Choose all of the following statements that are true about electron dot structures and valence electrons.

All stable atoms always have eight valence electrons.
Atoms can gain and lose electrons.
Atoms transfer electrons to become stable.
Stable atoms have a full outer shell.
Atoms cannot gain or lose electrons.

Calcium oxide has different physical and chemical properties as compared to calcium carbonate. Option 1.

Calcium carbonate and calcium oxide are unique from one another in terms of their physical and chemical properties, even though calcium oxide can be produced by the decomposition of calcium carbonate.

Both calcium carbonate and calcium oxide are only similar in terms of their color. They both appear white in color. Their differences include:

Thus, both calcium carbonate and calcium oxide exhibit different chemical and physical properties.

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The complete question is as below:

Calcium carbonate is heated and decomposes to form calcium oxide (CaO) and carbon dioxide (CO2). Which statement is true about the difference between calcium carbonate and calcium oxide?

The percent yield of the reaction is 82%

First step: make the chemist equation.

2 Al (s) + Fe2O3 (s) → 2 Fe (s) + Al2O3 (s)

As the statement says that aluminium is in excess, the limiting reactant is the Fe₂O₃.

Second step: Find out the moles in the reactant.

Molar weight Fe2O3: 159.7 g/m

Mass / Molar weight = moles

50 g /159.7 g/m = 0.313 moles

Third step: Analyse the reaction. 1 mol of Fe2O3 makes 2 moles of Fe.

1 mol Fe2O3 ____ 2Fe

0.313 mol Fe2O3 ____ 0.626 moles

Molar weight Fe = 55.85 g/m

Moles . molar weight = mass

55.85g/m . 0.626m = 34.9 grams

This will be the 100% yield of the reaction but we only made 22.6 g

34.9 g ____ 100%

22.6 g ____ 64.75 %

Hence, the percent yield is 64.75 %.

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The moles of the base should be equal to the moles of phenol.

What is Williamson ether synthesis ?

An alkoxide ion acts as a nucleophile in the Williamson ether synthesis, an SN2 reaction in which an alkyl halide loses a halide ion to produce an ether. The reaction involves configuration inversion at chiral centers and may be constrained by potential competing elimination reactions.

What is nucleophile?

An atom or molecule that seeks the positive center of a chemical reaction, such as the atom's nucleus, is referred to as a nucleophile in chemistry because it has an electron pair that is available for bonding.

Therefore, the moles of base should be equal the mole of phenol.

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Angle theta = 〖60.11〗^0

Angle theta = 〖60.11〗^0

Resistance is a measure of an electrical circuit's resistance to current flow. Resistance is measured in ohms, which is represented by the Greek letter omega (Ω). When electrons move through a conductor, such as a metal wire, an electric current flows. Electrons in motion can collide with ions in the metal. This complicates the current flow and causes resistance.

Given resistance  (R) = 155ohms

Capacitive reactance (Xc)  = 270 ohms

We have to find angle theta = ?

Tan θ= capacitive reactance/resistance

Tan θ = Xc/R

Tan θ = 270/155

θ = 〖tan^(-1) (〗⁡〖270/155〗)

θ = 〖tan^(-1) (〗⁡1.74)

θ = 60.11

Therefore angle theta = 〖60.11〗^0

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The pressure of the gas would now be 2/3 of its initial value.

We know that we can be able to use the ideal gas equation to be able to obtain the parameters that concern gases. In this case, we are dealing with the volume, temperature and volume all at once hence we need to use the general gas equation.

Initial pressure of the gas P1 = P

Final pressure of the gas P2 = ??

Initial volume of the gas V1 = V

Final volume of the gas V2 = 3V

Initial temperature of the gas T1 = T

Final temperature of the gas = 2T

P1V1/T1 = P2V2/T2

P1V1T2 = P2V2T1

P2 = P1V1T2/V2T1

P2 = P * V * 2T/3V * T

P2 = 2/3P

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When we simplify a given equation we get a following answer

8 moles of HCl needed to produce 16 moles of magnesium Chloride

As per definition, mole is a same amount of number which contains same number of chemical species like atoms, molecules, ion, etc.

Mg   +    2HCl   →   MgCl2 + H2

1mole     2mole      1 mole    1 mole

Here, when 1 mole of Mg reacts with 2 mole of HCl then 1 mole of MgCl2 and 1 mole of H2 forms.

As per the question, to form 16 moles of MgCl2 we need 8 moles of HCl

to get our euqation done.

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Elements created in stellar nucleosynthesis are carbon, oxygen, iron, calcium .

What is stellar nucleosynthesis ?

Stellar nucleosynthesis is a process involving nuclear reactions in which new atomic nuclei are synthesized from existing nuclei or nucleons. The first stage of nucleosynthesis occurred in the hot early universe, producing H, He, and trace amounts of Li-7 (primordial nucleosynthesis). In today's universe, nucleosynthesis takes place as follows.

(1) thermonuclear reaction and explosion inside the star (nucleus formation up to the Fe peak), (2) neutron capture and explosion inside the star (nucleus formation above the Fe peak), (3) stars Spallation reactions in interstitial matter, where light nuclei (Li, Be, and B) arise from the fragmentation of heavy nuclei (C, N, and O).

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Answer: They are related to spring.

Explanation:

It should be right, I got this question correct.

The full ionic equation for the conversion of aqueous lead (II) nitrate to solid lead (II) sulfate and aqueous potassium nitrate is as follows:

PbSO4(s) + 2 K+ + 2 NO3 = Pb2+(aq) + 2 NO3(aq), 2 K+(aq), and SO42(aq) (aq)

Let's look at the molecular formula that results in solid lead (II) sulfate and aqueous potassium nitrate when aqueous lead (II) nitrate and aqueous potassium sulfate interact. This reaction involves two displacements.

 PbSO4(s) + 2 KNO3 = Pb(NO3)2(aq) + K2SO4(aq) (aq)

All ions and molecular species are included in the full ionic equation.

PbSO4(s) + 2 K+ + 2 NO3 = Pb2+(aq) + 2 NO3(aq), 2 K+(aq), and         SO42(aq) (aq)

The full ionic equation for the conversion of aqueous lead (II) nitrate to solid lead (II) sulfate and aqueous potassium nitrate is as follows:

PbSO4(s) + 2 K+ + 2 NO3 = Pb2+(aq) + 2 NO3(aq), 2 K+(aq), and SO42(aq) (aq)

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Answer: The valence shell electrons are represented by crosses.

Explanation:

The outer shell of each atom is drawn as a circle. Electrons from one atom are shown as dots, and electrons from other atoms are shown as crosses. The circles overlap where covalent bonds are present.

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As the lattice energy increases the size of the ionic solids will decrease.

Lattice energy can be defined as the energy required to convert one mole of an ionic solid into gaseous ionic constituents. Or else, it can also be defined as the energy that must be supplied to one mole of an ionic crystal in order to separate it into its  gaseous ions in a vacuum through an endothermic process.

However, it also suggests the energy that facilitates the dissociation of one mole of a solid ionic compound into its constituent gaseous ions.

Lattice energy is inversely proportional to the size of the ions. So as the size of the ions increases, the lattice energy of the compound will  decreases. Because as the size increases, the charge density gets distributed through out and so there is more distance between the electrons and hence the lattice energy will decrease.

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The statement which describes a characteristic of a question that can be answered through scientific inquiry is that it can be answered using measurements.

This is referred to as a collection of quantitative or numerical data that describes a property of an object or a body. it has units which depicts the quantities which are present and an example is the unit of length being meter.

An example of a scientific method is experimentation which include different parameters. these parameters are mostly measured to get the actual values which makes it unique among other sets.

The features of a question that can be answered through scientific inquiry is that it can be answered using measurements because different values are getting and tested when dealing with a scientific method.

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The enthalpy of solution ∆H is positive when CH3CN dissolves in formaldehyde. Use this information to list the stages in order of increasing enthalpy A<D<B<C.

The net result of the energy absorbed or dissipated as heat by the solution when a given amount of solute is dissolved in a solvent at constant pressure. The amount of heat released or absorbed when a substance melts is not constant. It depends on the final solute concentration.

The enthalpy of a solution is expressed in kJ/mol at a nearly constant temperature. The energy change can be viewed as consisting of three parts endothermic bond breaking in the solute and solvent and the formation of an attractive force between the solute and solvent. The enthalpy of a solution describes the total amount of heat absorbed or released when two substances go into the solution. This sum can be either positive or negative.

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Reaction conditions that favor elimination in an acid-catalyzed dehydration : product is removed from the reaction mixture when formed. For reaction to be completed,  hypochlorous acid must be in excess during the reaction.

Acid-catalyzed dehydration of alcohols takes place when an acid puts an extra hydrogen atom on the alcohol. This causes  change in the OH alcohol group into an H2O or water group attached to the organic compound. When that particular molecule leaves then it leaves as water . Therefore dehydration occurs.

The activity of a solid acid on methanol dehydration reaction was found to be determined by the number of its acidic sites. The presence of such acid catalyst in the catalytic system  shifts the methanol synthesis reaction, increasing the pass conversion of CO.

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b. elemental composition d. shape and e. quantum mechanical effects  three factors significantly influence the properties of nanoscale materials.

Nanoscale material are the set of substances that have least one Critical dimension less than 100 nanometer. That have magnetic, electrical and optical properties. S and P blocks are there in the nanoscale materials. Nanoscale materials are mostly concentrated in the s and p blocks Nano elements. Nanoscale material have have structure with dimensions at the nanoscale.so it has size of 1-100nm.The shape of the nanomaterials are in various shapes like rod shape spherical shape ,fibers and cups. In the nanoscales quantum effects dominates the electrical optical properties of the system. They create new opportunity for manipulating the response of the system.

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The wavelength should be 600 nm to minimize the interference from the presence of the CO{2+} ions (aq).

What is spectrophotometer?

An analytical tool called as spectrophotometer is used to determine the emission or reflection of visible light, UV light, or infrared light objectively.  These are used to calculate intensity as a function of light source wavelength.

The spectrophotometer available to the student has a wavelength range of 400 nm to 700 nm. The maximum wavelength for CO{2+} curve is 500 nm. The two curves of CO{2+} and Cu{2+} intersects at 600 nm.

So, 600 nm should the student use for interference minimization for the presence of CO{2+} ions.

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Answer:

High temperatures reduced the growth of tubers more than of shoots. Photosynthetic rates were unaffected or increased slightly at the higher temperature. Heat stress increased the accumulation of foliar sucrose and decreased starch accumulation in mature leaves but did not affect glucose.

Explanation:

i hope this helped <3

Answer:

C I think, haven't done this in awhile

Explanation:

I took science

The reagent that will reduce an ester to an aldehyde is DIBAL-H  as a reducing agent and the reagent that will reduce an acid chloride to an aldehyde is LiAlH[OC(CH3)3]3

A reducing agent is typically is generally species that have lowest possible oxidation states, and is known as the electron donor. A reducing agent is oxidized itself, because it loses electrons during  the redox reaction.

According to the above cases given we can say that esters can be converted to aldehydes using diisobutylaluminum hydride (DIBAH). The reaction is usually carried out at -78 oC in order to prevent the formation of aldehyde as product.

Similarly Acid chlorides can be converted to aldehydes using lithium tri-tert-butoxyaluminum hydride (LiAlH(Ot-Bu)3).

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C₆H₁₂O₆ (glucose) has 72 valence electrons

Valence electrons are the electrons present in the outermost shell of any atom. So first we will find out the total number of atoms in glucose.

Total number of atoms in C₆H₁₂O₆ are:

    Number of carbon = 6

    Number of hydrogen = 12

    Number of oxygen = 6

Now we will find out the total number of valence electrons in each type of atom:

    Valence electrons in carbon = 4

    Valence electrons in hydrogen = 1

    Valence electrons in oxygen = 6

Calculate the total number of valence electrons in C₆H₁₂O₆ by multiplying the number of atoms with the number of valence electrons for each element. And then sum up all the valence electrons.

    valence electrons in C₆H₁₂O₆ = (6*4) + (12*1) + (6 * 6)

    valence electrons in C₆H₁₂O₆ = 24 + 12 + 36

    valence electrons in C₆H₁₂O₆ = 72

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The temperature in kelvin in a 0.0733 l bulb that contains 0.292 g of i2 vapor at a pressure of 0.462 atm is : T = 358.7K

Iodine is a chemical element with having symbol as I and atomic number is 53. It is the heaviest of the stable halogens and it exists as a semi-lustrous and non-metallic solid at standard conditions.

Given, volume (V) = 73.3mL = 73.3/1000 = 0.0733L;

and Mass of l2 = 0.292g;

and Pressure (P) = 0.462atm;

We have to find Temperature (T)

Mass of l2 = 0.292g

Molar Mass of I2 = 127 x 2 = 254g/mol

As we know that number of mole = Mass /Molar Mass

Hence, number of mole of I2 = 0.292/254

Number of mole of I2 = 1.15×10¯³ mole

The temperature in the bulb containing the iodine vapor can be found out by using the ideal gas equation as shown:

We know that, gas constant (R) = 0.0821 atm.L/Kmol

Using formula, PV = nRT

0.462 x 0.0733 = 1.15×10¯³ x 0.0821 x T

T = (0.462 x 0.0733)/(1.15×10¯³ x 0.0821)

Temperature  = 358.7K

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The protein's specific volume (0.73 mL g-1 for -lactoglobulin).

Enzyme-containing proteins help speed up the metabolism, or chemical changes, in our bodies. While some compounds are decomposed, others have been produced. Everything that is alive contains enzymes. Naturally, our bodies produce enzymes.

For instance, the enzyme pepsin is a vital component of gastric fluids and aids in the breakdown of food particles in the belly. Similar to how amylase, an enzyme found in saliva, turns starch into glucose to aid in the first stages of digestion. The thrombin enzymes is employed in medicine to speed up the healing of wounds.

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Answer: 3.5 miles Fe203 = 55.89078 grams

Explanation:

The sequence of the decreasing the order of stability of the given compounds is :

BaCl₂  >  CaCl₂  > MgCl₂ > AlCl₃  > HCl > AgCl

The reactivity series of metals or the activity series can be described as the arrangement of metals in the descending order of their reactivities.

The metals at the top of the activity series are powerful reducing agents and can be easily oxidized. These metals easily tarnish/corrode. The reducing ability grows weaker while moving down the series.

The electropositivity of the elements reduces as we move down the reactivity series of metals. All metals above hydrogen in the activity series liberate hydrogen gas upon reacting with dilute HCl.

As given the elements of the reactive metals form more stable compounds therefore, the metals like Ba, Ca, and Mg form more stable compounds than H or Ag.

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Answer:

pic attached

Explanation:

Balanced molecular chemical equation for the reaction of solid copper with aqueous lead(ii) nitrate is then there is no reaction so there is no copper

Chemical equation is a representation of a chemical reaction using symbols of the elements to indicate the amount of substance usually in moles of each reactant and product and solid copper with aqueous lead(ii) nitrate then there is no reaction between copper and lead nitrate solution and this is because copper is less reactive than lead

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The molecular mass of the unknown compound found in the aqueous solution was 223.2g/mol

The sum of the atomic masses of all atoms in a molecule is called as molecular weight

So to get molar mass of the compound from the given weight the concentration of compound is elucidated and thereby leading to the calculation of molar mass

Then the concentration of solute in an aqueous solution can be derived from the osmotic pressure equation

So the osmotic pressure = van't hoff factor then the molarity of solute(M) gas constant(R) temprature(T)

From the given values in the question and applying constant values

8.44 torr = 1(for non electrolytes)× M×62.3637L⁻¹torr⁻¹mol⁻¹×298K

M = 4.54×10⁻⁴M

From the molarity of the given compound the molare mass can be calculated as

Molarity = weight/ molecular weight × 1000/volume(ml)

4.54×10⁻⁴M = 0..0152g/molecular weight × 1000/150ml)

Molecular weight = 223.2g/mol

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Number of bonding electron pair in SF5+ is 5 in number and non bonding electron pairs are 15 in the Lewis structure

Lewis dot structure also called as the electron dot structure are diagrams that describe the chemical bonding between atoms in a molecule. Along with that they also display the total number of electron pairs that are bonded to the atoms and also the electron pairs that are not bonded as well. Lewis structures extend the concept of the electron dot diagram by adding lines between atoms to represent shared pairs in a chemical bond.

In the above given question we need to find out the number of non bonding electron pairs and the bonding electron pairs of SF5+. This molecule is basically derived from SF6 molecule. When SF6 loosed one F atom it becomes SF5+. So we can see that the SF5+ has 5 bonding electron pair which are all bonded to the central S atom.

The non bonded electrons are present around the F atom to complete the valency. So each F atom has 3 pairs of electrons which means in total there are 15 non bonding electron pairs.

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18.1 g is mass of mgf2 is contained in 80. 85 g of a 22. 4% by mass solution of mgf2 in water.

solution mass = 80.85 g

mass of solution percentage = 22.4%

% concentration =  Mass of solute/Mass of solution × 100/1

22.4 = x/80.85 × 100/1

x = 22.4 × 80.85/100

x = 18.1 g

The quantity of substance that makes up an element's atom is known as its atomic mass. One-twelfth of the mass of the carbon-12 atom, with an assigned atomic mass of 12 units, is expressed as a multiple of 1.992646547 1023 gram, or in other words, 1.992646547 gram. One atomic mass unit is equivalent to 1.660539040 1024 grams on this scale (amu). The atomic mass unit is sometimes referred to as the dalton in honor of English scientist John Dalton (Da).

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The process that is not a way for carbon dioxide to reach the atmosphere is Photosynthesis; option C

The carbon cycle is a biogeochemical cycle that describes the processes by which carbon is recycled between the living and non-living components of the environment.

The processes by which carbon is removed from the atmosphere and the processes by which carbon is returned to the atmosphere work together to ensure there is a balance of carbon in the environment.

The processes by which carbon is returned to the atmosphere in the form of carbon dioxide include the following:

The processes by which carbon is removed from the atmosphere include the following:

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Complete question:

Which of the following is not a way for carbon dioxide to reach the atmosphere?

a. forest fires

b. respiration

c. photosynthesis

d. burning of fossil fuels