The amount of UVA radiation hitting a surface at sea level in a lightly clouded day is about 70W/m2. About half of that can be absorbed by the skin. A typical carbon- carbon bond requires 348 kJ/mol to break. A person lies on the beach for about 1 hour without sunscreen (i.e. fully exposed to UVA radiation). Estimate the number of C-C bonds broken in this person’s back (about 0.18 m2) over that period. Assume that the average wavelength of UVA is 335 nm.

Answer:

helium

Explanation:

remaining three are efficient gas

Among the options given below, helium is not an efficient greenhouse gas. Thus, the correct option for this question is A.

Greenhouse gases are those gases that significantly allow solar radiation in order to enter but prevent the escape of heat radiations of longer wavelengths. The names of common greenhouse gases are carbon dioxide, methane, nitrous oxide, CFCs, etc.

According to the context of this question, the presence of these gases in the atmosphere is responsible for the phenomenon of keeping the earth warm. This is known as Greenhouse effect. These gases stimulate the phenomenon of global warming.

Therefore, among the options given below, helium is not an efficient greenhouse gas. Thus, the correct option for this question is A.

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Answer:

states that rock layers with the same unique groupings of fossils are of the same geologic age.

Explanation:

The principle of fossil correlation states that the presence of similar fossils of dead organisms in rock layers indicates that the organisms under investigation must have existed around the same geologic time. This principle can be used in dating the periods when the organism being studied lived.

The geological age system follows a chronological format in tracking the age of an item under study by grouping the time periods that organisms lived into strata.

Answer:

[tex]0.326\frac{N}{cm^2}[/tex]

Explanation:

Hello.

In this case, considering that 1 atm equals 1.01 kPa, we can compute the pressure in kPa first as shown below:

[tex]2.25atm*\frac{1.01kPa}{1atm} =3.26kPa[/tex]

Now, we convert kPa to Pa, considering 1 kPa equals 1000 Pa:

[tex]3.26kPa*\frac{1000Pa}{1kPa}=3260Pa[/tex]

Now, since Pa is equal to N/m², and 1 m equals 100 cm, the pressure in newton per square centimeter turns out:

[tex]3260\frac{N}{m^2}*(\frac{1m}{100cm})^2 \\\\0.326\frac{N}{cm^2}[/tex]

Best regards.

Answer:

O The sound waves are reflected.

Explanation:

When sound waves released by a bat hits an object, the sound waves are reflected back.

Bats used sound reflection for echolocation to determine the position of nearby objects.

Also, they use it to determine the shape and size of objects.

Answer:

B

The sound waves are reflected.

Explanation:

Answer:

Explanation:

i’m not sure but I think it’s 7648%

Answer:

red

Explanation:

blue litmus paper turns red under acetic conditions and red lettuce paper turns blue under basic and alkaline conditions with the color change occurring over the PH range the neutral litmus paper is purple

The answer is red.

took the test.

Answer:

Near the boiling point of the solvent

Explanation:

The process of recrystallization is hinged on the fact that the amount of solute that can be dissolved by a solvent increases with temperature. The process involves creation of a solution by dissolving a solute in a solvent at or near its boiling point.  At the boiling point of the solvent, the solute has a greater solubility in the solvent; not much volume of  the hot solvent is required to dissolve the solute.

Before the solution is later cooled, you can now filter out insoluble impurities from the hot solvent. The quantity of the original solute drops appreciably because impurities have been removed. At this lower temperature, the solution becomes saturated and the solute can no longer be held in solution hence it forms pure crystals of solute, which can be recovered.

Recrystallization must be carried out using the proper solvent. The solute must be relatively insoluble in the solvent at room temperature but more soluble in the solvent at elevated temperature.

As air undergoes conduction better in tile than in carpet, hence a carpeted floor feel warmer to bare feet than tile or wood even though all surfaces are the same temperature.

Conduction is defined as a process as a means of which heat is transferred from the hotter end of the body to it's cooler end.Heat flows spontaneously from a body which is hot to a body which is cold.

In the process of conduction,heat flow is within the body and through itself.In solids the conduction of heat is due to the vibrations and collisions of molecules while in liquids and gases it is due to the random motion of the molecules .

When conduction takes place, heat is usually transferred from one molecule to another as they are in direct contact with each other.There are 2 types of conduction:1) steady state conduction 2) transient conduction.According to the type of energy conduction is of three types:

1) heat conduction

2) electrical conduction

3)sound conduction

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Answer:

The sun's light is blocked by the moon.

Explanation:

During the eclipse, the moon rotates right in front of the sun, that's why the eclipse is so rare and only happens every four(?) years/

Answer:

1.14 M

Explanation:

Let's consider the following reaction.

butane ⇄ isobutane

We can use the concentrations at equilibrium to calculate the equilibrium constant.

Kc = [isobutane] / [butane]

Kc = 2.5 / 1.0

Kc = 2.5

If we add 0.50 M of isobutane, we get [isobutane] = 2.5 + 0.50 = 3.0 M.

This will be an initial concentration in an ICE chart.

        butane ⇄ isobutane

I           1.0              3.0

C         +x                -x

E        1.0+x           3.0-x

The equilibrium constant is:

Kc = 2.5 = [isobutane] / [butane]

2.5 = (3.0-x) / (1.0+x)

2.5 + 2.5x = 3.0-x

x = 0.14

The equilibrium concentration of butane is:

[butane] = 1.0+x = 1.14 M

Answer:

The orbitals on the carbon atom are hybridized; the bonds result from overlap of carbon hybrid orbitals with hydrogen atomic orbitals

Explanation:

In the formation of methane, carbon atoms are sp3 hybridized. One s orbital in carbon mixes with three p orbitals of carbon to yield a set of four sp3 orbitals which bonds to four hydrogen 1s orbitals by sigma bonds.

The molecule is tetrahedral with a bond angle of 109.5 degrees

Answer:

Electrons- 95

Protons- 95

Neutrons-146

Explanation:

An atoms is made up of three fundamental particles; electrons, protons and neutrons,

Americium belongs to the f block in the periodic table. It is an actinide element.

An atom of Am-241 contains 95 protons, 95 electrons and 146 neutrons.

Answer:

7.35 x 1023 atoms.

Explanation:

The mass in grams of a sample of Fli containing 7.35 × 10^23 atoms should be 255 grams.

Since The molar mass of bismuth (Bi) is 208.98 g/mol.

And, 1 mole Bi = 208.98 g/mol = 6.023×10^23 no of atoms

So, the mass in grams should be

= ( 208.98 g/mol ×7.35 × 10^23) ÷ (6.023×10^23)

= 255 grams.

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Answer:

Hope this helped :) good luck! ❤️

Explanation:

A coolant solution is a homogeneous mixture because the coolant particles are not chemically combined with the water (keep their properties) and they are evenly distributed throughout the water.

Answer:

B

Explanation:

The entropy will increase as the ice melts.  While in a solid state (ice) entropy is lower because the molecules are ordered and in a set position.  As the ice melts the molecular have a larger area to roam.  When going from a solid state to a liquid state, entropy rises.  When going from a liquid state to a gaseous state, entropy rises.

Answer:

W and Z

Explanation:

Atoms of the SAME element OR two atoms of DIFFERENT elements will form a MOLECULE.

E.g. 2 atoms of hydrogen + 1 atom of oxygen => 1 molecule of water. This 1 molecule of water can also be called a compound.

Also, 2 atoms of Oxygen can combine to form 1 molecule of Oxygen. This 1 molecule of Oxygen cannot be referred to as a compound.

Atoms of DIFFERENT elements form a COMPOUND.

Therefore, compounds are molecules, but molecules are not compounds.

Thus, the combination of atoms that will form a molecule, but not a compound is:

W(oxygen) + Z(oxygen) = molecule

Answer:

W and Z

Explanation:

Answer:

B. They are too small to be seen with only our eyes.

Explanation:

Why? Because if we could have the ability to see the particles that make-up an object, it may look weird. All particles (the types that make up matter) can not be seen with our eyes because they are too small.

Hope this helped!

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Complete Question

Magnesium sulfate forms a hydrate with the formula [tex]MgSO_4. 7H_20[/tex]. What is the maximum amount of water (in grams) that can be removed from 15 ml of toluene by the addition of 200 mg of anhydrous magnesium sulfate? The molar mass of [tex]MgSO_4[/tex] is 120.4 g/mol; H20 = 18 g/mol.

Answer:

The value  is  [tex]z =  0.2093 \  g[/tex] of  [tex]H_2O[/tex]

Explanation:

From the question we are told that

   The volume of toluene is  [tex]V = 15 mL[/tex]

    The mass of  anhydrous magnesium sulfate is  [tex]m =  200m g  = 200 *10^{-3} \  g[/tex]

   The formula of the hydrate is   [tex]MgSO_4. 7H_20[/tex]

    The molar mass of   [tex]MgSO_4[/tex]  is  [tex]z =120.4 \ g/mol[/tex]

From the formula given we see that

  1 mole of  [tex]Mg SO_4[/tex] wil remove  7 moles of [tex]H_2O[/tex] to for the given formula

Hence

  120.4 g (1 mole) will remove  7 moles (7 * 18 g = 126 g  ) of  [tex]H_2O[/tex] to for the given formula

Therefore 1 g of  [tex]Mg SO_4[/tex]  x g  of  [tex]H_2O[/tex]  

So

     [tex]x  =  \frac{x]126 *  1}{ 120.4 }[/tex]

=>     [tex]x  =  1.0465 \  g [/tex]

From our calculation we obtained that

  1 g of [tex]Mg SO_4[/tex] will remove  [tex]x  =  1.0465 \  g [/tex]  of  [tex]H_2O[/tex]  

Then  

   [tex]200 *10^{-3} \  g[/tex] of [tex]Mg SO_4[/tex] will remove z g of  [tex]x  =  1.0465 \  g [/tex]  of  [tex]H_2O[/tex]  

So

   [tex]z =  200 *10^{-3} *  1.0465[/tex]

=>[tex]z =  200 *10^{-3} *  1.0465[/tex]

=>[tex]z =  0.2093 \  g[/tex] of  [tex]H_2O[/tex]  

Answer:

The solubility of Zn(OH)₂ at 25ºC is 1.96x 10⁻⁶,

Explanation:

The solubility is the maximum amount of a solute that can be dissolved in a certain volume of liquid (usually water) at a given temperature.

First, we write the dissolution reaction of Zn(OH)₂ in water, which is:

Zn(OH)₂ (s)  ⇄ Zn²⁺ + 2 OH⁻

We know that the Kps, that is, the dissolution equilibrium constant for this compound at 25ºC is 3.0x 10⁻¹⁷.

Therefore, the Kps is:

Kps= [Zn²⁺][OH⁻]² (since Zn(OH)₂ is solid, it is not accounted for).

Given the reaction, we can see that for every single Zn²⁺ ion, two OH⁻ ions are produced. Therefore, if the concentration of Zn²⁺ dissolved is x M, the concentration of OH⁻ dissolved will be 2x M.

Substituting these values in Kps, we have:

[Zn²⁺][OH⁻]² = (x)(2x)² = 3.0x 10⁻¹⁷

                            4x³ = 3.0x 10⁻¹⁷

                             x= ∛ (3.0x 10⁻¹⁷ ÷ 4)

                            x= 1.96x 10⁻⁶

Therefore, the molar solubility of Zn(OH)₂ at 25ºC will be 1.96x 10⁻⁶.

Answer:

Even though oxygen is transported via the blood, you may recall that oxygen is not very soluble in liquids. A small amount of oxygen does dissolve in the blood and is transported in the bloodstream, but it is only about 1.5% of the total amount. The majority of oxygen molecules are carried from the lungs to the body’s tissues by a specialized transport system, which relies on the erythrocyte—the red blood cell. Erythrocytes contain a metalloprotein, hemoglobin, which serves to bind oxygen molecules to the erythrocyte (Figure 1). Heme is the portion of hemoglobin that contains iron, and it is heme that binds oxygen. One hemoglobin molecule contains iron-containing Heme molecules, and because of this, each hemoglobin molecule is capable of carrying up to four molecules of oxygen. As oxygen diffuses across the respiratory membrane from the alveolus to the capillary, it also diffuses into the red blood cell and is bound by hemoglobin. The following reversible chemical reaction describes the production of the final product, oxyhemoglobin (Hb–O2), which is formed when oxygen binds to hemoglobin. Oxyhemoglobin is a bright red-colored molecule that contributes to the bright red color of oxygenated blood.

Hb + O2 ↔ Hb − O2

Extremophiles are bacteria, archaea, as well as eukarya across all three domains of life. Cells make up every organisms.

Extremophiles contain bacteria, archaea, as well as eukarya from all three domains of life.

Any organic, biological system which works as a separate entity was referred to as an organism.

Extremophiles are organisms that can survive in harsh settings, such as those with high temperatures, radiation, salt, or pH levels. In the planet's evolutionary development, several creatures have been ecologically dominating.

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Answer:

Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β linked D-glucose units. Cellulose is an important structural component of the primary cell wall of green plants, many forms of algae and the oomycetes.

Explanation:

Answer:

Hope this helped.

Explanation:

Cellulose is a molecule, consisting of hundreds – and sometimes even thousands – of carbon, hydrogen and oxygen atoms. Cellulose is the main substance in the walls of plant cells, helping plants to remain stiff and upright. Humans cannot digest cellulose, but it is important in the diet as fibre.

Answer:

The correct answer is: K'= 0.033.

Explanation:

The formation of HI from H₂ and I₂ is given by:

H₂ + I₂ → 2 HI      K= 29.9

The decomposition of HI is the reverse reaction of the formation of HI:

2 HI → H₂ + I₂     K'

Thus, K' is the equilibrium constant for the reverse reaction of formation of HI. It is calculated as the reciprocal of the equilibrium constant of the forward reaction (K):

K' = 1/K = 1/(29.9)= 0.033

Therefore, the equilibrium constant for the decomposition of HI is K'= 0.033

Answer:

[tex]P=1.23atm[/tex]

Explanation:

Hello.

In this case, since the total pressure in the container includes the pressures of both hydrogen and water:

[tex]P=P_{H_2}+P_{H_2O}[/tex]

For the reacting solution of HCl, based on the 6:3 mole ratio with hydrogen in the chemical reaction, we can next compute the yielded moles o hydrogen:

[tex]n_{H_2}=0.235L*1.50\frac{molHCl}{L}*\frac{3molH_2}{6molHCl} =0.176molH_2[/tex]

Then, by using the ideal gas equation we compute the pressure of hydrogen for the collected 3.60 L at 25.0 °C (298.15 K):

[tex]P_{H_2}=\frac{n_{H_2}RT}{V} =\frac{0.176mol*0.082\frac{atm*L}{mol*K}*298.15K}{3.60L}=1.20atm[/tex]

Finally, since the vapor pressure of water in at is 0.03129, the total pressure is then:

[tex]P=1.20atm+0.03129atm\\\\P=1.23atm[/tex]

Best regards!

Moles of [tex]H_2O[/tex] ,

[tex]n_{H_2O}=\dfrac{42}{2\times 1 + 16}=\dfrac{42}{18}\\\\n_{H_2O}=2.33\ moles[/tex]

Moles of acetic acid [tex]HCH_3CO_2[/tex] ,

[tex]n_{A.A}=\dfrac{77}{1 + 12 + 3 + 12 + 16\times 2}=\dfrac{77}{60}\\\\n_{A.A}=1.28\ moles[/tex]

Mole fraction of water :

[tex]M.F_{H_2O}=\dfrac{n_{H_2O}}{n_{H_2O}+n_{A.A}}\\\\M.F_{H_2O}=\dfrac{2.33}{2.33+1.28}\\\\M.F_{H_2O}=0.645[/tex]

Therefore, mole fraction of water in this solution is 0.645 .

Hence, this is the required solution.

Answer:

D

Explanation:

Answer:

D

Explanation:

So. Radiation happens when heat moves as energy waves, called infrared waves, directly from its source to something else.... When the heat waves hits the cooler thing, they make the molecules of the cooler object speed up.