Which of the following statements is one of the postulates in Dalton’s atomic theory?1. Atoms of different elements can physically mix together.2. Atoms of one element can be changed into atoms of another element through a chemical reaction.3. All compounds are composed of multiple elements combined together.4. Atoms of one element cannot be changed into another element through a chemical reaction.

Light below the necessary critical frequency doesn't eject electrons from metal because no electrons will be emitted when the light shines on the metal.

This is a term in physics which is used to describe the number of occurrences of a repeating event per unit of time.

The amount of energy which is present in each photon in the beam is determined by and proportional to the frequency of the beam. This therefore means that if there is light which is below the threshold frequency, there will be no electrons emitted when light shines on the metal thereby making it the correct choice.

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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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The moles of gas added could not be determined because of an apparent error in the data provided for the volume of the container.

The moles of gas in the container is calculated from the ideal gas equation as follows;

Data given:

P = 131,874 Pa or 131.874 kPa

V = 54.7 mL = 0.0547 L

T = 113.7 °C or (113.7 + 273) K

T = 386.7 K

R, molar gas constant  = 8.314 L⋅kPa.K/mol

n = (131.874 * 0.0547 L) / (8.314 * 386.7 )

n = 0.000224 moles

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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.

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:

Remember: solution = NaOH + water

Volumen here = 1 L

Molecular mass NaOH = 39.99 g/mol

Answer: Contration = 14.32 M

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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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

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

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:

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

Answer:1=B

2=A

Explanation:

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

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.

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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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]

Ca(NO3)2 and H₂O. Option C is correct

The combination of acid and base to form salt and water at the product is known as a neutralization reaction.

Hence the products of the neutralization reaction between HNO3 and Ca(OH)2 must be salt and water

From the given option, the equivalent product that are salt and water is Ca(NO3)2 and H₂O which gives the required product.

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.

Taking into account the definition of pH and pOH, the concentration of OH⁻ is 1×10⁻² M.

pH is a measure of acidity or alkalinity that indicates the amount of hydrogen ions present in a solution or substance.

The pH is defined as the negative base 10 logarithm of the activity of hydrogen ions:

pH= - log [H⁺]

Similarly, pOH is a measure of hydroxyl ions in a solution and is expressed as the logarithm of the concentration of OH⁻ ions, with the sign changed:

pOH= - log [OH⁻]

The following relationship can be established between pH and pOH:

pOH + pH= 14

Being [H⁺]=1.0×10⁻¹² M, the pH is calculated as:

pH= - log (1.0×10⁻¹² M)

Solving:

pH= 12

Being pH= 4.85, and considering the relationship between pH and pOH, pOH is calculated as:

pOH + 12= 14

pOH= 14 - 12

pOH= 2

Replacing in the definition of pOH the concentration of OH⁻ ions is obtained:

- log [OH⁻]= 2

Solving

[OH⁻]= 10⁻²

[OH⁻]= 1×10⁻² M

In summary, the [OH⁻] is 1×10⁻² M.

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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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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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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:

Explanation:

molar mass of 13c = 13 grams

number of moles = mass / molar mass

therefore,

number of moles = 7 / 13

To know the number of atoms in 7/13 moles, we simply multiply the number of moles by Avogadro's number as follows:

number of atoms = (7/13) x 6.022 x 10^23 = 3.2426 x 10^23 atoms

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

Answer

2NaCl + Cal₂ → 2Nal + CaCI₂

Explanation

Given unbalanced equation;

NaCl + _Cal₂ → Nal + CaCI₂

Step 1: Balance the Cl atom on both the reactant and product sides of the equation by putting 2 as the coefficient of NaCl in the reactant side.

2NaCl + _Cal₂ → Nal + CaCI₂

Step 2: Balance the Na atom on both the reactant and product sides of the equation by putting 2 as the coefficient of NaI in the product side.

2NaCl + Cal₂ → 2Nal + CaCI₂

Therefore, the balanced equation is: 2NaCl + Cal₂ → 2Nal + CaCI₂

The detailed steps to measure the volume of a piece of rock using a graduated cylinder and beaker are based on Archimedes' Principle, which states that an object that is displacing fluid has a weight equal to that of the object it is displacing.

The submersion or dunking method is another name for the displacement method.

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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.

Answer:

Explanation:

Carbon is the only element listed. Carbon Dioxide consists of Carbon AND Oxygen x2 so this is a compound. As stated earlier, air is a mixture of compounds. Water is another compound consisting of Hydrogen x2 and Oxygen.

The concertation of the HI that would be present in the new equilibrium position is 0.15 M.

We have to first obtain the equilibrium constant that we have under the initial conditions and then we have; H2 + I2 ------> 2HI

K = [HI]^2/[H2] [I2]

K = (0.490)^2/(0.080) (0.060)

K = 0.2401/(0.080) (0.060)

K = 50

Again;

                               H2      +      I2                     ------> 2HI

Initial                     0.080           0.060                        0.060

concentration         +x                   +x                            -2x

Equilibrium     0.080 + x      0.060 + x                 0.490 - 2x

50 = (0.490 - 2x)^2/( 0.080 + x) (0.060 + x)

Working through the quadratic we have;

46x^2 + 10.2 x - 0.38 = 0

x = 0.32 M

In each case we now have;

 H2 =  0.080 +  0.32  = 0.4 M

[I2] = 0.060  +  0.32  = 0.38 M

[HI] = 0.790 - 2( 0.32 ) = 0.15 M

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Answer:

262

Explanation: