How many atoms can be found in a sample of 75g of silicon

Answer:

It is the one that has start and finish and a compass on it...I am sorry I can share images for some reason. And underneath the compass, it says 1.0 Mile. It also has a compass in the bottom right-hand corner.

Explanation:

I just took the quiz and got it correct!

Answer:

Use the Rydberg Equation 1/λ = R(1/n²(final) - 1/n²(initial) where R = 109,678 cm⁻¹. Substitute initial orbital number and final orbital number and solve for wavelength (λ).

Explanation:

Example:

Assume an electron transition from n = 5 to n = 2.

1/λ = 109,678cm⁻¹(1/2² - 1/5²) = 109,678(0.25 - 0.04)cm⁻¹ = 23,032cm⁻¹

λ = 1/23,032cm⁻¹ = 4.34 x 10⁻⁵cm x 10⁻²m/cm x 10⁹nm/m = 434nm

As far as the intelligence of canines, it is widely accepted as a fact that the Border Collie is the most intelligent breed of dog.

The conclusion that border collies are the most intelligent breed of dog is credited to a canine psychologist by the name of Stanley Coren. He studied over 138 recognized breeds of dogs to measure the ease with which they learned new commands and the obedience rate of each breed.

Coren studies the learning and obedience of Border Collies over the course of 199 trials and found that this breed of dog performed 95% better than most other breeds, with only 9 of the 138 breeds studied coming close to the results of the border collie. Easily earning the title of the most intelligent breed of dogs.

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Answer:

you see le bear

you brain sends signals

your heart and lungs receive said signals

spring to action

Answer:

I think it's C. hope this helps:)

Answer:

Your answer would be 6

Answer:

1 it is 1

Explanation:

Answer -ˋˏ ༻༺ ˎˊ-

A common use for gravity filtration is for separating anhydrous magnesium sulfate (MgSO4) from an organic solution that it has dried (Figure 1.68b). Anhydrous magnesium sulfate is powdery, and with swirling in an organic solvent creates a fine dispersal of particles like a snow globe.

Answer:

Every amino acid also has another atom or group of atoms bonded to the central atom known as the R group. This R group, or side chain, gives each amino acid proteins specific characteristics, including size, polarity, and pH.

Explanation:

The R group is another atom or group of atoms that is attached to the core atom in every amino acid. This R group, or side chain, provides each amino acid protein with unique properties such as size, polarity, and pH.

Amino acids are chemical molecules that are used to construct proteins. Proteins are vital macromolecules in living organisms, serving a variety of functions including enzymatic catalysis, structural support, transportation, immunological response, and others. A polypeptide chain is formed by linking amino acids in a precise sequence, which subsequently folds into a three-dimensional structure to make a functioning protein.

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Considering the reaction stoichiometry, the enthalpy change if enough propane was burned to give off 12 moles of carbon dioxide gas is 8228 kJ.

The balanced reaction is:

C₃H₈(g) + 5 O₂(g) → 3 CO₂(g) + 4 H₂O(l)

The heat of combustion of propane, C₃H₈, is -2057 kJ/mol. This is, 2057 kJ is released for every 1 mol C₃H₈.

So to determine the enthalpy change if enough propane was burned to emit 12 moles of carbon dioxide, you must take into account the stoichiometry of the reaction.

By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:

Then you can apply the following rule of three: if by stoichiometry 3 moles of CO₂ are produced by 1 mole of C₃H₈, 12 moles of CO₂ are produced by how many moles of C₃H₈?

[tex]amount of moles of C_{3} H_{8} =\frac{12 moles of CO_{2}x1 mole of C_{3} H_{8} }{3 moles of CO_{2}}[/tex]

amount of moles of C₃H₈= 4 moles

So to determine the enthalpy change, you can apply the following rule of three: If for each mole of C₃H₈ 2057 kJ are released, for 4 moles of C₃H₈ how much heat is released?

[tex]Heat released=\frac{4 molesx2057 kJ}{1 mole}[/tex]

Heat released= 8228 kJ

The enthalpy change if enough propane was burned to give off 12 moles of carbon dioxide gas is 8228 kJ.

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Answer:

chu papi

Explanation:

Answer:

C

Explanation:

The azimuthal quantum number can take values from 0 to (n-1)

So in answer C n= 3, l can take values between 0

and 2.

l can't be 3.

ml can take values from -l to +l.

Hope you understood

Answer :

[tex] \: [/tex]

Concentration of Solutions

Recall that a solution consists of two components: solute (the dissolved material) and solvent (the liquid in which the solute is dissolved). The amount of solute in a given amount of solution or solvent is known as the concentration. The two most common ways of expressing concentration are molarity and molality.

Molarity

The molar concentration (M) of a solution is defined as the number of moles of solute (n) per liter of solution (i.e, the volume, V solution):

M = n / V solution

The units of molarity are mol/L, often abbreviated as M.

For example, the number of moles of NaCl in 0.123L of a 1.00M solution of NaCl can be calculated as follows:

[tex]0.123 \: l \: \: of \: solution \: \times \: \frac{1.00 \: mole}{1.00 \: l \: of \: solution \: } \: \\ = 0.123 \: moles[/tex]

Molality :

The molal concentration (m) of a solution is defined as the number of moles of solute (n) per kilogram of solvent (i.e., the mass of the solvent, msolvent):

[tex]m = \frac{n}{v \: solution} [/tex]

For example, the number of moles of NaCl dissolved in 0.123kg of H2O (the solvent), in order to make a 1.00m solution of NaCl, can be calculated as follows:

[tex]0.123 \: kg \: of \: solvent \: = \frac{1.00 \: mole}{1.00 \: kg \: of \: solvent \: } \\ = 0.123 \: moles[/tex]

Answer:

We can say that we need 171 g barium hydroxide needed to make one model equals solution.

Explanation:

I hope this answered your question.

171 gram of  Ba(OH)2, in grams, is needed to make a 1.00 m aqueous solution.

Mass is the quantity of matter. The mass is calculated by the density divide by the volume.

In 1.00 solution, the mass of Ba(OH)2 is 171 gram.

Thus, the mass of Ba(OH)2 is 171 gram.

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Answer:

Sound requires a medium to move through; light does not.

Sound and light are similar in that both are forms of energy that travel in waves.

Explanation:

Sound and light are similar in that both are forms of energy that travel in waves. They both have properties of wavelength, freqency and amplitude. Sound can only travel through a medium (substance) while light can travel through empty space. Sound is a form of mechanical energy caused by vibrations of matter.

Light waves DO NOT require a medium, they travel fastest in empty space; Sound waves REQUIRE a medium, they travel fastest in dense material like solids. Sound is a longitudinal wave.

Experiment: Does it Dissolve?

Materials Needed:

Step 1: Form a question before starting the experiment.

Step 2: Make a hypothesis for each substance.

Step 3: Scoop a teaspoon of each substance in the jars, only adding one substance per jar. Stir it up!

Step 4: Observe whether or not each substance dissolves and record the findings.

Answer:

c

Explanation:

allow plants to absorb water and nutrients from the soil

Answer: 1 mole

Explanation:

One mole reacts because there is a 1:1 ratio between the potassium and water at the beginning of the equation. 2K+2H2O has a 1 to 1 ratio. If one potassium reacts there is one h2o that also reacts.

Taking into account the reaction stoichiometry, if one mole of potassium reacts, 1 mole of water are consumed.

In first place, the balanced reaction is:

2 K + 2 H₂O → 2 KOH + H₂

By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:

The amount of water consumed is calculated from the following rule of three: if by stoichiometry 2 moles of K react with 2 moles of H₂O, 1 mole of K react with how many moles of H₂O?

[tex]amount of moles of H_{2} O=\frac{1 mole of Kx2 moles ofH_{2} O }{2 moles of K}[/tex]

amount of moles of H₂O= 1 mole

In summary, if one mole of potassium reacts, 1 mole of water are consumed.

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Answer:

Specific heat of ethyl chloride in gas and liquid phases, enthalpy of vaporization and specific heat of solid surface.

Explanation:

In order to determine the final temperature, the heat lost by the chloride needs to be found. This would require the specific heat in both phases and the enthalpy of vaporization. (you will use q=mc(delta)T and q=m(delta)H)

Then the energy gained by the surface needs to be found. This will require the specific heat in order to use the q=mc(delta)T equation.

The enthalpies that we consider to calculate the final temperature of the surface are Specific heat of surface and ethyl chloride as well as Heat of vaporization of liquid & vapor ethyl chloride.

Enthalpy of any reaction tells about the total amount of heat absrobed and released during a chemical reaction.

According to the question, heat released by the surface is absorbed by the ethyl chloride and by absorbing this energy ethyl chlorode will change into the vapor form. In the whole process if we want ot calculate the final temperature on the surface then we should consider:

Hence, required enthalpies are Specific heat of surface and ethyl chloride as well as Heat of vaporization of liquid & vapor ethyl chloride.

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Answer:

The answer is B

B = Petri dishes and sterile droppers

Explanation:

Answer:

There are 95 atoms in mercury phosphate

Explanation:

You just add the atomic number for both elements

Answer:

3. 0.819L (819 mL)

Explanation: Before we go about solving this, we need to do some conversions prior to using the gas law, the gas law is as follows...

P(atm)*V(L)=n(mol)*r(constant)*T(in kelvin)

So here are all the conversions you need.

620 mm Hg -> 0.816 atm

1140 mL -> 1.14 L

37 C -> 310.15 K

After plugging in our new converted values, we will proceed to solve the number of moles of the gas present, our n value, so our equation will look like this...(Note: Constant r in this case is 0.08206 L*atm/K*mol)

(0.816 atm)(1.14 L) = n(0.08206)(310.15)

Solving for n we get 0.03653 moles.

Now our second part is to figure out the volume AT STP (standard temperature/pressure). In the STP conditions, your temperature defaults to 0 C (273.15 K) and 1 atm. Now there is an easier way to do this, but I'll also show the more comprehensive way. Here is the easier method...

Since 1 mole of every gas occupies 22.4 L at STP, we can simply multiply this by our number of moles. So (22.4L)(0.3653 mol) to give us 0.818272.

However, a more accurate answer can be given like this...

Plugging n back into the same equation and this time resetting pressure to 1 atm and temperature to 273.15 K and conserving our number of moles we get...

(1 atm)(v) = (0.03653 mol)(0.08206)(273.15 K)

v = (0.03653)(0.08206)(273.15)

v = 0.8188 L = 0.819 L or 819 mL

no I will not please put you because that's the god of the Bible

Metals are good conductors of heat and electricity, and are malleable (they can be hammered into sheets) and ductile (they can be drawn into wire).

Nonmetals are (usually) poor conductors of heat and electricity, and are not malleable or ductile; many of the elemental nonmetals are gases at room temperature, while others are liquids and others are solids. 

The metalloids are intermediate in their properties.  In their physical properties, they are more like the nonmetals, but under certain circumstances, several of them can be made to conduct electricity.

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Answer:

In the previous section, we discussed the relationship between the bulk mass of a substance and the number of atoms or molecules it contains (moles). Given the chemical formula of the substance, we were able to determine the amount of the substance (moles) from its mass, and vice versa. But what if the chemical formula of a substance is unknown? In this section, we will explore how to apply these very same principles in order to derive the chemical formulas of unknown substances from experimental mass measurements.

Explanation:

tally. The results of these measurements permit the calculation of the compound’s percent composition, defined as the percentage by mass of each element in the compound. For example, consider a gaseous compound composed solely of carbon and hydrogen. The percent composition of this compound could be represented as follows:

\displaystyle \%\text{H}=\frac{\text{mass H}}{\text{mass compound}}\times 100\%%H=

mass compound

mass H

×100%

\displaystyle \%\text{C}=\frac{\text{mass C}}{\text{mass compound}}\times 100\%%C=

mass compound

mass C

×100%

If analysis of a 10.0-g sample of this gas showed it to contain 2.5 g H and 7.5 g C, the percent composition would be calculated to be 25% H and 75% C:

\displaystyle \%\text{H}=\frac{2.5\text{g H}}{10.0\text{g compound}}\times 100\%=25\%%H=

10.0g compound

2.5g H

×100%=25%

\displaystyle \%\text{C}=\frac{7.5\text{g C}}{10.0\text{g compound}}\times 100\%=75\%%C=

10.0g compound

7.5g C

×100%=75%

There are two modes in which unstable nuclei of radioactive elements may decay. They are by α - emission or by β - emission. Among the given options, the α - emission is ₆₄¹⁴⁸Gd → ₆₂¹⁴⁴Sm + ₂⁴He. The correct option is D.

According to the theory of radioactive disintegration, the atoms of all the radioactive elements undergo spontaneous disintegration with the emission of α or β particles to yield atoms of new elements. When a radionuclide decays by emitting an  α - particle, it is called α - decay.

When a radionuclide undergoes  α - emission, i.e. a helium nucleus there occurs a decrease of 2 units in the atomic number and a decrease of 4 units in the mass number. The new nuclide produced has an atomic number 2 units less and a mass number 4 units less than the parent.

₆₄¹⁴⁸Gd → ₆₂¹⁴⁴Sm + ₂⁴He represents α - emission.

Thus the correct option is D.

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Answer:

The dipole forces (particularly H-bonds) that keep polar solute molecules together can be replaced by polar solute-solvent interactions, so substances that are predominantly polar (like glucose) dissolve in polar solvents like water but not in nonpolar solvents like hexane (H-bonds).

Explanation:

Explanation:

A moon orbits in a roughly circular path around a planet with a mass of 8.6 x 1023 kg. The distance from the center of the moon to the center of the planet is 7.04 x 106 meters. Calculate the speed of the moon in m/s.