Scientists discover remains of wooden structures near a Celtic runes site. What kind of testing will indicate when the stones were moved into place by the Celts?

Carbon dating

Radioactive dating

Moles of MgF₂ : 1.2 x 10⁻⁴

Maybe the complete question is like this

A student prepares 100. mL of a saturated solution of MgF2 by adding 0.50 g of solid MgF2 to 100. mL  of distilled water at 25°C and stirring until no more solid dissolves. (Assume that the volume of the  undissolved MgF2 is negligibly small.) The saturated solution is analyzed, and it is determined that [F−] in  the solution is 2.4 × 10−3 M.

The dissociation reaction of MgF₂

MgF₂(s)⇒ Mg²⁺(aq)+2F⁻(aq)

mol ratio MgF₂ : F⁻ = 1 : 2

mol of F⁻ in 100 ml solution :

[tex]\tt mol=M\times V\\\\mol=2.4\times 10^{-3}\times 0.1=2.4\times 10^{-4}[/tex]

mol MgF₂ :

[tex]\tt \dfrac{1}{2}\times 2.4\times 10^{-4}= 1.2\times 10^{-4}[/tex]

Answer:

If an atom gains or loses an electron, it bacomes an ion. An atom that gains a negative electron, it becomes a negative ion. If it loses an electron it becomes a positive ion

Explanation:

A lithium atom has 3 protons and 3 electrons. It can lose one of its electrons, making it an ion. It now has more positive protons than electrons so it has an overall positive charge. Therefore it is a positive ion.

A fluorine atom will tend to gain, rather than lose, an electron. By gaining a negative electron, it has an overall negative charge. It has become a negative ion.

Answer:

3.64g

Explanation:

Given parameters:

Mass of NH₃  = 18.1g

Mass of Cu₂O  = 90.4g

Unknown:

Limiting reactant  = ?

Mass of N₂ formed  = ?

Solution:

The reaction equation is given as:

       Cu₂O + 2NH₃ → 6Cu + N₂ + 3H₂O

The limiting reactant is the one in short supply in the reaction. Let us find the number of moles of the given species;

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

Molar mass of Cu₂O = 2(63.6) + 16  = 143.2g/mol

Molar mass of NH₃  = 14 + 3(1) = 17g/mol

Number of moles of Cu₂O = [tex]\frac{18.1}{143.2}[/tex]   = 0.13moles

Number of moles of NH₃   = [tex]\frac{90.4}{17}[/tex]   = 5.32moles

  From this reaction;

       1 mole of  Cu₂O combines with 2 mole of NH₃

So   0.13moles of  Cu₂O will combine with 0.13 x 2 mole of NH₃

                                              = 0.26moles of NH₃

Therefore, Cu₂O is the limiting reactant. Ammonia is in excess;

Mass of N₂;

   Mass = number of moles x molar mass

    1 mole of Cu₂O  will produce 1 mole of N₂

    0.13 mole of Cu₂O  will produce 0.13 mole of N₂

    Mass  = 0.13 x (2 x 14) = 3.64g

Answer:

The description is outlined in subsection downwards and according to the query given.

Explanation:

The solubility of a soap is due to the hydrophilic head which interacts with water.

A triglyceride is a compound that is based on propane 1,2,3 - triol where all the -OH groups have been replaced with fatty acid chains. The triglycerides are insoluble in water because it contains a long alkyl chain which does not interact with water.

However, a soap is a salt of a glyceride having a hydrophilic head and a hydrophobic tail. The hydrophilic head is responsible for the solubility of the soap in water.

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Answer: C

Explanation:

No matter the location on Earth, the sun always rises in the east due to its rotation pattern.

Answer:

iron i believe is ionic and carbon is covalent

Explanation:

if im wrong correct me

CO₂ produced : 11.92 moles

Reaction

2C₂H₆ (g)+7O₂ (g) ⇒4CO₂ (g)+6H₂O(g)

mol ratio C₂H₆ : CO₂ = 2 : 4

moles of CO₂ :

[tex]\tt \dfrac{4}{2}\times 5.95=11.92~moles[/tex]

Answer:

4moles of carbon trihydride

Answer:

This question is incomplete

Explanation:

This question is incomplete but the answer to the question can be correctly predicted from the available information from the question.

1. If a "container" (in this case a crucible) is closed throughout a heating experiment. Then it must be noted that water vapor will not be able to escape during the course of the experiment. The water vapor will form a "cloud" of water droplets under the cover of the crucible. And when this crucible is cooled, this water droplets return back to the content/substance inside the crucible.

2. When compared with the initial amount of water present in the substance in the crucible, the percentage of water "left" in the hydrate or substance in the crucible would be high. This is because the water vapor that was suppose to leave the crucible did not leave because the crucible was closed (thus causing very low amount of water vapour to leave).

Because of the student error, the percent water of crystallization value the hydrate will be lower than its actual value.

Evaporation is the process by which a liquid changes spontaneously to vapor.

In the experiment to determine percentage water of crystallization, the crucible is left open to ensure all the water molecules are removed by evaporation.

However,, since the student did not remove the crucible cover during heating, some water molecules will not be able to escape completely, but will return back to the salt.

Hence, the percent water of crystallization value the hydrate will be lower because the of mass of the anhydrous salt will be higher than its actual value.

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Answer:

Explanation:

The mass of the bicycle can be found by using the formula

[tex]m = \frac{p}{v} \\ [/tex]

p is the momentum

v is the velocity

From the question we have

[tex]m = \frac{25}{2.5} \\ [/tex]

We have the final answer as

Hope this helps you

Answer: 16.21

Explanation:

A student measures the length of two pieces of paper as 8.21 in and 8.0 in. the total length is 16.21 with 4 significant figures.

The significant figures or digits are the form of scientific methd which represent the digit from zero to nine and use when the value is uncertain where starting zeros are not significant and decimal is also not a significant figure.

In the given value the total is 16.21 with 4 significant figures with it has 4 significant digits and the decimal with it is not significant after adding from which the respective value is here.

Therefore,  with 4 significant figures where the student measures the length of two pieces of paper as 8.21 in and 8.0 in. the total length is 16.21.

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Answer:

[tex]\boxed {\boxed {\sf882 \ Joules}}[/tex]

Explanation:

Potential energy can be found by multiplying the mass by the height by the gravitational acceleration.

[tex]PE=mgh[/tex]

The mass is 45 kilograms. The height is 2 meters. The gravitational acceleration on Earth is 9.8 meters per seconds squared.

[tex]m=45 \ kg \\h= 2 \ m \\g=9.8 \ m/s^2[/tex]

Substitute the values into the formula.

[tex]PE=45 \ kg * 2 \ m * 9.8 m/s^2[/tex]

Multiply.

[tex]PE=441 kg*m/s^2*2 \ m[/tex]

[tex]PE= 882 \ kg *m/s^2 *m[/tex]

1 kg*m/s^² is equal to 1 Newton (N). Substitute N in for kg*m/s²

[tex]PE=882 \ N*m[/tex]

1 Newton meter (N*m) is equal to 1 Joule (J). Our current answer is equivalent to 882 Joules.

[tex]PE= 882 \ J[/tex]

The sled's potential energy is 882 Joules.

Answer:

882 J

Explanation:

Answer:

the answer is d. frequency

Answer:

[tex]T_f=26.7\°C[/tex]

Explanation:

Hello.

In this case, when two substances at different temperature are placed in contact in an isolated container, we can say that the heat lost by the hot substance is gained by the cold substance. In such a way, since granite is at 76.0 °C and water at 22.0 °C we infer granite is hot and water is cold, so we write:

[tex]Q_{granite}=-Q_{water}[/tex]

In terms of mass, specific heat and change in temperature, we write:

[tex]m_{granite}C_{granite}(T_f-T_{granite})=-m_{water}C_{water}(T_f-T_{water})[/tex]

Thus, since the temperature is the same for both substance, we can solve for it as shown below:

[tex]T_f=\frac{m_{granite}C_{granite}T_{granite}+m_{water}C_{water}T_{water}}{m_{granite}C_{granite}+m_{water}C_{water}}[/tex]

By plugging in each variable, we obtain:

[tex]T_f=\frac{11.1g*0.790\frac{J}{g\°C} *76.0\°C+22.0g*4.18\frac{J}{g\°C} *22.0\°C}{11.1g*0.790\frac{J}{g\°C} +22.0g*4.18\frac{J}{g\°C}}\\\\T_f=26.7\°C[/tex]

Best regards!

Answer: D

Explanation:

Hydropower

Answer:

compound

Explanation:

Answer:

The answer is compound

Explanation:

Answer:

The best and most correct answer among the choices provided by your question is the fourth choice.

The data explains that sodium atoms hardly ever form 2+ ions.

I hope my answer has come to your help. Thank you for posting your question here in Brainly. We hope to answer more of your questions and inquiries soon. Have a nice day ahead!

Explanation:

Answer:

CaHPO4 i think

Explanation:

Answer:

6.711 × 10²⁴ molecules Mg(OH)₂

General Formulas and Concepts:

Chemistry - Atomic Structure

Explanation:

Step 1: Define

650.0 g Mg(OH)₂

Step 2: Define conversions

Avogadro's Number

Molar Mass of Mg - 24.31 g/mol

Molar Mass of O - 16.00 g/mol

Molar Mass of H - 1.01 g/mol

Molar Mass of Mg(OH)₂ - 24.31 + 2(16.00) + 2(1.01) = 58.33 g/mol

Step 3: Convert

[tex]650.0 \ g \ Mg(OH)_2(\frac{1 \ mol \ Mg(OH)_2}{58.33 \ g \ Mg(OH)_2} )(\frac{6.022 \cdot 10^{23} \ molecules \ Mg(OH)_2}{1 \ mol \ Mg(OH)_2} )[/tex]

= 6.71061 × 10²⁴ molecules Mg(OH)₂

Step 4: Check

We are given 4 sig figs. Follow sig fig rules.

6.71061 × 10²⁴ molecules Mg(OH)₂ ≈ 6.711 × 10²⁴ molecules Mg(OH)₂

Percent by mass : 4.10⁺³%

The concentration of a solution can be expressed in units such as molarity, normality, mass percent, volume percent etc.

[tex]\tt \%mass=\dfrac{mass~solute}{mass~solution}\times 100\%[/tex]

mass solute= mass of NaOH  

mass of NaOH :

[tex]\tt 0.001~mol/L\times 1~L\times 40~g/mol=0.04~g[/tex]

mass solution = 1000 g

% mass :

[tex]\tt \dfrac{0.04}{1000}\times 100=4.10^{-3}\%[/tex]

The percent by mass concentration of NaOH in the given solution is approximately 0.004%.

To calculate the percent by mass concentration of NaOH, we must find the mass of NaOH in solution.

First, we determine how many moles of NaOH are present in the solution:

Molarity (M) is calculated as moles of solute per liter of solution.

1 L = 0.001 M = mole of NaOH

We rearrange the equation to find that one mole of NaOH is equal to 0.001 moles.

Mass of NaOH = moles of NaOH * molar mass of NaOH

Mass of NaOH = 0.001 mol * 40.00 g/mol

Mass of NaOH = 0.04 g

The mass of the solution is 1000 g which is given in the question.

Percent by mass concentration of NaOH = (mass of NaOH / mass of solution) * 100%

Percent by mass concentration of NaOH = (0.04 g / 1000 g) * 100%

Percent by mass concentration of NaOH = 0.004%

Hence, the percent by mass concentration of NaOH in the given solution is approximately 0.004%.

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Answer:

1.1 M

General Formulas and Concepts:

Explanation:

Step 1: Define variables

1.2 mol KCL

1.1 L of solution

M = unknown

Step 2: Solve for Molarity

Step 3: Check

We are given 2 sig figs. Follow sig fig rules.

1.09091 M ≈ 1.1 M

Answer:

Ne

Explanation:

It has the lowest density.

Neon has the lowest density since it has the smallest atomic size and the lowest atomic number.

The atomic density of an element refers to the number of atoms contained in an element per unit volume.

The size of an atom has an effect on atomic density. The size of an atom increases from left to right across the period and top to bottom down the group.

As such, on the periodic table, as we move from top to bottom down the group, the density of an atom increases.

The atomic element of the given elements are:

Therefore, we can conclude that Neon (Ne) will have the lowest density since it has the smallest atomic size and the lowest atomic number.

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Answer:

[tex]V_{base}=9.442mL[/tex]

Explanation:

Hello!

In this case, when acetic acid is titrated with sodium hydroxide, the following chemical reaction is carried out:

[tex]CH_3COOH+NaOH\rightarrow CH_3COONa+H_2O[/tex]

Whereas there is a 1:1 mole ratio between the acid and the base, which means that at the equivalence point we evidence:

[tex]n_{acid}=n_{base}[/tex]

Which in terms of volumes and concentrations is written as:

[tex]M_{acid}V_{acid}=M_{base}V_{base}[/tex]

Thus, solving for the required volume of base, we obtain:

[tex]V_{base}=\frac{M_{acid}V_{acid}}{M_{base}}=\frac{0.1894M*10.00mL}{0.2006M}\\\\ V_{base}=9.442mL[/tex]

Best regards!

Answer:

5.00 moles O₂

General Formulas and Concepts:

Chemistry - Atomic Structure

Explanation:

Step 1: Define

3.01 × 10²⁴ molecules O₂

Step 2: Convert

[tex]3.01 \cdot 10^{24} \ mc \ O_2(\frac{1 \ mol \ O_2}{6.022 \cdot 10^{23} \ mc \ O_2} )[/tex] = 4.99834 moles O₂

Step 3: Check

We are given 3 sig figs. Follow sig fig rules and round.

4.99834 moles O₂ ≈ 5.00 moles O₂

C : 52.2%, H : 13.1%, O:34.7%

The empirical formula is the smallest comparison of atoms of compound forming elements.  

A molecular formula is a formula that shows the number of atomic elements that make up a compound.  

(empirical formula) n = molecular formula  

11.5 g of Ethanol-C₂H₅OH contains 6.00 g of Carbon and 1.51 g of Hydrogen.

mass of Oxygen :

[tex]\tt 11.5-(6+1.51)=4~g[/tex]

Percent composition :

[tex]\tt \dfrac{6}{11.5}\times 100\%=52.2\%[/tex]

[tex]\tt \dfrac{1.51}{11.5}\times 100\%=13.1\%[/tex]

[tex]\tt \dfrac{4}{11.5}\times 100\5=34.7\%[/tex]

Answer:

Dissolves in water: Acetone, 1-propanol, Methanol

Do not dissolve in water: Hexane, Decane

Explanation:

From the principle that like dissolves like,polar substances will dissolve in polar solutions, while non-polar substances will dissolve in non-polar substances.

Water is a polar solution, therefore, polar substances will dissolve in it.From the given options:

Acetone is a polar molecule, therefore, it will dissolve in water.

1-propanol is a polar molecule, therefore, it will dissolve in water.

Hexane is a non-polar molecule, therefore, it will not dissolve in water.

Methanol is a polar molecule, therefore, it will dissolve in water.

Decane is a non-polar molecule, therefore, it will not dissolve in water

Answer:

Number of moles = 0.94 mol

Explanation:

Given data:

Number of moles of sodium chloride = ?

Volume of sodium chloride = 1.25 L

Concentration of solution = 0.750 mol/L

Solution:

Formula:

Concentration = number of moles/ volume in L

By putting values.

0.750 mol/L = number of mole / 1.25 L

Number of moles =  0.750 mol/L×1.25 L

Number of moles = 0.94 mol

Answer:

Molar mass of NH4SO2=104gmol`

No of moles of NH4SO2=2.3g/104gmol`=0.022×(avagadro's constant)

Answer:

C

Explanation:

Grams 3/4

Answer:

9g

Explanation:

number of moles × the moleculars mass