Need help on 17,19,20 please.

Mass in grams of CH₃OH would need to be added to 380.1 g of water in order to lower the freezing point of water by 12.0 °C is 78.53 g .

The depression in freezing point is given as :

ΔT = i × K × m

given that :

molar mass of  CH₃OH = 32.04 g/mol

volume of water = 380.1 g = 0.3801 kg

change in freezing point = 12 °C

K = 1.86 °C/m

i = 1  (CH₃OH does not dissociate in water , so i =1 )

putting all the values :

m = 12 / 1 ×1.86

m =  6.45 m

now, molality =  moles of solute / solvent in kg

           6.45 moles/kg   =   moles / 0.3801 kg

        moles of solute = 2.451 moles

therefore,

mass = moles × molar mass

mass = 2.451 moles × 32.04 g/mol

         =  78.53 g  CH₃OH is needed

Thus , Mass in grams of CH₃OH would need to be added to 380.1 g of water in order to lower the freezing point of water by 12.0 °C is 78.53 g .

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The Minnesota Study is an example of the twins study

The Minnesota twin study of adult development began in 1986 to identify what causes individual differences in aging and study of identical (MZ) and fraternal (DZ) twins allows for estimation of how genes and environment affect the aging process and monozygotic or identical twins because they shared 100% of their inherited genes. Therefore, the researchers assumed that any differences between identical twins raised apart would be due to environment and similarities between identical twins raised apart would be due to genetics and this study proves that allow disentanglement of the shared genetic and environmental factors for the trait of interest.

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Answer:

283.5 of radioisotopes. Each mL has 105 micrograms, so multiply 105 x 2.70.

A certain protein was found to contain 0.793% zinc by mass. The minimum molecular mass of the protein is 8264.46 grams.

Molecular mass is the sum of the all atoms of an element. The molecular mass can be calculated by checking the mass of the atom from the periodic table.

In 100 grams of proteins, we have, 0.793% zinc

The molar mass of zinc is 65.3820 g/mol

0.793 / 65.3820 = 0.0121 moles of zinc

So, in 100 grams of protein

1 mole = 100 / 0.0121 = 8264.46 grams / mol

Thus, the minimum molecular mass of the protein is 8264.46 grams.

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If the students look out a window for 5 min. and record the number of vehicles that pass, the type of vehicle and color of the vehicle, then the students are observing (Option D is correct).

The scientific method is a series of sequential steps by which we can collect empirical evidence about a scientific question, and it involves observation and experimentation.

In conclusion, If the students look out a window for 5 min. and record the number of vehicles that pass, the type of vehicle and color of the vehicle, then the students are observing (Option D is correct).

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Answer:

Assume you have 1g of your sample.

Then 13.6% of this sample is Na, that is 0.136g.

Since you are to find the empirical formula, you need to find the number of moles of Na in 0.136g. You can do that by dividing by the atomic mass of Na: n(Na)=0.136g / 23.0 g/mol = 0.00591 mol

Next, you repeat this for all the other elements.

The last step is to pick the smallest number of moles that you get and divide the others by it. That way you should arrive at whole number coefficients for the empirical formula. The element with the smallest number of moles gets 1 as its coefficient).

Answer: Required personnel protection equipment (PPE) must be worn at all times

Explanation:

Taking into account the definition of density, you have:

Density is defined as the property that matter has to compress into a given space. That is, density is a quantity that is defined as the amount of mass in a given volume of a substance.

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

density= mass÷ volume

Density is inversely proportional to volume: the smaller the volume occupied by a given mass, the higher the density.

In this case, you know that:

Replacing in the definition of density:

0.00523 kg/mL= 0.22777 kg÷ volume

Solving:

0.00523 kg/mL× volume= 0.22777 kg

volume= 0.22777 kg÷ 0.00523 kg/mL

volume= 43.55 mL= 0.04355 L (being 1000 mL= 1 L)

Finally, the volume will be 0.04355 L.

In this case, you know that:

Replacing in the definition of density:

density= 5880 mg÷ 1.91 mL

Solving:

density= 3,078.534 mg/mL

Finally, the density of the substance is 3,078.534 mg/mL.

In summary, you have:

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Answer:

the awnster is A

Explanation:

Brainly

Answer:

Earth formed in this manner about 4.54 billion years ago (with an uncertainty of 1%) and was largely completed within 10–20 million years. The solar wind of the newly formed T Tauri star cleared out most of the material in the disk that had not already condensed into larger bodies

Explanation:

Earth formed in this manner about 4.54 billion years ago (with an uncertainty of 1%) and was largely completed within 10–20 million years. The solar wind of the newly formed T Tauri star cleared out most of the material in the disk that had not already condensed into larger bodies

Answer:

More than 70 meteorites that have fallen to Earth have had their ages calculated by radiometric dating. The oldest of these are between 4.4 billion and 4.5 billion years old. Fifty thousand years ago, a rock hurled down from space to form Meteor Crater in Arizona.Scientists now think the Earth's story began around 4.6 billion years ago in a disk-shaped cloud of dust and gas rotating around the early sun, made up of material left behind after the sun's formation.

Explanation:

Earth is estimated to be 4.54 billion years old, plus or minus about 50 million years. Scientists have scoured the Earth searching for the oldest rocks to radiometrically date. In northwestern Canada, they discovered rocks about 4.03 billion years old.By measuring the age of rocks on the moon, and meteorites found on Earth, scientists estimate the Earth consolidated by 4.54 billion years ago.Formation. When the solar system settled into its current layout about 4.5 billion years ago, Earth formed when gravity pulled swirling gas and dust in to become the third planet from the Sun. Like its fellow terrestrial planets, Earth has a central core, a rocky mantle, and a solid crust.

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Considering the definition of molar mass, there are 162 grams of Al in 6 moles of Al.

The molar mass of substance is a property defined as its mass per unit quantity of substance, in other words, molar mass is the amount of mass that a substance contains in one mole.

You want to determine the mass in 6 moles of Al. So, being the molar mass of Al is 27 g/mole, you can apply the following rule of three: If by definition of molar mass 1 mole of Al contains 27 grams, 6 moles of Al contains how much mass?

mass= (6 moles× 27 grams) ÷1 mole

mass= 162 grams

In summary, there are 162 grams of Al in 6 moles of Al.

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Answer:

14.4g/cm³

Explanation:

114/10=14.4g/cm³

The fungicide reaches to the leaves through the xylem's transpiration pull.

1. The fungicides are the chemicals which are used to removes fungus which on the plants and also stops the growth of fungus present on plants.

2. The fungicides are dissolved in water to make the dilute solution so that when it sprayed on the leaves, it easily absorbed by the soil.

3. The plants have special mechanism which helps in absorption of all the minerals that are present in the soil.

4. The xylem absorb mineral and water in the soil and phloem absorbs nutrients from the soil. Xylem pull ups the solution against the gravity and moves this solution to the surface of the leaves is called transpiration pull.

5. There are 3 mechanism that involved in the movement of fungicide are• Root pressure • Cohesive force • Capillary action

6. All these forces are worked to pull up the solution upward to the leaves.

Thus the xylem is a specialized mechanism present in the plants to pull up the solution upward against the gravity.

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Answer:

Friar Laurence's plan of action once he realizes Romeo hasn't received his letter is to be their when juliet wakes up and taker her back to his cell until Romeo is told of the plan. Who is the first person to arrive at Juliet's tomb in Scene 3?

22202 are the number of atoms to be placed side by side to span a distance of 6.0um.

The smallest unit of substance into which it is possible to divide without releasing electrically charged particles is the atom.

In addition, it is the smallest unit of matter with chemical element-like characteristics. The atom is thus the fundamental component of chemistry.

An atom of Rhodium (Rh) diameter d = 2.7x[tex]10^{-10}[/tex] m.

Now assuming that keeping n atoms side by side , the distance will be L= 6um = 6.5 x [tex]10^{-6}[/tex] m.

Now, the total length is given by total sum of diameter,

so the equation is given by,

L= nd

n= [tex]\frac{L}{d}[/tex]

n= [tex]\frac{6.0x 10^{-6} m}{2.7x10^{10} } m[/tex]

n= 22202 atoms.

Hence, there are total 22202 Rh atoms have to be placed side by side to span a distance.

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Because oxygen is a gas that naturally occurs in the environment, you rarely encounter it as either solid or liquid.

Oxygen is a substance that, depending on its temperature and pressure, can exist as a solid, liquid, or gas. It exists as a gas, specifically a diatomic gas, in the atmosphere. Because oxygen is a gas that naturally occurs in the environment, you rarely encounter it as either solid or liquid. Since gas has too much energy to have volume or structure, it cannot be solid or liquid. Because the tank keeps the gas contained, you can't see oxygen in the air outdoors or in substances like water, which is why you see oxygen tanks (water).

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Answer:

1) Raises the temperature. 2) Increases volume.

we need to cancel the units

b/c would be equal to 1 to retain the same amount, remember, 1a=a

so

b/c=1mol/44g or 44g/1mol

alrighty

we waant to convert 27.8mols

so therefor a=27.8mol

27.8mol times b/c=D

we want c to be mols and b to be grams so the mols cancel

so thefor c=1mol

it would look like this:

I would write 1 mol of carbon dioxide for C (choice A)

Answer:

arsenic

Explanation:

So basically it can be seen that the element is arsenic. Yeah. And now we see the element which has 6, 2 p electrons and lies in the 2nd period. So that is basically now because if we observe the electronic configuration of now it has atomic number 10 and its electronic configuration is one has to to s to two P six.

Answer:

scientific is a study of things and scientific law is law

Explanation:

you can study scientific a ND and law

hshdfhdh

Answer:

Scientific theories and laws are both factual. However, scientific theories are statements that have been proven over and over again by dozens of scientists. For example, a theory would be that the solar system is heliocentric (planets revolve around the sun). Theories are also subject to change in the event of new technological innovations. Scientific laws are statements that are universal and are based on logic/math. These will not change because they describe what happens and they are rules. For example, Newton's laws of motion would be laws because they are rules of motion. Overall, scientific theories and laws describe why and what happens based on certain conditions and circumstances.

Explanation:

is there a difference in speed between cooling down and warming up ?

so, when will both reach room temperature ? relatively at the same rate (I assume the hot milk is further from room temperature than the cold milk) ? or maybe even absolutely at the same time ?

Answer:

0.399

Explanation:

Sig Fig rules

In the isotopes of Helium, Helium-3 has 2 electrons, 2 protons and 1 neutron whereas Helium-4 has 2 electron, 2 protons and 2 neutrons in it.

Isotopes are the atoms of same element having same atomic number but different mass number.

Mass number is represented as Z and atomic number is represented as A.

Atomic number = number of protons in the atom = number of electrons in the neutral state of the atom.

Mass number = number of protons + number of neutrons in the atom

so, number of neutrons can be calculated as = Atomic number - number of protons in it

For Helium-3

mass number = 3

and atomic number = 2

so number of electrons = number of protons = atomic number = 2

number of neutrons = mass number - number of protons

                                 = 3-2 = 1

For Helium-4

mass number = 4

and atomic number = 2

so number of electrons =number of protons = 2

number of neutrons = mass number - number of protons = 4-2 = 2

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Answer: .007825

Explanation:

.313 / 40 = .007825

The boiling point of a 0.21 M solution of CaSO₄ in water is  0.107 °C.

For a dilute solution,

molarity ≅ molality

Molarity is approximately equal to the molality.

The elevation in the boiling point is a phenomenon that the boiling point of any liquid will be higher if any other compound is added to it. It depicts that a solution has higher boiling point than that of a solvent.

            ΔTb = i x Kb x m

where,

ΔTb = Boiling point elevation

i = Van't Hoff factor

Kb = Molal boiling point constant

m = Molality of solution

Van't Hoff factor is measurement of effect of solute. It is a ratio of concentration of particles to concentration of substance.

Here, i = 1, as CaSO₄ does not dissociate into ions in water.

Given data -

  Kb = 0.512°C/m

  m = 0.21 m

  i = 1

Putting the values,

ΔTb = 1 x 0.512 x 0.21

ΔTb = 0.107°C

Hence,

The boiling point of CaSO₄ is 0.107 °C

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The frequency of an irradiation with wavelength of 2.54 × 10-⁷ metres is 1.18 × 10¹⁵ Hz.

The frequency of a radiation is the rate of occurrence of anything i.e. the relationship between incidence and time period.

The frequency of a wave can be calculated using the following formula;

λ = v/f

Where;

According to this question, an irradiation with wavelength of 2.54 × 10-⁷ metres is given. The frequency can be calculated as follows;

2.54 × 10-⁷ metres × f = 3 × 10⁸ metres/seconds

f = 3 × 10⁸ ÷ 2.54 × 10-⁷

f = 1.18 × 10¹⁵ Hz

Therefore, the frequency of an irradiation with wavelength of 2.54 × 10-⁷ metres is 1.18 × 10¹⁵ Hz.

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The baking of bread follows the law of conservation of mass. Baking is an irreversible chemical change in which chemical substances-  Ethanol and Carbon dioxide are formed.

During baking the dough loses weight during cooling. The total percentage loss is around 13%.Mass of the bread is also lost as steam. Carbon dioxide is also formed due to yeast, which converts the sugar. But the volume of the bread doubles. The steam puffs up the bread, giving it high hydration. After the bread is baked, the puffiness is reduced which makes the bread fluffy and light. 

Therefore, baking is a chemical change, occurring through the process of fermentation, which includes a series of steps to make a bread in which carbon dioxide rises the dough which eventually settles after cooling. 

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The density of the iron pyrite cube is 1.343 g/cm³.

Given,

Side of iron pyrite cube = 0.31 cm

Mass of iron pyrite = 0.040 g

The volume of iron pyrite cube = s³ cm³

Or, volume = 0.029791 cm³

We have to find the density of the sample.

Density is defined as the mass per unit volume. Or, it is the ratio of mass to the volume of the substance.

Using the formula for density, we get,

Density = mass/volume

Or, density = 0.40/0.029791

Or, density = 1.343 g/cm³

Hence, the density of the iron pyrite cube is 1.343 g/cm³.

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A stick of butter weighs 0.25lbs. The weight of the stick of butter in milligrams is 113398.1.

Milligrams are the measurement quantity that is used to measure a substance in very minute quantities. It is the SI unit of mass. It is equivalent to one thousand grams.

lb is the symbol of a pound. It is used to measure an object in American and British systems of measurement. It is a value of weight.

1 lb = 453592 milligrams

0.25 lbs = 113398.1 milligrams

Therefore, the weight of the stick of butter in milligrams is 113398.1.

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