pls help 8th grade k12

Answer:

D. works with bones to help you move

Explanation:

Your muscles and tendons are what help bones move.

Answer:

12 kilograms is larger.

Explanation:

Of the three units, the kilogram is the largest and the milligram is the smallest. The prefix “kilo” means a thousand and “milli” means one-thousandths. A gram is the basic unit of mass.

The mole fraction of N₂ after the mixture of 4.0 L of N₂ at 15 atm with 4.0 L of H₂ at 7.0 atm is 0.68.

We can calculate the mole fraction of N₂ with the following equation:

[tex] X_{N_{2}} = \frac{n_{N_{2}}}{n_{t}} = \frac{n_{N_{2}}}{n_{N_{2}} + n_{H_{2}}} [/tex]   (1)

The number of moles of N₂ and H₂ can be found with the ideal gas law:

[tex] PV = nRT [/tex]

Where:

P: is the pressure

R: is the gas constant

T: is the temperature

V: is the volume

For nitrogen gas we have:

[tex] n_{N_{2}} = \frac{P_{N_{2}}V_{N_{2}}}{RT} [/tex]   (2)

And for hydrogen:

[tex] n_{H_{2}} = \frac{P_{H_{2}}V_{H_{2}}}{RT} [/tex]   (3)

After entering equations (2) and (3) into (1), we get:

[tex] X_{N_{2}} = \frac{\frac{P_{N_{2}}V_{N_{2}}}{RT}}{\frac{P_{N_{2}}V_{N_{2}}}{RT} + \frac{P_{H_{2}}V_{H_{2}}}{RT}} [/tex]  

Since RT are constants, we have:

[tex] X_{N_{2}} = \frac{P_{N_{2}}V_{N_{2}}}{P_{N_{2}}V_{N_{2}} + P_{H_{2}}V_{H_{2}}} [/tex]                

We know that:

[tex] P_{N_{2}} = 15 atm[/tex]                

[tex] V_{N_{2}} = 4.0 L[/tex]                

[tex] P_{H_{2}} = 7.0 atm[/tex]                

[tex] V_{H_{2}} = 4.0 L[/tex]          

so:

[tex] X_{N_{2}} = \frac{15 atm*4.0 L}{15 atm*4.0 L + 7.0 amt*4.0 L} = 0.68 [/tex]                

Therefore, the mole fraction of N₂ is 0.68.

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Answer:

the answer is B.

Explanation:

your welcome

Answer:

the answer is B

Explanation:

i have the same exact questionn

Answer: Atomic number

Explanation:

I hope this helps you!

Answer:

EDTA disodium salt | C10H14N2Na2O8

Explanation:

The heat produced by 4.5 moles of magnesium when burnt is 2700 kJ.

A thermochemical reaction is a reaction in which the amount of heat lost or gained is included in the reaction equation. The thermochemical reaction equation for the combustion of magnesium is shown as follows;

2 Mg(s) + O2(g) → 2 MgO(s) + 1200 kJ

From the reaction equation;

2 moles of magnesium produced 1200 kJ of heat

4.5 moles of magnesium will produce 4.5 moles × 1200 kJ/2 moles

= 2700 kJ

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Evidence that water was once present on a planet is evidence that the planet may once have had living organisms. When landforms on different rocky planets look similar, it is evidence that they may have been formed by the same geologic process. The channel on Mars may have been caused by flowing water or flowing lava.

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Answer:

Explanation:

Firstly, let us calculate the molar mass of the glucose. To find the molar mass we need to add the masses of individual elements which constitute one glucose molecule.

Now, we know that

Molar mass of Carbon C=12gmol−1

Molar mass of Hydrogen H=1gmol−1

Molar mass of oxygen O=16gmol−1

Therefore, Molar Mass of glucose (C6H12O6) can be calculated as shown below

⇒ 6×12+12×1+6×16

⇒72+12+96⇒180gmol−1

Given mass of glucose = 300g

Now, we can calculate the number of moles in given mass of glucose, using the below formula,

Using the Formula numberofmoles=givenmassmolarmass we get

numberofmoles=300180 = 1.7 moles or 2 moles (approx.)

Hence the number of moles present in 300 g of glucose is 1.7 moles or 2 moles approximately.

Answer:

D  BLESSS Y

Explanation:

Answer:

Tristan wraps some gifts and then brings them to the post office where they are delivered to people in different parts of the country. Which organelle is Tristan most like?

Answer: Tristan is most like the Golgi Body

Explanation:

Answer:

c) single bonds, double bonds, carbon atoms and hydrogen atoms

Answer:

KNO2, KBr

Explanation:

Chemical compounds are any substance composed of identical molecules consisting of atoms of two or more chemical elements. So NO2 and KBr are compounds, Br2 and Fe are not.

Answer:

increase the number of gas particles

Explanation:

The sample of white powder contains 47.1% K2CO3 and 0.39% Na2CO3.

Molar mass of sodium carbonate = 106 g/mol

Molar mass of potassium carbonate = 138 g/mol

Number of moles of HNO3 = 10/1000 L × 0.8903 M = 0.008903 moles

Mass of HNO3 =  0.008903 moles × 63 g/mol = 0.56 g

Mass of sample added = 1.091 g

Mass of sample left over = 0.573 g

Mass of sample reacted = 1.091 g - 0.573 g = 0.518 g

The reacted sample contains xg of Na2CO3 and (0.518 - x) g K2CO3.

Na2CO3 + 2HNO3 --> 2NaNO3 + CO2 + H2O

106g of Na2CO3 reacts with 126g of HNO3

x g of Na2CO3 reacts with (126 × x/106)g of HNO3

K2CO3 + 2HNO3 --> 2KNO3 + CO2 + H2O

138 g of K2CO3 reacts with 126 g of HNO3

(0.518 - x) g of K2CO3 reacts with [(0.518 - x) × 126/138] g

Total mass of HNO3 used;

1.19x + 0.47 + 0.91x = 0.56

2.1x + 0.47 = 0.56

2.1x = 0.56 - 0.47

2.1x = 0.09

x =  0.09/2.1

x = 0.0043 g

Mass of K2CO3 = (0.518 - x) g = 0.518 - 0.0043 = 0.5137 g

Mass percent of K2CO3  = 0.5137 g/ 1.091 g × 100/1 = 47.1%

Mass percent of Na2CO3 = 0.0043/1.091 g × 100/1 = 0.39%

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The amount of the sample remaining at 4pm is 0.0625 g

We'll begin by calculating the number of half-lives that has elapsed

Half-life (t½) = 1 hour

Time (t) = 4 hour

n = t / t½

n = 4 / 1

Number of half-lives (n) = 4

Initial amount (N₀) = 1 g

[tex]N = \frac{N_0}{ {2}^{n}} \\ \\ N = \frac{1}{ {2}^{4}} \\ \\ N = \frac{1}{16} \\ \\ N = 0.0625 \: g[/tex]

Thus, the amount remaining at 4pm is 0.0625 g

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Answer:

e

Explanation:

Explanation:

Carbon dioxide and water

I hope it helps

Answer:

The usual products of combustion reactions are carbon dioxide and water.

Explanation:

Combustion reaction is when a substance reacts with oxygen gas, resulting in a release of energy in the form of light and heat. Combustion reactions must have oxygen (O2) as one of the reactants.

The mass of the carbon dioxide that will be produced when 144 g of carbon react with 384 g of oxygen gas is 528 g

We'll begin by calculating the masses of C and O₂ that reacted and the mass of CO₂ produced from the balanced equation.

C + O₂ —> CO₂

Molar mass of C = 12 g/mol

Mass of C from the balanced equation = 1 × 12 = 12 g

Molar mass of O₂ = 2 × 16 = 32 g/mol

Mass of O₂ from the balanced equation = 1 × 32 = 32 g

Molar mass of CO₂ = 12 + (2×16) = 44 g/mol

Mass of CO₂ from the balanced equation = 1 ×44 = 44 g

SUMMARY:

From the balanced equation above,

12 g of C reacted with 32 g of O₂ to produce 44 g of CO₂

From the balanced equation above,

, 12 g of C reacted with 32 g of O₂.

Therefore,

144 g of C will react with = (144 × 32)/12 = 384 g of O₂.

From the calculations made above, we can see that both C and O₂ are sufficient for the reaction. Thus, C and O₂ are both limiting reactants.

From the balanced equation above,

balanced equation above, 12 g of C reacted to produce 44 g of CO₂.

Therefore,

144 g of C will react to produce = (144 × 44)/12 = 528 g of CO₂.

Thus, the mass of CO₂ obtained from the reaction is 528 g

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Answer:

hydrogen bond is a type of dipole-dipole interaction; it is not a true chemical bond it is a mere electrostatic attraction. These attractions can occur between molecules or within different parts of a single molecule. Intramolecular hydrogen bonds are those which occur within one single molecule.

Explanation:

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When the value of secondary quantum number (l) = 1, the magnetic quantum number can be from -1 to +1. The answer would be false.

The angular quantum number (l) can take any integer between 0 and the value of the principal quantum number (n) less by 1.

In other words, l can be from 0 to n-1.

The magnetic quantum number (m), on the other hand, can take any value between -l to +l.

For example, if l = 1, m can be -1,0, and +1.

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#SPj1

Answer:BF3

Explanation:USA test prep

Answer:

landslide mudflows slump and creep

Explanation:

no explanation

Answer:

dog dog im not gon hold u we kinda screwed

Diamond is composed of hexagonal rings in which sp3 hybridized carbon atoms are linked together.

Hybridization refers to the mixing of atomic orbitals to yield hybrid orbitals that are suitable for bonding. The energy of orbitals that combine to form hybrid orbitals must be close enough for such combination to take place.

Diamond is composed of hexagonal rings in which sp3 hbridized carbon atoms are linked together. Each carbon atom in diamond is tetrahedral.

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The mixing of the two different orbitals to form a compound is called hybridization. For example mixing of s and p orbits.

The correct answer is sp3.

The arrangement of the elements in a different manner to form a new compound is called allotropes. For example, diamond and graphite are the allotropes of carbon.

The valence electrons are in p orbitals and p orbit mixed after the s orbitals.

Therefore, the correct answer is sp3

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0.04 moles of iodide is required to precipitate all the lead II ions from  25.0 mL of a 1.6 M Pb(NO3)2 solution.

The reaction equation is;

2KI(aq) + Pb(NO3)2(aq) -------> PbI2(s) + 2KNO3(aq)

The net ionic equation is;

Pb^2+(aq) + 2I^-(aq) ------> PbI2(s)

Number of moles of Pb(NO3)2  = 25/1000 L ×  1.6 M = 0.04 moles

Number of moles of Pb^2+ = 0.04 moles /2 = 0.02 moles

Since 2 moles of iodide reacts with 1 mole of Pb^2+

x moles of iodide reacts with 0.02 moles of Pb^2+

x =  2 moles × 0.02 moles/ 1 mole

x = 0.04 moles of iodide

Hence,  0.04 moles of iodide is required to precipitate all the lead II ions from  25.0 mL of a 1.6 M Pb(NO3)2 solution.

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Answer:

sorry i dont know

Explanation:

Answer:

go get the stuff.

Explanation:

The heat of fusion of the given sample of the ethyl alcohol is 104.16 J/g.

The given parameters:

The heat of fusion of the given sample of the ethyl alcohol converted from solid to liquid phase is calculated as follows;

[tex]H_f = \frac{Q}{m} \\\\H_f = \frac{3.833 \times 10^3\ J}{36.8 \ g} \\\\H_f = 104.16 \ J/g[/tex]

Thus, the heat of fusion of the given sample of the ethyl alcohol is 104.16 J/g.

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Answer:

it gives an atom its charge