other hydrocarbons and aromatic compounds. Their main applications are in inks, paints, varnishes, lacquers, extractive processes, industrial cleansers, medicines, and media for chemical synthesis.

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Answer: solvent

Explanation:

In the complete combustion of 1.60 moles of benzene, C6H6, 12 moles of oxygen, O2, is consumed.

Combustion is defined as the process of burning something. In chemistry, combustion refers to the chemical process between a fuel and an oxidant, usually oxygen to produce heat and light in the form of flame.

In a complete combustion, oxygen is sufficient to react with any hydrocarbons to produce carbon dioxide and water.

Balancing the combustion reaction of benzene, we have:

2C6H6 + 15 O2 = 12CO2 + 6H2O

Based on the balanced combustion reaction above, 2 moles of benzene requires 15 moles of oxygen to have a complete combustion.

If we have 1.60 moles C6H6,

moles O2 = mole ratio x mole of benzene

moles O2 = (15 moles O2/2 moles C6H6) x 1.60 moles C6H6

moles O2 = 12

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A molecule with a trigonal bipyramidal electron geometry must have a central atom with how many bonding and nonbonding electron groups around it Equatorial.

An atom is a single neutral particle. A molecule is a neutral particle with two or more atoms bonded together. Water is a simple molecule consisting of one oxygen atom bonded to two different hydrogen atoms. The bond is a polar covalent bond (polar bond) due to the high electronegativity of the oxygen atom.

About 99% of the body consists of atoms of hydrogen, carbon, nitrogen, and oxygen. It also contains much smaller amounts of other elements necessary for life. Something like table salt (NaCl) is a compound because it is made up of multiple elements (sodium and chlorine), but it is not a molecule because the bonds that hold NaCl together are ionic bonds.

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Answer:

22.68

Explanation:

Since about 2.2 lbs = 1kg, 50 pounds is about 22.68.

The density is the ratio of  the mass to the volume.

The term density refers to the ratio of mass to the volume of a substance. Given that mass is the quantity of matter in a body, we could use it to obtain the density of the body.

We know that solids have a definite volume, liquids have a definite volume but a gas does not have a definite volume. The volume of a gas is the same as the volume of the container where it is kept. This is why gases could be compressed but a solid and a liquid can not be compressed likewise.

The volume tells us how much space that an object expects to occupy. We have to combine the mass and the volume to get the density of an object. As such, we can see that the density is the ratio of  the mass to the volume.

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According to the research, the correct option is do not perform photosynthesis. Animal cells lack chloroplasts because they do not perform photosynthesis.

It is a eukaryotic type cell belonging to the Animalia kingdom and can reproduce independently and depending on the tissue to which they belong, they fulfill specific functions that define their morphology, their function and their needs.

In this sense, plants carry out photosynthesis since their cells have chloroplasts, which house chlorophyll, essential for obtaining energy from sunlight, on the other hand, animal cells lack these organelles and instead have what is necessary for oxidation glucose (respiration).

Therefore, we can conclude that according to the research, the correct option is do not perform photosynthesis. Animal cells lack chloroplasts because they do not perform photosynthesis.

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A sugar crystal is placed in water, every time a sucrose molecule dissociates from the crystal, water molecules surround it in a cloud forming a hydration shell.

What is a hydration shell?

The term "hydration shell" refers to a more or less continuous cluster of water molecules that surround and are somewhat linked to another substance that the water molecules are drawn to because it is hydrophilic, or water loving.

Since there is space between matter particles and sugar crystals, the level of water does not significantly rise when sugar crystals dissolve in it, keeping the water level constant.

Thus, every time a sucrose molecule separates from a sugar crystal in water, a cloud of water molecules forms around the crystal, creating a hydration shell.

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The 14.1 ml solution has a density of 2.1365 g/ml.

Density is defined as the ratio between the mass of a substance and the volume it occupies. Denoted by ρ, density is mass per unit volume and the formula is given below:

ρ =  mass / volume

To solve for the density of a mixture or solution of two substances with different densities, the mass and volume of each substance must be known, as:

ρ mix = (M1 + M2) / (V1 + V2)

The volume and densities of the two given substances are known and can be used to solve for the unknown mass of each substance.

M1 = ρ x V1

M1 = 1.492 g/ml x 7.60 ml

M1 = 11.3392 g

M2 = ρ x V2

M2 = 2.890 g/ml x 6.50 ml

M1 = 18.785 g

Solving for the density of the mixture,

ρ mix = (M1 + M2) / (V1 + V2)

ρ mix = (11.3392 g + 18.785 g) / (7.60 ml + 6.50 ml)

ρ mix = 30.1242 g / 14.1 ml

ρ mix = 2.1365 g/ml

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0.389×10^−19J  is the change in energy for the combination of these processes.

λ1=410nm=410×10^−9m

λ2=2628nm=2628×10^−9m

E1−E2 = Energy absorbed by the atom in the process =hc[1/λ1−1/λ2]

=6.63×3[1/410−1/2628]×10^−9 = 0.389×10^−19J

We get, 0.389×10^−19J.

Energy is the quantitative property that is transferred to a body or to a bodily system, recognizable in the performance of work and in the structure of warmth and light. Energy is a conserved quantity—the regulation of conservation of energy states that strength can be transformed in form, however not created or destroyed. The unit of size for energy in the International System of Units (SI) is the joule (J).

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If an object weighs 38.325 lbs = 17,400 g would be mass in grams

In physics, mass is a numerical representation of inertia, which is a basic characteristic of all matter. The resistance a body of matter offers to a change in its speed or location as a result of the application of a force is what it is in essence. The change a force applies produces a change that is smaller the more mass a body has.

The kilogram, which is defined in terms of Planck's constant as equal to 6.62607015 × 10^ -34 joule second, is the unit of mass in the International System of Units (SI). One kilogram times one square meter per second squared is equivalent to one joule.

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Because they lack the stiffness required for alignment, molecules with only single bonds do not generally display liquid-crystalline characteristics. One or more atoms make up a molecule. The biological substances, such as proteins and DNA, can be composed of thousands of the atoms.

A molecule is composed of atoms that have been joined together. So, whereas an atom is a separate thing, a molecule is generated when those atoms come together. These elements are may be the same, such as the two oxygen atoms bonded together (O2), or they may be different atoms linked together, such as the water (H2O).

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if ammonia is fed to a continuous reactor at a rate of 100.0 kmol nh3/h

175 Kmol/h is oxygen the fed rate that corresponds to 40% excess O₂.

Given chemical reaction is

4NH₃ + 5O₂ → 4NO + 6H₂O

The molecular weight of NH₃ is 17.03, O₂ is 32, NO is 30, and, H₂O  is 18.

To find the ratio,

Ratio = lb-mole O₂ react / lb-mole NO formed

Or, ratio = 5/4

Or, ratio = 1.25

NH₃ fed rate = 100 Kmol/h

We have to find out whether the Oxygen fed rate corresponds to 40% excess O₂.

For each 4 Kmol of NH₃, 5 Kmol of O₂ is required.

4 Kmol of NH₃ ≡ 5 Kmol of O₂

100 Kmol of NH₃ ≡ 125 Kmol of O₂

So, 125 Kmol of O₂  is required for 100 Kmol of NH₃.

For 40% excess of O₂, the required Kmol is = 125 + 125 × 40%

The required Kmol of oxygen is 175 Kmol/h for excess of O₂.

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A given short peptide, SGYAL contains four peptide bonds. Any given short peptides/protein contain at least one amino group(s) (nh3 ) and one carboxyl group(s) (-coo- ).

SGYAL stands for secretaria general y asuntos legales. Sgyal is also written as Ser-Gly-Tyr-Ala-Leu . The structure of SGYAL is shown in the image attached. SGYAL contains four peptide bonds as highlighted by yellow color in the structure of SGYAL.

Peptide bond is formed by the condensation of carboxylic group of one molecule and amino group of other molecule. Any given short peptides/protein contain at least one amino group(s) ([tex]NH_{3}[/tex]) and one carboxyl group(s) ( -COO-).

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As long as the sample has the same number of atoms for both elements, the mass ratio is independent of the sample size.

The arithmetic mean is calculated by adding a set of numbers, dividing by their count, and then taking the result. The molecular masses of different substances vary. Therefore, variable numbers of atoms, molecules, or moles exist in masses of equal mass. On the other hand, equal quantities of moles of different substances have different masses. The result will be disproportionately impacted by the one data point if you attempt to calculate an "average of averages". In essence, the value of the average of 10,000 data points is the same as that of the average of a single data point.

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The foreign substance responsible for causing an allergic reaction is called an allergen.

The exaggerated reaction of our body’s immune system to certain foreign substances is known as an allergy.

The symptoms of allergy are sneezing, watery eyes, running nose, and difficulty in breathing which occur due to the release of certain chemicals like histamine and serotonin in our body.

The foreign substance that causes allergy is called an allergen.

Common examples of the allergens are pollen grains of certain plants, animal dander, and food items like peanuts, mushrooms etc.

To control the symptoms of allergy, drugs like antihistamines and steroids are used.

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Answer:

A. They conduct heat.

Explanation: