1. What is the atmospheric layer responsible for long-distance radio communication?

Question 1 options:

Troposphere


Stratosphere


Exosphere


Thermosphere

Answer:

Photovoltaic cell or solar cells

Explanation:

Solar cells are cells that converts light energy from the sun into electrical energy for use in appliances. Light energy impinges on these cells, the photons of light causes electrons in the solar cells to move thereby resulting in the production of electricity in the cells.

Light slows down when traveling through more dense substances; does not require a medium to travel through; can be absorbed and transformed into heat; speeds up when traveling through less dense substances; is refracted when it changes direction and speed.

Light wave is a form of electromagnetic wave which enables us to see.

It is a form of transverse wave form.

Some of the properties of light wave include:

Therefore, the correct options are, Light slows down when traveling through more dense substances; does not require a medium to travel through; can be absorbed and transformed into heat; speeds up when traveling through less dense substances; is refracted when it changes direction and speed.

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Light slows down when traveling through more dense substances; does not require a medium to travel through; can be absorbed and transformed into heat; speeds up when traveling through less dense substances; is refracted when it changes direction and speed.

Light wave is a form of electromagnetic wave which enables us to see.

It is a form of transverse wave.

Some of the properties of light wave include:

Therefore, the correct options are,

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Answer:

Carbon (c) !!!! :)))))

Carbon (C) is the name and symbol of the element in the second row and fourteenth column of the periodic table , therefore  option (b) is correct.

The columns on the periodic table of elements are called groups. The elements in a group share the same configuration of valence electrons, which gives the elements similar chemical properties.

Properties of carbon element-

Carbon (C) is the name and symbol of the element in the second row and fourteenth column of the periodic table , hence  option (b) is correct among all.

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Answer:

89.34%

Explanation:

First, write a balanced reaction.

Mg3N2 + 6H2O --> 3Mg (OH)2 + 2NH3

Next determine the moles of the known substance, or limiting reagent ( H2O)

n= m/MM

n ( H2O) = 4.33/(1.008×2)+16

n(H2O)= 0.2403

Use the mole ratio to find the moles of Mg(OH)2

0.2403 ÷2

n (Mg (OH)2) = 0.1202

Next, find the theoretical mass of Mg (OH)2 that should have been produced

m= n × MM

m= 0.1202 × (24.305 + (16×2) +(1.008 ×2))

=7.007g

To find percentage yield, divide the experimental amount by the theoretical amount and multiply by 100.

6.26/ 7.007 × 100

=89.34%

Answer:

Sublimation is used to separate a mixture of sand and ammonium chloride. Sublimation is a separation process that entails heating a mixture of solids, where one of the solids transitions from solid to gas without passing through the liquid state. ... This process leaves behind the sand in its natural state.

Explanation:

Answer:

When a mixture of sand and ammonium chloride is heated, the ammonium chloride sublimates out and sand is left behind.

Explanation:

Sublimation is the process in which, a substance directly goes into its gaseous state, without passing through the liquid state, on heating.

Answer:

Option A= copper

Explanation:

According  to specific heat capacity of substances, copper will reach to the our body temperature first.

Specific heat capacity:

It is the amount of heat required to raise the temperature of one gram of substance by one degree.

Formula:

Q = m × c × ΔT

specific heat capacity of copper = 0.385 J/g. °C

specific heat capacity of aluminium = 0.902 J/g. °C

so copper will absorb the heat very quickly and raise the temperature in very less time as compare to aluminium.

Final answer:

Copper reaches body temperature before aluminum because it requires less heat to increase its temperature due to its lower specific heat capacity.

Explanation:

The student is asking which metal, copper or aluminum, each weighing one gram and initially at 0° C, will reach body temperature first if they both absorb heat at the same rate. This question is related to thermal properties of materials, specifically specific heat capacity, which indicates the amount of heat required to raise the temperature of a certain mass of a substance by one degree Celsius.

Copper has a lower specific heat capacity (0.386 J/g°C) compared to aluminum (0.900 J/g°C), as indicated by the given data. Therefore, copper will reach body temperature before aluminum because it needs less heat to raise its temperature.

Answer: Energy transfers from the metal to the water and calorimeter until they are all at room temperature.

Explanation: hope this helps

Making a mixture is a physical change and, therefore, mixtures can be separated by physical means.

Answer: Option D

Explanation:

Mixtures are combination of two or more substances irrespective of their state of matter. The mixtures can be classified as solution, suspension and colloids. In mixtures , the combining substances will retain their chemical properties, they will combine only physically and not chemically.

So the chemical properties of the mixture will be the chemical properties of each of its constituent. As mixtures form by physical change of the combining substances, they can be separated by physical means only like distillation, evaporation etc.

Thus, making a mixture can be physically changed and therefore mixtures can be separated by physical means.

Answer:

68027 cells

Explanation:

First they need to be in the same units.

To convert 0.0147mm^3 into cm^3, divide by 1000

This gives 0.0000147cm^3

Next, divide 1 cm^3 by 0.0000147 cm^3

[tex] \frac{1}{0.0000147} [/tex]

=68027.2108844

= 68027 cells

Answer:

68027 cells

Explanation:

Answer:

Explanation:

                                          1. State

                                        2. Physical properties

        3. Solid                            4. liquid                             5. gas.

6. incompressible           7. virtually incompressible     8. compressible

9. tightly packed           10. loosely packed particles     11. particles far apart

    particles

The concept map briefly shows the different states of matter and their physical properties. Matter is anything that has weight and occupies space. There are 3 states of matter which are solid, liquid and gas.

The terms are organized based on the three states of matter: solid, liquid, and gas. Solids and liquids are incompressible and have tightly or loosely packed particles respectively while gas is compressible with particles far apart.

The terms can be organized into a concept map that focuses on the three states of matter and their respective physical properties.

The term 'virtually incompressible' would typically be used to describe liquids and solids, as while they are not absolutely incompressible, they are so relative to gases.

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Answer:

9.61 % error

Explanation:

The formula for percent error is as follows:

% error = (experimental value - theoretical value) ÷ theoretical value × 100%

So to calculate the percent error all you have to you is plug in your values.

% error = (4.45cm - 4.06cm)/4.06 × 100%

= 0.39/4.06 × 100%

= 0.0961 × 100%

= 9.61 % error

Answer:

Statistics

Explanation:

The science of statistics deals with the collection, storage, manipulation, analyzing, visualizing and interpretation of data. Graphs and tables are very good tools in order to achieve statistical problems. Tables can be used to compare a given data set and present them in a very simple relational way. Graphs are useful for data visualization and their trend is vital in making interpretations.

Answer:

average atomic mass of sulfur = 32.066 amu

Explanation:

The average atomic mass is calculated as following:

average atomic mass = fraction of isotope (1) × mass number of the isotope (1) + fraction of isotope (2) × mass number of the isotope (2) + ... + fraction of isotope (n) × mass number of the isotope (n)

average atomic mass of sulfur = (95/100) × 32 + (0.76/100) × 33 + (3.22/100) × 34 + (0.89/100) × 36 = 32.066 amu

(amu - atomic mass units)

Answer:

For instance look at N (Nitrogen), you will see the atomic mass is 14.00674 grams. So that means if you had 1 mole of nitrogen atoms, it would weight, 14.00674 grams. Now we have to get what fraction of a mole you have. To start, you need know that all a mole means is you have 6.022 x 1023 atoms of that type.

HOPE THIS HELPED!!!!!!!!!!!!!!!!XDDDDDDDD

The mass of one atom of nitrogen is approximately 2.325 × 10⁻²⁶ kg.

To calculate the mass of one atom of nitrogen, we need the atomic mass and Avogadro's number. The atomic mass of nitrogen (N) is approximately 14.01 atomic mass units (amu).

First, convert the atomic mass to kilograms:

14.01 amu × 1.66053906660 × 10⁻²⁷ kg/amu = 2.325 × 10⁻²⁶ kg

Next, we use Avogadro's number to find the mass of one mole of nitrogen atoms. Avogadro's number is 6.022 × 10²³ atoms/mol.

Mass of one mole of nitrogen atoms = 14.01 g/mol

Convert grams to kilograms for consistency:

14.01 g/mol × 10⁻³ kg/g = 0.01401 kg/mol

The mass of one nitrogen atom is then:

0.01401 kg/mol ÷ 6.022 × 10²³ atoms/mol ≈ 2.325 × 10⁻²⁶ kg/atom

Thus, the mass of one nitrogen atom is approximately 2.325 × 10⁻²⁶ kg.

Answer:

Be2+ is a positively charged ion [cation] of Be. It is formed when Be donate the two electrons that are in its outermost shell. Be2+ is a charged ion. ... Be has 5 electrons while Be2+ has 3 electrons.

Explanation:

Answer: They have the same number of protons

They have the same number of neutrons

Explanation:

Considering Be and Be2+, two electrons were lost from the atom for the ion to be formed. The number of protons and the number of neutrons remain the same. Hence the atom and its ion share a similarity in the number of protons and neutrons present in both the atom and ion being exactly the same. This is a similarity between Be2+ and Be- the both possess the same number of neutrons and the both also posses the same number of protons.

Answer:

2.343 g/ cm³

Explanation:

Density:

Density is equal to the mass of substance divided by its volume.

Units:

SI unit of density is Kg/m3.

Other units are given below,

g/cm3, g/mL , kg/L

Formula:

D=m/v

D= density

m=mass

V=volume

Symbol:

The symbol used for density is called rho. It is represented by ρ. However letter D can also be used to represent the density.

Given data:

density = ?

volume= 350 cm³

mass= 820 g

Now we will put the values in the formula,

d= m/v

d= 820 g/ 350 cm³

d= 2.343 g/ cm³

The density of silicon is 2.343 g/ cm³

The density of a sample of pure silicon, given its mass is 820 grams and its volume is 350 cm^3, is calculated by dividing mass by volume. Using this formula, the density of the silicon sample is approximately 2.34 g/cm^3.

The subject of your question falls under Physics and it is about the concept of density. More specifically, you are asking about the density of a sample of pure silicon. Density is defined as the mass of an object divided by its volume which is usually measured in grams per cubic centimeter (g/cm3). Given that the mass of the silicon sample is 820 grams and its volume is 350 cm3, we can calculate the density using the following formula for density:

Density = Mass / Volume

In this case, Density = 820g / 350cm3. So, the density of the silicon sample is approximately 2.34 g/cm3.

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Final answer:

The components that are a part of all scientific investigations include a scientific question, hypothesis, variables, control, procedure, and conclusion. These align with the scientific method and are essential in conducting a thorough and systematic inquiry.

Explanation:

The components that are part of all scientific investigations include several elements that align with the scientific method. These are essential for ensuring a systematic approach to the inquiry process. Let's review these components:

By following these components, scientists conduct thorough and replicable experiments that contribute to the body of scientific knowledge. Each step is crucial in ensuring results are reliable and valid.

Final answer:

The components of all scientific investigations include a scientific question, a hypothesis, variables, control, procedure, and a conclusion. These elements structure the investigation for consistency and repeatability.

Explanation:

The components that are part of all scientific investigations typically include:

These elements help in structuring a scientific investigation, allowing for repeatability and verifiability by other scientists.

Answer:

Negative numbers don't have real square roots since a square is either positive or 0.

Explanation:

Negative numbers don't have real square roots since a square is either positive or 0.

It depends, but this is how I would do it:

Let's take the square root of -8 --> [tex]\sqrt{-8}[/tex]

First, I would take out an "i" and put it outside of the square root:

[tex]i\sqrt{8}[/tex]

The i represents the negative sign. Then, I would treat the square root of 8 as a normal problem and simplify by factoring it:

Factors of 8: 2,2,2

Because you're looking for a square root and you can "loop" two 2s together, you can take one set out:

[tex]2i\sqrt{2}[/tex] would be your final answer.

Hope I helped :)

actually it is 5% of 100 is 5

Therefore, 5% of 500 is 5 x 5 = 25g

Taking into account the definition of weight / volume percentage (% w/v), the mass of sucrose would be 25 grams.

In first place, it is necessary to know that a solution is a mixture of two or more components, perfectly homogeneous since each component is intimately mixed with the other, in such a way that they lose their individual characteristics.

The latter means that the constituents are indistinguishable and the whole is presented in a single well-defined phase.

In a solution, a solute is that component that is found in the least amount and is the one that dissolves, while the solvent is that component that is in the greatest amount and is the medium that dissolves the solute.

The weight / volume percentage (% w/v) expresses the grams of solute that are dissolved in 100 mL of solution.  The expression for its calculation is:

[tex]weight/volume percentage=\frac{mass solute}{volume solution}x100[/tex]

In this case, you know that:

Replacing:

[tex]5=\frac{mass solute}{500 mL} x100[/tex]

Solving:

[tex]mass solute=\frac{5x500 mL}{100}[/tex]

mass solute= 25 grams

In summary, the mass of sucrose would be 25 grams.

Learn more:

Answer:

The bottom number on each element of the periodic table are called the 4f series or lanthanoids and 5f or actanoids. They are also called inner transition elements.

Final answer:

Steel production requires a fluid phase to allow the removal of impurities and the addition of alloying elements, producing steel with specific properties including enhanced strength and durability. The introduction of processes like the Bessemer and open-hearth methods facilitated cheaper and more efficient steelmaking. Controlled diffusion of carbon and other elements during the fluid phase is crucial to achieving the desired qualities of steel.

Explanation:

Steel production is a critical process in industrial manufacturing, transforming wrought iron into steel with superior strength and durability. Steel goes through a fluid phase during production because this allows for the removal of impurities and the integration of essential alloying elements. The Bessemer process and the open-hearth process both revolutionized steelmaking, enabling production at higher temperatures and larger quantities, thus reducing costs and facilitating widespread industrial use.

During the fluid phase, controlled amounts of carbon and other elements such as manganese, chromium, nickel, tungsten, molybdenum, and vanadium are added to create various steel alloys tailored for specific applications. The presence of carbon is particularly crucial; if not carefully managed, excess carbon can make steel brittle.

Diffusion plays an essential role in this process, particularly in carburizing, which increases the surface hardness of iron by allowing carbon to diffuse into it at high temperatures, turning it into hardened steel. This phase is vital for achieving the correct balance of mechanical properties required for steel's various industrial uses.

I suppose that the question ask the following:

What is the mass of a sample, composed of C₃H₅N₃O₉ molecule, that contains 100 g carbon?

First we calculate the molecular mass of our molecule  C₃H₅N₃O₉.

molecular mass = 12 × 3 + 1 × 5 + 14 × 3 + 16 × 9 = 227 g/mol

Now we devise the following reasoning:

if          227 g of our molecule contains 27 g of carbon

then      X    g of our molecule contains 100 g carbon

X = (100 × 227) / 27 = 840.7 g

Answer:

A new Dana system of classification contains 78 different classes of minerals based on composition and then further classified by type and group. To be considered a mineral, a substance must be an inorganic, naturally formed solid, with a specific chemical formula and a fixed internal structure. To test whether something is a mineral, there are several identification tests to which the substance is subjected, including its resistance to scratching, its density in comparison to water, its color, the degree of light it reflects, the color of the powdered mineral, its breakage pattern and its crystalline form.

Explanation:

Answer: chemical makeup and crystal lattice structure

Explanation:

The minerals are the inorganic substances that are extracted beneath the earth crust. These minerals are associated with the gangue particles that are required to be removed by processing.

The minerals can be classified on the basis of the chemical and physical properties. The chemical properties define the chemical composition of the mineral. The physical properties define how minerals react with the external environment.

Thus chemical makeup and crystal lattice structure can be a useful approach to classify the minerals as the minerals may differ chemically as well as in structural makeup.    

Answer:

Acetone is a compound.

Acetone is a compound comprising of carbon,hydrogen and oxygen atoms.

Compound is defined as a chemical substance made up of identical molecules containing atoms from more than one type of chemical element.

Molecule consisting atoms of only one element is not called compound.It is transformed into new substances during chemical reactions. There are four major types of compounds depending on chemical bonding present in them.They are:

1)Molecular compounds where in atoms are joined by covalent bonds.

2) ionic compounds where atoms are joined by ionic bond.

3)Inter-metallic compounds where atoms are held by metallic bonds

4) co-ordination complexes where atoms are held by co-ordinate bonds.

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Answer:

Control

Explanation:

The control is the variable that you don't change. Like, imagine you're doing an experiment and are trying to figure out how much of a faster growth rate occurs with fertilized plants. You will compare the fertilized plant to the unfertilized one, which is the control, to see the difference the fertilizer made.

Hope this helped :)

6 meters is a longer distance. It takes 100 centimeters to equal 1 meter.

HOPE IT HELPS :)

Answer: 3.22

Explanation: it did not go above the 3rd line instead it stayed about 2 or 3 cm below.

Answer:

3.22 mL

Explanation:

To see the volume indicated you have to look at the center of the tube, not at the region near the glass of the cylinder. It's clear from the picture that the level is slightly above 3.2 and less than 3.3, so the answer is 3.22 mL

C: They should try to reproduce Dr. Maxwell's research to verify his results

Other scientists may or may not agree to Dr. Maxwell, so they should test Dr. Maxwell's research again to see if his conclusion is true or not.

Hope this helps!

Answer:

In gaseous form matter take the shape and volume of container.

Explanation:

Properties of gases:

Molecule of gases randomly move every where and occupy all available space.

Gases don't have definite volume and shape and take the shape and volume of container in which it present.

Their densities are very low as compared to the liquid and solids.

Gas molecules are at long distance from each other therefore by applying pressure gases can be compressed.

The very weak inter molecular forces are present between gas molecules.

Properties of Liquid:

Liquid have definite volume but don,t have definite shape.

Their densities are high as compared to the gases but low as compared to the solids.

In liquid, molecules are close to each other and have greater inter molecular forces as compared to the gas molecules.

Properties of solids:

Solids have definite volume and shape.

In solids molecules are tightly pack and very close to each other.

Their melting and boiling point are every high.

The densities of solids are also very high as compared to the liquid and gas.

There are very strong inter molecular forces are present between solid molecules.

Answer:

The element oxidized is the one whose oxidation number INCREASES......

Explanation:

And thus......

+

I

I

  2CuO

+

C

→

2

0

C

u

+

C

O

2

↑

⏐

⏐

And here while copper (as  

C

u

2

+

) is reduced, carbon is oxidized,  

0

C

→

+

I

V

C

.

The second reaction represents the reduction  

C

r

(

V

I

+

)

to  

C

r

(

I

I

I

+

)

C

r

2

O

2

−

7

+

14

H

+

+

6

e

−

→

2

C

r

3

+

+

7

H

2

O

(

i

i

)

And the oxidation of ethanol to carbon dioxide:

H

3

C

−

C

H

2

O

H

+

H

2

O

→

2

C

O

2

+

8

H

+

+

8

e

−

(

i

i

i

)

i.e.  

H

3

−

I

I

I

C

−

−

I

C

H

2

O

H

→

2

+

I

V

C

O

2

We takes  

4

×

(

i

i

)

+

3

×

(

i

i

i

)

to eliminate the electrons.....

3

H

3

CC

H

2

O

H

+

3

H

2

O

+

4

C

r

2

O

2

−

7

+

56

H

+

+

24

e

−

→

8

C

r

3

+

+

28

H

2

O

+

6

C

O

2

+

24

H

+

+

24

e

−

To give finally............

3

H

3

CC

H

2

O

H

+

4

C

r

2

O

2

−

7

+

32

H

+

→

8

C

r

3

+

+

25

H

2

O

+

6

C

O

2

Dichromate ion

is reduced to  

chromic ion

The oxidation takes place in option B (Fe2O3 + 3CO - 2Fe + 3CO2) where Carbon (C) in CO gets oxidized to CO2 moving from an oxidation state of +2 to +4.

In Chemistry, an oxidation reaction is characterized by the loss of electrons during the reaction. Looking into the provided options for reactions, we can understand which compound gets oxidized by observing which substance loses electrons (i.e., has a valence increase).

Option A cannot be the answer since copper (Cu) reduces from Cu to Cu and carbon (C) also reduces from atomic state to be part of CO2.

Option B, (Fe2O3 + 3CO - 2Fe + 3CO2), showcases oxidation. In this case, Carbon (C) in CO is getting oxidized to form CO2. In the process of this reaction, Carbon (C) changes from an oxidation state of +2 (in CO) to +4 (in CO2).

Option C, shows the reduction of Mg from atomic state to ionic state in MgO. Option D, shows Mn reducing from +4 oxidation state to +2 oxidation state in MnCl2, with Cl also transforming component state. However, none of these are examples of oxidation.

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