A number should be rounded up if________? it is the first digit, the number after it is between 0 and 4, the number after is between 5 and 9, it is the last digit

Answer:

23.71J is the work that the gas do.

Explanation:

The work that a gas do under isobaric conditions follows the formula:

W = P*ΔV

Where W is work in atmL, P is the pressure and ΔV is final volume -Initial volume In Liters

Replacing with the values of the problem:

W = P*ΔV

W = 0.600atm*(0.44000L - 0.0500L)

W = 0.234atmL

In Joules (1atmL = 101.325J):

0.234atmL × (101.325J / 1 atmL) =

Answer:

[tex]\%m/m=6.85\%[/tex]

Explanation:

Hello,

In this case, we are asked to compute the by mass percent for the given 3.2 g of ethylene glycol in 43.5 g of water. In such a way, since the by mass percent is computed as follows:

[tex]\%m/m=\frac{m_{solute}}{m_{solute}+m_{solvent}} *100\%[/tex]

Whereas the solute is the ethylene glycol and the solvent the water, therefore we obtain:

[tex]\%m/m=\frac{3.2g}{3.2g+43.5g} *100\%\\\\\%m/m=6.85\%[/tex]

Best regards.

Answer:

one atom of carbon

Explanation:

The relative atomic mass of elements can be used to determine their relative masses. If we look at all the options, we will notice that carbon has a relative atomic mass of 12, hydrogen has a relative atomic mass of 1 and lithium has a relative atomic mass of 7

We can now see that carbon has the greatest relative atomic mass among the options provided in the question.

Answer:

Peripheral device, also known as peripheral, computer peripheral, input-output device, or input/output device, any of various devices (including sensors) used to enter information and instructions into a computer for storage or processing and to deliver the processed data to a human operator or, in some cases.

Explanation:

Hope it helps

Answer: Input and output data

Explanation:

Plato!!!!!!!!!

Answer:the volume of a water droplet in a cloud

Explanation:

Answer:

The volume of a water droplet in a cloud

Explanation:

just took the test

Answer:

Al(s) 28.3

Explanation:

Aluminum forms a layer of aluminum oxide when exposed to air which protects the bulk metal from further corrosion.

Aluminum forms a layer of aluminum oxide when exposed to air which protects the bulk metal from further corrosion.4Al(s) + 3O2(g) ? Al2O3(s)

AnswerAluminum forms a layer of aluminum oxide when exposed to air which protects the bulk metal from further corrosion.

4Al(s) + 3O2(g) ? 2Al2O3(s)

Using the thermodynamic data provided below, calculate S° for this reaction.

S°(J/K.mol)

Al(s) 28.3

O2(g) 205.0

Al2O3(s) 50.99

2. Aluminum forms a layer of aluminum oxide when exposed to air which protects the bulk metal from further corrosion.

4Al(s) + 3O2(g) ? Al2O3(s)

Calculate G° for this reaction, given that ?G°f of aluminum oxide is –1576.4 kJ/mol.

Answer:

Explanation:

Explanation:

Answer:

3

Explanation:

Three significant figures

Answer:

Density, [tex]\rho=24.68\ g/cm^3[/tex]

Explanation:

Mass of a marble slab is 38.6 kg 38600 grams

The dimensions of the marble is 17 cm×23 cm×4 cm

We need to find its density. Mass per unit volume equals density. So,

[tex]\rho=\dfrac{m}{V}\\\\\rho=\dfrac{m}{lbh}\\\\\rho=\dfrac{38600\ g}{(17\times 23\times 4)\ cm^3}\\\\\rho=24.68\ g/cm^3[/tex]

So, the density of the marble slab is [tex]24.68\ g/cm^3[/tex]

Answer:

The answer is "Option A"

Explanation:

At 3300 cm-1, the wide region is equal to OH. It is a possible group of alcoholic features that includes drugs. In the given choices option a is correct that's the structure can be defined in attachment file please find it, and the wrong choice can be defined as follows:

Answer:

The correct answer is 8.04 mL

Explanation:

Given the neutralization reaction:

HCl(aq) + NaOH(aq) ––––> NaCl(aq) + H₂O(l)

1 mol of HCl reacts with 1 mol of NaOH.

The number of moles of NaOH there is in 15.8 mL is calculated as follows:

0.321 mol/L x 1 L/1000 mL x 15.8 mL = 5.07 x 10⁻³ mol NaOH

Thus, we need 5.07 x 10⁻³ mol of HCl to react with 5.07 x 10⁻³ mol NaOH. We have a 0.631 M HCl solution. We calculate the volume of HCl we need by considering that 1 mol NaOH reacts with 1 mol HCl and that there are 0.631 moles of HCl in 1 liter of solution (1000 mL):

5.07 x 10⁻³ mol NaOH x 1 mol HCl/1 mol NaOH x 1000 mL/0.631 mol HCl = 8.04 mL

Answer:

pH = 4.56

Explanation:

The strychnine reacts with HCl as follows:

C₂₁H₂₂N₂O₂ + HCl ⇄ C₂₁H₂₂N₂O₂H⁺ + Cl⁻

For strychnine buffer:

pOH = 5.74 + log [C₂₁H₂₂N₂O₂H⁺] / [C₂₁H₂₂N₂O₂]

Initial moles of C₂₁H₂₂N₂O₂ are:

0.025L * (0.400 mol / L) = 0.01 moles C₂₁H₂₂N₂O₂

And of HCl are:

0.05L * (0.200 mol / L) = 0.01 moles HCl

That means after the reaction, you will have just 0.01 moles of C₂₁H₂₂N₂O₂H⁺ in 50mL + 25mL = 0.075L. And molarity is:

[C₂₁H₂₂N₂O₂H⁺] = 0.01 mol / 0.075L = 0.1333M

This conjugate acid, is in equilibrium with water as follows:

C₂₁H₂₂N₂O₂H⁺(aq) + H₂O(l) ⇄ C₂₁H₂₂N₂O₂ + H₃O⁺

Where Ka = Kw / Kb = 1x10⁻¹⁴ / 1.8x10⁻⁶ = 5.556x10⁻⁹

Ka is defined as:

Ka = 5.556x10⁻⁹ = [C₂₁H₂₂N₂O₂] [H₃O⁺] / [C₂₁H₂₂N₂O₂H⁺]

In equilibrium, concentrations are:

C₂₁H₂₂N₂O₂ = X

H₃O⁺ = X

C₂₁H₂₂N₂O₂H⁺ = 0.1333M - X

Replacing in Ka expression:

5.556x10⁻⁹ = [X] [X] / [0.1333M - X]

7.39x10⁻¹⁰ - 5.556x10⁻⁹X = X²

7.39x10⁻¹⁰ - 5.556x10⁻⁹X - X² = 0

Solving for X:

X = - 2.72x10⁻⁵M → False solution. There is no negative concentrations

X = 2.72x10⁻⁵M → Right solution.

As H₃O⁺ = X

H₃O⁺ = 2.72x10⁻⁵M

And pH = -log H₃O⁺

Answer:

no c

Explanation:

Answer:

The mass of nitrogen molecule [tex]N_2[/tex] = 45.65 g

Explanation:

The equation for the redox reaction can be represented as follows:

[tex]\mathtt{2N_2H_4 +N_2O_4 \ \to \ 3N_2 + 4H_2O}[/tex]

We know that:

numbers of moles = mass/molar mass

For [tex]\mathtt{N_2O_4}[/tex] :

number of moles = 50g/92 g/mol

number of moles = 0.5435 mol

For [tex]\mathtt{N_2H_4}[/tex] :

number of moles = 45 g/ 32 g/mol

number of moles = 1.40625 mol

From the above equation;

number of moles of [tex]\mathtt{N_2O_4}[/tex] needed = 1/2 moles of [tex]\mathtt{N_2H_4}[/tex]  = 1/2 ×  1.40625 mol

= 0.703125 mol

The amount of [tex]\mathtt{N_2O_4}[/tex] present = 0.5435 moles which is less than the needed. As such [tex]\mathtt{N_2O_4}[/tex] is the limiting reagent

The number of moles of nitrogen molecule [tex]N_2[/tex] produced = 3 × ([tex]\mathtt{N_2O_4}[/tex])

= 3 × 0.5435

= 1.6305  mol

The mass of nitrogen molecule [tex]N_2[/tex] = number of moles of  [tex]N_2[/tex]  ×  molar mass of [tex]N_2[/tex]

The mass of nitrogen molecule [tex]N_2[/tex] =  1.6305  mol × 28 g/mol

The mass of nitrogen molecule [tex]N_2[/tex] = 45.654 g

The mass of nitrogen molecule [tex]N_2[/tex] = 45.65 g

Answer:

Distance between the carbon atom = 491 pm

Explanation:

Given:

1 pm = 1 × 10⁻¹² m

Distance between the carbon atom = 2.81 × 10⁻⁸ cm

Find:

Distance in picometers

Computation:

Distance between the carbon atom = 2.81 × 10⁻⁸ cm = 491 X 10⁻¹² m

Distance between the carbon atom = 491 pm

Answer:

Monomer liquid and polymer powder nail enhancement are lucrative service

[tex]3y-20=7\implies y=\frac{20+7}{3}=9[/tex].

Hope this helps.

y= 9

Explanation:

=> 3y - 20 = 7

=> 3y = 7+20

=> 3y = 27

=> y = 27/3

=> y = 9

HOPE OT HELPS. ◉‿◉

Answer:

1.4 moles.

Explanation:

The following data were obtained from the question:

Initial mole (n1) = 1.8 moles

Initial pressure (P1) = 25.5 atm

Final pressure (P2) = 5.7 atm

Number of mole removed =?

Next, we shall obtain an expression relating pressure and number of mole together.

This is illustrated below:

From the ideal gas equation:

PV = nRT

Divide both side by V

P = nRT /V

Divide both side by n

P/n = RT/V

But volume (V) and temperature (T) are constant.

P/n = constant

P1/n1 = P2/n2

P1 is initial pressure.

P2 is final pressure.

n1 is the initial mole.

n2 is the final mole.

Next, we shall determine the final mole in tank as follow:

Initial mole (n1) = 1.8 moles

Initial pressure (P1) = 25.5 atm

Final pressure (P2) = 5.7 atm

Final mole (n2) =.?

P1/n1 = P2/n2

25.5/1.8 = 5.7/n2

Cross multiply

25.5 x n2 = 1.8 x 5.7

Divide both side by 25.5

n2 = (1.8 x 5.7) /25.5

n2 = 0.40 mole.

Therefore, the final mole in the tank is 0.40 mole.

Finally, we shall determine the number of mole that was removed as follow:

Initial mole (n1) = 1.8 moles

Final mole (n2) = 0.4 mole

Number of mole removed =?

The number of mole removed from the tank can be obtained by finding the difference between the initial mole and final mole as illustrated below:

Number of mole removed = initial mole – final mole

Number of mole removed = n1 – n2

Number of mole removed = 1.8 – 0.4

Number of mole removed = 1.4 moles

Therefore, 1.4 moles were removed from the tank.

Answer:

[tex]M=6.03M[/tex]

Explanation:

Hello,

In this case, since the molarity is computed by:

[tex]M=\frac{n_{solute}}{V_{solution}}[/tex]

Whereas the solute is the hydrochloric acid, we compute the corresponding moles with its molar mass (36.45 g/mol):

[tex]n_{solute}=0.200gHCl*\frac{1molHCl}{36.45gHCl} =0.00549molHCl[/tex]

Next, since the solution contains both HCl and water, we compute the volume in liters by using its density:

[tex]V_{solution}=(0.200+0.801)g*\frac{1mL}{1.10g} *\frac{1L}{1000mL} =9.1x10^{-4}L[/tex]

Therefore, the molarity turns out:

[tex]M=\frac{0.00549mol}{9.1x10^{-4}L}\\ \\M=6.03M[/tex]

Regards.

Answer:

The answer is "33.95 [tex]\bold{ \frac{kj}{mol}}\\[/tex]".

Explanation:

Formula:

[tex]\bigtriangleup G_0= -R \times T l_n \times K_{eq}\\[/tex]

where

[tex]K_{eq} = \text{equilibrium constant}\\[/tex]

Given value:

[tex]T =35^{\circ} C\\[/tex]

convert temperature celsius (°C) to Kelvin (K):

[tex]= (273+45) \ kelvin \\\\= 318 \ Kelvin \\\\= 318 \ K[/tex]

[tex]R = 8.314 \ \ \frac{J}{ mol \cdot K}[/tex]

[tex]\bigtriangleup G_0= -(8.314 ) \times 31.8 \times l_n (2.65\times 10^{-6})\\[/tex]

        [tex]=-(8.314 ) \times 31.8T l_n \times (2.65\times 10^{-6})\\\\[/tex]

After solving the value it will give:

        = 33.95  [tex]\bold{ \frac{kj}{mol}}\\[/tex]

Answer:

c. isotope number

Explanation:

Mass Number is the sum total of mass of protons and neutrons present in the nucleus of an atom.  Generally they are being used in distinguishing isotopes. E.g Carbon - 12, Carbon - 13

Atomic Number is the number of protons. Every single element has it's unique atomic number and can be used in identification purpose. E.g Carbon - 6, Hydrogen - 1.

The correct option is option C. This is the symbol that is not necessary for the identification of a nuclide.

Answer: B, atomic number

Answer:

See explanation

Explanation:

The reactivity of metals has a lot to do with their position in the electrochemical series. However, it is also known that metallic character decreases across the period. This implies that as we move from left to right along the periodic table. Sodium, magnesium, aluminum and silicon continues to decrease in metallic character. As a matter of fact, silicon is a metalloid and not a pure metal.

Sodium reacts with cold water to give a vigorous reaction,magnesium and aluminium reacts with steam at red heat.

Silicon does not react with water, even as steam, under normal conditions.

Reactivity can be given as the ability of the atom to lose or gain electrons. The reactivity can be silicon is least as compared to sodium and other metals in water.

The periodic table has the arrangement of the elements in groups and periods in the table.

On moving from left to right in the periodic table, the number of electrons in the same shell increase, thereby making the loss of electrons difficult. Thus, on moving from left to right in the periodic table, the metal reactivity decreases.

Hence, silicon present in the right most of the periodic table has the lower reactivity as compared to the sodium, magnesium, and aluminum on the left side of the periodic table.

In the periodic table, on moving from top to bottom, the number of shells increases, decreasing the force of attraction to the outermost electron. Thus, the metal reactivity increases down the group.

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Answer:

1) 1,1,1-trichloropropane

2) 1,1,2-trichloropropane

3) 1,2,2-trichloropropane

4) 1,2,3-trichloropropane

Explanation:

For this question, we must remember that isomers are molecules that have the same formula but different structures. For the formula [tex]C_3H_5Cl_3[/tex] we can draw a linear chain of three carbons and change the position of the chlorine atoms in the carbon chain.

With this in mind, if we put all the chlorine atoms on the same carbon we will get 1,1,1-trichloropropane. If we change an atom from chlorine to carbon 2 we will obtain 1,1,2-trichloropropane. If we move another chlorine atom to carbon two we will get 1,2,2-trichloropropane. Finally, if we put a chlorine atom in each carbon we will obtain 1,2,3-trichloropropane.

See figure one for further explanations

I hope it helps!

Answer:

0.5 g/L.

Explanation:

Hello,

In this case, for this solubility problem, we can write for the lead (II) fluoride:

[tex]PbF_2(s)\rightleftharpoons Pb^{2+}(aq)+2F^-(aq)[/tex]

And the equilibrium expression is:

[tex]Ksp=[Pb^{2+}][F^-]^2[/tex]

Whereas Ksp of lead (II) fluoride is 3.3x10⁻⁸. In such a way, we can write the equilibrium expression in terms of the molar solubility [tex]x[/tex] as follows:

[tex]Ksp=(x)(2x)^2=3.3x10^{-8}[/tex]

Hence, solving for [tex]x[/tex] we find:

[tex]x=\sqrt[3]{\frac{3.3x10^{-8}}{4} }\\\\x=2.02x10^{-3}M[/tex]

Moreover, since the molar mass of lead (II) fluoride is 245.2 g/mol, the solubility turns out:

[tex]2.02x10^{-3}\frac{molPbF_2}{L}*\frac{245.2gPbF_2}{1molPbF_2}\\ \\0.5\frac{g}{L}[/tex]

Best regards.

Answer:

D) 5.15

Explanation:

Step 1: Write the equation for the dissociation of HCN

HCN(aq) ⇄ H⁺(aq) + CN⁻(aq)

Step 2: Calculate [H⁺] at equilibrium

The percent of ionization (α%) is equal to the concentration of one ion at the equilibrium divided by the initial concentration of the acid times 100%.

α% = [H⁺]eq / [HCN]₀ × 100%

[H⁺]eq = α%/100% × [HCN]₀

[H⁺]eq = 0.0070%/100% × 0.10 M

[H⁺]eq = 7.0 × 10⁻⁶ M

Step 3: Calculate the pH

pH = -log [H⁺] = -log 7.0 × 10⁻⁶ = 5.15

The pH of the 0.10 M HCN solution that is 0.0070% ionized is 5.15 and the correct option is option D.

pH is a measure of the acidity or alkalinity of a solution. It is a logarithmic scale that indicates the concentration of hydrogen ions (H+) in the solution.

The pH scale ranges from 0 to 14, where a pH of 7 is considered neutral, pH values below 7 indicate acidity, and pH values above 7 indicate alkalinity.

The pH of a solution can be calculated using the formula:

pH = -log[H+]

Where [H+] represents the concentration of hydrogen ions in moles per liter.

Since HCN is a weak acid and only 0.0070% of it is ionized, assuming that the concentration of H+ ions is equal to 0.0070% of 0.10 M HCN.

0.0070% of 0.10 M HCN = (0.0070/100) × 0.10

= 0.000007 M

pH = -log(0.000007)

= 5.15

Thus, the ideal selection is option D.

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Answer:

d) PO4^3-, HPO4^2-

Explanation:

Basically, an acid and a base which differs only by the presence or absence of  proton (hydrogen ion) are called a conjugate acid-base pair.

a) HI, I

This is incorrect. For the acid, HI the conjugate base is I⁻ ion.

b) HCHO2, SO4^2-

This is incorrect, there's no relationship between both entities.

c) CO3^2-, HCI

This is incorrect, there's no relationship between both entities.

d) PO4^3-, HPO4^2-

This is correct. The difference between both entities is the Hydrogen ion. This is the conjugate acid-base pair

Answer:

Number of students-this has nothing to do with the question, its called a distractor.

The variable that would most likely not affect the time it takes the ice to melt is the Number of students. The correct option is C.

Variables are the different substances or objects that participate in the experiment directly or indirectly. They are substances that together form the experiment. These variables impact the result of the experiment.

There are two types of variables. They are Dependent and independent variables. Dependent variables can be controlled in the experiment, but independent variables can't be controlled.

Students are performing the experiment, so they cannot be the variables because their presence or absence would be to impact the experiment.

Thus, the correct option is C. Number of students.

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Answer:

You are comparing a reaction that produces a chemical change and one that produces a physical change. What evidence could you use to determine which type of change is occurring?

If the reaction is a chemical change, new substances with different properties and identities are formed. This may be indicated by the production of an odor, a change in color or energy, or the formation of a solid.

Sample Response: If the reaction is a chemical change, new substances with different properties and identities are formed. This may be indicated by the production of an odor, a change in color or energy, or the formation of a solid.

What did you discuss in your response? Check all that apply.

the production of an odor

a change in energy

a change in color

the formation of a solid

the formation of new substances

a change in properties and identities

A chemical change may result in the following;

A Physical change may result in the following;

A chemical change leads to the formation of a new substance. This implies that the composition of the substance has being changed.

A physical change does not lead to a change in the nature of the substance. However, the appearance, shape, texture or size of the substance may change.

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Answer:

B. If students spend at least 1 hour per night studying math, then  they will get a grade of 85 or higher.

Explanation:

A hypothesis is defined as a tentative or predictions or an educated guess of scientific questions. A hypothesis is always done before performing an experiment.

The correct hypothesis for the given experiment will be "If students spend at least 1 hour per night studying math, then  they will get a grade of 85 or higher" because it has an if-then statement which is a conditional statement where statement after "if represents hypothesis" and "then represents conclusion".

Hence, the correct answer is "B. If students spend at least 1 hour per night studying math, then  they will get a grade of 85 or higher."

Answer:

The answer is "Al= 9.8% and Fe=18.0%"

Explanation:

Given:

The weight of [tex]FeCl_3\ and \ ALCl_3[/tex] = 5.95g

[tex]gFeCl_3=gFe (\frac{Mw\ FeCL_3}{\text{atomic weight of Fe}})\\\\gAlCl_3=gAl (\frac{Mw\ AlCL_3}{\text{atomic weight of Al}})\\\\[/tex]

[tex]\to a = FeCl_3+AlCl_3\\\\\to a=x+y \\\\ \to a= 5.95[/tex]

[tex]\to a =x \ gFe (\frac{Mw\ FeCL_3}{\text{atomic weight of Fe}})+ y \ gAl (\frac{Mw\ AlCL_3}{\text{atomic weight of Al}})\\\\[/tex]

[tex]\to x (\frac{162.2}{55.85})+ y (\frac{133.34}{26.98})= 5.95\\\\\to 2.90x+4.94y=5.95\\\\\ similarly \ for \ oxidies:\\\\\to 143x+1.89y=2.62\\\\\to x= 1.07 \ \ \ and \ \ y= 0.58\\\\\to \ Al \% = \frac{0.58}{5.95} \times 100= \bold{9.8} \%\\\\\to \ Fe \% = \frac{1.07}{5.95} \times 100= \bold{18.0} \%[/tex]

The mass of the compound has been given as the mass of each element in the compound. The percent Fe in the mixture is 18%, and the percent Al in the mixture is 9.8%.

The percent composition has been given as the mass of the element in the compound. The percent of iron and aluminum in their chlorides can be given as:

[tex]\rm Fe=Fe\;\times\;\dfrac{Mwt\;FeCl_3}{Mwt\;Fe}[/tex]

[tex]\rm Al=Al\;\times\;\dfrac{Mwt\;AlCl_3}{Mwt\;Al}[/tex]

The total mass of the compounds has been 5.95 grams.

Thus,

[tex]5.95=\rm FeCl_3+AlCl_3[/tex]

The mass of Fe and Al will be x and y of the mass in the compounds. Thus,

[tex]5.95=\rm x\;Fe\;\times\;\dfrac{Mwt\;FeCl_3}{Mwt\;Fe}\;+\;y\;Al\;\times\; \dfrac{Mwt\;AlCl_3}{Mwt\;Al}[/tex]

The oxides of the chemical has the sum of mass of 2.62 grams.

The mass of oxides can be given as:

[tex]2.62=\rm x\;Fe\;\times\;\dfrac{Mwt\;Fe2O_3}{Mwt\;Fe}\;+\;y\;Al\;\times\; \dfrac{Mwt\;Al_2O_3}{Mwt\;Al}[/tex]

Substituting the values of mass of Al, aluminum chloride, oxide, and Fe and its compounds.

[tex]\rm 2.90x+4.94y=5.95\\143x+1.89y=2.62[/tex]

Solving the equation, x = 1.07, and y = 0.58

The percent mass of the compounds has been given as the ratio of mass with compound mass.

Thus, the percent mass of Fe has been:

[tex]\rm Fe=\dfrac{1.07}{5.95}\;\times\;100\\ Fe=18\;\%[/tex]

The percent mass of Al has been:

[tex]\rm Al=\dfrac{0.58}{5.95}\;\times\;100\\ Al=9.8\;\%[/tex]

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