The mole is used in chemistry

A) to count large numbers of very small particles, such as atoms or molecules.
B) to relate the mass and the number of particles of a substance to each other.
C) to relate the mass and the volume of a substance to each other.
D) all of these are true.

Answer:

H₂O₂

Explanation:

Hydrogen peroxide is a typical example of a compound molecule. A compound is made up of one or more atoms that are combined together in a definite grouping.

The properties of a compound is different from those of the elements that combines to from them.

Answer:

A. Nucleus

Nucleus is the answe

Answer:

it is 1,4

Explanation:

Just took the test hope you get it right. c:

Answer:

It is made of numbers

Explanation:

Found the hard way.

Answer:

Explanation:

(1) The primary industry is mainly agriculture, which includes agricultural, forestry, animal husbandry and fishery components. Agriculture is the foundation of social economy. (2) The secondary industry, which mainly includes the industrial and construction industries.

Answer:

The answer is chlorine

Explanation:

Answer:

A or B they do it for different reasons.

Explanation:

Answer:

Dissolving sugar in water, burning paper, and melting gold are all chemical changes

Explanation:

The action cannot be reversed, or undone. Therefore it is a chemical change.

Boiling water is a physical change.

Answer:

I belive 2 of them are Bromine and Mercury there are more then just 2 but im not the best at science sorry.

Explanation:

Answer:

b

Explanation:

The balanced equation for the synthesis of sulfuric acid is SO₃ + H₂O → H₂SO₄.

Those chemical reactions in which amount of species are present in equal amount on left side as well as on right side of the chemical reaction.

Sulphuric acid is formed by the combination of water with the sulphur trioxide, chemically it is represented as:
SO₃ + H₂O → H₂SO₄

Above reaction is balanced as each element is present in same amount on both side.

Hence, option (b) is correct.

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Answer:

[(x-37.5)/x]*100%

62.5%  (assuming the original sample weighs 100.0g)

Explanation:

Let's say that the original sample is x

Mass of I-125 which has decayed: x-37.5

Percentage of decayed mass: [(x-37.5)/x]*100%

Please recheck, for this may not be the correct answer

Answer:

Manganese

Explanation:

The electronic configuration of the atom is:

         1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁵

The powers in this configuration is the number of electrons in each orbital:

2 + 2 + 6 + 2 + 6 + 2 + 5  = 25

The compound has 25 electrons and it is Manganese

The electron configuration 1s22s22p63s23p64s23d5 corresponds to the element manganese (Mn).

In the electron configuration provided:

1s2 represents the filling of the 1s subshell with two electrons.

2s2 represents the filling of the 2s subshell with two electrons.

2p6 represents the filling of the 2p subshell with six electrons.

3s2 represents the filling of the 3s subshell with two electrons.

3p6 represents the filling of the 3p subshell with six electrons.

4s2 represents the filling of the 4s subshell with two electrons.

3d5 represents the filling of the 3d subshell with five electrons.

Based on this electron configuration, we can correctly identify the element as manganese (Mn), which has an atomic number of 25.

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Answer:

Weathering involves the use of water and or wind to wear down the environment. The sand dunes were most likely carried by wind to form them and form its shape. Erosion most likely took away parts of the sand to make the sand dune. Deposition most likely deposited sand to the area.

Explanation:

If you possibly want a better explanation, try looking it up :).

#teamtrees #WAP (Water And Plant)

Answer:

The first question is option 2

and the second question in option 1

Explanation:

Answer:

Fluorine gas reacts violently with water to produce hydrogen fluoride and ozone according to the following unbalanced equation. How many moles of o, are created assuming STP conditions are in effect, given

Explanation:

3

Answer:

There are 2 atoms of Oxygen (O) present in SO2 therefore it's atomicity is 2

Answer:

A. The number of atoms of each element is the same on the reactant side as the product side.

Explanation:

The equation demonstrates the law of conservation of mass in such a way that the number of atoms of each element is the same on the reactant side as the product side.

According to the law of conservation of mass "matter is neither created nor destroyed in a chemical reaction but they are changed from one form to another".

Answer:

6.944 liters of O₂ at STP will react with 8.7 grams of C₂H₄ to form CO₂ and H₂O.

Explanation:

The balanced reaction is:

C₂H₄ + 3 O₂ ⇒ 2 CO₂ + 2 H₂O

Being the molar mass of the elements:

Then the molar mass of compound C₂H₄ is:

C₂H₄= 2*12 g/mole + 4*1 g/mole= 28 g/mole

By stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction), 1 mole of C₂H₄ acts. Then, being the mass of a mole of a substance, which can be an element or a compound, 1 mole of C₂H₄ is 28 g, which is the amount of mass that reacts in this case.

Then be able to apply the following rule of three: if by stoichiometry 28 grams of C₂H₄ react with 3 moles of O₂, 8.7 grams of C₂H₄ with how many moles of O₂ do they react?

[tex]moles of O_{2} =\frac{8.7 grams ofC_{2} H_{4}*3 moles of O_{2} }{28grams ofC_{2} H_{4}}[/tex]

moles of O₂= 0.31  

The STP conditions refer to the standard temperature and pressure. Pressure values at 1 atmosphere and temperature at 0 ° C are used and are reference values for gases. And in these conditions 1 mole of any gas occupies an approximate volume of 22.4 liters.

Then we can apply the following rule of three: if by definition of STP 1 mole occupies 22.4 L, 0.31 moles how much volume will it occupy?

[tex]volume=\frac{0.31 moles*22.4 L}{1 mole}[/tex]

volume= 6.944 L

6.944 liters of O₂ at STP will react with 8.7 grams of C₂H₄ to form CO₂ and H₂O.

The volume of O₂ at STP that will react with the given C₂H₄ is 20.8 L

First, we will determine the number of moles of O₂ required.

From the given balanced chemical equation,

C₂H₄ + 3O₂ → 2CO₂ + 2H₂O

This means

1 mole of C₂H₄ is required to react completely with 3 moles of O₂

Now, we will determine the number of moles of C₂H₄ present

Mass of C₂H₄ = 8.7 g

Using the formula

[tex]Number\ of\ moles = \frac{Mass}{Molar\ mass}[/tex]

Molar mass of C₂H₄ = 28.05 g/mol

∴ Number of moles of C₂H₄ = [tex]\frac{8.7}{28.05}[/tex]

Number of moles of C₂H₄ = 0.31016 mole

Since

1 mole of C₂H₄ is required to react completely with 3 moles of O₂

Then,

0.31016 mole of C₂H₄ will react completely with 3 × 0.31016 mole of O₂

3 × 0.31016 = 0.9305 mole

∴ Number of moles of O₂ required is 0.9305 mole

Now, for the volume of O₂ at STP that will react

Since 1 mole of a gas occupies 22.4 L at STP

Then,

0.9305 mole of O₂ will occupy 0.9305 × 22.4 L at STP

0.9305 × 22.4 = 20.8432 L

≅ 20.8 L

Hence, the volume of O₂ at STP that will react with the given C₂H₄ is 20.8 L

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Answer: Strontium has 219 pm

Iodine has 115 pm

Explanation: So the answer is Sr-Strontium

Answer:

[tex]Distance = 40km[/tex]

Explanation:

Given

[tex]Speed = 80km/hr[/tex]

[tex]Time = 0.5hr[/tex]

Required

Determine the distance covered

Distance is calculated as:

[tex]Distance = Speed * Time[/tex]

Substitute values for Speed and Time

[tex]Distance = 80km/hr * 0.5hr[/tex]

[tex]Distance = 80km * 0.5[/tex]

[tex]Distance = 40km[/tex]

Hence, you travelled 40km

Answer:

4.00L

Explanation:

Using Charle's law, which have the following equation:

V1/T1 = V2/T2

Where;

V1 = initial volume (litres)

T1 = initial temperature (Kelvin)

V2 = final volume (litres)

T2 = final temperature (Kelvin)

According to the information provided, T1 = 275K, T2 = 400K, V1 = ?, V2 = 5.82L

Hence, using the formula;

V1/275 = 5.82/400

400 × V1 = 275 × 5.82

400V1 = 1600.5

V1 = 1600.5 ÷ 400

V1 = 4.001

Therefore, volume of the gas before it is heated is 4.00L

Answer:

Mercury, Venus, Earth and Mars.

Explanation:

Answer:118

Explanation: it’s right

Answer:

118 elements

Hope that helps

Answer:

The number of formula units in 3.81 g of potassium chloride (KCl) is approximately 3.08 × 10²²

Explanation:

The given parameters is as follows;

The mass of potassium chloride produced in the chemical reaction (KCl) = 3.81 g

The required information = The number of formula units of potassium chloride (KCl)

The Molar Mass of KCl = 74.5513 g/mol

[tex]The \ number \ of \ moles \ of \ a \ substance, n = \dfrac{The \ mass \ of \ the substance}{The \ Molar \ Mass \ of \ the \ substance}[/tex]

Therefore, we have;

[tex]The \ number \ of \ moles \ of \ KCl= \dfrac{3.81 \ g}{74.5513 \ g/mol} \approx 0.051106 \ moles[/tex]

1 mole of a substance, contains Avogadro's number (6.022 × 10²³) of  formula units

Therefore;

0.051106 moles of KCl contains 0.051106 × 6.022 × 10²³  ≈ 3.077588 × 10²² formula units

From which we have, the number of formula units in 3.81 g of potassium chloride (KCl) ≈ 3.08 × 10²² formula units.

The number of formula units in 3.81 g of potassium chloride (KCl) is approximately 3.08 × 10²²

Given:

Mass of KCl= 3.81 g

To find:

Formula units of KCl=?

Molar Mass of KCl = 74.55 g/mol

So, substituting the values in order to calculate number of moles

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}} \\\\\text{Number of moles}=\frac{3.81}{74.55} \\\\\text{Number of moles}=0.051 \text{ moles}[/tex]

1 mole of a substance = Avogadro's number (6.022 × 10²³) of  formula units

Thus, 0.051 moles of KCl will contain

[tex]0.051106 * 6.022 * 10^{23} =3.077588 * 10^{22} \text{ formula units}[/tex]

→The number of formula units in 3.81 g of potassium chloride (KCl)

= 3.08 × 10²² formula units.

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Answer:

precipitation

Explanation:

gravity pulls down rain

Answer:

B. 3+

Explanation:

When Fe²⁺ loses an electron, it becomes an Fe³⁺ ion.

   The loss of an electron in an atom makes the atom becomes positively charged. Further losing electrons makes the atom more positive.

 For the given ion;

 Fe²⁺   if it loses an electron more, it becomes Fe³⁺.

The expression is given as:

         Fe²⁺    →    Fe³⁺  +  e⁻

Answer:

percent yield = 80.7%

Theoretical yield of silver sulfide = 30.975 g

Actual yield  = 25 g

Explanation:

Given data:

Mass of silver = 27 g

Mass of silver sulfide formed = 25 g

Theoretical yield of silver sulfide = ?

Actual yield = ?

Percent yield = ?

Solution:

Chemical equation:

2Ag + S   →     Ag₂S

Number of moles of Ag:

Number of moles = mass/molar mass

Molar mass of silver = 107.8 g/mol

Number of moles = 27 g/ 107.8 g/mol

Number of moles = 0.25 mol

Now we will compare the moles of silver with silver sulfide.

               Ag         :       Ag₂S

               2            :         1

              0.25        :      1/2×0.25 = 0.125 mol

Theoretical yield of silver sulfide:

Mass = number of moles × molar mass

Mass = 0.125 mol ×  247.8 g/mol

Mass = 30.975 g

Actual yield is given in question = 25 g

Percent yield:

Percent yield = (actual yield / theoretical yield) × 100

Percent yield = (25 g/ 30.975 g ) × 100

percent yield = 80.7%

Answer:

It kinda helps but not  really

Thanks for trying anyway doe!

Explanation:

Answer:

The pan on the bottom right with the arrows pointing up.

Explanation:

conduction is the transfer of heat through touching surfaces, so when you place the pan on a hot stove, the heat heats up the bottom of the pan, and then the water in it.

The transfer of energy between systems through work is the expansion of gas in a steam engine. Therefore, the second diagram in the second row shows the correct direction of flow of heat.

Energy transfer is a phenomenon in which energy transfer from one matter to another matter. Energy can be transferred in two forms that are by doing work or by transferring heat.

Heat can be transferred by three ways conduction, convention and radiation. In conduction, when two object are in direct contact, transfer of molecules takes place. When heat flow through touching surfaces is called conduction. Heat flows in the upward direction from bottom in a pan.

Therefore, the second diagram in the second row shows the correct direction of flow of heat.

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