1. A dining hall had a total of 25 tables-some long rectangular tables and some round
ones. Long tables can seat 8 people. Round tables can seat 6 people. On a busy
evening, all 190 seats at the tables are occupied.
How many long tables, x, and how many round tables, y, are there?

​

Answer:

c = 0.13 j/ g.°C

Explanation:

Given data:

Mass of mercury = 29.5 g

Initial temperature = 32°C

Final temperature = 161°C

Heat absorbed = 499.2 j

Solution:

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

Q = m.c. ΔT

ΔT  = T2 - T1

ΔT  = 161°C - 32°C

ΔT  = 129 °C

Q = m.c. ΔT

c = Q / m. ΔT

c = 499.2 j / 29.5 g. 129 °C

c =  499.2 j / 3805.5 g. °C

c = 0.13 j/ g.°C

C

Immunization shots are given to ensure immunity against future attacks on the body against the disease in which the vaccine is made.

Explanation:

The vaccine prepares the body by giving immune cells memory against the disease agent. The vaccine achieves this by introducing an attenuated form of the agent of the disease into the body. This means the introduced disease agents cannot cause disease but are enough to evoke an immune response from the body. The immune system, after eradicating the attenuated disease agent from the body, acquires memory such that it fights a real-world disease agent in case of infection.  

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Final answer:

If the experimental value equals the accepted value, the percentage error is 0%, indicating perfect accuracy in the measurement.

Explanation:

When the experimental value of a measurement precisely matches the accepted value, the percentage error is 0%. This indicates that there is no discrepancy between the measured value and the standard or true value. Percentage error is a way to express the accuracy of an experimental measurement and is calculated using the formula: |experimental value - accepted value| × 100% / accepted value.

Therefore, if both values are equal, the formula results in 0%. As the accuracy of a measurement decreases, signified by a larger discrepancy between the experimental and accepted values, the percentage error correspondingly rises. Reporting the percentage error is critical for underscoring the reliability and precision of an experiment's results.

Answer:

3.07 seconds is the half-life of the isotope.

Explanation:

Initial mass of an isotope = x

Time taken by the sample, t = 8.40 s

Mass of an isotope decayed= 85.0%

Final mass of an isotope left=(100%-85%)of x= 15.0% of x = 0.15x

Half life of an isotope =[tex]t_{\frac{1}{2}} = ?[/tex]

Formula used :

[tex]N=N_o\times e^{-\lambda t}\\\\\lambda =\frac{0.693}{t_{\frac{1}{2}}}[/tex]

where,

[tex]N_o[/tex] = initial mass of isotope

N = mass of the parent isotope left after the time, (t)

[tex]t_{\frac{1}{2}}[/tex] = half life of the isotope

[tex]\lambda[/tex] = rate constant

[tex]0.15x=x\times e^{-(\frac{0.693}{t_{1/2}})\times 8.40 s}\\\\N=N_o\times e^{-0.693}[/tex]

Now put all the given values in this formula, we get

[tex]t_{1/2]=3.07 s[/tex]

3.07 seconds is the half-life of the isotope.

Final answer:

A Lucas reagent is a mixture of zinc chloride and concentrated hydrochloric acid that is used to distinguish between primary, secondary, and tertiary alcohols.

Explanation:

A Lucas reagent is a mixture of zinc chloride (ZnCl2) and concentrated hydrochloric acid (HCl) that is used to distinguish between primary, secondary, and tertiary alcohols.

When the Lucas reagent is added to an alcohol, a reaction occurs where a cloudy precipitate of alkyl chlorides is formed. The rate at which the precipitate forms depends on the type of alcohol:

Answer:

B.False

Explanation:

Volume is used in 3D shapes, 2D is found by area.

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Answer:

The color of the light.

Explanation:

When an atom is heated, its electrons are excited and they jump to higher energy levels. The electrons will return to their normal energy level, and by doing this, they will emit a photon of energy, which is in the form of light. The color of the light depends on the difference of energy of the two levels, and because of that is different for each element.

Each atom emits light at different wavelengths that form its unique atomic emission spectrum when heated. By studying this spectrum, one can distinguish between different atoms. For example, hydrogen and helium atoms yield different spectral patterns due to the unique energy transitions in their electrons.

When atoms are heated, they emit light consisting of many different colors or wavelengths, which is collectively referred to as an atom's spectral lines or spectrum.  Every atom has a unique spectrum, equivalent to a 'fingerprint' because its electron energies are unique. This concept is called the atomic emission spectrum. Thus, by studying the spectrum emitted by an atom, we can tell one atom from another.

For instance, when hydrogen atoms are heated, they emit a specific spectral line that looks predominantly red because of the transitions that hydrogen's single electron makes. On the other hand, a helium atom's spectrum would look different, containing more diverse and vibrant colors due to the different energy transitions in its two electrons. By comparing the observed spectrum to known emission spectra, we can identify the type of atom.

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Similar rocks found on different continents, Mountains created by colliding continents, Evidence of glaciers in unexpected places are the evidences to support the idea that all the continents were once joined together.

Option D, All the above.

Earth did not have seven continents but only one, nearly 300 million years ago. There was one "massive super continent", called the Pangaea. The Pangaea was also surrounded by the ocean named panthalassa. Experts say that the formation of the seven continents happened due to the movement in the tectonic plates.

Similar kinds of rocks were found on different continents, it is also believed that the Aps were formed due to the separation of continents, coal deposits of the same constituents were also found on different continents.

Answer:

all of the above

Explanation:

Answer:

V = 6.17 L

Explanation:

Given data:

Volume = ?

Number of moles = 0.382 mol

Pressure = 1.50 atm

Temperature = 295 k

R = 0.0821 L. atm. /mol. k

Solution:

According to ideal gas equation:

PV= nRT

V = nRT/P

V = 0.382 mol × 0.0821 L. atm. /mol. k ×295 k / 1.50 atm

V = 9.252  L. atm.  / 1.50 atm

V = 6.17 L

Final answer:

Using the ideal gas law, the volume of 0.382 moles of hydrogen gas at 1.50 atmospheres pressure and 295 K is approximately 6.17 L.

Explanation:

Using the ideal gas law, PV = nRT, we can calculate the volume of 0.382 moles of hydrogen gas at 1.50 atmospheres pressure and 295 K temperature. where T is the temperature, R is the ideal gas constant, n is the number of moles, V is the volume, and P is the pressure.

The provided values are: P = 1.50 atm, n = 0.382 moles, R = 0.0821 L•atm/mol•K, and T = 295 K. When we enter these numbers into the ideal gas law, we obtain:
V = nRT/PV = (0.382 mol) × (0.0821 L•atm/mol•K) × (295 K) / (1.50 atm)

Calculating this, we find the volume (V) of hydrogen gas:

V ≈ 6.17 L

Chemical formula of calcium sulfate dihydrate: CaSO₄ · 2 H₂O

There is a 1 : 2 mole ratio between calcium sulfate and water.

Explanation:

The calcium sulfate may be find as an anhydrous salt or a dihydrate. In the case of the dihydrate the chemical formula is CaSO₄ · 2 H₂O.

In the calcium sulfate dihydrate there are 1 mole of CaSO₄ and 2 moles of H₂O, so the mole ratio between the salt and the water molecules is 1 : 2.

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Final answer:

The hydrated form of calcium sulfate, also known as gypsum, has a chemical formula of CaSO4·2H2O, indicating a 1:2 mole ratio of calcium sulfate to water.

Explanation:

The hydrated form of calcium sulfate is commonly known as gypsum, and its chemical formula is CaSO4·2H2O. This indicates that there is a whole number mole ratio of 1:2 between calcium sulfate and water. Hydrates are compounds that include water molecules absorbed into their structure, and this absorbed water plays an essential role in the physical properties of the material. In the case of gypsum, the two water molecules are crucial for its use in construction and medical applications, such as in plaster of Paris.

Answer:

c.) location of earthquakes epicenter

Explanation:

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Examples of indirect evidence used to study Earth's interior are analysis of several seismographs and identification of seismic wave direction, which allow scientists to gain insights into the Earth's structure through the behavior of seismic waves.

Indirect evidence used to study Earth's interior includes seismic-related observations as they offer insights without direct sampling. The correct examples of indirect evidence for studying Earth's internal structure are:

This evidence is gathered through monitoring how seismic waves travel through and interact with the Earth's layers. Seismic waves behave similarly to sound waves in a struck bell; they reflect, refract, and vary in velocity depending on the material they pass through, providing a model of the internal structure. Therefore, by setting up a network of seismographs around the globe, scientists can detect the pattern of waves, which helps them understand the different layers within Earth's interior.

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Answer:

A.   The new molarity of the diluted solution is 1.0176 M

B.   The new molarity of the diluted solution is 0.9947  M

C.   20 mL of volume is required to prepare 100ml of 1 M NaOH

Explanation:

Part A:

___________

This problem will be solved by using the following formula

                               M₁V₁ =  M₂V₂                        (1)

Given Data:

Initial Molarity of Solution M₁ = 3.24 M

Initial volume V₁ = 1.25 L

Initial volume V₂ = 3.98 L

Final Molarity M₂= ?

Put the values in formula 1

                          3.24 M x 1.25 L = M₂ x 3.98 L

By Rearranging

                         M₂  =  3.24 M x 1.25 L / 3.98 L

                         M₂  =  4.05 / 3.98

                          M₂  =  1.0176 M

The new molarity of the diluted solution is 1.0176 M

_________________

Part B:

This problem will be solved by using the following formula

                               M₁V₁ =  M₂V₂                        (1.1)

Given Data:

Initial Molarity of Solution M₁ = 7.0 M

Initial volume V₁ = 270 mL

As the initial volume is in ml and final volume in Litre (L)

So we have to convert mL to L

       1000ml= 1L

       270 ml = ? L

       1 x 270/ 1000 = 0.27 L

So

Initial volume V₁ = 0.27 L

Initial volume V₂ = 1.9 L

Final Molarity M₂= ?

Put the values in formula 1.1

                                               M₁V₁ =  M₂V₂  

                            7.0 M x 0.27 L = M₂ x 1.9 L

By Rearranging

                         M₂  =    7.0 M x 0.27 L / 1.9 L

                         M₂  =  1.89 / 1.9

                          M₂  =  0.9947 M

The new molarity of the diluted solution is 0.9947  M

_________________

Part 3

This problem will be solved by using the following formula

                               M₁V₁ =  M₂V₂                        (1.2)

Given Data:

Initial Molarity of Solution M₁ = 5 M

Initial volume V₁ = ? mL

Initial volume V₂ =  100 mL

Final Molarity M₂= 1 M

Put the values in formula 1.2

                                               M₁V₁ =  M₂V₂  

                            5 M x V₁ = 1 M x 100 mL

By Rearranging

                         V₁  =   1 M x 100 mL/ 5 M

                         V₁  =   100 / 5

                          V₁  =   20

20 mL of volume is required to prepare 100ml of 1 M NaOH

Explanation:

The formula for tryptophan is [tex]C_{11}H_{12}N_{2}O_{2}[/tex]

Mass of [tex]C[/tex] in tryptophan is [tex]11\times 12=132g[/tex]

Mass of [tex]H[/tex] in tryptophan is [tex]12\times 1=12g[/tex]

Mass of [tex]N[/tex] in tryptophan is [tex]2\times 14=28g[/tex]

Mass of [tex]O[/tex] in tryptophan is [tex]2\times 16=32g[/tex]

So,[tex]\text{total mass}=132+12+28+32=204g[/tex]

[tex]\text{mass of carbon}=132g[/tex]

[tex]\text{mass percent of carbon}=\frac{\text{mass of carbon}}{\text{total mass}}\times 100 =\frac{132}{204}\times 100 =64.7[/tex]%

Final answer:

The mass percent of carbon in tryptophan is approximately 64.68%, calculated by determining the total mass of carbon.

Explanation:

By using the atomic masses of carbon (C), hydrogen (H), nitrogen (N), and oxygen (O), we can calculate the molar mass of tryptophan. After that, we determine the total mass contributed by carbon atoms (by multiplying the number of carbon atoms by the atomic mass of carbon) and then divide this by the molar mass of tryptophan to get the mass percent of carbon.

So, the mass of carbon in tryptophan is 11 × 12.01 g/mol = 132.11 g/mol.

The molar mass of tryptophan is approximately 204.23 g/mol. The mass percent of carbon in tryptophan can thus be calculated as (132.11 g/mol) / (204.23 g/mol) × 100%, which yields approximately 64.68%.

This value indicates that carbon makes up about 64.68% of the mass of a tryptophan molecule. Understanding these kinds of compositions is important for fields like biochemistry and nutrition where the analysis of the biochemical roles of various compounds is crucial.

Answer:

R = 0.083 atm .L /  mol.K

Explanation:

Given data:

Pressure of gas = 259,392.00 Pa

Temperature = 2.0 °C

Moles = 1 mol

Volume = 8.8 dm³

R = ?

Solution:

First of all we will convert the units.

Pa to atm

259,392.00 /101325 = 2.56 atm

dm³ to L

8.8 dm³ = 8.8 L

2.0 °C to K

2+273 = 275 K

Now we will calculate the R:

PV = nRT

R = PV/ nT

R =  2.56 atm . 8.8 L / 1 mol. 275 K

R = 22.528  atm .L / 1 mol. 275 K

R = 0.083 atm .L /  mol.K

It total there are 18 atoms.

Iron (Fe) is a metal.

Sulfur (S) is a nonmetal.

Oxygen (O) is a nonmetal.

Explanation:

We have the chemical formula of iron (III) sulfate Fe₃(SO₄)₃.

It total there are 18 atoms, 3 iron (Fe) atoms, 3 sulfur (S) atoms and 12 oxygen (O) atoms.

Iron (Fe) is a metal.

Sulfur (S) is a nonmetal.

Oxygen (O) is a nonmetal.

Iron is found as Fe²⁺ cation while the sulfate group SO₄⁻ as an anion.

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There are a total of 17 atoms in Fe2(SO4)3.

A compound is formed when atoms of elements combine chemically together. A compound is defined as a group of elements which are chemically combined together.

In the compound Fe2(SO4)3, there are;

This makes a total of 17 atoms in the compound Fe2(SO4)3. Iron is a metal while oxygen and sulfur are nonmetals.

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Answer:

Diphosphorus pentoxide

Carbon dichloride

BCl3

N2H4

Explanation:

These are all covalent compounds. To name covalent compounds, you add prefixes to the beginning of their names depending on what the subscript is of each element. The prefixes are:

1: Mono

2: Di

3: Tri

4: Tetra

5: Penta

6: Hexa

7: Hepta

8: Octa

9: Nona

10: Deca

For example, since the first one is Phopsphorus with a 2 next to it, you add the prefix Di to it.

If the first element in the compound only has one, meaning no number next to it, you do not say mono. This is why we just say "Carbon" for the second one instead of "Monocarbon."

Finally, you always have to end the second element in the compound with "ide." So, "chlorine" becomes "chloride," "oxygen" becomes "oxide," and so on.

3, 2, 1, 6

Explanation:

To balance the chemical equation the number of atoms of each element  

entering the reaction have to be equal to the number of atoms of each  

element leaving the reaction, in order to conserve the mass.

In our case we have:

3 CaCl₂ + 2 Na₃PO₄ → Ca₃(PO₄)₂ + 6 NaCl

So the stoechiometric coefficients will be:

3, 2, 1, 6

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Answer:

R = 0.064 dm³ atm K⁻¹ mol⁻¹

Explanation:

Data Given:

volume of gas V = 8.8 dm³

no. of mole of gas (n) = 1 mole

Pressure P = 259,392.00 Pa

Convert Pascal (Pa) to atm (atmospheric pressure)

As,

101,325 Pa = 1 atm

So,

259,392.00 Pa = 2 atm

Then Pressure (P) = 2 atm

Temperature T = 2.00 °C

change the temperature from °C to K

As to convert °C to K the below formula used

                       0°C + 273.15 = 273.15K

So, for 2 °C

                      2°C + 273.15 = 275.15 K

So,

Temperature T = 275.15 K

ideal gas constant = ?

formula used for Ideal gases

                           PV = nRT

as we have to find R of the gas:

we will rearrange the ideal gas equation as below:

                           R = PV / nT ........................................... (1)

Put value in equation (1)

                             R = 2atm x 8.8 dm³ / 1 mole x 275.15 K

                             R = 17.6 atm. dm³ / 275.15 mol. K

                             R = 0.064 dm³ atm K⁻¹ mol⁻¹

So the value of R is 0.064 dm³ atm K⁻¹ mol⁻¹

and the unit of R (ideal gas constant) is dm³ atm K⁻¹ mol⁻¹

Answer:

It’s to gain territory

Because they wanted more territory than what they already had.

Answer:

Answer:  To get revenge for recent French losses in North America.

Explanation:

The Seven Years War was fought in Europe from 1756-63.  That conflict as it extended to colonial territories in the New World was known as the French and Indian War.  Losing that conflict in North America to the British didn’t sit well with France. And so when the colonial Americans broke out in revolution against the British monarchy, France devoted enormous financial aid (as well as officer support) to the Americans. The cost to France for supporting America’s revolution added up to 1 billion livers  (about 4 billion in today’s dollars). This is part of what put France’s debt problem over the edge and led to the French Revolution.

Answer:

Therefore F ∠ 2.5N

Explanation:

Definition of Work:

It is the amount of energy transferred.

Mathematical expression:

W = F × d

By taking the friction into count it will define as:

Input work = work against friction ×  output work

No we will put the values:

25 J = w + 10 m

j = kg m²/s²

25 kg m²/s² =  w + 10 m

when friction is exist then w > 0

25 kg m²/s² - 10 m  > 0

15 N > 0

Therefore F ∠ 2.5N

Answer:

6 moles of CuCl₂  will produced 4 moles of  AlCl₃ .

Explanation:

Given data:

Moles of CuCl₂ = 6 mole

Moles of AlCl₃ produced = ?

Solution:

3CuCl₂ + 2Al → 2AlCl₃ + 3Cu

Now we will compare the moles of CuCl₂ with AlCl₃ .

            CuCl₂        :        AlCl₃

                3            :          2

                6           :         2/3 ×6 = 4 mol

So, 6 moles of CuCl₂  will produced 4 moles of  AlCl₃ .

Answer:if you could be more spesific id be happpy to help

Explanation:

thanks sm.

Answer:

The density of the material is 7.5 g/m^3

Explanation:

The volume of a rectangle is:

Volume = Length*Height*Width

Replacing with data:

Volume = 5 m * 2 m * 4 m = 40 m^3

Density is computed as follows:

Density = Mass/Volume

Replacing with data:

Density = 300 g/40 m^3

Density = 7.5 g/m^3

Answer:

4 mol  of lithium nitride would be produced

Explanation:

6Li + N2  → 2Li3N

This equation means that 6 mol of lithium are reacted with 1 mol of nitrogen to make, 2 mol of lithium nitride.

So this is the rule of three to find out, how many moles of lithium nitride are been made, from 12 mol of Li.

6 Li _____ 2 Li3N

12 Li ________ (12. 2) / 6 = 4 moles

Answer:

4 mol  of lithium nitride would be produced

Explanation:

6Li + N2  → 2Li3N

This equation means that 6 mol of lithium are reacted with 1 mol of nitrogen to make, 2 mol of lithium nitride.

So this is the rule of three to find out, how many moles of lithium nitride are been made, from 12 mol of Li.

6 Li _____ 2 Li3N

12 Li ________ (12. 2) / 6 = 4 moles

Answer: Cement is a mixture.

Explanation: It is composed of different types of compound particles. Each of the components of concrete by themselves would be pure substances. For example, a sample of just calcium oxide would be a pure substance because the particles in the sample would all be identical calcium oxide compounds.

Concrete is a heterogeneous mixture comprised of cement, water, sand, and gravel, retaining the individual properties of its components and can be separated physically.

Concrete is a mixture, not a pure substance. Pure substances are materials made up of only one type of matter, either a single element or a single compound, with a constant composition and set of properties throughout. In contrast, mixtures are combinations of two or more pure substances that retain their individual identities and can be separated by physical methods. Concrete is specifically a heterogeneous mixture as it consists of several different components such as cement, water, sand, and gravel that are not uniform throughout. These components can be identified and, in theory, could be separated by physical means.

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Answer:

WO2:

Explanation:

If any element symbol in a formula has no subscript, implying a subscript of one, the formula is already empirical.

The correct answer to the question is Option 2. Br

Electronegativity is simply defined as the ability of an atom to attract electron(s)

Non metals are more electronegative than metals.

Krypton, Kr is a group 18 element which have completely filled outermost shell. They do not involve in bond formation.

Calcium, Ca and Barium, Ba are group 2 metals. They form bond by losing their 2 valence electrons.

Bromine, Br is a group 17 element which have 7 valence electrons. It is difficult for Br to lose its valence electron(s) and as such, it will form bond by either gaining 1 electron or sharing 1 electron.

With the above information, we can conclude that Option 2. Br gives the correct answer to the question.

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Answer: In photosynthesis, producers combine carbon dioxide, water, and sunlight to produce oxygen and sugar (their food). Other organisms get energy by eating producers. ... It cannot directly use the Sun's energy to make food. As a consumer, it has to eat— or, consume— other organisms for energy.

Explanation: Thats how both producers and consumers get energy

Producers like plants and algae utilize photosynthesis to convert sunlight into energy, which is then consumed by animals in an ecosystem. All life forms are reliant on the sun's energy for survival.

Producers such as plants, algae, and some bacteria, capture sunlight to make food through photosynthesis, converting it into glucose. Consumers, like animals, obtain energy from producers directly or indirectly by feeding on them or other consumers. Energy flow in ecosystems ensures that all life forms ultimately depend on the sun's energy for survival.

Answer:

carbon dioxide and water

Explanation:

ncompletely oxidized (in this sense, oxidation means the removal of electrons or hydrogen atoms), the end product being (apart from carbon dioxide and water)

Oxidation is the process of losing electron or reaction with oxygen. If the reactant burn in oxygen then it gives water and carbon dioxide and this type of oxidation is called combustion.

Oxidation is the process of combining with oxygen or to lose electron to form the higher oxidation state. For example metals lose electrons forming their higher oxidation states. Fe lose its 2 electrons forming Fe²⁺ ion is an example of oxidation.

When a compound burns in oxygen it oxidizes to carbon dioxide and water, and the reaction is called combustion. Fuel gases such as hydrocarbons easily undergoes combustion reaction.

Similarly, organic molecules such as alcohols, ketones, aldehydes etc. undergo oxidation forming corresponding acids. The reagents which oxidizes other reactants is called oxidizing agent.

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Answer:

Mg+

Explanation:

Cation is an ion that has lost its electron(s).

So, it has a positive charge.

Any ion with a positive charge (superscript has a + sign) is a cation.