What period has 3 valence electrons?

B) 20g/cm³

Hi there !

density formula

d = m/V

volume formula

V = l×w×h

V = 3cm×2cm×1cm = 6cm³

d = 120g/6cm³

d = 20g/cm³

Good luck !

Answer:

20g

Explanation:

Answer: 2.04

Explanation:

Answer:

Approximately \(0.821\; \rm mol\).

Explanation:

Look up the relative atomic mass of \(\rm Ba\), \(\rm O\), and \(\rm H\) on a modern periodic table:

Calculate the formula mass of \({\rm Ba(OH)_2}\):

\(\begin{aligned}& M({\rm Ba(OH)_2}) \\ &= 137.327 + 2\times(15.999 + 1.008) \\ &\approx 171.334\; \rm g \cdot mol^{-1}\end{aligned}\).

Calculate the number of moles of \({\rm Ba(OH)_2}\) formula units in that \(235\; \rm g\) of this compound:

\(\begin{aligned}& n({\rm Ba(OH)_2}) \\ &= \frac{m({\rm Ba(OH)_2})}{M({\rm Ba(OH)_2})} \\ &= \frac{235\; \rm g}{171.334\; \rm g \cdot mol^{-1}} \approx 1.37159\; \rm mol \end{aligned}\).

Calculate the volume of a \(c({\rm Ba(OH)_2}) = 1.67\; \rm mol \cdot L^{-1}\) with approximately \(n({\rm Ba(OH)_2}) = 1.37159\; \rm mol\) of the solute:

\(\begin{aligned}& V({\rm Ba(OH)_2}) \\ &= \frac{n({\rm Ba(OH)_2})}{c({\rm Ba(OH)_2})} \\ &= \frac{1.37159\; \rm mol}{1.67\; \rm mol \cdot L^{-1}} \approx 0.821\; \rm L \end{aligned}\).

Comparing the data obtained online, the first group is more precise

The reason the above selection is correct is as follows;

Question: Parts of the question appear missing from a similar question online and included here;

First Group:

\(\begin{array}{|c|c|c|c|c|c|c|} Team \ a &Team \ b&Team \ c&Team \ d&Team \ e&Team \ f&Team \ g\\2.77 \ cm&2.60 \ cm&2.80 \ cm&2.65 \ cm&2.75 \ cm&2.65 \ cm& 2.68 \ cm\end{array}\right]\)

Second Group

\(\begin{array}{|c|c|c|c|c|c|c|} Team \ a &Team \ b&Team \ c&Team \ d&Team \ e&Team \ f&Team \ g\\2.70 \ cm&2.78 \ cm&2.62 \ cm&2.65 \ cm&2.75 \ cm&2.80 \ cm& 2.60 \ cm\end{array}\right]\)

Calculations for the first group:

The average = (2.77 + 2.60 + 2.80 + 2.65 + 2.75 + 2.65 + 2.68)/7 = 2.7

The range = 2.80 - 2.60 = 0.20

The approximate ± range of the average = ±0.2/2 = ±0.1

The precision of the first measurement is 2.7 ± 0.1 cm

Calculations for the second group:

The average = (2.70 + 2.78 + 2.62 + 2.65 + 2.75 + 2.80 + 2.60)/7 = 2.7

The range = 2.80 - 2.60 = 0.20

The approximate ± range from the average = ±0.2/2 = ±0.1

The range of values from the average is approximately ±0.1 cm

The precision of the first measurement is 2.7 ± 0.1 cm

Method to determine precision:

Precision is given by the finding the average deviation and the standard deviation as follows;

\(\mathbf{Average \ deviation} = \dfrac{\sum \left | x - \mu \right |}{n}\)

\(\mathbf{Standard\ deviation} =\sqrt{\dfrac{\sum \left ( x - \mu \right )^2}{n}}\)

Where;

μ = The mean or average = 2.7

n = The number of items (count) of the data = 7

For the first group, we have;

\(\mathbf{\dfrac{\sum \left | x - \mu \right |}{n}} = \dfrac{0.07 + 0.1 + 0.1 + 0.05 + 0.05 + 0.05 + 0.02 }{7} = \mathbf{0.062857}\)

The average deviation of the first group = 0.062857

∑(x - μ)² ≈ 0.0328

\(\mathbf{The \ standard\ deviation} =\sqrt{\dfrac{0.0328}{7}} \approx \mathbf{0.068452}\)

For the second group, we have;

\(\mathbf{\dfrac{\sum \left | x - \mu \right |}{n}} = \dfrac{0.0+ 0.08 + 0.08 + 0.05 + 0.05 + 0.1 + 0.1 }{7} = \mathbf{0.06571428571}\)

∑(x - μ)² ≈ 0.0378

\(\mathbf{The \ standard\ deviation} =\sqrt{\dfrac{0.0378}{7}} \approx \mathbf{0.073485}\)

By using the average deviation, and standard deviation values, the deviation of the second group is more than the first group and therefore the first group is more precise

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Answer:

Well elements are chemical substances while a compound consists of two or multiple elements put together.

Explanation:

Answer:

Elements

iron,

copper,

silver,

gold,

hydrogen,

carbon,

nitrogen,

and oxygen.

Compounds

Sugar (sucrose - C12H22O11)

Table salt (sodium chloride - NaCl)

Water (H2O)

Carbon dioxide (CO2)

Sodium bicarbonate (baking soda - NaHCO3)

Answer:

Hertz is the rate at which current changes direction. SO frenquency

Explanation:

the Sun light from different parts of the Moon as the Moon revolves around the Earth

Answer:

Explanation:

The correct answer is B. isotopes.

Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. This difference in the number of neutrons leads to variations in their atomic mass but does not affect their chemical properties or reactivity. Isotopes of an element have similar chemical behaviors but may have slightly different physical properties due to the difference in atomic mass.

Hope this answer your question

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For your question about diagram it is definitely A

Answer:

A

Explanation:

I am only in 6th grade so all I have to say is good luck and I wish you the best on that quiz.

The value of Avogadro's number is:

\(N = 6.02214076*10^{23}\)

So the correct option is the second one.

Avogadro's number represents the number of molecules in a mole.

The value of the Avogadro's number is such that the mass of one mole of a compound is numerically equal to the mass of that compound in daltons.

And, by definition, Avogadro's number is:

\(N = 6.02214076*10^{23}\)

With this in mind, we conclude that the correct option is the second one.

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Answer:

Explanation:

6.02x10^23

Answer:

a

Explanation:

From the given images, it is clear that both rocks are non-foliated rocks because they don't have distinct repetitive layers.  Hence option a is correct.

Metamorphic rocks are formed through intense pressure and heating from the sedimentary or igneous rocks. Sometime the change n heat or pressure make the metamorphic rocks gets foliated.

Foliation occurs when pressure forces flat or elongate minerals within a rock to align. These rocks form a platy or sheet-like structure that reflects the pressure direction. There is no platy or sheet-like structure in non-foliated metamorphic rocks.

Non-foliated rocks can be created in a variety of ways. Some rocks, like limestone, are composed of minerals that are not flat or elongate. Therefore, the given rocks are non-foliated.

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Understanding the relationship between reactants and products in a reaction is crucial for understanding chemistry. That is what stoichiometry is.

It is a quantitative relationship between the mass (and thus the number of moles) of different products and reactants in a chemical reaction.

Chemical reactions must be balanced, or in other words, the products and reactants must both contain the same number of different atoms.

A chemical reaction cannot yield any knowledge about the relationship between its products and reactants if it is not balanced. In order to balance a chemical reaction, you should do so initially.

By placing coefficients in front of the reactants and products, we may balance processes. The stoichiometric coefficients are these values.

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Answer:

A molecule is usally formed when two or more atoms join together chemically. If atoms combine that are of two or more different elements, we call that a compound. When two hydrogen atoms combine with one oxygen atom, it becomes the compound water.

Explanation:

Answer:

C₂H6

Explanation:

Among the given options, the formula A) C₂H6 represents a hydrocarbon (specifically, ethane). Option A

A hydrocarbon is a compound that consists of only carbon and hydrogen atoms. It is important to identify the formula that represents a hydrocarbon among the given options:

A) C₂H6: This formula represents ethane, which is a hydrocarbon. Ethane consists of two carbon atoms bonded together with single bonds and six hydrogen atoms.

B) C₂H5OH: This formula represents ethanol, which is not a hydrocarbon. Ethanol contains a hydroxyl group (-OH), indicating the presence of oxygen in addition to carbon and hydrogen atoms. It is an alcohol, not a hydrocarbon.

C) C₂H5Cl: This formula represents ethyl chloride, which is not a hydrocarbon. Ethyl chloride contains a chlorine atom (Cl) in addition to carbon and hydrogen atoms. It is a haloalkane, not a hydrocarbon.

D) C₂H6O: This formula represents ethanol, which, as mentioned before, is not a hydrocarbon. Ethanol contains an oxygen atom (O) in addition to carbon and hydrogen atoms. It is an alcohol, not a hydrocarbon.

Among the given options, the formula A) C₂H6 represents a hydrocarbon (specifically, ethane). It consists only of carbon and hydrogen atoms, making it a suitable representation of a hydrocarbon.

In summary, the formula C₂H6 (option A) represents a hydrocarbon, while the other options contain additional elements (oxygen or chlorine) that make them non-hydrocarbon compounds. Option A

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Burning and other changes in matter do not destroy matter. The mass of matter is always the same before and after the changes occur. The law of conservation of mass states that matter cannot be created or destroyed

The thing that is happen in a food sample as it is burned is the chemical and physical change.

Comubustion reactions are those reactions in which organic compound get burnt in the presence of oxygen for the formation of carbon dioxide gas and water molecule.

If the food sample contains the organic compound then it will convert into water and carbon dioxide gas and if it contains the matter in the form of inorganic compounds then it will convert into another product but having the same mass.

Hence if matter of food sample is burned then it will convert into small products as a result of physical or chemical change.

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Answer:

Ecosystems contain biotic or living, parts, as well as abiotic factors, or nonliving parts. Biotic factors include plants, animals, and other organisms. Abiotic factors include rocks, temperature, and humidity. Every factor in an ecosystem depends on every other factor, either directly or indirectly.

To prepare the pH 4.00 buffer solution, you should mix approximately 61.35 mL of the 0.100 M benzoic acid solution with 38.65 mL of the 0.240 M sodium benzoate solution.The ratio of benzoic acid to sodium benzoate in the buffer solution using the Henderson-Hasselbalch equation.

To prepare a pH 4.00 buffer solution using benzoic acid and sodium benzoate, we need to calculate the appropriate volumes of the 0.100 M benzoic acid and 0.240 M sodium benzoate solutions.

First, we need to determine the ratio of benzoic acid to sodium benzoate in the buffer solution. The Henderson-Hasselbalch equation can help us with this calculation:

pH = pKa + log([A-]/[HA])

Given that the pH is 4.00 and pKa is 4.20, we can rearrange the equation:

log([A-]/[HA]) = pH - pKa

log([A-]/[HA]) = 4.00 - 4.20

log([A-]/[HA]) = -0.20

Next, we take the antilog of -0.20 to find the ratio of [A-] to [HA]:

[A-]/[HA] = antilog(-0.20)

[A-]/[HA] = 0.63

The ratio of [A-] to [HA] is 0.63.

Now, let's calculate the volumes of each solution needed. Let's assume x represents the volume (in mL) of the 0.100 M benzoic acid solution and y represents the volume (in mL) of the 0.240 M sodium benzoate solution.

Since the total volume is 100.0 mL, we have the equation: x + y = 100

Considering the ratio of [A-] to [HA] as 0.63, we can write the equation: y/x = 0.63

Solving these two equations simultaneously will give us the volumes of each solution:

x + y = 100

y/x = 0.63

By substituting y = 0.63x from the second equation into the first equation, we get:

x + 0.63x = 100

1.63x = 100

x = 61.35 mL (rounded to two decimal places)

Substituting this value back into the equation x + y = 100, we find:

61.35 + y = 100

y = 38.65 mL (rounded to two decimal places)

Therefore, to prepare the pH 4.00 buffer solution, you should mix approximately 61.35 mL of the 0.100 M benzoic acid solution with 38.65 mL of the 0.240 M sodium benzoate solution.

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The time of burial, the organic material will be about 34,880 years old.

Half-life (t½) is the time which is required for a quantity of the substance to reduce to the half of its initial value. The term is commonly used in the nuclear physics to describe how quickly the unstable atoms or chemical elements undergo the radioactive decay or how long the stable atoms survive.

The amount of carbon 14 (14C) which can be found in the organic matter decreases due to the radiocarbon process. This process is also called as the radioactive decay. The half-life of carbon-14 (14C) is 5730 years. An organic material which was buried in the sedimentary rocks is examined, and it is the parent-daughter ratio is equal to about 1:15, indicating that there will be 1/16 of the parent element and 15/16 of the daughter element.

The organic material is supposed to have no daughter element at the time of burial. The age of this organic material is to be calculated. As given, the ratio of parent-daughter elements is 1:15 (1/16 parent, 15/16 daughter). After one half-life (i.e., 5730 years), half of the parent atoms will have decayed to the daughter atoms. Therefore, the parent-to-daughter ratio would be 1/32 parent, 31/32 daughter.

After the two half-lives (5730 + 5730 = 11460 years), 1/4 of the original parent atoms will remain, and the ratio will be 1/4 parent, 3/4 daughter. 1/4 is equal to 4/16. 4/16 + 12/16 = 16/16 = 1. This implies that the original amount of carbon 14 (14C) was about 4/16 of what it would have been if there were no daughter material present. To determine the age of the organic material, we may set up the following equation:

Parent to daughter ratio = 1:15 after 2 half-lives,

which is 5730 × 2 = 11,460.15/16 = (1/2)² × (1/16) = 1/64 (15 daughter atoms)

Therefore, there were originally 4 × 15 = 60 carbon 14 (14C) atoms.

1/64 = 1/60 × (1/2)n where n is the number of half-lives which have occurred.

Multiplying both sides by 60 × 64 gives: 1 = 64 × (1/2)n

Subtracting 64 from both sides gives: 63 = (1/2)n

Taking the natural logarithm of both sides gives: ln(-63) = n ln(1/2)

The value of ln(1/2) is -0.69315, so:

n = ln(-63)/ln(1/2)n = 6.0 half-lives have passed (rounded up).

Therefore, the organic material is 6 × 5730 = 34,380 years old.

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Answer:

27.9 g

Explanation:

CsF + XeF₆ → CsXeF₇

First we convert 73.1 g of cesium xenon heptafluoride (CsXeF₇) into moles, using its molar mass:

As 1 mol of cesium fluoride (CsF) produces 1 mol of CsXeF₇, in order to produce 0.184 moles of CsXeF₇ we would need 0.184 moles of CsF.

Now we convert 0.184 moles of CsF to moles, using the molar mass of CsF:

Answer:

Calibration curves are used to understand the instrumental response to an analyte, and to predict the concentration of analyte in a sample.

Answer: 2

Explanation: For the equation to be balanced, the elements or compounds from the reactant and product sides must be equal.

Everything else was equal except the Na and Cl which on the reactant side it had 2 molecules each and on the product side 1 molecule.  

All you have to do is add 2 Infront of NaCl on the product side to make the reaction balance.

This is a substitution reaction

The efficiency percentage of Pulley A : 75%

Given

input work = 100 J

output work = 75 J

Required

the efficiency

Solution

The efficiency percentage : the ratio of output work to input work

The efficiency of Pulley A :

\(\tt \%efficiency=\dfrac{out}{in}\times 100\%\\\\\%efficiency=\dfrac{75}{100}\times 100\%\\\\\%efficiency=75\%\)

Answer:4

Explanation: I got it right

According to ideal gas law and kinetic molecular theory,the statement which describes  the characteristic of an ideal gas system is that  straight-line motion of the gas molecules is constant and random.

The ideal gas law is a equation which is applicable in a hypothetical state of an ideal gas.It is a combination of Boyle's law, Charle's law,Avogadro's law and Gay-Lussac's law . It is given as, PV=nRT where R= gas constant whose value is 8.314.The law has several limitations.

The ideal gas law was proposed by Benoit Paul Emile Clapeyron in the year 1834.He was a physicist and an engineer.It is often written in empirical form.It is called as an ideal gas  equation which is a good approximation of behavior of many gases.It has several limitations.

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Answer: The concentration of a solution made by combining 52 grams of  \(NaCH_{3}COO^{-}\) with 150 mL of water is 4.22 M.

Explanation:

Given: Mass = 52 grams

Volume = 150 mL (1 mL = 0.001 L) = 0.150 L

Molarity is the number of moles of a substance present in liter of a solution.

And, moles is the mass of a substance divided by its molar mass.

Hence, moles of \(NaCH_{3}COO^{-}\) (molar mass = 82.034 g/mol) is as follows.

\(Moles = \frac{mass}{molar mass}\\= \frac{52 g}{82.034 g/mol}\\= 0.633 mol\)

Therefore, concentration of given solution is as follows.

\(Molarity = \frac{moles}{Volume(in L)}\\= \frac{0.633 mol}{0.150 L}\\= 4.22 M\)

Thus, we can conclude that the concentration of a solution made by combining 52 grams of  \(NaCH_{3}COO^{-}\) with 150 mL of water is 4.22 M.

The correct statement concerning galvanic (voltaic) cells and electrolytic cells is that external electric energy must be supplied to an electrolytic cell, while in a galvanic (voltaic) cell, the redox reaction is always spontaneous.

Galvanic cells produce electrical energy from a spontaneous redox reaction, where the anode undergoes oxidation and the cathode undergoes reduction. This flow of electrons generates an electrical current that can be used to power electronic devices. In contrast, electrolytic cells require an external source of electrical energy to drive a non-spontaneous redox reaction. The anode serves as the site of oxidation, and the cathode serves as the site of reduction. By supplying electrical energy, the reaction can proceed in the desired direction, producing a product that would not form spontaneously.
In summary, galvanic cells can serve as a source of electrical energy, while electrolytic cells require external electric energy to drive a non-spontaneous reaction. The cathode is the site of reduction in a galvanic (voltaic) cell, but the cathode is the site of oxidation in an electrolytic cell. Finally, in a galvanic (voltaic) cell, the redox reaction is always spontaneous, while in an electrolytic cell, an external energy source is required to drive the non-spontaneous reaction.

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process energy and nutrients.

All cells use changes in its DNA to adapt to its environment. Hope I helped!