Which events contributed to life evolving on Earth? Check all that apply.

Organisms began to photosynthesize.
The surface cooled, and water condensed.
Volcanoes added carbon dioxide to the atmosphere.
Ozone formed and blocked ultraviolet rays from the Sun.
Comets crashed into Earth, releasing water

Answer:

Explanation:

To produce CO2 (g), the necessary chemicals are a carbonate (such as sodium bicarbonate or calcium carbonate) and an acid (such as vinegar or hydrochloric acid). The net ionic equation would be: H+ (aq) + CO32- (aq) → CO2 (g) + H2O (l) or 2H+ (aq) + CO32- (aq) → CO2 (g) + H2O (l)

Based on your lab procedure, the necessary chemicals to produce CO2 (g) are typically a carbonate or bicarbonate salt, such as sodium carbonate (Na2CO3) or sodium bicarbonate (NaHCO3), and an acid, such as hydrochloric acid (HCl).

The net ionic equation for the generation of CO2 (g) using sodium bicarbonate (NaHCO3) and hydrochloric acid (HCl) is as follows:

HCO3- (aq) + H+ (aq) → CO2 (g) + H2O (l)

This equation represents the reaction between bicarbonate ions and hydrogen ions to produce carbon dioxide gas and water.

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Option E IR absorptions are caused by electron excitation  isn't true about IR spectroscopy.

IR absorptions are caused by changes in the vibrational energy of bonds in a molecule, not by electron excitation. This means that IR spectroscopy is based on the measurement of the absorption of infrared light by a sample, not on the excitation of electrons.

IR spectroscopy, or Infrared spectroscopy, is a type of vibrational spectroscopy that measures the vibrations of bonds between atoms in a molecule, it is used to identify and quantify the composition of a sample by analyzing the absorption or transmission of infrared light through the sample.

By analyzing the pattern of IR absorptions, it is possible to identify the functional groups and the chemical composition of a sample, which can provide valuable information about its structure and properties.

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Answer:

it is C 65

Explanation:

Answer:

bri its c 65

Explanation:

Answer:

Fractional distillation (often shortened in high school to just distillation)

Explanation:

Some elements have different boiling points and can be separated by boiling one element out and condensing it. This is how sodium acetate is made, for example.

Hope this helped!

Acetone is a liquid substance that could be used in the laboratory for dissolving dry mortar on the floor.

Acetone is a commonly used solvent in laboratories due to its ability to dissolve a wide range of substances, including adhesives and resins. It is a volatile and flammable liquid with a low boiling point, making it convenient for cleaning purposes. Acetone is effective in dissolving dried mortar on floors as it can break down the cementitious components and facilitate their removal.

Acetone is a liquid substance that could be used in the laboratory for dissolving dry mortar on the floor.

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Answer:

D. Something that splits up light into different colors

Explanation:

A prism separates light into various different colors. Thus, D is correct. :)

Answer:

Endothermic is identified if the process requires heat as a reactant, since endothermic means "intake of heat", so it has to take in some type of heat.

Answer:

0.0423 L

Explanation:

Molarity can be represented by the following ratio:

Molarity = moles / volume (L)

You can plug the given values into the equation and simplify to find the volume.

Molarity = moles / volume

0.730 M = 0.0309 moles / volume

(0.730 M) x volume = 0.0309 moles

volume = 0.0423 L

According to stoichiometry and balanced chemical equation 10 iron atoms  react with 30 molecules of chlorine.

Stoichiometry is the determination of proportions of elements or compounds in a chemical reaction. The related relations are based on law of conservation of mass and law of combining weights and volumes.

Stoichiometry is used in quantitative analysis for measuring concentrations of substances present in the sample.It is important in balancing chemical equations.It is useful in chemical calculations while making solutions of different concentrations.

Two atoms of iron reacts with 6 molecules of chlorine , so  for 30 molecules of chlorine it is, 30×2/6=10 atoms of iron.

Thus, 10 atoms of iron will react with 30 molecules of chlorine.

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The equation for the reaction of the burning splint and hydrogen will be H2 + 12O2 --> H2O.

This burning splint test is mostly  used to identify hydrogen, which ignites with a distinctive sound of pop.  

Hydrogen can be easily ignited, because it is flammable with a wide range pressure of the air, making useful. Burns brightly and rapidly too.

Therefore, equation for the reaction of the burning splint and hydrogen will be H2 + 12O2 --> H2O.

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To determine the molar concentration of the hydrofluoric acid (HF) solution, we need to use the concept of molarity (M), which is defined as moles of solute per liter of solution.

Given:

Density of the solution = 1.15 g/mL

Mass percentage of HF = 48.0%

The molar mass of HF (MW) = 20.01 g/mol

First, we need to calculate the mass of HF in 1 liter of the solution:

Mass of HF = (Mass percentage of HF / 100) × Density × Volume

Since the volume is not given, we can assume a convenient volume of 1 liter for calculation purposes. Therefore, the mass of HF in 1 liter of the solution is:

Mass of HF = (48.0 / 100) × 1.15 g/mL × 1000 mL

Mass of HF = 552 g

Next, we can calculate the number of moles of HF using the molar mass:

Number of moles of HF = Mass of HF / Molar mass of HF

Number of moles of HF = 552 g / 20.01 g/mol

Number of moles of HF ≈ 27.59 mol

Finally, we can determine the molar concentration (M) by dividing the number of moles by the volume in liters:

Molar concentration (M) = Number of moles / Volume in liters

Molar concentration (M) ≈ 27.59 mol / 1 L

Molar concentration (M) ≈ 27.59 M

Therefore, the molar concentration of the hydrofluoric acid solution is approximately 27.59 M.

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Answer:

the answer to the question is X3Y2

Answer:

Magnesium permanganate

Explanation:

Answer:

Magnesium Permanganate

Explanation:

Explanation:

The Absorption of Light by Chlorine, Bromine and their Gaseous Mixtures

The name of the process by which glucose is regenerated from lactate is called Cori cycle.

Cori cycle is the metabolic pathway in which lactate produced by anaerobic glycolysis in the muscles moves to the liver and is converted to glucose, which then returns to the muscles and is metabolized back to lactate.

This process was named after its discoverers as follows; Carl Ferdinand Cori and Gerty Cori.

The Cori cycle is a way to bring energy to the muscles during intense workouts and other times of lower oxygen levels in the body.

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Answer:

Chemical reaction, a process in which one or more substances, the reactants, are converted to one or more different substances, the products.

A chemical reaction rearranges the constituent atoms of the reactants to create different substances as products.

Chemical reactions are an integral part of technology, of culture, and indeed of life itself. Burning fuels, smelting iron, making glass and pottery, brewing beer, and making wine and cheese are among many examples of activities incorporating chemical reactions that have been known and used for thousands of years. Chemical reactions abound in the geology of Earth, in the atmosphere and oceans, and in a vast array of complicated processes that occur in all living systems.

Explanation:

hope it help

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Answer:

Chemical reaction, a process in which one or more substances, the reactants, are converted to one or more different substances, the products

Explanation:

Substances are either chemical elements or compounds. A chemical reaction rearranges the constituent atoms of the reactants to create different substances as products.

The reaction you're describing is a halogenation reaction where an unsymmetrical alkene reacts with a halogen (X2) and water (H2O) to form a halohydrin. The general reaction can be represented as follows:

Asymmetrical alkene + X2 + H2O → Halohydrin

For example, let's consider the reaction between propene (an asymmetrical alkene) and chlorine gas (Cl2) in the presence of water (H2O):

CH3CH=CH2 + Cl2 + H2O → CH3CH(Cl)CH2OH

In this reaction, the double bond of propene is broken and a chlorine atom is added to one carbon atom, while a hydroxyl group (-OH) is added to the other carbon atom.

This forms a halohydrin, which in this case is 2-chloropropanol. The reaction mechanism involves the formation of a cyclic intermediate called a halonium ion, which is then attacked by water to form the halohydrin.

Note that the halogenation of an unsymmetrical alkene can lead to the formation of different products, depending on the regioselectivity of the reaction. In the example above, the reaction is regioselective because the chlorine atom is added to the less-substituted carbon atom of the alkene.

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answer

When an electron temporarily occupies an energy state greater than its ground state, it is in an excited state. An electron can become excited if it is given extra energy, such as if it absorbs a photon, or packet of light, or collides with a nearby atom or particle

The common name for a benzene ring with an ammonia group (-NH2) attached is "aniline."

Aniline is an important aromatic compound widely used in various industries, such as dyes, pharmaceuticals, and rubber processing. It is derived from benzene by replacing one hydrogen atom with an amino group (-NH2).

The name "aniline" originates from the indigo-yielding plant called "anil," from which it was first isolated. It has a distinct odor and is often colorless to pale yellow in its pure form. Aniline possesses unique chemical properties due to the presence of the amino group. This compound serves as a starting material for the synthesis of numerous organic compounds.

Aniline is primarily used in the production of dyes, where it imparts vibrant colors to fabrics, plastics, and fibers. Its derivatives find applications in the pharmaceutical industry, serving as intermediates in the synthesis of drugs, such as analgesics, antibiotics, and antimalarials. Additionally, aniline is utilized in the manufacturing of rubber accelerators, antioxidants, and herbicides.

Although aniline has several industrial applications, it is essential to handle it with caution as it can be toxic and absorbed through the skin. Stringent safety measures should be followed during its handling, storage, and disposal to ensure the well-being of workers and the environment.

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Answer:

73.5 million metric tons

Explanation:

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Answer:

The mass of the Moon is approximately 8.1 x 10^19 tons (7.3 x 10^22 kg or . 01 x Earth mass).

Explanation:

Answer:

A. Corn has changed over time due to selective breeding.

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Answer: The enthalpy change of formation (ΔfH∘) of FeBr3(s) is -269 kJmol−1, which means the amount of energy released when one mole of FeBr3(s) is formed from its constituent elements (Fe and Br) at standard conditions (298K and 1 atm pressure) is -269 kJ.

The enthalpy change of reaction (ΔrH∘) for the reaction 2Fe(s)+3Br2(g) → 2FeBr3(s) is -631 kJ, which means that when the reaction takes place at standard conditions, 631 kJ of energy is released for every mole of FeBr3(s) produced.

We can use the enthalpy of formation and the enthalpy of reaction to calculate the enthalpy of reaction per mole of Fe(s) and per mole of Br2(g).

The balanced equation shows that 2 moles of Fe react with 3 moles of Br2 to produce 2 moles of FeBr3. Therefore, the enthalpy change of reaction per mole of Fe is:

ΔrH∘/2 = -631 kJ/2 = -315.5 kJ/mol

Similarly, the enthalpy change of reaction per mole of Br2 is:

ΔrH∘/3 = -631 kJ/3 = -210.3 kJ/mol

Note that the enthalpy of formation is always for one mole of the substance, so the enthalpy change of formation of FeBr3 can be directly compared to the enthalpy change of reaction per mole of FeBr3.

Overall, the negative values of ΔfH∘ and ΔrH∘ indicate that the formation of FeBr3 from its elements and the reaction of Fe with Br2 to form FeBr3 are exothermic processes, meaning that they release energy to the surroundings.

Explanation:

Answer:

6.25%

Explanation:

Given data:

Half life of lutetium-117 = 6.75 days

Percentage remaining after 27 days = ?

Solution;

Number of half lives = Time elapsed / half life

Number of half lives = 27 days / 6.75 days

Number of half lives = 4

At time zero = 100%

At first half life = 100%/2 = 50%

At second half life = 50%/2 = 25%

At 3rd half life = 25%/2 = 12.5%

At 4th half life = 12.5%/2 = 6.25%

Arsenic, hydraulic fracturing, lead, and PFAS present chemical threats to global drinking water supplies in different ways.

Let's discuss each of them in detail:

(a) Arsenic - The origin of arsenic exposure is natural deposits or contamination from agricultural or industrial practices. Human health consequences include skin, lung, liver, and bladder cancers. It can also lead to cardiovascular diseases, skin lesions, and neurodevelopmental effects. Drivers of continued exposure include poor regulation and monitoring. Modern solutions include rainwater harvesting and treatment.

(b) Hydraulic fracturing - Hydraulic fracturing involves using a mixture of chemicals, water, and sand to extract natural gas and oil from shale rock formations. The origin of exposure is contaminated surface and groundwater due to the release of chemicals from fracking fluids and other sources. Human health consequences include skin, eye, and respiratory irritation, headaches, dizziness, and reproductive and developmental problems. Drivers of continued exposure include lack of regulation and poor oversight. Modern solutions include alternative energy sources and regulation of the industry.

(c) Lead - Lead contamination in drinking water can occur due to corrosion of plumbing materials. Human health consequences include neurological damage, developmental delays, anemia, and hypertension. Drivers of continued exposure include aging infrastructure and poor maintenance. Modern solutions include replacing lead service lines, testing for lead levels, and implementing corrosion control.

(d) PFAS - PFAS (per- and polyfluoroalkyl substances) are human-made chemicals used in a variety of consumer and industrial products. They can enter the water supply through wastewater discharges, firefighting foams, and other sources. Human health consequences include developmental effects, immune system damage, cancer, and thyroid hormone disruption. Drivers of continued exposure include the continued use of PFAS in consumer and industrial products. Modern solutions include reducing the use of PFAS in products and treatment methods such as granular activated carbon.

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Answer:where are the statements

Explanation:

Answer:

the Respiratory System and  Circulatory system

Explanation: