hcfcs are a temporary solution to the problem of ozone depletion and will be replaced over the next 20 years by which class of compounds?

neon the answer as the electron arrangement is 2,8

The Robinson annulation is a reaction that involves the conjugate addition of a stabilized carbanion to an alpha,beta-unsaturated ketone, followed by intramolecular aldol condensation.

The Robinson annulation reactions are in the image attached below

The reaction proceeds in two steps: in the first step, the carbanion attacks the electrophilic carbon of the alpha,beta-unsaturated ketone, forming a new carbon-carbon bond. In the second step, the newly formed double bond acts as a nucleophile and attacks the carbonyl group of the same molecule, leading to the formation of a cyclic product. The Robinson annulation is a powerful method for the synthesis of cyclic compounds, particularly those containing a six-membered ring with an alpha,beta-unsaturated ketone as a key intermediate.

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Complete question:

Draw the product obtained by heating each pair of ketones in a basic solution.

The figure is in the image attached below

Preparing a supersaturated solution involves dissolving more solute in a solvent than it can normally hold at a given temperature.

Start with a clean and dry container to minimize impurities.

Gradually add the solute to the solvent while continuously stirring. It is crucial to add the solute slowly to avoid triggering crystallization.

Continue stirring the solution until no more solute can dissolve, resulting in a saturated solution.

Apply external factors to increase the solubility of the solute. This can be done by raising the temperature or adding pressure, depending on the specific solute-solvent combination.

Once the solute is fully dissolved under these altered conditions, carefully cool or depressurize the solution while keeping it undisturbed. This promotes the formation of a supersaturated solution.

The resulting supersaturated solution contains an excess of dissolved solute that exceeds its normal solubility limit.

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Answer:

According to the formula of mass in grams

Mass in grams= Moles/ Molar mass

Rearranging the formula

Moles= Mass/ Molar mass

Given:

Mass: 34.5 g

Molar mass: NH3

: 14 + 1×3

: 17g

Moles: ?

Solution:

Moles= Mass/ Molar mass

= 34.5 / 17

Moles= 2.025 mol

Answer:

So 2.025 moles of hydrogen are needed produce 34.5 grams of ammonia

Hope it helps

The heat (q) in kJ released with combustion of methanol using 801 grams of water and the change in temperature is 4.3 degree Celsius. the specific heat of water is 4.18 J/(g °C) is 14397.17 J.

given that :

The specific heat capacity is given as :

q = mc ΔT

where ,

m = mass = 801 g

c = specific heat capacity = 4.18 J/g °C

ΔT = change in temperature = 4.3  °C

q = heat = ?

now, by solving the values we get :

q = mc ΔT

q = 801 × 4.18 × 4.3

q = 14397.17 J

Thus, The heat (q) in kJ released with combustion of methanol using 801 grams of water and the change in temperature is 4.3 degree Celsius. the specific heat of water is 4.18 J/(g °C) is 14397.17 J.

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Answer:

Mitosis: Cell division in Asexual Reproduction. 2 Daughter cells exactly like the parent. Heredity is passed to offspring: 100% DNA from 1 parent. Meiosis: Cell division in Sex Cells during Sexual Reproduction.

Explanation:

Answer:

Following are the solution to this question:

Explanation:

Mendeleev has been the chemist that designed a periodic table for component identification based on the increasing number of elements. Thus, the is traditionally called a table parent and this periodic table had some drawbacks.

Consequently, Mosley rebuilt Mendeleev's periodic table to once again overcome this disadvantage. Which atoms were arranged as per the increasing order of atomic number instead of mass number. The traditional table, therefore, comprises seven horizontal lines regarded as cycles. But 18 control limits were named group lines.

The whole Periodical Tables is classified as a,p,d, and f block

S block, groups have 1 and 2.

P block, group has 13-18  

D block, group has 3 to 12

F block, – Two lines far below the periodic table.

The type of glass that has been exposed to high temperatures and shatters into tiny pebble-like fragments when it breaks is called tempered glass.

Tempered glass is a type of safety glass that has been treated with heat and chemicals to make it stronger and more durable than regular glass. When it breaks, it shatters into small, rounded fragments that are less likely to cause injury than the sharp shards produced by regular glass. Tempered glass is commonly used in applications where safety is a concern, such as car windows, shower doors, and storefront windows. It is also used in the construction of buildings, furniture, and appliances.

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Answer:

A. The rate of the reverse reaction increases with an increase in the concentration of CaCO3(s)

Explanation:

If the concentration of a reactant has increased, The substance will shift in the direction of the reaction that uses the reactants, So that the Reactants substance Increases.

Answer:

As the size of a star increases, luminosity increases. If you think about it, a larger star has more surface area. That increased surface area allows more light and energy to be given off.

Explanation:

1. First, let's rewrite the equation:

FeO + H2O --> Fe(OH)2

1 mole of FeO react with one mole of H2O producing 1 mole of Fe(OH)2.

Let's transform 1000g of FeO and 800 g of H2O into moles using: n = m/MM

MM of FeO = 72 g/mol

MM of H2O = 18 g/mol

n FeO = 1000/72

n FeO = 13.89 moles

n H2O = 800/18

n H2O = 44.4 moles

We can see that we have less moles of FeO than of water. The ratio between them is 1:1, so FeO is our limiting reactant.

Answer 1: FeO is the limiting reactant.

2. To calculate the theoretical yield, we need to use the number of moles of the limiting reactant, which is 13.89.

So it will be produced 13.89 moles of Fe(OH)2, since the ratio between FeO and Fe(OH)2 is 1:1.

So let's transform 13.89 moles of Fe(OH)2 into grams:

m = n*MM

MM of Fe(OH)2 = 90 g/mol

m = 13.89*90 = 1250.1 g of Fe(OH)2

Answer 2: Theoretical yield = 1250 g of Fe(OH)2

4. The excess reactant is H2O.

After the reaction, it will left 44.4 - 13.89 = 30.51 moles of H2O.

It is in grams:

m = n*MM

m = 30.51*18

m = 549 g

Answer: 549 g

The total bond energy of the reactants and products must be subtracted to obtain the energy change in the reaction \(2H_2O --- > 2H_2 + O_2\) using the provided bond energy.

Reactants:

2H-O-H (2 molecules) = 2 * (2 * O-H) = 2 * (2 * 463 kJ/mol) = 1852 kJ/mol

Products:

2H-H (2 molecules) = 2 * (2 * H-H) = 2 * (2 * 436 kJ/mol) = 1744 kJ/mol

O=O = 1 * O=O = 1 * 495 kJ/mol = 495 kJ/mol

1852 kJ/mol is the total binding energy of the reactants.

The combined binding energy of the products is 1744 kJ/mol + 495 kJ/mol, which is equal to 2239 kJ/mol.

Energy change (ΔE) = Total bond energy of the products - Total bond energy of the reactants

ΔE = 2239 kJ/mol - 1852 kJ/mol = 387 kJ/mol

So, the answer is E.

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Your question is incomplete, most probably the complete question is:

Calculate the energy change of the following reaction

based on the bond energies given.

2H2O2H2 + O2

H-H: 436kJ/mol

O=0: 495kJ/mol

O-H: 463kJ/mol

Select one:

Pg denotes gauge pressure, which is related to absolute pressure as follows: Pa is the local atmospheric pressure, and pg is equal to p - pa.

An automobile tire gauge, for instance, reads 32.0 psi. 14.2 psi is the atmospheric pressure in the area. The gauge pressure equation states that gauge pressure equals the difference between absolute pressure and atmospheric pressure: P G = P P A, or PG=PPA. A tire pressure gauge, for example, monitors the pressure in the tire above ambient pressure. Gauge pressure is the pressure in particular items. Thus, gauge pressure plus atmospheric pressure add up to the total pressure, or absolute pressure: Pabs=Pg+Patm Pabs is the absolute pressure, Pg is the gauge pressure, and Patm is the atmospheric pressure. P abs = P g + P atm

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The rate of consumption of Ca is 0.0833 g/s.

The rate of consumption of Ca can be determined by dividing the mass of Ca consumed (2.50 g) by the time taken for the reaction to occur (30.0 seconds). This gives us a rate of 0.0833 g/s, indicating that 0.0833 grams of Ca are consumed every second during the reaction at the given temperature.

In chemical reactions, the rate of consumption or production of a substance is typically expressed in terms of the change in concentration over time. In this case, since the mass of Ca consumed is given, we can directly calculate the rate of consumption.

It's important to note that the rate of consumption of Ca may vary with temperature and other reaction conditions. The given rate applies specifically to the given temperature and the specific reaction conditions mentioned in the problem.

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Answer:

190

Explanation:

Gold has atomic number of 79, which is the number of protons.

Mass number = #protons + #neutrons = 79 + 111 = 190

The pH after the following volumes of titrant have been added 0 ml 20 mL 59. 1 mL 60. 0 mL 71. 4 mL 73. 4 mL are 11.89, 11.89, 8.45, 8.45, 7.98, 8.95 respectively.

The reaction between NH3 and HCl can be represented by the following equation: NH3 + HCl → NH4+ + Cl-

To calculate the pH after different volumes of titrant have been added, we need to determine the amount of titrant that has reacted with the analyte and the resulting concentration of the products.

A. 0 mL of titrant (initial state)

At the start, there is no titrant added to the analyte, so the concentration of NH3 is 0.050 M. NH3 is a weak base, so we can use the Kb expression to calculate the concentration of OH-:

\(Kb = [NH4+][OH-] / [NH3]\)

\(1.8 * 10^{-5} = x^2 / (0.050 - x)\)

initial concentration of NH3 is much greater than the initial concentration of HCl, we can assume that the concentration of NH3 does not change significantly during the titration.

\(Kb = x^2 / 0.050\\x = \sqrt{Kb * 0.050} = 1.3 * 10^{-3} M\)

The concentration of OH- is equal to \(1.3 * 10^{-3} M\), so we can calculate the pH:

\(pH = 14 - pOH = 14 - (-log[OH-]) = 11.89\)

Therefore, the pH at the start of the titration is 11.89.

B. 20 mL of titrant

After adding 20 mL of 0.025 M HCl, the volume of the solution is 50 mL (30 mL NH3 + 20 mL HCl). The moles of HCl added is:

moles of HCl = volume x concentration = 0.020 L x 0.025 mol/L = 5 x 10^-4 mol

Since the reaction is a 1:1 reaction, the moles of NH3 remaining is equal to the moles of HCl added.

concentration of NH3 = moles of NH3 / volume of NH3 = (0.050 mol/L x 0.030 L - 5 x 10^-4 mol) / 0.030 L = 0.048 mol/L

Since the concentration of NH3 has decreased, we need to recalculate the concentration of OH- using the new concentration of NH3:

\(Kb = [NH4+][OH-] / [NH3]\\1.8 * 10^{-5} = x^2 / (0.048 - x)\)

Solving for x, we get:

\(x = 1.3 * 10^{-3} M\)

The concentration of OH- is still \(x = 1.3 * 10^{-3} M\), so we can calculate the pH:

pH = 14 - pOH = 14 - (-log[OH-]) = 11.89

Therefore, the pH after adding 20 mL of titrant is still 11.89.

Similarly for  C. 59.1 mL of titrant

The pH after adding 59.1 mL of titrant is 8.45.

D. 60 mL of titrant

The pH after adding 60 mL of titrant is 8.45.

E. 71.4 mL of titrant

The pH after adding 71.4 mL of titrant is 7.98.

F. 73.4 mL of titrant

The pH after adding 73.4 mL of titrant is 8.95.

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The balanced equation in acidic solution is: 3 Br₂ + 10 Br⁻ + 18 H₂O → 6 BrO₃⁻ + 36 H⁺

A balanced chemical equation is an equation where the number of atoms of each type in the reaction is the same on both reactants and product sides.

An unbalaced chemical equation is not an accurate representation of a chemical equation and thus requires balancing.

The law of conservation of mass is the governing law for balancing a chemical equation.

The law states that ‘mass can neither be created nor be destroyed in a chemical reaction’

The unbalanced equation is written as -

Br₂ → 2 BrO₃⁻ + 3 Br⁻

Identify the oxidation and reduction half-reactions:

Br2 is reduced to BrO₃⁻ (reduction)

Br₂ → BrO₃⁻

Br- is oxidized toBrO₃⁻ (oxidation)

3 Br- → 3 BrO₃⁻

Balance the atoms in each half-reaction:

Br₂ + 6 H₂O → 2 BrO₃⁻  + 12 H⁺ (reduction)

3 Br- → 3 BrO₃⁻ + 6 e⁻ (oxidation)

Balance the charges in each half-reaction by adding electrons:

Br₂ + 6 H₂O → 2 BrO₃⁻  + 12 H⁺ + 10 e⁻

3 Br⁻ → 3 BrO₃⁻ + 6 e⁻

Multiply the half-reactions by appropriate coefficients to equalize the number of electrons transferred:

3 Br₂ + 18 H₂O → 6 BrO₃⁻ + 36 H⁺ + 30 e⁻

10 Br- → 10 BrO₃⁻ + 20 e⁻

Add the balanced half-reactions together and cancel out the common species:

3 Br₂ + 10 Br⁻ + 18 H₂O → 6 BrO₃⁻ + 36 H⁺ + 30 e⁻

10 Br⁻ + 30 e⁻ → 10 BrO₃⁻ + 20 e⁻

Simplify the equation by canceling out the electrons:

3 Br₂ + 10 Br⁻ + 18 H₂O → 6 BrO₃⁻ + 36 H⁺

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Answer: 3Br2 + 3H2O = 6H+ + BrO3- + 5Br-

The correct option is option B, camouflage the chameleon from predators.

Chameleons belong to the reptile family of the animal kingdom, they are creatures with their own special abilities i.e. they can change the color of their body to match them with the surrounding.

This ability of theirs is very helpful for them to hunt for prey as they can camouflage in the environment the prey doesn't get the chance to recognize them as their potential threat and thus they get attacked. Chameleons generally hunt small insects like butterflies, ants, etc.

Another and the most important use of this ability is to hide from the potential threats or predators of the wild. It helps them to blend in with their environment and avoid detection by predators. For example, if a chameleon is in a green plant, it can change its skin color to green and become nearly invisible to predators.

This adaptation allows the chameleon to survive in its environment by remaining undetected, which is essential for its survival.

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Answer:

The motion towards or away from us based on the Doppler effect and corresponding red shift or blue shift.

Explanation:

The emission and absorption spectra demonstrates the lines where light has been absorbed by the atoms. The spikes can be observed due to atoms releasing photons at those wavelengths. Infrared and ultra violet waves can be observed during spectroscopy.

Answer:

3.96 × 10⁻³ mol Pb

Explanation:

Step 1: Find molar mass

Pb (Lead) - 207.2 g/mol

Step 2: Use Dimensional Analysis

\(0.821 \hspace{2} g \hspace{2} Pb(\frac{1 \hspace{2} mol \hspace{2} Pb}{207.2 \hspace{2} g \hspace{2} Pb} )\) = 0.003962 mol Pb

Step 3: Simplify

We have 3 sig figs

0.003962 mol Pb ≈ 0.00396 mol Pb

0.00396 mol Pb = 3.96 × 10⁻³ mol Pb

Answer:

\(H _{3}O {}^{ + } \)

Hydroxonium ion

Answer:

This type of meat is substance. If you were talking about meters then it would be a system of measurement.

Answer:

Mixture

Explanation:

Meat is composed of approximately 72–75 % water, 21 % nitrogenous compounds (19 % proteins and 1.5 % nonprotein nitrogen compounds which include nucleotides, peptides, creatine, and creatinine), 2.5–5 % lipids, 1 % non-nitrogenous compounds (vitamins) and carbohydrates (a very small amount of glycogen).

19. moth balls in the closet and observe after several days.

20. whenever wax or a candle burns it turns from solid to liquid but again at room temperature it turns to solid

21. evaporation, condensation, precipitation

22. it produces new substances

23. vinegar Bubbles when baking soda is added

24. steam

Answer:

By making sense of the World around them

Explanation:

maybe?

Answer:

It’s eutrophication

Explanation:

There is no way it can be DEFORESTATION or NON  SUSTAINABLE SPECIES

Non sustainable harvesting has something to do with animals and eutrophication means adding excessive nutrients

Answer:A.

Explanation: I took the test, sorry if this is incorrect

(a) Acidic oxides: CO2, NO2, Al2O3, NO, SO3

(b) Basic oxides: CaO, CO, SO3, K2O, BaO

(c) Amphoteric oxides: K2O, Al2O3, CaO, CO2, SnO2

(d) Neutral oxides: CO, NO, SnO2, N2O5, BaO

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Answer: saturated

Explanation: i am right.