what percent of a sample of As-81 remains un decayed after 43.2 seconds

Explanation:

We have a gas sample of carbon dioxide and we know its volume, the pressure and the temperature. We can find the number of moles of that sample using the ideal gas law.

P * V = n * R * T

Where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas law and T is the temperature.

R = 0.082 atm*L/(mol*K)

Since R is in atm*L/(mol*K) we have to convert the volume from mL to L, the temperature from °C to K and the pressure from torr to atm.

1000 mL = 1 L

V = 26 mL = 26 mL * 1 L/(1000 mL)

V = 0.026 L

760 torr = 1 atm

P = 623 torr = 623 torr * 1 atm/(760 torr)

P = 0.820 atm

T = (273.15 + 11 ) K

T = 284.15 K

Now we can replace these values in the formula and solve it for n to find the number of moles that are present in the sample.

P * V = n * R * T

n = P * V/(R * T)

n = 0.820 atm * 0.026 L/(0.082 atm*L/(mol*K) * 284.15 K)

n = 0.000915 mol

Finally we can convert the moles of the sample into grams using the molar mass of carbon dioxide.

molar mass of C = 12.01 g/mol

molar mass of O = 16.00 g/mol

molar mass of CO₂ = 1 * 12.01 g/mol + 2 * 16.00 g/mol

molar mass of CO₂ = 44.01 g/mol

mass of CO₂ = 0.000915 mol * 44.01 g/mo

mass of CO₂ = 0.040 g

Answer: There are 0.040 g of carbon dioxide in the sample.

The complete ground-state electronic configuration of Mn⁺⁴ is:

Mn⁺⁴: [Ar] 4s⁰ 3d³

The electronic configuration is written according to the following principles:

Manganese being a d-block element possesses d-orbitals in the electron cloud. There are 25 electrons present in the ground-state configuration.

In order to reach the excited state, electrons will be removed from the ground state. The removal of electrons is centripetal in nature. Initially, 2 electrons will be removed from 4s, followed by the removal of 2 electrons from 3d.

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The wavelength and the energy would be 2.72 × 10⁻⁹  meter 6.886 × 10⁻¹⁷ Joules and respectively if the light has s a frequency of 1.1 × 10¹⁷ Hz.

It can be understood in terms of the distance between any two similar successive points across any wave.

C = λν

As given in the problem we have to calculate the energy of the light if the frequency of light is  1.1 × 10¹⁷ Hz

The wavelength of the light = 3 × 10⁸ / 1.1 × 10¹⁷

                                               = 2.72 × 10⁻⁹  meter

The energy of the light = h ν

                                       = 6.26 × 10⁻³⁴ × 1.1 × 10¹⁷

                                        = 6.886 × 10⁻¹⁷ Joules

Thus, the wavelength and the energy would be 2.72 × 10⁻⁹  meter 6.886 × 10⁻¹⁷ Joules and respectively if the light has s a frequency of 1.1 × 10¹⁷ Hz.

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Answer:

1.33 moles

Explanation:

[tex]n = \frac{mass}{molar \: mass} [/tex]

note Molar Mass according to websearch is 64 066

you could calculate this using the individual elements on a periodic table (sulfur and oxygen) and their masses

[tex]n = \frac{85}{64.066} [/tex]

[tex]n = 1.33[/tex]

Precipitin test is used to determine antigens and human blood from other sources. It is widely used in forensic laboratories. Thus we can determine the blood groups such as A, B,O etc.

Precipitin is an antibody which precipitates when other antigens binds with it. Thus, antigens from other source can be easily determined using precipitin reaction.

Precipitin reaction involves a specific serological precipitation of an antigen . Varying amounts of the antigen is added to the serum source where each antigen molecule extensively bound to the antibody excess zone.

A small antibody - antigen complex is formed there with  crosslinking reaction. The advantages of this test is that very small amount of test sample is needed and about fifty specimens can be easily tested within few minutes.

Therefore, the precipitin test can used to determine the antigen type of blood A, B or O. Hence, option A is correct.

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Answer: A

Explanation:

Explanation:

Iron (III) oxide will react with hydrogen gas to produce iron and water. They will react according to the following equation.

Fe₂O₃ + 3 H₂ -----> 2 Fe + 3 H₂O

We have to find the grams of Fe that can be made from 24.5 g of Fe₂O₃. So, first we have to convert those grams into moles using the molar mass of iron (III) oxide.

molar mass of Fe₂O₃ = 159.69 g/mol

mass of Fe₂O₃ = 24.5 g

moles of Fe₂O₃ = 24.5 g * 1 mol/(159.69 g)

moles of Fe₂O₃ = 0.153 mol

Fe₂O₃ + 3 H₂ -----> 2 Fe + 3 H₂O

According to the coefficients of the equation, we know that 1 mol of Fe₂O₃ will react with 3 moles of H₂ to give 2 moles of Fe and 3 moles of H₂O. So the molar ratio between Fe₂O₃ and Fe is 1 to 2. We can use that relationship to find the number of moles of Fe that can be made from 0.153 moles of Fe₂O₃.

1 mol of Fe₂O₃ : 2 moles of Fe molar ratio

moles of Fe = 0.153 moles of Fe₂O₃ * 2 moles of Fe/(1 mol of Fe₂O₃)

moles of Fe = 0.306 moles

So we found that we can produce 0.306 moles of Fe from 0.153 moles of Fe₂O₃ or 24.5 g of it. Finally we can convert the 0.306 moles of Fe into grams using the molar mass of Fe.

molar mass of Fe = 55.85 g/mol

mass of Fe = 0.306 moles * 55.85 g/mol

mass of Fe = 17.1 g

Answer: 17.1 g of iron can be made from 24.5 g of iron (III) oxide.

There are only two electrons that could posses the quantum numbers as shown.

We now that it is often common to seek to describe the probability of finding the electrons in the atom. While it is know that the electron is not a given point in the atom. The probability of finding the electron in the atom is given by the help of the quantum numbers that can be used to describe the position of the electron as shown.

In tis case, we have an electron that has the quantum numbers; n = 3, l = 2, ml = -2. This describes an orbital and there are two electrons in a given orbital.

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Considering the definition of STP conditions, 4.83 × 10⁻³ moles of HF will occupy a volume of 0.108192 L at STP.

STP conditions is the abbreviation that refers to standard temperature and pressure. The standard value for pressure is 1 atmosphere and the standard value for temperature is 0°C. They are valid reference values for all gases, and under these conditions 1 mole of any gas occupies an approximate volume of 22.4 liters.

In this case, you have 0.804 moles CCl₄. You can apply the following rule of three: if by definition of STP conditions 1 mole of CCl₄ occupies a volume of 22.4 liters, 0.804 moles occupies how much volume?

volume= (0.804 moles ×22.4 L)÷ 1 mole

volume= 18.0096 L

Finally, the volume will be 18.0096 L at STP.

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Answer:

the water becomes solvent, and the mixture becomes the solution.

Explanation:

Answer:

a solution

Explanation:

solute and solvent(water) put together would produce a solution

Combination (also called synthesis): Where two elements or one compound and one element will bond and form a new compound as a product, the representation for this reaction is:

A + B -> AB

Decomposition: The opposite from Combination, now one compound will decompose and form 2 new elements or compounds as the product:

AB -> A + B

Single Replacement: One element will take the place of another element in already existing compound:

A + BC -> AB + C

Double Replacement: Now we have two compounds switching elements and forming two new compounds:

AB + CD -> AC + BD

Combustion: Reactions that involve oxygen as reactant and we have CO2 and H2O as products:

X + O2 -> CO2 + H2O

According to the explanation, what we have in this reaction is a Single Displacement reaction, letter A

Answer

% mass of KCl = 25.76%

Explanation

Given:

mass of KCl = 42.5 g

mass of water = 122.5 g

Required: The % mass of KCl

Solution:

Step 1: Calculate the total mass

42.5 g + 122.5 g = 165 g

Step 2: Calculate the % of KCl

%KCl = (42.5/165)*100

%KCl = 25.76%

Answer:

61.09 grams SmO

Explanation:

To find the number of grams SmO, you need to multiply the moles by the molar mass of SmO. The molar mass is a ratio which represents the mass of SmO per every 1 mole. It is important to arrange the ratio in a way that allows for the cancellation of units (moles should be in the denominator). The final answer should have 4 sig figs like the given value (0.3672 = 4 sig figs).

Atomic Mass (Sm): 150.36 g/mol

Atomic Mass (O): 15.999 g/mol

Molar Mass (SmO): 150.36 g/mol + 15.999 g/mol

Molar Mass (SmO): 166.359 g/mol

 0.3672 moles SmO           166.359 grams
--------------------------------  x  --------------------------  =  61.09 grams SmO
                                                   1 mole

The stability of alkene can be determined by measuring the amount of energy that is associated with the hydrogenation of the molecule.

Because those branched alkanes are more stable than their linear isomers (Figure 1), the origins of this stability are unclear. For each branch in an alkane, the measured heat of formation is lower than expected by about 2 kcal mol−1 in comparison to the linear isomer. The fullness structures in which all atoms have complete valence shells are more stable. The structures with the least number of ritual charges are more stable. The structures with a negative charge on the further electronegative atom will be more stable. The three main factors determining the relative stability of alkenes are i) the number of substituents attached to the double-bond carbon atoms, ii) hyperconjugation, and iii) the stereochemistry of the double bond.

So we can conclude that the more electron-donating alkyl groups are the more stable the alkene

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The nitrogen in ammonium nitrate contains a greater percentage of nitrogen by mass

The formula for ammonium nitrate is given as NH4NO3.

Determine the molar mass of NH4NO3

Molar mass = 14 + 4(1) + 14 + 3(16)

Molar mass .= 14 + 4 + 14 + 48

Molar mass of NH4NO3 = 80g/mol

Determine the percentage of nitrogen in the compound

%N = 28/80 * 100

%N = 35%

The formula for ammonium phosphate is (NH4)3PO4

Determine the molar mass of (NH4)3PO4

Molar mass = 3(14) + 4(3) + 4(16) + 3(31)

Molar mass = 42 + 12 + 64 + 31

Molar 1ass = 149g/mol

Determine the percentage of nitrogen in ammonium phosphate:

%N = 42/149 * 100

%N = 28.18%

Hence the nitrogen in ammonium nitrate contains a greater percentage of nitrogen by mass

The moles of Cl⁻ ions present in 1.8 L of the intravenous solution is 0.063 moles.

The moles of Cl⁻ ions in the intravenous solution are calculated using the conversion factor between mEq/L to mmoles

The conversion between milliequivalents per Liter and millimoles per Liter is:

1 Millimole per Liter = 1 Milliequivalents per Liter.

Hence 35 mEq/L = 35 mmol/L

The mmoles of Cl⁻ ions in 1.8 liters of the intravenous solution will be:

moles of Cl⁻ ions = 35 mmol/L * 1.8 L

moles of Cl⁻ions = 63 mmoles

Converting to moles by dividing by 1000:

moles of Cl⁻ ions = 63 / 1000

moles of Cl⁻ ions = 0.063 moles.

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Aluminum Oxide decomposes to Aluminum metal and Oxygen gas.

- First, write down each compound:

- Second, write the number of moles of each compound, so that we have the same amount of reactants as products. Here, it is important not to change the subscript of compound elements.

For example, let's start by adding a number 2 in front of the aluminum metal to balance:

So far, the amount of aluminum has been balanced but the amount of oxygen is unbalanced, so let's add a number 3 for the oxygen gas.

Now, to have the same amount of moles of oxygen on both sides, let's put a number 2 in the aluminum oxide:

Here, the amount of aluminum moles is unbalanced, so we add a number 4 for the aluminum metal to balance:

- This is the final balanced equation of decomposition of aluminum oxide:

Answer:

Explanation:

Here, we want to order the radiations in terms of energy

There is a proportional relationship between the mass and the energy

It is established that the radiation with a higher mass would have the lesser energy

Alpha decay has the highest mass and thus, the lowest energy. This is followed by beta decay, and finally, gamma decay

Hetergeneous mixture   peanuts and almonds mixed ,a bucket full of sand and gravel. Homogeneous Mixture -food coloring dissolved in water together in a bowl,cup of tea and sugar .          

When the composition of a mixture is not constant throughout the mixture, the mixture is said to be heterogeneous. A variety of  make up vegetable soup. Each mouthful of soup will have variable proportions of the soup's various veggies and other ingredients.

For illustration A mixture of sugar and water, or salt and water, both of which have the same component ratio throughout the mixture, are examples of homogenous mixes.

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Answer:1=B

2=A

Explanation:

To calculate how polar a bond is we can look at the difference in electronegativity. An electronegativity greater than 1.7 represents an ionic bond, a bond less than 1.7 will be a covalent bond.

Let's see wich is the wich is the electronegativity of each element:

C=2.55

O=3.44

N=3.04

The difference of electronegativity of each pair of bonds will be:

Polar bonds are covalent bonds that have a difference in electronegativities. The greater the difference in electronegativity, the greater the polarity.

So, in this case, C-O bond will be more polar that C-N bond, the polarity.

The direction of the polarity will go towards the more electronegative element. So, we will have:

Answer: The most polar bond will be the C-O bond and the direction of polarity will be toward oxygen for the C-O bond and toward nitrogen for the C-N bond.

In order to find the percent composition for Nitrogen in NH4NO3, we will need to work with all the masses from this compound, so let's list them below:

NH4NO3 = 80.04 g/mol

N = 14 grams, but we have 2 nitrogens, therefore = 28 grams

H = 1 gram, 4 Hydrogens = 4 grams

O = 16 grams, 3 Oxygens = 48 grams

Now we take the total mass of the compound as 100% and check how much it will be made by Nitrogen:

80.04 g = 100%

28 g = x %

x = 34.98%, which we can round up to 35% therefore the answer will be letter E

Answer:

Explanations:

Answer:

Explanations:

Answer:

A: 0

B: 0

Explanation:

Initially the concentration of Mg+2 ions and F- ions is zero. The ICE table is:

Answer:

The pH of the solution is 1.60.

Explanation:

1st) It is necessary to write and balance the chemical reaction:

Now we can see that 1 mole of NaOH reacts with 1 mole of HCl.

2nd) We have to calculate the moles contained in 15mL of 0.10M NaOH solution and the moles contained in 25mL of 0.10M HCl solution:

• Moles contained in NaOH solution:

• Moles contained in HCl solution:

Now we know that there are 1.5x10^-3 moles of NaOH and 2.5x10^-3 moles of HCl.

3rd) According to the stoichiometry of the reaction, 1 mole of NaOH reacts with 1 mole of HCl, so in this case, 1.5x10^-3 moles of NaOH will react with 1.5x10^-3 moles of HCl, because NaOH will be the limiting reactant and HCl will be the excess reactant.

So, now we have to calculate the excess of HCl:

2.5x10^-3moles - 1.5x10^-3moles = 1x10^-3moles

Now we know that there are 1x10^-3 moles of HCl left.

4th) Excess HCl will remain dissociated into H+ and Cl-, according to the following equation:

That means that for every mole of HCl, 1H+ dissociates. So, in this case, there are 1x10^-3 moles of H+.

Remember that these moles are contained in 40mL, so the molarity of H+ is 0.025M:

5th) Finally, we can calculate the pH of the solution, by replacing the H+ concentration in the pH formula:

So, the pH of the solution is 1.60.

Remember: solution = NaOH + water

Volumen here = 1 L

Molecular mass NaOH = 39.99 g/mol

Answer: Contration = 14.32 M

To solve this question, we need to use the Clapeyron formula.

Clapeyron's formula is a mathematical expression that relates quantities such as pressure (P), volume (V), temperature (T) and the number of particles (n) that make up an ideal gas.

The formula is: PV = nRT

First, let's discover the number in moles of N2. We have:

P = 1.5 atm

V = 10 L

n = ???

R = 0.082 atm.L/mol.k

T = 273 K

1.5 x 10 = n x 0.082 x 273

15 = n x 22.386

n = 15/22.386

n = 0.67 moles

As we can see in the chemical reaction equation, the ratio between NaN3 and N2 is 2:3.

So:

2 mol of NaN3 --- 3 mol of N2

x mol of NaN2 --- 0.67 moles

3x = 2 x 0.67

x = 0.45 moles of NaN3

Now we transform this value into grams, using NaN3 formula mass, which is 65 g/mol:

65 g ---- 1 mol

x g ---- 0.45 mol

x = 29 g

Answer: 29 g of NaN3

Avogadro's Law is

In the second column of the table, we have to find n1 when V1 = 51 mL, V2 = 13 mL, and n2 = 2.68x10^-4 mol. Solve the equation for n1.

Therefore, the number of moles of n1 is 0.0011 moles.

Explanation:

A mixture of differet iron oxides is heated and they it absorbs oxygen from the air to form iron (II) oxide. The reaction can be represented like this:

2 Fe₃O₄ + 2 FeO + O₂ ----> 4 Fe₂O₃

The mass of the mixture of Iron oxides is 3.939 g. The mass of Fe₂O₃ formed is greater than the original mass, it is 4.197 g. That means that the sample absorbed oxygen.

mass of Fe₃O₄ + mass of FeO = 3.939 g

mass of Fe₂O₃ = 4.197 g

The law of conservation of mass states that no mass is loss or created in a chemical reaction. A mass balance can be written:

mass of Fe₃O₄ + mass of FeO + mass of O₂ = mass of Fe₂O₃

The known values can be replaced in the equation, and it can be solved for mass of O₂ to obtain the answer to the problem.

mass of Fe₃O₄ + mass of FeO + mass of O₂ = mass of Fe₂O₃

mass of O₂ = mass of Fe₂O₃ - (mass of Fe₃O₄ + mass of FeO)

mass of O₂ = 4.197 g - 3.939 g

mass of O₂ = 0.258 g

Answer: the mass of oxygen reacted is 0.258 g

Answer:

[tex]\blue{\boxed{\red{\sf CCl_4 \: will \: dissolve \: in \: gasoline}}}[/tex]

Explanation:

The simple concept that would be applied is

'Like Dissolves Like.'

According to this, the polar solvent will dissolve the polar solutes and the non-polar solvent will dissolve the non-polar solutes.

classification of given compounds as polar or non-polar,

[tex]\begin{gathered}\boxed{\begin{array}{c|c} \bf Polar & \bf Non-polar \\ \\ \frac{\qquad \qquad}{} & \frac{\qquad \qquad}{} \\ \sf NaCl & \sf CCl_4 \\ \\ \sf NaOH & \sf - \\ \\ \sf KCl & \sf - \end{array}} \\ \end{gathered}[/tex]

Also, the given data says water is a polar solvent while gasoline is a non-polar solvent. From all the information we have, we can conclude that CCl4 is the only compound that will dissolve in gasoline.

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To balance the given equation remember to start by the elements that are different from oxygen and hydrogen, in this case, let's start by chlorine:

As chlorine in AlCl3 is 3 times and in CaCl2 is 2 times, we have to write a 2 in AlCl3 and a 3 in CaCl2, with this coefficients we will have 6 chlorines in total at each side of the equation.

Then, as we put that 2 in front of AlCl3, we will also have 2 aluminium. After the reaction we have only one aluminium, it means that we need to write 2 in front of Al to balance the number of aluminium in the equation.

The correct option is 2.