you use 25% ethyl acetate (an ester) in hexane to run a tlc and obtain a single round spot with an rf of 0.9 for the main compound. what would you do?conclude that the sample is pure.assume that tlc will be useless and find a different way to see if the sample if pure.try a completely different set of solvents, as ethyl acetate and hexanes will never work.try 10% ethyl acetate to see the results.try 35% ethyl acetate to see the results.

Answer:

answer is option A 1523.24 it is the correct answer of this question ...

plz mark my answer as brainlist plzzzz vote me also so.....

In oxidation-reduction reactions, energized electrons are transferred from one reactant to another.

Redox is a sort of chemical reaction where the substrate's oxidation states change. An rise in an object's oxidation state or the loss of electrons is referred to as oxidation. Reduction is the increase in electrons or a reduction in the oxidation state of an element's chemical constituents or atoms.

The reduction and oxidation reactions that take place at electrodes are referred to as electronation and deelectronation, respectively, by the electrochemist John Bockris.  Protonation and deprotonation are comparable terms.  Despite the fact that the IUPAC has acknowledged the word "electronation," they have not yet been extensively embraced by chemists worldwide.

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Assuming there are no other changes to the system, the change in internal energy is 0 joules.

This is because the internal energy of a system is a measure of the total amount of energy stored within the system. If there are no changes to the system, then the amount of energy stored in the system remains the same and thus the change in internal energy is 0 joules.

Is a unit of measurement used to determine the total amount of energy stored within a system. This amount of energy varies depending on the work done in the system, as well as the transferred between the system and its environment. When dealing with a closed system, i.e., a system that is not affected by any external change, the change in internal energy is zero.

This is because in a closed system, there is no work done and no heat transferred to the system. This means that the total amount of energy stored within the system does not change, so the change in internal energy is zero.

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K⁺ potassium ion has total 19 proton, 18 electron and 19 neutron. It belongs to group 2 of periodic table and period 4. K has total 1 valence electron.

A material is considered an element if it cannot be divided into two or even more simpler compounds by any kind of chemical process, including the use of light or heat.

For instance, when a piece of gold is melted, the gold element still melts and is there. These substances are monoatomic, meaning they are made up of just one kind of atom. K⁺ potassium ion has total 19 proton, 18 electron and 19 neutron. It belongs to group 2 of periodic table and period 4. K has total 1 valence electron. Cl⁻ chlorine ion has total 17 proton, 18 electron and 17 neutron. It belongs to group 17 of periodic table and period 3. It has total 1 valence electron.

Therefore, K⁺ potassium ion has total 19 proton, 18 electron and 19 neutron. It belongs to group 2 of periodic table and period 4. K has total 1 valence electron.

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Answer:

Disturbance

Explanation:

I believe it is Disturbance because waves are normally caused by wind, and wind classifies as Disturbance.

Depending on the chemical, these longer-term health effects might include:

The freezing point of water will be lowered most by dissolving 1.0 mole of magnesium chloride (MgCl₂).

When a solute is dissolved in a solvent, such as water, it disrupts the orderly arrangement of water molecules, making it more difficult for them to form solid ice crystals. This disruption leads to a lowering of the freezing point of the solvent.

The extent to which the freezing point is lowered depends on the nature of the solute and its concentration. In this case, comparing the given options, dissolving 1.0 mole of magnesium chloride (MgCl2) will have the greatest effect on lowering the freezing point of water.

Magnesium chloride dissociates into three ions in water: one magnesium ion (Mg2+) and two chloride ions (Cl-). The presence of multiple ions increases the number of solute particles per mole, leading to a greater disruption of the water structure.

As a result, the freezing point depression caused by 1.0 mole of magnesium chloride is more significant compared to other solutes.

In contrast, naphthalene is a nonpolar solute and does not dissociate into ions in water. Sodium chloride (NaCl) dissociates into two ions, and ether is a nonpolar compound. Therefore, these substances would have a lesser effect on lowering the freezing point of water compared to magnesium chloride.

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The compounds which have higher entropy is, CH₃CH₂OH, CH₄ and NH₄Cl(aq).

CH₃CH₂OH should have a higher entropy value compared to CH₃OH. This is because CH₃CH₂OH has a larger molecular size and more degrees of freedom, leading to a larger number of microstates available to the system at the same temperature.

CH₄ should have a higher entropy value compared to CH₃Br. This is because CH₄ is a gas at room temperature and has a larger number of microstates available to the system compared to CH₃Br, which is a liquid at room temperature.

NH₄Cl(aq) should have a higher entropy value compared to NH₄Cl(s). This is because NH₄Cl(aq) is a solution and has more degrees of freedom, leading to more microstates available to the system than NH₄Cl(s), which is a solid.

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--The complete question is, Which of the compounds in each pair should have the higher entropy value at the same temperature? Why?
a) CH3OH or CH3CHzOH
b) CH3Br or CH4
c) NH4CI (aq) or NH4Cl(s)--

Answer:

The second one

Explanation:

It the graph is correct, it has the most nuetrons

Answer:

Your answer is attached DAME!!!

The reaction of ethanol catalyzed by alcohol dehydrogenase produces acetaldehyde (CH₃CHO) and NADH. Option A and D is correct.

Alcohol dehydrogenase is an enzyme that plays a crucial role in the metabolism of alcohol (specifically ethanol) in living organisms. It catalyzes the oxidation of alcohols, including ethanol, by removing hydrogen atoms from the alcohol molecule.

The overall reaction will be represented as follows;

Ethanol + NAD⁺ → Acetaldehyde + NADH + H⁺

Alcohol dehydrogenase is an enzyme that facilitates the oxidation of ethanol (CH₃CH₂OH) to acetaldehyde (CH₃CHO). In this reaction, NAD⁺ acts as a coenzyme and is reduced to NADH, which means it gains a hydride ion (H⁻). Simultaneously, ethanol loses two hydrogen atoms, resulting in the formation of acetaldehyde. The reaction will also releases a proton (H⁺).

Hence, A. D. is the correct option.

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Answer:

347.4 (19.3 mole)

Explanation:

CH4 + 2O2 = CO2 + 2H2O

1(mole) - 9.65(mole)

2(mole) - x ⇒x = 9.65*2=19.3

m=n*M ⇒ m= 19.3*(1*2+16)= 19.3*18=347.4(g)

Answer:

yes

Explanation:

as it had got crushed down in the dinosaurs age

The dienes that will react with h2c=ch2 in a diels–alder reaction are conjugated dienes.

Conjugated dienes are dienes that have alternating double and single bonds. In a diels–alder reaction, the diene reacts with a dienophile, such as h2c=ch2, to form a cyclic compound. The diene must be in the s-cis conformation in order for the reaction to take place. Examples of conjugated dienes that will react in a diels–alder reaction include 1,3-butadiene and 2,4-hexadiene.

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1: Medical imaging

2: Antibiotics

3: Compass

4: Microscope

I hope this helps! :)

Answer:

plz give my brainliest

Explanation:

1 – Antibiotics

Antibiotics revolutionised medicine in the twentieth century, and together with vaccinations, have almost completely eradicated many once-common diseases such as tuberculosis. While the use of mould to treat infections was first noted by ancient civilisations such as the Egyptians and the Greeks, it was Sir Alexander Fleming who discovered the first antibiotic substance, Penicillin G. For the millions of lives that antibiotics have, and continue to, save worldwide, antibiotics have to be in my scientific top five.

2 – DNA

Over the last 60 years, our rapidly evolving understanding of DNA has catapulted medical knowledge and treatments and even transformed the way we solve crimes. Since James Watson and Francis Crick’s discovery of the double helix structure of DNA in 1953, the scientific community has split in many different directions to investigate the building blocks of life to understand what makes us who we are. Without the discovery of DNA, we wouldn’t have all the ground-breaking studies going on right now in genome mapping and sequencing, so for that reason, DNA has to be my number one scientific discovery of all time.

3-The idea of an atom-

The idea of atoms stretches back to ancient Greece when the philosopher Democritus declared that all matter is made of tiny particles. The philosopher Plato even decided-- wrongly-- that different substances had different shaped atoms, like pyramids or cubes. The first modern evidence for atoms appears in the early 1800s when British chemist John Dalton discovered that chemicals always contain whole number ratios of atoms.

4 – Medical imaging

Medical imaging is an essential tool for clinical analysis, allowing doctors to see beyond what is hidden by skin and bone to accurately diagnose and treat diseases. From X-rays and radiography to MRI scans and ultrasound technology, these scientific innovations have all helped to ensure modern medicine is the least invasive it can be while ensuring the best outcomes for patients. Medical imaging really showcases how science and technology are complementary disciplines, as one advances the other. Marie Curie played a vital role in discovering radioactive elements to do radioactive scans  

When 80 ml of 1.0 x 10^-5 M Ba(OH)2 is added to 20 ml of 1.0 x 10^-5 M Fe2(SO4)3, no precipitate will form.

When 80 ml of 1.0 x 10^-5 M Ba(OH)2 is added to 20 ml of 1.0 x 10^-5 M Fe2(SO4)3, a precipitate may form if the product of the concentrations of the ions exceeds the solubility product constant (Ksp) for the compound. To determine if a precipitate will form, we need to calculate the concentrations of the Ba^2+ and OH^- ions.

To calculate the concentration of Ba^2+ ions, we can use the formula:

Concentration = (moles of solute) / (volume of solution in liters)

Converting the volume of Ba(OH)2 solution to liters:

80 ml = 0.080 L

Calculating the moles of Ba^2+ ions:

Moles of Ba^2+ = concentration × volume
            = (1.0 x 10^-5 M) × (0.080 L)
            = 8.0 x 10^-7 moles

Similarly, for the OH^- ions:

Moles of OH^- = concentration × volume
            = (1.0 x 10^-5 M) × (0.080 L)
            = 8.0 x 10^-7 moles

Since the ratio of Ba^2+ to OH^- ions in Ba(OH)2 is 1:2, we need to multiply the moles of Ba^2+ ions by 2 to get the moles of OH^- ions.

Moles of OH^- = 2 × (8.0 x 10^-7 moles)
            = 1.6 x 10^-6 moles

Now, we can calculate the concentration of OH^- ions:

Concentration = (moles of solute) / (volume of solution in liters)
            = (1.6 x 10^-6 moles) / (0.100 L)
            = 1.6 x 10^-5 M

The concentration of OH^- ions is 1.6 x 10^-5 M.

Now, we can compare the concentrations of the ions with the Ksp values of potential precipitates. If the product of the concentrations exceeds the Ksp, a precipitate will form.

For example, the Ksp of Ba(OH)2 is 5.0 x 10^-3.

Product of concentrations = (1.6 x 10^-5 M) × (8.0 x 10^-7 M)²
                      = 1.024 x 10^-17

Since the product of the concentrations is less than the Ksp of Ba(OH)2, no precipitate will form.

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Answer:

B 2:2

Explanation:

Mole ratio is the comparison of the ratio of two compounds or elements in a chemical reaction. In a balanced equation, the moles of a particular compound or element is written as a coefficient. This means that mole ratio is the ratio of the coefficient of two substances in a reaction.

In this balanced chemical equation given as follows:

2CO + 02 → 2CO2

The number of moles/coefficient of carbon monoxide (CO) is 2 while that of carbon dioxide (CO2) is 2.

Hence, the mole ratio of CO to CO2 is 2:2

Answer: Theft starts at c4 down

impression starts L14 left

investigator starts at m3

criminalistics starts at o1

pathologists starts at m14

toxicology b11

fingerprints c2

court n13

witness n8

microscope j13

edmond locard m1

expertise m4

murder j13

cant find other ones rn

Explanation:

Taking into account the definition of calorimetry and sensible heat, the heat added to the system is 331.2 cal.

Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.

Sensible heat is defined as the amount of heat that a body absorbs or releases without any changes in its physical state (phase change).

So, the equation that allows to calculate heat exchanges is:

Q = c× m× ΔT

where:

In this way, between heat and temperature there is a direct proportional relationship.

In this case, you know:

Replacing in the expression to calculate heat exchanges:

Q= 0.23 \(\frac{cal}{gC}\)× 24 g× 60 C

Solving:

Q= 331.2 cal

In summary, the heat added to the system is 331.2 cal.

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The half-life of a certain radioactive isotope is 5 days. After 3 days, we need to estimate the percentage of the original amount of the isotope that remains.

To find the percentage remaining, we can use the formula: Percentage remaining = (1/2)^(number of half-lives) * 100%
In this case, since 3 days have passed and the half-life is 5 days, we can determine the number of half-lives as: Number of half-lives = 3 days / 5 days = 0.6 half-lives

Plugging this into the formula, we get: Percentage remaining = (1/2)^(0.6) * 100%
Using a calculator, we find that (1/2)^(0.6) is approximately 0.796, so: Percentage remaining = 0.796 * 100% = 79.6%
Therefore, approximately 79.6% of the original amount of the isotope released by the explosion remains 3 days after the explosion.

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1. Cl (chlorine) - smallest
2. Na (sodium)
3. Mg (magnesium)
4. K (potassium)
5. Rb (rubidium) - largest

Hi! I'm happy to help you rank these elements according to the radii of their atoms from smallest to largest. The elements you've provided are Na (sodium), Mg (magnesium), Cl (chlorine), K (potassium), and Rb (rubidium).

The ranking based on atomic radii is as follows:

1. Cl (chlorine) - smallest
2. Na (sodium)
3. Mg (magnesium)
4. K (potassium)
5. Rb (rubidium) - largest

This ranking considers the general trend in the periodic table where atomic radii increase as you move down a group and decrease as you move from left to right across a period.

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Unicellular organisms such as amoeba and leishmania undergo binary fission.

Binary fission can be described as a form of asexual reproduction where an organism divides into two, each part having one copy of genetic material.

Binary fission can be described as a kind of asexual reproduction observed in prokaryotes and a few single-celled eukaryotes. In asexual reproduction, there is a separation of the parent cell into 2 new daughter cells. This process occurs with the division and duplication into two parts.

Binary fission is a primary of reproduction in prokaryotic organisms. Binary Fission happens without spindle apparatus formation in the cell.  The single DNA molecule starts replication and attaches each copy to parts of the cell membrane.

Prokaryotes and eukaryotes such as euglena reproduce via binary fission. This process is rapid, and its speed varies in species. The time needed by bacteria to double the cells it has is called known as doubling time.

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Answer:

It's gotta be the third answer

Explanation:

Hope this helpped!

The value of the gas constant will be high due to the increase in gas pressure.

Solution:

According to Ideal Gas Law, PV=nRT

where, P = Gas pressure (in atmospheres),   V= Gas Volume (in Liters),  n = number of moles of gas sample T=  Gas Temperature (in Kelvins), R = Gas Constant.

\(\therefore R=\frac{(P\ast V)}{(n\ast T)}\) ....... (1)  

P = \(P_{atm}\) - \(P_{water vapor}\)

where = Atmospheric pressure\(P_{water vapor}\) = Partial pressure of water vapor.

If students forgot to include the vapor pressure of water in the calculation of gas constant then the magnitude of pressure due to gas(P) will be more because they are not substracting the Water vapor value from the \(P_{atm}\)to get the actual P value.

The value of the gas constant will be high due to the increase in gas pressure.

The ideal gas constant R can be found experimentally by determining the number of moles of gas occupying a given volume of measurement at a known pressure and temperature. This information is obtained in this laboratory by collecting the oxygen produced by the decomposition of potassium chlorate over water. The water level inside the tube should match the water level outside the tube.

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Answer:

A. 7

(assuming the water is neutral)

Acid has a pH below 7 while water has a pH of 7. A strong acid with a pH of roughly 3, HCl is. Water gets more acidic and loses pH in the range of 4-5 when HCl is added to it.

A substance's pH is a gauge of how basic or acidic it is. It is a measurement of the amount of H+ present in the solution. It is equivalent to the negative logarithm of the concentration of H+ ions mathematically.

A solution is acidic if its pH value is less than 7, and basic if it is greater than 7. Acids have a lower pH because they contain more H+ ions. Strong acid hydrochloric acid has a pH between 2 and 3.

Water has no charge. Water becomes acidic in pH if any acid is introduced. Therefore, if HCl is given to water, the pH of the water will change to 3-5 depending on the acid content.

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Palm to palm is referred to as the best way to maintain control of the subsection when cutting with a vertical or diagonal cutting line thereby preventing the risk of injuries or inaccuracy.

This method is used during cutting or styling and involves the two palms of the hands in a position such that they are facing each other or opposite to one another and helps to reduce the different types of strain in the affected part of the body.

This method isn't a compulsory one to be done but is best suited for an individual who wants to maintain control of the subsection when cutting with a vertical or diagonal cutting line.

This is therefore the main reason why palm-to palm technique was chosen as the most appropriate choice.

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Answer:

Single replacement

Explanation: Al is replacing Cu