In which orbitals would the valence electrons for selenium (Se) be placed?

Answer:

Explanation:

The density of a substance can be found by using the formula

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

From the question we have

[tex]density = \frac{18}{3} \\ [/tex]

We have the final answer as

Hope this helps you

Explanation:

i cant even see any thing

Answer: A and D

Explanation:

High concentrations of carbon dioxide make it harder for marine animals to respire (to extract oxygen from seawater). This, in turn, makes it harder for these animals to find food, avoid predators, and reproduce. Low concentrations of oxygen can have similar effect

Becay the Ocean's Carbon Balance. The idea seemed simple enough: the more carbon dioxide that people pumped into the atmosphere by burning fossil fuels, the more the oceans would absorb. ... Water trapped at the surface would become saturated, at which point, the ocean would slow its carbon uptake.

Answer:

20000

Explanation:

Answer:

I say the second one, im not rlly sure tho

Explanation:

For the extraction of at least 95% of Y in water, 3 extractions are to be performed.

Distribution coefficient can be defined as the ratio of the concentration of solute in an organic solvent to water.

Distribution coefficient = [tex]\rm \dfrac{concentration\;in\;solvent}{concentration\;in\;water}[/tex]

Concentration in water = 100-X per 50 ml

Distribution coefficient = [tex]\rm \dfrac{\frac{X}{10} }{\frac{100-X}{50} }[/tex]

4 = [tex]\rm \dfrac{\frac{X}{10} }{\frac{100-X}{50} }[/tex]

4 = [tex]\rm \dfrac{50X}{1000-X}[/tex]

4000 - 4X = 50X

X = 74.1 %

Thus, after the first extraction, the amount of Y extracted is 74.1%.

We have to extract at least 95% of Y. Thus, the second extraction is performed.

Remaining y = 25.9%

The concentration in organic solvent = X per 10 ml

Concentration in water = 25.9 -X

Distribution coefficient = [tex]\rm \dfrac{\frac{X}{10} }{\frac{25.9-X}{50} }[/tex]

4 = [tex]\rm \dfrac{\frac{X}{10} }{\frac{25.9-X}{50} }[/tex]

4 = [tex]\rm \dfrac{50X}{259-X}[/tex]

1036 - 4X = 50X

X = 19.2%

Thus, after the second extraction the amount of Y extarcted = first extraction + second extraction

The amount of Y extracted = 74.1 + 19.2 %

The amount of Y extracted = 93.3%

The remaining Y for third extraction = 100 - 93.3

The remaining Y for the third extraction = 6.7%

Concentration in water = 100 - 6.7

Distribution coefficient = [tex]\rm \dfrac{\frac{X}{10} }{\frac{6.7-X}{50} }[/tex]

4 = [tex]\rm \dfrac{\frac{X}{10} }{\frac{6.7-X}{50} }[/tex]

4 = [tex]\rm \dfrac{50X}{67-X}[/tex]

268 - 4X = 50X

X = 5.0%

The total extraction after third extraction = 93.3 + 5%

The total extraction after third extraction = 98.3%.

Thus for the extraction of at least 95% of Y in water, 3 extractions are to be performed.

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Answer:

The radius of O^2- is  1.5*10^-8 cm and the radius of

Mg ^2+ is 6.2*10^-9 cm

Explanation:

Face centered cubic : 1/8 atoms on each edges + 1/2 atoms on each face

                                           = [tex]\frac{1}{8}* 8 + \frac{1}{2}*6[/tex]  = 4 effective atoms

MgO have a structure like NaCl forms a lattice of FCC.

density of the lattice =  [tex]\frac{ z.M}{a^3*Na}[/tex]

z : no of atoms

M: mass of the atoms

a: radius of the atom

Na: Avogadro's number

a^3(radius)  = [tex]\frac{ 4*40.3}{3.58*6.022*10^23}[/tex]

a^3 = 7.477 * 10^-23 cm^3

a = 4.21 * 10^-8 cm

Now calculating the anionic(ra O^2-) and cationic (rc Mg^2+)

in Fcc a = 2[tex]\sqrt{2} ra[/tex]

ra = 1.5*10^-8 cm

a = 2ra + 2rc

rc = a/2 -ra

rc = 6.2*10^-9 cm

The radius of O^2- is  1.5*10^-8 cm and the radius of Mg ^2+ is 6.2*10^-9 cm

Answer:

3.43×10¹ mol

Explanation:

Given data:

Initial number of  moles = 12.4 mol

Initial volume = 122.8 L

Final volume = 339.2 L

Final number of moles = ?

Solution:

The number of moles and volume are directly proportional to each other at same temperature and pressure.

Formula:

V₁/n₁  =  V₂/n₂

Now we will put the values,

122.8 L/ 12.4 mol  =  339.2 L / n₂

n₂ = 339.2 L× 12.4 mol  / 122.8 L

n₂ = 4206.08 L.mol /122.8 L

n₂ = 34.3mol

In scientific notation:

3.43×10¹ mol

Answer:

Butanoic acid.

Explanation:

Answer:

Iron is natural. Paper is man-made

Explanation:

Answer:

iron

Explanation:

Answer:

The answer is Option a, that is "−9kJmole,5kJmole".

Explanation:

Please find the complete question in the attached file.

In the question, it uses the catalyst inside a process, which does not modify the process eigenvalues, however, it decreases the active energy with an enthalpy of -9kJmole, and also the power for activating decreases around 13 to 5 kJ mole, that's why the choice a is correct.

Answer:

B

Explanation:

i just read it na, but i forgot the explanation

Answer:

A. and B.

Explanation:

Anion is negative as well as a negative ion.

(Just took the quiz)

The visible light with a wavelength of 4.7x10^-7 meters will have a frequency of 0.67 × 10¹⁵ Hz.

The term wavelength is defined as the distance between two successive crest and two successive trough. Wave length is represented by the symbol "λ" (lambda). The formula of wavelength is given by equation as follows:

λ = ν × f

So, the distance between either one crest or trough of one wave and the next wave is known as wavelength.

Wavelength relates to frequency as follows:

λ = ν × f

Where,

λ = Wavelength of light

ν = speed of light

f = frequency of light

We have

λ = 4.7x10^-7 meters

F = ?

ν = 3 × 10⁸ m/s

By substituting this values in given equation we get,

λ = ν × f

f = 3 × 10⁸ / 4.7x10^-7

f = 0.67 × 10¹⁵ Hz

Thus, visible light with a wavelength of 4.7x10^-7 meters will have a frequency of 0.67 × 10¹⁵ Hz.

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Answer:

0.322 mols of NaSO4

Explanation:

Molality = Mols of Solute / kg of Solvent

Molality is given as 0.140 m = mols/kg

kg of solution is given as 2.30 kg

Mols of Solute = Molality * kg of Solvent

Mols of Solute = [tex]\frac{0.140 }{ 1 kg } *2.30 kg[/tex]

Mols of Solute = 0.322 mols

The number of mole of Na₂SO₄ required to prepare the solution is 0.322 mole

The Molality of a solution is defined as the mole of solute per Kg of water i.e

Molality = mole / mass (Kg) of water.

With the above formula, we can obtain the mole of Na₂SO₄ in the solution as follow:

Molality of Na₂SO₄ = 0.140 M

Mass of water = 2.30 Kg

Mole = Molality × mass of water

Mole of Na₂SO₄ = 0.140 × 2.30

Therefore, the mole of Na₂SO₄ in the solution is 0.322 mole

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Answer:c

Explanation:

it’s gained kinetic from the gravitational potential energy at the top

Answer:

[tex]M=0.16M[/tex]

Explanation:

Hello!

In this case, since the molarity is defined as moles of solute divided by liters of solution, since we have phenol with a molar mass of 94.12 g/mol, we can first compute the moles in 1.5 g of phenol:

[tex]n=1.5g*\frac{1mol}{94.12 g}=0.016mol[/tex]

Next, since 1000 mL = 1 L, we notice that the volume of the solution is 0.100 L and therefore, the molarity of such solution turns out:

[tex]M=\frac{n}{V}=\frac{0.016mol}{0.100L}\\\\M=0.16M[/tex]

Best regards!

Answer:

Positive charge if there are more protons than electrons. Negative charge if there are more electrons than protons. If there's the same amount of protons and electrons, it's a neutral charge.

Explanation:

All matter is made up of electrons and protons. Electrons have a negative charge, protons have a positive charge. A charge is a type of particle measurement, and it is determined based on the amount of protons or electrons in a certain thing. The charge is which one there are more of, and there’s no charge (neutral) if they’re balanced.  

Answer:

A river and its tributaries make up a watershed (aka river system or drainage basin)

Pls mark me as brainliest

Answer:

river system

Explanation:

a river and all its tributaries make up a river system

Complete Question

Calculate the pH during the titration of 20.00 mL of 0.1000 M trimethylamine, (CH3)3N(aq), with 0.2000 M HClO4(aq) after 9.48 mL of the acid have been added.Kb of trimethylamine = 6.5 x 10-5.

Answer:

The pH is  [tex]pH = 9.84[/tex]  

Explanation:

From  the question we are told that

   The  volume of trimethylamine, (CH3)3N(aq) is [tex]V_{t} = 20.00mL[/tex]

    The concentration of trimethylamine is [tex]C_t = 0.1000 \ M[/tex]  

    The  volume of HClO4(aq) is [tex]V_{h} = 9.48 mL[/tex]

    The  concentration of  HClO4(aq) is  [tex]C_h = 0.200 M[/tex]

      The Kb  value is  [tex]K_b = 6.5 * 10^{-5}[/tex]

Generally the the pOH of this reaction is mathematically represented as

       [tex]pOH = pK_b + log [\frac{N_h}{N_b} ][/tex]

Here [tex]N_h[/tex] is the number of moles of acid which is evaluated as

      [tex]N_h = C_h * V_h[/tex]

=>    [tex]N_h = 0.200 * 9.48[/tex]

=>    [tex]N_h = 1.896[/tex]

Here [tex]N_t[/tex] is the number of moles of acid which is evaluated as

      [tex]N_t = C_t * V_t[/tex]

=>    [tex]N_t = 0.100 * 20[/tex]

=>    [tex]N_t = 2[/tex]

So

     [tex]pOH = -log(K_b) + log [\frac{N_h}{N_b} ][/tex]

     [tex]pOH = -log(6.5*10^{-5}) + log [\frac{1.896}{2} ][/tex]

=>   [tex]pOH = 4.1639[/tex]

Generally the pH is mathematically represented as

       [tex]pH = 14 - pOH[/tex]

=>    [tex]pH = 14 - 4.1639[/tex]  

=>    [tex]pH = 9.84[/tex]  

Answer:

[tex]m_{O_2}=120gO_2[/tex]

Explanation:

Hello!

In this case, since the decomposition of potassium chlorate is:

[tex]2KClO_3\rightarrow 2KCl+3O_2[/tex]

We can see a 2:3 mole ratio between potassium chlorate and oxygen (molar mass 32.0 g/mol), thus, via stoichiometry, we compute the mass of oxygen that are produced by the decomposition of 2.50 moles of this reactant:

[tex]m_{O_2}=2.50molKClO_3*\frac{3molO_2}{2molKClO_3} *\frac{32.0gO_2}{1molO_2}\\\\m_{O_2}=120gO_2[/tex]

Best regards!

Answer:

0.56 mL

Explanation:

Methane gas and chlorine gas react to form hydrogen chloride gas and carbon tetrachloride gas. What volume of carbon tetrachloride would be produced by this reaction if 1.1 mL of chlorine were consumed.

Step 1: Write the balanced equation

CH₄(g) + 2 Cl₂(g) → CCl₄(g) + 4 HCl (g)

Step 2: Calculate the moles corresponding to 1.1 mL of Cl₂

At standard temperature and pressure, 1 mole of a gas has a volume of 22.4 L.

1.1 × 10⁻³ L × 1 mol/22.4 L = 4.9 × 10⁻⁵ mol

Step 3: Calculate the moles of CCl₄ formed from 4.9 × 10⁻⁵ moles of Cl₂

The molar ratio of Cl₂ to CCl₄ is 2:1. The moles of CCl₄ are 1/2 × 4.9 × 10⁻⁵ mol = 2.5 × 10⁻⁵ mol.

Step 4: Calculate the volume corresponding to 2.5 × 10⁻⁵ moles of CCl₄

At standard temperature and pressure, 1 mole of a gas has a volume of 22.4 L.

2.5 × 10⁻⁵ mol × 22.4 L/mol = 5.6 × 10⁻⁴ L = 0.56 mL

Answer:

Molarity acetate: 0.1353M

Molarity acetic acid: 0.0418M

Explanation:

When in solution you have a weak acid (Acetic acid) and its conjugate base (sodium acetate) a buffer is produced. The pH of this buffer is obtained using the H-H equation:

pH = pKa + log [A⁻] / [HA]

Where pH is pH of the solution = 5.25

pKa is pKa of acetic buffer = 4.74

[A⁻] is molarity of acetate ion - Molar mass sodium acetate: 82.03g/mol-:

11.1g * (1mol / 82.03g) = 0.1353moles A⁻ / 1.0L = 0.1353M

And [HA] are moles of acetic acid.

Solving for HA:

5.25 = 4.74 + log [0.1353] / [HA]

0.51 =  log [0.1353] / [HA]

3.236 = [0.1353] / [HA]

[HA] = 0.1353M / 3.236

[HA] = 0.0418M

Answer: The force on the firefly

The unfortunate firefly hitting the bus does not change the velocity of the bus very much. Technically there is a change, but it's so very small and miniscule that it barely registers. To any casual observer not paying very close attention, they don't notice anything at all. So effectively the force on the firefly is a lot greater since the firefly got the worst end of the deal.

So in short, we look at the velocity of each object and see which velocity changed the most. In this case, the firefly's velocity changed from whatever speed it was flying to 0 when it stops flying all together. That's why the force is greater on the bug.

Answer:

E = 165.75×10⁻²⁶ J

Explanation:

Given data:

Wavelength = 0.12 m

Energy of wave = ?

Solution:

Formula:

E = h c/λ

c = 3×10⁸ m/s

h = 6.63×10⁻³⁴ Js

Now we will put the values in formula.

E = 6.63×10⁻³⁴ Js × 3×10⁸ m/s / 0.12 m

E = 19.89×10⁻²⁶ J.m / 0.12 m

E = 165.75×10⁻²⁶ J

Answer:

See explanation

Explanation:

The boiling point of  a substance at a location depends mostly on the atmospheric pressure in that location. The lower the atmospheric pressure in a location, the lower the boiling point and vice versa.

Boiling point is defined as the temperature at which the vapor pressure of the liquid becomes equal to the atmospheric pressure.

In Denver (the mile high city), alcohol will boil at a lower temperature(due to its high altitude) than in Houston because pressure decreases with height.

The boiling point of alcohol in Houston and Denver will vary as a result of the difference in atmospheric pressure.

The boiling point of  a compound at a particular location depends on the

atmospheric pressure of that location. The lower the atmospheric pressure

of a given place or area, the lower the boiling point and vice versa.

In Denver (the mile high city), alcohol will boil at a lower temperature as a

result of its higher altitude than in Houston because atmospheric pressure

decreases with increase in height and vice versa.

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Answer: D) Nitrogen Dioxide

Explanation:

The characteristics of moles allow you to find that the correct answer for which sample weighs more is:

             D) Nitrogen Dioxide

The molecular weight of the substance is the weight of one mole of a material, where one mole is Avogadro's number of particles.

In all chemical reactions the relationships are given as a function of moles.

Let's find the molecular weight of each of the substances, we take the atomic weights from the periodic table

Element      PA (gr / mol)

   H                     1

   C                   12

   N                   14

   O                   16

   Ar                  40

A) Ammonia with NH₃ formula

     weight of a mole of molecules

           MP = 14 + 3

           PM = 17 gr / mol

B) Argon symbol Ar

    It is a noble gas and does not react

         PM = 40 gr / mol

C) Carbon dioxide formula CO₂

      Weight per mole of substance

        PM = 12 + 2 16

        Pm = 44 gr / mol

D) Nitrogen dioxide formula NO₂

       Weight per molecular

         MP = 14 + 2 16

         PM = 46 gr / mol

E) Oxygen symbol O formula O₂

      Molecular weights

         PM = 2 16

         PPM = 32 gr / mol

It indicates that we have two liters of sample, so the number of moles of each substance is the same, therefore the substance that weighs more is Nitrogen Dioxide (NO₂)

When reviewing the different answer, the correct one is:

            D) Nitrogen Dioxide

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Answer:

[Ar]3d4 is the ground-state electron configuration for the Mn4 ion

but i don't know whether it is paramagnetic or daimagnetic