Why is mining for coal a long-term concern?

A. It is being replenished faster than it can be mined.
B. The supply will eventually be exhausted.
C. New methods of mining need to be developed.
D. The demand for coal is diminishing.

Answer:

For the CH3- structure use the periodic table to find the total number of valence electrons for the CH3- molecule. Once we know how many valence electrons there are in CH3- we can distribute them around the central atom with the goal of filling the outer shells of each atom.

In the Lewis structure of CH3- structure there are a total of 14 valence electrons.

Also note that you should put the CH3- Lewis structure in brackets with as 1- on the outside to show that it is an ion with a negative one charge.

----- Steps to Write Lewis Structure for compounds like CH3- -----

1. Find the total valence electrons for the CH3- molecule.

2. Put the least electronegative atom in the center. Note: Hydrogen (H) always goes outside.

3. Put two electrons between atoms to form a chemical bond.

4. Complete octets on outside atoms.

5. If central atom does not have an octet, move electrons from outer atoms to form double or triple bonds.

Lewis Structures, also called Electron Dot Structures, are important to learn because they help us understand how atoms and electrons are arranged in a molecule. This can help us determine the molecular geometry, how the molecule might react with other molecules, and some of the physical properties of the molecule (like boiling point and surface tension).

Explanation:

CH3CNO can be represented by at least three different but valid Lewis structures called resonance forms, or resonance structures, shown below.

The concentration of 25 mL of potassium hydroxide can be determined from 0.1 M solution of hydrobromic acid by titration.

Titration involves the process by which the concentration of an unknown solution is determined by reaction a known volume of the unknown solution with a carefully measured volume of a standard solution. By determining the volume of the standard solution required to react completely with the solution of unknown concentration, its concentration can be accurately determined by calculation.

In order to determine the concentration of  25 mL of potassium hydroxide, this volume of solution is put into a conical flask and titrated against a known volume of 0.1 M solution of hydrobromic acid. At the end point, usually signified by a color change, the concentration of the 25 mL of potassium hydroxide solution can be calculated from the stoichiometry of the reaction.

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From the ideal gas law, the pressure of the gas is 106 kPa.

First we must obtain the number of moles of the gas;

Number of moles = mass/molar mass

Molar mass of fluorine gas = 38 g/mol

Number of moles of F2 = 6.40 g/38 g/mol = 0.168 moles

Using the ideal gas equation;

PV = nRT

P = ?

V = 3.90 L

n =  0.168 moles

T = 25.0 ⁰C + 273 = 296 K

R = 8.314  kPa L K-1 mol-1

Substituting values;

P = nRT/V

P =  0.168 moles × 8.314  kPa L K-1 mol-1 ×  296 K/3.90 L

P = 106 kPa

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The pressure of the vessel at a temperature of 25 °C is 106.73 KPa

We'll begin by calculating the number of mole of fluorine gas. This can be obtained as follow:

Mass of F₂ = 6.40 g

Molar mass of F₂ = 19 × 2 = 38 g/mol

Mole = mass / molar mass

Mole of F₂ = 6.40 / 38

Finally, we shall determine the pressure. This can be obtained as follow:

Volume (V) = 3.90 L

Temperature (T) =  25.0 °C = 25 + 273 = 298 K

Mole of F₂ (n) = 0.168 mole

Gas constant (R) = 8.314 L.KPa/Kmol

PV = nRT

P × 3.9 = 0.168 × 8.314 × 298

P × 3.9 = 416.232096

Divide both side by 3.90

P = 416.232096 / 3.90

Therefore, the pressure of the vessel is 106.73 KPa

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Answer:

C

Explanation:

It depends on the bonding for an explanation.

If one atom is a metal and one is a non metal it will be ionic. This is because one atom transfers its electron to the other atom giving them both a charge. They will then be bonded due to opposite forces of attraction.

If both atoms are non metals it will be covalent. Electrons pair together in the center of two atoms that have merged together and they share their electrons.

(Makes more sense with diagrams)

Answer:

"They can be reversed by physical changes."

Explanation:

A chemical change can form a new substance, can be detected by the change in color and they have properties different from their starting materials.

Answer:

vinegar and soda

Explanation:

Mixing baking soda (sodium bicarbonate) and vinegar (acetic acid) causes a chemical reaction that produces a salt (sodium acetate) and water, as well as carbon dioxide gas.

Answer:

Fertilizer and vinegar

Explanation:

Fertilizer is a base, and vinegar is an acid. Salt is made when you combine a base and an acid. Plus, I got a 100% on the test and this was my answer.

Taking into account the definition of density and scientific notation, the density of olive oil is 0.000911 [tex]\frac{kg}{mL}[/tex] or 9.11×10⁻⁴[tex]\frac{kg}{mL}[/tex]

Density is defined as the property that matter, whether solid, liquid or gas, has to compress into a given space.

In other words, density is a quantity that allows us to measure the amount of mass in a certain volume of a substance.  That is, density is the relationship between the weight (mass) of a substance and the volume it occupies.

The expression for the calculation of density is the quotient between the mass of a body and the volume it occupies:

[tex]density=\frac{mass}{volume}[/tex]

In this case, you know that:

Replacing in the definition of density:

[tex]density=\frac{0.216 kg}{237 mL}[/tex]

Solving:

density= 0.000911 [tex]\frac{kg}{mL}[/tex]

On the other side, scientific notation is a quick way to represent a number using powers of base 10.  

The numbers are written as a product:

a×10ⁿ

where:

In this case, the density expressed in scientific notation is: 9.11×10⁻⁴[tex]\frac{kg}{mL}[/tex]

In summary, the density of olive oil is 0.000911 [tex]\frac{kg}{mL}[/tex] or 9.11×10⁻⁴[tex]\frac{kg}{mL}[/tex]

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At before Duberinor,Mendeleev tried to use atomic weight but they failed .

Answer:

An exergonic reaction is a type of chemical reaction that releases free energy to the surroundings. The final state of this reaction is less than its initial state. ... “Exothermic” literally means “outside heating” while “exergonic” literally means “outside work.”

Explanation:

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70 tons of hematite (Fe₂O₃) is needed to produce 49 tons of iron (Fe).

We'll begin by calculating the tons of hematite (Fe₂O₃) that reacted and the tons of Fe produced from the balanced equation. This is illustrated below:

2Fe₂O₃ + 3C —> 4Fe + 3CO₂

Molar mass of Fe₂O₃ = (56×2) + (16×3) = 160 g/mol

Mass of Fe₂O₃ from the balanced equation = 2 × 160 = 320 g

Divide by 907185 to express in ton

320 / 907185 = 0.000353 ton

Molar mass of Fe = 56 g/mol

Mass of Fe from the balanced equation = 56 × 4 = 224 g

Divide by 907185 to express in ton

224 / 907185 = 0.000247 ton

From the balanced equation above,

0.000353 ton of Fe₂O₃ reacted to produce 0.000247 ton of Fe.

Finally, we shall determine the tons of hematite (Fe₂O₃) needed to produce 49 tons of Fe. This can be obtained as follow:

From the balanced equation above,

0.000353 ton of Fe₂O₃ reacted to produce 0.000247 ton of Fe.

Therefore,

X ton of Fe₂O₃ will react to produce 49 tons of Fe i.e

X ton of Fe₂O₃ = [tex]\frac{0.000353 * 49}{0.000247} \\\\[/tex]

X ton of Fe₂O₃ = 70 tons

Thus, 70 tons of hematite (Fe₂O₃) is needed to produce 49 tons of Fe.

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From the graph shown, Y2 = N2, X2 = O2, Z2 = H2.

When atoms of elements are at a large distance from each other, the potential energy of the system is high. However, as the atoms approach each other, the potential energy of the system decreases steadily. The closer the atoms come to each other, the lower the potential energy. This implies that potential energy is proportional to bond length.

Since N2 has a shorter bond length and higher energy, Y2 must be N2. The bond energy of hydrogen is small hence H2 must be X2. The bond energy of a double bond is intermediate between that of a single and triple bond hence Z2 must be O2.

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It will take 56 days to go from 100% iodine-131 to less than 1% iodine-131.

From the table, we can see that the half life of iodine-131 is 8 days. We can see that it takes 8 days to have 50% of iodine-131

After 16 days, we will have 25 % of iodine-131

After 24 days, we will have 12.5 % of iodine-131

After 32 days, we will have 6.25% of  iodine-131

After 40 days, we will have 3.125% of  iodine-131

After 48 days, we will have 1.5625% of iodine-131

After 56 days, we will have 0.78125% of iodine-131

After 56 days, the percentage of iodine-131 drops to less than 1%.

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Answer:

The answer is Zeta

Explanation:

The three types of nuclear decay are Gamma, Beta, and Alpha.

Answer: These are all examples of the waves you listed

B- Soundwave, ultrasound waves

A-Surface ripples on water

C- water waves

D-The heat that we feel from sunlight, a fire, a radiator or a warm sidewalk is infrared.

E-The heat emitted from a campfire.

F-Long Distance Wireless Transmission. Most wireless transmission systems are based on microwave technology.

G- Disinfectants

Explanation:

Hope this helps!!

Have a nice day!

Answer:

True I think so

Explanation:

I have asked question in my profile please tell me the answer

Answer:

Calcium is then pumped back into the sarcoplasmic reticulum breaking the link between actin and myosin.

Explanation:

Actin and myosin return to their unbound state causing the muscle to relax. Alternatively relaxation (failure) will also occur when ATP is no longer available.

Answer:

Explanation:

Answer:

any form of water that falls from the sky

Answer:

Answer

The limitations are-

1. Privacy of the individuals involved in the research process.

2. Physical and psychological risks should be minimized

3. The subjects should be chosen equitably

4. Only reasonable exposure to risks is admissible.

Explanation

The privacy of the individuals involved in the research must be taken into consideration. This will ensure safety of patient data and information. The risk of physical and physiological well being of the person must be taken into consideration in such a research. In addition to that, the subject must be made to understand every procedure and the risks involved before testing. Moreover, only minimal exposure to risks is allowed and must have been previously tested in animals to avoid deaths.

Answer:

A chromosome is a thread-like structure present in the nucleus  that is made up of a single molecule of DNA and proteins, carrying some or all genetic materials of an organism. A chromatid is an identical half of a duplicated chromosome

Explanation:

Answer:

The alkyne is linear

Explanation:

Any molecule with a triple bond is considered an alkyne. In regards to the shape, because carbon can only bond to 4 different atoms at once a triple bond fills in 3 of the required 4 atoms needed to reach the molecules ground state (when it's most stable). The more electrons shared between atoms, the shorter the bond will be which results in a stronger and more linear line. Keep in mind a quadruple bond is not possible between carbons as of now.

Answer: yes it is

Explanation:Bond order

The antibonding orbital is empty. Thus, H2 is a stable molecule

Answer:

2Cu + S ~~~> Cu2S Copper (C) reacts with sulfur (S) to form copper sulfide as shown in the equation. A scientist adds 12.7 grams of Cu to 3.2 grams of S to start the reaction.

Explanation:

Answer:

Explanation:

sory i dont know

Answer: Using the standardized NaOH solution in the previous question, the titration of 5.00 mL of vinegar required 42.25 mL of NaOH. What is the % of acetic acid in the vinegar? Concentration of NaOH from previous question= 0.0986 M. David C.

Explanation:

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The percentage of acetic acid in vinegar is 4.988 %., When the titration of 5.00 mL of vinegar required 42.25 mL of NaOH.

Titration is defined as the process of chemical analysis method in which the amount of a sample's constituent is determined by mixing a precisely measured amount of the desired constituent with another material in a precise, known proportion. The equivalence point, or the point at which chemically equivalent amounts of the reactants have been combined, is to be detected by the titration.

According to the titration principle, V1=the volume of acetic acid and V1S1=V2S2

S1 is the acetic acid's strength

V1 = 42.25 ml * 0.0986 M / 5 ml = 0.833 M where V2 = Volume of NaOH S2 = Strength of NaOH

Hence, 1000 ml Vinegar contains 0.833 moles of acetic acid per 100 ml of vinegar (0.0833*60). G=4.998 grams of acetic acid

The amount of acetic acid in vinegar is 4.988%.

Thus, the percentage of acetic acid in vinegar is 4.988 %., When the titration of 5.00 mL of vinegar required 42.25 mL of NaOH.

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Answer:

Hydrogen and oxygen

Explanation:

Hydrogen

2 × atomic number = 2

atomic mass = 1.008 amu

Oxygen

2 × atomic number = 16

atomic mass = 15.999 amu