why is an element considered a pure substance​

Answers

Answer 1

Answer:

Because they cannot be separated into more then one type of substance.

Explanation:

Answer 2

Answer:

Elements are made of only one kind of atom. The particles can be a single atom or a molecule made of only one kind of atom. There is no physical change that can separate elements into more than one kind of substance. This makes an element a pure substance.An element is made up of only one type of atom. An element cannot be broken down into a simpler form.


Related Questions

If two solutions with concentrations of 0.4 M sugar and 0.7 M sugar respectively are separated by a semipermeable membrane, during osmosis there is a net flow of Group of answer choices sugar molecules from the dilute to the concentrated solution sugar molecules from the concentrated to the dilute solution water molecules from the concentrated to the dilute solution water molecules from the dilute to the concentrated solution

Answers

Answer: Water molecules from the dilute to the concentrated solution

Explanation:

During Osmosis if a solution is separerated by a semipermeable membrane, the solvent (typically water) from the less concentrated solution in terms of solute goes through the semipermeable membrane to the solution with the higher concentration so that the concentrations between the solutions can be balanced.

With the above solutions therefore, water molecules would move from the solution of 0.4M of sugar to the solution with a 0.7M of sugar through the semipermeable membrane.

During osmosis, water molecules move from the dilute to the concentrated solution.

OSMOSIS:

Osmosis is the movement of water molecules from a region of higher concentration (low concentration of solute) to a region of lower concentration (higher concentration of solute).

The principle of movement is based on the concentration gradient i.e. difference in concentration across a semipermeable membrane.

According to this question, two solutions have sugar concentrations of 0.4 M sugar and 0.7 M respectively and are separated by a semipermeable membrane.

Therefore, water molecules will move from the dilute (0.4M) to the concentrated (0.7M) solution during osmosis.

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does the tendency to gain electrons decrease as we go down grp 17?

Answers

Explanation:

Hi, there!!!!

Let me simply clear you..

Yes,The tendency to gain electrons (in nonmetal) decreases when we go down group 17.

The reason for above answer is when we go downwards in periodic table then the atomic size increases with the addition of number of shells and force of attraction between the nucleus and valance shell decreases. The force of attraction between the nucleus and valance shell becomes weaker due to which the force of attracting the electrons gets decreased.

So, we can say that the tendency to gain electrons decreases as we go down in periodic table.

Hope it helps....

How many moles are present in 136 grams of MgCl2? 1.46 mol 1.43 mol 2.27 mol

Answers

Answer:

1.43 mol

Explanation:

Explain the different between a molecule and a compound.

Answers

Answer:

-A molecule is the smallesr part is compound whereas a compound is the combination of two or more atoms in a fixed proportion by wiehgt.

- A glass of water is an example of compound but a small portion of water can be called molecule.

If an object's mass is 70 g, and its volume is 10cm cubed, what is its density?

Answers

The answer is 7,000

If an object's mass is 70 g, and its volume is 10cm cubed,  its density is 7 centimeter cube.

What is density?

The density of any solid substance is the unit of the area occupied by it in per centimeter of the cube of the volume in the given sample and calculated by dividing the mass and the volume of the compound unit will be centimeter cube.

The mass of the given object is 70 gram and the volume is given is 10 cm to find the density,

                       Density = mass of object / volume of object

substituting the value in the formula,

                 Density = 70 / 10

                 Density = 7 centimeter cube.

Therefore, the density of the given object will be 7 centimeter cube if  an object's mass is 70 g, and its volume is 10cm cubed.

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I'll GIVE BRAINLIEST: In a redox reaction, CO is changed to CO2. How many electrons must be lost or gained by C and why?

Answers

Answer:

C is gaining 2 electrons

Explanation:

O has a 2- charge so for CO to pick up another O atom would add 2 more electrons.

Answer:

C gains 2 electrons

Explanation:

In the redox reaction, CO is changed into CO2 which means there is an additional oxygen. Oxygen loses 2 of its electrons in order to neutralize. So, C must be gaining 2 electrons in order to make the bond.

What is ionic bond and explain it​

Answers

Answer:

An ionic bond is a chemical bonding involving the attraction between oppositely charged ions

Explanation:

On the periodic table, elements from group 1 and 7 are attracted to each other and when they bond, it's called ionic bonding. This is because of their valence electrons and ions.

Answer:

Ionic bonding is a type of chemical bonding that involves the electrostatic attraction between oppositely charged ions, and is the primary interaction occurring in ionic compounds. It is one of the main types of bonding along with covalent bonding.

1. Which material had the highest rate of absorption? What can you conclude about the rate
of absorption in the natural world? How might this influence climate regions?

Answers

it might be porous materials

Answer:

Air had the highest rate of absorption.  Air absorbs most of the suns heat and sun rays and air can move to different areas which are warm and colder.

Explanation:

What are the properties of alkynes

Answers

These double-bonded compounds are colourless and odourless in nature. ...
Solubility. The alkenes are insoluble in water due to their nonpolar characteristics. ...
Boiling Point. The boiling points of the compounds increase as the number of carbon atoms in the compound increases. ...
Melting Point. ...
Polarity.
Alkynes are nonpolar, unsaturated hydrocarbons with physical properties similar to alkanes and alkenes. Alkynes dissolve in organic solvents, have slight solubility in polar solvents, and are insoluble in water. Compared to alkanes and alkenes, alkynes have slightly higher boiling points.

Alkenes are chemically more reactive than alkanes.
This because alkenes are unsaturated hydrocarbons that have a double bond, C=C, between two carbon atom.
Almost all of the chemical reactions of alkene occur at the double bond.

Tips for memorizing the first 20 elements of the periodic table?​

Answers

Answer:

hydrant flying with balloon, balloon has lithp letting air out, bee: really yum balloon

    =                           =                                 =                                   =

hydrogen              helium                     lithium                     beryllium

be bore on the balloon, balloon pops, hydrant drops and makes a car bomb

           =                                                                                                  =

    boron                                                                                              carbon

night row general gets hurt by car bomb nearby, that general gets off boat

        =                                

nitrogen

wearing oxygen mask, mask is full of fluride gel, then he got neon teeth

             =                                               =                                      =

         oxygen                                fluorine                                neon

(try making a story out of the elements, use your imagenation)

I will give u tips to learn whole periodic table

1. Break down the table into sections

2. Spread out the memorisation process

3. Learn the elements in a song

4. Make none sense words made from element symbols

5. Use colour to learn element groups

6. Use mnemonic device to help remember the order of elements

I am sure this will be helpful for uuu

Explanation:

Ytu perform an electrolysis reaction using FeCl, iron (1) chloride. Which of the following will happen?
A. Chlorine will move to the positive electrode and become reduced.
B. Iron will move to the positive electrode and become oxidized.
C. Chlorine will move to the negative electrode and become oxidized.
D. Iron will move to the negative electrode and become reduced.

Answers

Answer:

The answer is "Option B"

Explanation:

when we react with FeCl, iron, and chloride to both the electrolysis. So, iron is charged positive ion, as well as passes to the negative, is cathode electrode. But there is a decrease in the cathode.

The equation can be defined as follows:

[tex]FeCl_2[/tex] [tex]\longrightarrow[/tex][tex]Fe + Cl_2[/tex]

In the above equation, when the iron chloride electrolysis solution, it will give the iron(II) and the chlorine. This process happens when the hydrogen chloride solution at a temperature of about 90 ° C.

Answer: D

Explanation: As Fe is positive charged while chlorine is negative charged.

(D) is correct. As iron moves to negative and it get reduce as negative electrode is cathode

Select the correct answer from each drop-down menu. At chemical equilibrium, the amount of because .

Answers

Answer:

The answer that completes the question are in BOLD:

At chemical equilibrium, the amount of PRODUCT AND REACTANT REMAIN CONSTANT because the RATES OF THE FORWARD AND REVERSE REACTIONS ARE EQUAL.

Explanation:

In a reversible chemical reaction, an equilibrium is said to be achieved when the rates of the forward reaction is equal to that of the reverse reaction. A reversible reaction is one in which products are formed from reactants simultaneously with the formation of reactants from products.

The combination of two or more substances called REACTANTS gives rise to another substance called PRODUCT, which can in turn give rise to Reactants again. With time, the rate at which the reactants give rise the products, which is called the FORWARD REACTION will be equal to the rate at which the products give rise to the reactants, which is called REVERSE REACTION. At this point, the chemical reaction is said to be in a STATE OF EQUILIBRIUM.

When the rate at which both reaction occurs becomes equal i.e. at an equilibrium state, the concentration of both the reactants and the products becomes constant i.e. no longer changes. Hence, the amount of the reactants forming the products is the same as the amount of products forming the reactants.

N.B: At chemical equilibrium, the amount of the reactants and products does not necessarily equals zero (0). It simply means that there is no net change in the concentration/amount of both reactants and products.

PLEASE HELP WILL GIVE BRAINLIEST!!!!
If the concentration of substance A of a reversible reaction in dynamic equilibrium increases, how will the equilibrium change?
A. It will shift to create more of substance A.
B. It will shift towards the reactants.
C. It will shift towards the products.
D. It will shift to create less of substance A.

Answers

Answer:

[tex]\boxed{It\ will\ shift\ to\ create\ less\ of\ substance\ A}[/tex]

Explanation:

If the concentration of any substance A in a dynamic equilibrium increases, The equilibrium will be  shifted to its opposite side so that Substance A can be created less and the substance opposite to A can be created more so that a "dynamic equilibrium" can again be established.

which of the following molecules would you expect to be optically active

1. CCl2F2
2. 2-methyl butane
3. butan-2-ol​

Answers

Answer:

waaaaaaaaaaqwwwwwwwwwwww

Please help me...

Atoms of elements X, Y and Z have 16, 17 and 19 electrons, respectively. Atoms of argon have 18 electrons.

a Determine the formulae of the compounds formed by the combination of the atoms of the elements:
(i) X and Z
(ii) Y and Z
(iii) X with itself.

b In each of the cases shown in
A (i)–(iii) above, name the type of chemical bond formed.

c Give two properties you would expect to be shown by the compounds formed in an (ii) and an (iii).

Answers

Answer:

a 1) XZ2

2) YZ

3) X2

b 1) Ionic bond

2) Ionic bond

3) covalent bond

c) ionic compounds has high melting and boiling point

ionic compounds can conduct electicity in aqueous form

covalent compounds have electrons shared between the atoms

covalent compounds have lower melting point compared to ionic compound

Answer:

(i) XZ = Potassium Sulfide [K2SO4]

(ii) YZ = Potassium Chloride [KCI]

(iii) X = Sulfur [S]

b) (i) Ionic Bond. (ii) Ionic Bond. (iii) Covalent Bond.

c) (i) Ionic compounds have high melting and boiling points.

(ii) Ionic compounds can conduct electricity in a molten state or a solution as they have ions that can move and carry charge.

(iii) Covalent compounds have low melting and boiling points.

(iv) Covalent compounds can not conduct electricity as all electrons are involved in bonding so there are no free electrons or ions to carry the charge.

Hope this is OK :))

Please mark me as Brainliest:))

Which is the correct definition of metallic bonding? Select one: a. an array of positive ions in a sea of electrons b. complete transfer of valence electrons c. atoms share electrons to to be stable

Answers

Answer:

I believe it's A) an array of positive ions in a sea of electrons

A chemical equation is balanced when Group of answer choices the number of atoms of each element is the same in reactants and products. the charge on each atom is the same in reactants and products. the sum of the coefficients of the reactants is equal to the sum of the coefficients of the products. the total number of ions is the same in reactants and products. the total number of molecules is the same in reactants and products.

Answers

Answer:

a

Explanation:

A chemical equation is said to balanced only when the number of atoms of each element is the same in both reactants and products side. Rest all options are absurd. Hence, option a is correct.

Balancing of the reaction has no relation with coefficient, molecules or charge of the elements

List the metals Mg, Cu, Au, Na and Al in the decreasing order of their reactivity with air.

Answers

Answer:

Na is most reactiveAlcuAu is less reactiveIN HERE

Answer:

Potassium  (K)

Sodium  (Na)    

Calcium  (Ca)

Magnesium (Mg)  

Aluminium  (Al)

Iron  (Fe)  

Lead  (Pb)

Copper  (Cu)  

Silver  (Ag)

Gold  (Au)

100 cm^3 of oxygen diffuses through a Porous in 3second how long will it take 150 cm^3 of sulphur (iv) oxide diffuse through the same pot? ( oxygen= 16 sulphur = 32)​

Answers

Answer:

3.18 seconds

Explanation:

Given the following :

Volume of oxygen (V1) = 100cm^3

Time taken (t1) = 3 seconds

Volume of Sulphur (iv) oxide (v2) = 150cm^3

From Graham's Law of diffusion:

(r1/r2) = √(m1/m2)

Where r = rate of diffusion

m = molar mass

Note rate (r) = (volume / time)

[(V1/t1) ÷ (v2/t2)] = √(m1/m2)

(v1/t1) * (t2/v2) = √(m1/m2)

m1 = 02 = (16 * 2) = 32

m2 = SO2 = (32 + (16 * 2)) = 64

(100/3) * (t2/150) = √(32/64)

100t2 / 450 = √(32/64)

100t2 / 450 = √32 / 8

100t2 / 450 = √32 / 8

100t2 * 8 = 450 * √32

800t2 = 2545.5844

t2 = 2545.5844 / 800

t2 = 3.1819805

t2 = 3.18 seconds

It will take 3.18s for 150cm^3 of Sulphur (iv) oxide to diffuse through the same pot.

percentage of carbon in urea

Answers

The percentage of carbon in urea is [CO(NH 2) 2] is 20%

anyone knows how to do this-

Answers

Explanation:

The number of protons in the element C^12 (Carbon) is 6, number of electrons 12 and number of Neutrons is 6, same as the number of protons it contains

C^13 has 13 electrons, 6 protons and 7 Neutrons this one's neutron number is different from proton number because it's an isotope

Na^-1 has gained an electron so the number of electrons it has = 24 and the number of protons shown as 11 which means there are 23 - 11 = 12 Neutrons

O^-2 has gained two electrons and got 18 electrons in total, 8 protons and 8 neutrons

Which of the following elements has a complete outer shell of electrons? A. Iron (Fe) B. Hydrogen (H) C. Neon (Ne) D. Nitrogen (N)

Answers

Answer:

The answer is Neon

Answer:

neon

Explanation:

neon has a complete outer 2n shell

If a gas displays a solubility of 0.00290M at a partial pressure of 125 kPa, what is the proportionality constant for this gas in this solvent and at this temperature?

Answers

Answer:

The proportionality constant ( Henry’s constant) = 2.32 * 10^-5 M/kPa

Explanation:

Here in this question, we are concerned with calculating the proportionality constant for this gas.

Mathematically, we can get this from Henry law

From Henry law;

Concentration = Henry constant * partial pressure

Thus Henry constant = concentration/partial pressure

Henry constant = 0.00290 M/125 kPa = 2.32 * 10^-5 M/kPa

If you are designing an experiment, how will you determine your independent or dependent variable?

Answers

Answer:

The independent variable effects the dependent variable.

Explanation:

The independent variable Is what you change whereas the dependent variable would change because of that.

for example, the indipendent variable could be how much you water a plant in ml each day, and the dependent variable would be how tall each plant grown]s with that water doseage per day.

What happens when two objects when they are brought closer together The mass of both objects decrease The mass of both objects increase The gravitational force between them decreases The gravitational force between them increases

Answers

Answer:

The correct option is

The gravitational force between them increases

Explanation:

According to Newton's law of universal gravitation states that the force of attraction between two bodies is directly proportional to the product of the masses of the bodies and inversely proportional to the square of the distance of their centers from each other.

The formula for universal gravitation is given as follows;

[tex]F_{1} = F_{2} =G \times \dfrac{m_{1} \times m_{2}}{r^{2}}[/tex]

Where;

F₁, and F₂ = The gravitational forces of attraction on each mass

G = The gravitational constant

m₁ = The mass of one body

m₂ = The mass of the body

r = The distance between the centers of the two bodies

Therefore, the gravitational force of attraction on each object is inversely proportional to the as the distance between the centers of the two bodies

When the distance between the centers of the two bodies decreases, the two objects are brought closer together, the gravitational force of attraction between them increases.

Answer:

Gravitational force between two objects of masses m1/m2

Explanation:

is defined by Gm1xm2/r^2, where G is a universal constant, and r is the distance between the masses. This shows you why B is wrong; it would increase. Also, A is not a good choice, as shown. In the case of B, it would increase by say, 2/1 to 4/1 by doubling ones mass. In C's case the bottom would decrease on the fraction alot (square) if they were moved closer, thus the force would be greater.

Explanation:

in other words the  answer is The gravitational force between them increases

the overall take away of an experiment’s results is the______. A. hypothesis B. introduction C. conclusion

Answers

Answer:

conclusion

Explanation:

it can't be a hypothesis since tests are carried out to verify so it is not a theory

an introduction to an experiment only gives the basis of what we are investigating therefore nothing has been proven and the question is still unanswered

The overall takeaway of an experiment’s results is the conclusion. Hence, option C is correct.

What is a hypothesis?

A hypothesis is a testable statement about the relationship between two or more variables or a proposed explanation for some observed experiment.

The overall takeaway of an experiment’s results can't be a hypothesis since tests are carried out to verify so it is not a theory

An experiment only gives an idea about the investigation therefore nothing has been proven and the question is still unanswered.

Hence, the overall takeaway of an experiment’s results is the conclusion.

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write the formula of three compounds which you know and name the elements in them​

Answers

Answer:

[tex]\boxed{\sf{view \ explanation}}[/tex]

Explanation:

Compound definition:

A compound is a chemical substance formed by two or more chemically bonded elements.

Three compounds:

Water is a compound with the formula [tex]\sf H_2O[/tex].

Two hydrogen atoms and one oxygen atom is present in one molecule of water.

Sodium chloride or table salt is a compound with the formula [tex]\sf NaCl[/tex].

One sodium atom and one chlorine atom is present in one molecule of sodium chloride.

Ammonia is a compound with the formula [tex]\sf NH_3[/tex].

In one molecule of ammonia, one nitrogen atom and three hydrogen atoms are present.

Answer:

See below

Explanation:

Three compounds are:

1) [tex]\mathrm {H_{2}SO{4}}[/tex] [Sulfuric acid]

The elements in this compound are hydrogen (H) , Sulfur (S) and Oxygen (O).

2) [tex]\mathrm {NaOH}[/tex] [Sodium hydroxide]

The elements in this compound are Sodium (Na) , Oxygen (O) and Hydrogen (H).

3) [tex]\mathrm {HCl}[/tex] [Hydrochloric acid]

The elements are Hydrogen (H) and Chlorine (Cl).

.hlp me to solve mcq​

Answers

Answer:

i) b

ii) c

Explanation:

Please see attached picture for full solution.

how many oxygen atoms are in 7.25g of calcium nitrate

Answers

Answer:

The answer to this question is approximately equal to 1.6 ×

[tex] 1.6 \times {10}^{23} atom \: o[/tex]

A baseball has a mass of 135 grams and a softball has a mass of 270 grams. In which of the following situations would they have the same momentum? The baseball and softball are thrown at the same speed in the same direction.

Answers

Answer:

The baseball is thrown twice as fast as the softball in the same direction.

Explanation:

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