How do scientific models help us teach students about systems?
A)Models make systems more complicated and easier to learn.
B)Models cannot help students learn because they are too complicated to use.
C)Models can only help students in rich schools that can afford to purchase models which are very expensive.
D)By increasing or decreasing the size of systems that are difficult to study we make it easier for students to see how they work and therefore make it easier for them to learn.

Answer: 28000m/s

Explanation:

Displacement = 700 km due north = 700000m

Time = 25secs

Velocity =?

Velocity = Displacement / Time

V = 700000 / 25 = 28000m/s

Answer:

1.43×10⁶ > 2.34×10⁵> 3.25×10⁴>4.56×10³> 5.17×10²

Explanation:

First of all we will write these values in simple notation.

1) 1.43×10⁶

1.43×1000000

1430000

2) 5.17×10²

5.17×100

517

3) 2.34×10⁵

2.34×100000

234000

4) 3.25×10⁴

3.25×10000

32500

5) 4.56×10³

4.56×1000

4560

Rank from greatest to least.

1.43×10⁶ > 2.34×10⁵> 3.25×10⁴>4.56×10³> 5.17×10²

Answer:

2.255 x 10²³ g

Explanation:

Data Given:

no. of molecules of BeO = 5.43 x 10⁴⁵ molecules

mass of BeO = ?

Solution:

first we will find no. of moles

Formula used

       no. of moles = no. of molecules / Avogadro's number

Where

Avogadro's number = 6.022 x 10²³

Put values in above equation

    no. of moles = 5.43 x 10⁴⁵ molecules / 6.022 x 10²³ (molecules/mol)

    no. of moles = 9.02 x 10²¹ mol

So,

There are 9.02 x 10²¹  moles of BeO of 5.43x10⁴⁵

Now we will find the mass

For this formula will be used

            No. of moles = Mass in grams/ molar mass

Rearrange the above equation

           mass in grams = no. of moles x molar mass . . . . . (1)

molar mass of BeO = 9 + 16 = 25 g/mol

Put values in equation 1

          mass in grams = 9.02 x 10²¹  moles x 25 g/mol

          mass in grams = 2.255 x 10²³ g

So,

Mass of 5.43 x 10⁴⁵ molecules of BeO = 2.255 x 10²³ g

The mass of 5.43x10^45 molecules of BeO can be calculated using the atomic masses provided in Appendix A.

The mass of 5.43x10^45 molecules of BeO can be calculated using the atomic masses provided in Appendix A. The atomic mass of BeO is given by the formula BE = {[2m(^1H) + 2mn] - m(ª X)}c². We can substitute the atomic masses of ^1H (1.007825 u) and mn (1.008665 u) into the formula to calculate the binding energy (BE). By rearranging the formula, we can solve for the mass of 5.43x10^45 molecules of BeO.

Answer:

hello im breanna and i believe your answer is b.

Explanation:

Answer:

Mass= 314.96  grams

Explanation:

The density of the substance is defined as mass per unit volume of it.

The formula is :

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

Unit conversion:

1 liter = 1000 ml

[tex]1dm^{3}=1Liter[/tex]

So

[tex]1dm^{3}=1000ml[/tex]....(1)

[tex]1dm^{3} = (10cm)^{3}[/tex]

[tex]1dm^{3}=1000cm^{3}[/tex]

Replace The dm3 by cm3 in (1)

[tex]1000cm^{3}=1000mL[/tex]

[tex]1cm^{3}=1mL[/tex]

Volume = 254 mL = 254 cm3

Calculation of mass

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

[tex]1.24=\frac{mass}{254cm^{3}}[/tex]

[tex]mass=1.24\times 254[/tex]

Mass= 314.96  grams(or 315 grams)

Note: Always makes same units before solving the question. You can not determine the mass if Volume is in mL and Density is in g/cm3. Change mL into cm3 first

The mass of 254 mL of the liquid is [tex]\( 314.96 \)[/tex] grams.

To find the mass of 254 mL of liquid with a density of [tex]1.24 g/cm³[/tex], we can use the formula.

[tex]\[ \text{Mass} = \text{Density} \times \text{Volume} \][/tex]

Given.

- Density = [tex]1.24 g/cm³[/tex]

- Volume = 254 mL

Convert the volume from milliliters mL to cubic centimeters cm³ because 1 mL = 1 cm³.

[tex]\[ 254 \text{ mL} = 254 \text{ cm³} \][/tex]

Now, plug in the values into the formula.

[tex]\[ \text{Mass} = 1.24 \text{ g/cm³} \times 254 \text{ cm³} \][/tex]

Calculate the mass.

[tex]\[ \text{Mass} = 1.24 \times 254 \][/tex]

[tex]\[ \text{Mass} = 314.96 \][/tex].

Answer: Heat energy is absorbed by the substance

Explanation: Boiling is an endothermic process in which water molecules absorbs heat energy to break bonds. During boiling the amount of heat absorbed is used to break chemical bonds of water having its temperature remains in constant. The absorption of heat energy increases the kinetic energy of molecules which allows them to escape into the gaseous phase.

Answer:

Explanation:

ggg

From the given compounds, the compounds having ionic bonding are LiF, CaCl₂, NaOH, FeO and the compounds having covalent bonding are Cl₂, NH₃, NO₂ and H₂O.

Ionic bonding is a type of chemical bonding which involves a transfer of electrons from one atom or molecule to another.

Ionic bonding is between a metal and a non metal.

A covalent bond indicates the sharing of electrons between atoms. Compounds that contain carbon (also called organic compounds) commonly exhibit this type of chemical bonding.

Covalent bonding is usually between two non metals.

Therefore, From the given compounds, the compounds having ionic bonding are LiF, CaCl₂, NaOH, FeO and the compounds having covalent bonding are Cl₂, NH₃, NO₂ and H₂O.

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The molar concentration of ethyl alcohol in a 14% (m/v) aqueous solution is 3.04M

Molarity is a unit of concentration measuring the number of moles of a solute per litre of solution.

Chemists primarily need the concentration of solutions to be expressed in a way that accounts for the number of particles that react according to a particular chemical equation. Since percentage measurements are based on either mass or volume, they are generally not useful for chemical reactions. A concentration unit based on moles is preferable.

Given,

14g of ethyl alcohol in 100 ml

density = 1 g/ml

Mass = 0.14g

Concentration = number of moles ÷ volume

= 0.14 / 46 × 1000

= 3.04 M

Therefore, The molar concentration of ethyl alcohol in a 14% (m/v) aqueous solution is 3.04M

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Answer:

Explanation V= New mL displaced water - original old water that was already in the grad. cylinder basically 8.0 mL:

The volume of the metal cylinder is found by calculating the difference between the initial and final water levels in a graduated cylinder, which is 8.0 mL in this instance.

The volume of the metal cylinder can be determined using the water displacement method, where the initial volume of water in the graduated cylinder is recorded, and then the volume after placing the metal cylinder inside is measured. The difference between these two readings gives the volume of the metal cylinder. In this case, the initial volume is 70.0 mL, and after the cylinder is placed, the new volume is 78.0 mL.

The rise in water level, from 70.0 mL to 78.0 mL, indicates that the volume of the metal cylinder is 8.0 mL, since the volume of water displaced is equal to the volume of the submerged part of the cylinder.

It's important to consider factors such as the meniscus and potential distortions of the graduated cylinder's calibration when estimating and reading the volumes to ensure accuracy.

Answer:

45.4 g

Explanation:

Data given:

mole of oxygen = 1.26 mol

mass of water = ?

Reaction Given:

     2H₂ (g) + O₂(g) --------> 2H₂O (g)

Solution:

To solve this problem we look for mole mole ratio oxygen to water we look for the chemical reaction

                    2H₂ (g) + O₂(g)   ---------->  2H₂O (g)

                                    1 mole                  2 mol

So,

It is clear from the reaction that 1 mole oxygen gives 2 mole water then how many mole of water will produce by 1.26 moles of oxygen.

So apply unity formula

               2 moles H₂O ≅ 1 mole O₂

               X moles H₂O ≅ 1.26 mole O₂

Do cross multiplication

              X moles H₂O = 2 mol x 1.26 mole / 1 mole

              X moles H₂O ≅ 2.52 mol

So,

1.26 mole of oxygen produce 2.52 mole of water.

Now convert moles of water to mass

Formula will be used

      mass in grams = no. of moles x molar mass

molar mass of water (H₂O)

molar mass of H₂O = 2(1) + 16

molar mass of H₂O = 2 + 16 = 18 g/mol

put value in above equation:

           mass in grams = 2.52 mole x 18 g/mol

           mass in grams = 45.4 g

So,

1.26 moles oxygen produce 45.4 g water

Answer:

Helium has the highest First Ionization Energy in the Noble Gases group. Ionisation energy is the energy required to remove one mole of electrons from one mole of gaseous atoms.

Final answer:

Helium (He) has the highest first ionization energy among the noble gases, attributed to its stable valence shell configuration and minimal electron shielding effect.

Explanation:

The noble gas with the highest first ionization energy is Helium (He). This can be understood considering the general trend that ionization energy increases as one moves across a period from left to right in the periodic table. Noble gases, situated at the far right of the periodic table, consequently have the highest ionization energies within their respective periods due to their stable electronic configurations, with filled valence shells.

Among the noble gases, Helium, being the lightest and having the least number of electron shells, demonstrates the least shielding effect. This results in its valence electrons being more strongly attracted to the nucleus compared to other noble gases, thereby requiring more energy to remove an electron, i.e., higher ionization energy. In contrast, heavier noble gases like Xenon (Xe) and Radon (Rn) exhibit relatively lower first ionization energies due to increased electron shielding from inner electrons.

Answer:

Metaphase

prophase

anaphase

telophase

Explanation:

Answer:

Arsenic (As)

Explanation:

Phosphorus is present in the group fifteen. It is belongs to the nitrogen family.

This group consist of Nitrogen, Phosphorus, Arsenic, Antimony and Bismuth.

As we move down the group the atomic number increased so in given list of elements Arsenic is present after the phosphorus it means its atomic number if greater than the phosphorus. The elements present in the same group having similar properties.

Thus nitrogen and arsenic having properties similar to the phosphorus but as it is mentioned that atomic number must be greater than the phosphorous  so it will not nitrogen because the atomic number if nitrogen is 7 and that of phosphorus is 15 and Arsenic is 33.

While sulfur and silicon are belongs to other groups that's why their properties are not similar to the phosphorus.

Sulfur is present in group 18 while silicon is present in group 14.

Answer:

Arsenic

Explanation:

Option B

dumbbell is the shape of 3p atomic orbital

Explanation:

Atomic orbitals are three-dimensional places inside an atom where there is a tremendous chance of detecting electrons.  The p orbital, which develops in complexity and ought 2 spaces encompassing the atom core, or is defined as possessing a dumbbell pattern. The 3p atomic orbital is at energy level 3, as seen by the number 3 filed ere the character.

These orbitals have identical appearances but are arranged asymmetrically in location. p orbitals are wavefunctions with l=1. They ought an angular frequency that is ununiform at each angle. They have an appearance that is much defined as a "dumbbell".

The shape of the 3p atomic orbital is a dum_bbell.

The shape of the 3p atomic orbital is a dum_bbell. The p orbitals have dum_bbell shapes, with a nucleus at the center and two lobes on either side. Each lobe can be thought of as a probability cloud, representing where the electron is most likely to be found.

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This is an example of displacement reaction

Explanation:

                                AB + C -----> AC +B

                        2ZnS + 3O2 -----> 2ZnO + 2SO2

Answer:

OH⁻ = 1.05×10⁻¹³ M

Explanation:

Given data;

H₃O⁺ = 9.61×10⁻² M

OH⁻ = ?

Solution:

First of all we will calculate the pH.

pH = -log [H⁺]

pH = -log [H₃O⁺]

Because pH is also the hydronium ion concentration.

pH = -log [ 9.61×10⁻²]

pH = 1.02

It is known that,

pH + pOH = 14

1.02 + pOH = 14

pOH = 14 - 1.02

pOH = 12.98

Concentration of OH⁻.

pOH = -log [OH⁻]

12.98 =  -log [OH⁻]

OH⁻ = 10∧-12.98

OH⁻ = 1.05×10⁻¹³ M

Answer:

The number of electrons in the outermost shell of a particular atom determines its reactivity, or tendency to form chemical bonds with other atoms. This outermost shell is known as the valence shell, and the electrons found in it are called valence electrons

Explanation:

Answer:

Scientific investigation aims to design and implement an experiment to learn new information, where

development aims to design a product to solve a problem.

Explanation:

Answer:

D

Explanation:

Scientific investigation aims to design and implement an experiment to learn new information, whereas technological development aims to design a product to solve a problem.

According to the food and safety guidelines, it takes 2 hours to cool 140 F to 70 F. Then in the second stage it takes 4 hours to cool 70 F to 40 F. Hence, for the next four hours, the soup will reach a temperature of 40 F.

The "Temperature Risk Zone" is defined by the USDA as the range between 40°F and 140°F (4°C and 60°C) (TDZ). They give it its name since that is the range in which germs may multiply most rapidly.

If you don't think that seems extremely quick, think about this: If a soup has 150 bacteria floating on it, in 20 minutes it will have 300, and in another 20 minutes it will have 600. At this rate, you'll have 100,000 Salmonella bacteria, which is sufficient to produce a serious infection, in just over three hours.

The TDZ must be crossed from 140°F (60°C) to 70°F (21°C) after 2 hours of cooking, then from 70°F (21°C) to 40°F (6°C) within another 4 hours, according to the criteria for ServSafe, a nationally recognized food safety training programme.

Therefore, the soup will reach 40 F in the four hours to be cooled properly.

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Answer:  Different people want different things out of life

               Your Welcome ^_^            

Answer: B) Demonstrate the importance of worker-employer cooperation.

Explanation: Slow down or strike is a demenstration to the employer just how important the workers are to the corp and work place. Nothing can function or run properly without them.

The statement that explains the purpose of a worker slowdown.

B) Demonstrate the importance of worker-employer cooperation.

A slow down might be utilized as either an introduction or an option in contrast to a strike, as it is viewed as less problematic as well as safer and exorbitant for laborers and their association. Striking laborers typically go neglected and risk being supplanted, so a slow down is viewed as a method for coming down on administration while keeping away from these results.

Thus, correct option is B.

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Explanation:

Given,

The density of honey[tex](\rho)[/tex] = 1.45[tex]\dfrac{kg}{L}[/tex] and

the volume of honey (V) = 500 mL = 0.5 L

To find, the mass of honey in grams(M)  = ?

We know that,

Density = [tex]\dfrac{Mass}{Volume}[/tex]

⇒ Mass( M) = Density × Volume

= 1.45 × 0.5 kg

= 0.725 kg

= 0.725 × 1000 grams

= 725 grams

Thus, the mass of honey in grams(M)  = 725 grams

The mass of honey in a 500 mL bottle with a density of 1.45 kg/L, first convert the volume to liters, then multiply by the density, and finally convert the mass from kilograms to grams, yielding a mass of 725 g for the honey.

The density of honey is 1.45 kg/L. We need to calculate the mass of the honey in grams when a bottle contains 500 mL. To convert this volume to liters, we use the fact that 1 L = 1,000 mL, and therefore 500 mL is 0.5 L. Since density is mass per volume, the mass can be found by multiplying the density by the volume:
Mass = Density times Volume = 1.45 kg/L  imes 0.5 L = 0.725 kg. To convert this mass into grams, we use the conversion 1 kg = 1,000 g, resulting in 725 g of honey in the 500 mL bottle.

Answer:

11.442E23molecules

Explanation:

Given data:

Number of moles of water = 1.9 mol

Number of molecules of water = ?

Solution:

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

For example,

18 g of water = 1 mole = 6.022 × 10²³ molecules of water

In 1.9 moles:

1.9 mol × 6.022 × 10²³ molecules / 1 mol

11.442 × 10²³ molecules

In e notation:

11.442E23 molecules

Explanation:

Green house effect

It can be explained as :

Answer:

C, hope this helps you!

The statement about white light which is true is: C. White light is made up of a spectrum of many different colors.

Light energy can be defined as an electromagnetic wave that does not require a medium of propagation, for it to travel through a vacuum (space), where no particles exist.

Also, light energy is mainly different from both sound and heat energy because light energy can exist independent of matter.

A white light can be defined as any form of visible light reaching planet Earth from the Sun. For example, the visible light energy from distant galaxy of stars and the Sun.

Generally, white light is a visible light that comprises a spectrum of several different colors such as red, orange, yellow, green, blue and violet.

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Answer:

Option D is correct: It has stayed the same.

Explanation:

Data Given:

fixed amount of gas

volume = 2x

Absolute temperature = 2x

effect on Pressure according to ideal gas law.

Solution:

To know the effect we will made calculation by ideal gas law

As,

we know that pressure for ideal gas law = 1 atm

Now we look for this change in pressure from 1 atm

new pressure can be calculated by using ideal gas formula

       PV = nRT

Rearrange the equation for Pressure

      P = nRT / V . . . . . . . . . (1)

where

P = pressure

V = Volume

T= Temperature

n = Number of moles

R = ideal gas constant

Standard values

T = 273 K and its double will be

Fixed amount of gas

R = 0.08206 L.atm / mol. K

V = 22.42 L/mol and its double will be

V = 2(22.42 L/mol) = 44.84 L/mol

Now put the value in formula (1) to calculate Pressure

         P = 1 x 546 K x 0.08206 L.atm/mol.K / 44.84 L/mol

         P = 44.772 L.atm/mol / 44.84 L/mol

         P = 0.9996 atm

So,

         P ≅ 1 atm

It means there is no change in the pressure by double amount of temperature and volume.

Option D is correct. It has stayed the same.

Answer:

D

Explanation:

im taking the final rn too

Answer:

The number of electrons in the outer energy level

Explanation:

The correct option is c. The column that an element is in on the periodic table tells us about the number of electrons in the outer energy level, which is also known as the valence electrons.

This number is crucial because it determines the chemical properties of the element, including its reactivity and how it bonds with other elements. The number of valence electrons is indicated by the group number for the main group elements (groups 1, 2, and 13-18). For transition metals and inner transition metals, the electron configuration, including the d and f orbitals, plays a role in their placement in the periodic table, but the column still gives information about their valence electrons.

To clarify the other options provided in the question:

- The year the element was discovered: This information is not represented by the column an element is in on the periodic table. The year of discovery is a historical fact and is not related to the position of the element in the table.

- The number of protons in the nucleus: This is indicated by the atomic number of the element, which is unique to each element and determines its identity. The atomic number increases as we move from left to right across a period (row) of the periodic table.

- The mass of the atom: The mass of an atom is related to the total number of protons and neutrons in the nucleus, known as the mass number. While the atomic mass, which is an average of the masses of all isotopes of an element, is often listed on the periodic table, it does not directly correlate with the column the element is in. Instead, the atomic mass increases as you move across a period due to the increasing number of protons and neutrons.

In summary, the column an element is in on the periodic table primarily indicates the number of electrons in the outer energy level, which is a key factor in the element's chemical behavior.

The complete question is- What can we tell from the column that an element is in?

a. The year the element was discovered

b. The number of protons in the nucleus

c. The number of electrons in the outer energy level

d. The mass of the atom

Answer: D

The correct way of writing a vector is to put a bar (-) on it.

Acceleration usually has the symbol a. It is a vector. The correct way

to write the symbol to show that it is a vector is  â. Option A is correct.

Acceleration refer to the rate of change of velocity with time. That is velocity divided by time.

Uniformly accelerated motion refer to the movement of velocity in a straight line and when the amount increase in velocity is in equal interval with amount increase in time.

Vector quantity is the quantity that have both magnitude and direction. Example include acceleration.

Scalar quantity refer to quantity with magnitude and no direction.

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