What is the half life of sodium-24 if after 12 days the sample has a mass of 1.2 g from an initial mass of 9.6 g?
Group of answer choices

A. 36 days

B. 12 days

C. 24 days

D. 4 days

The number of mole of solute particles are present in 1 mL (exact) of aqueous 0.0040 M Ba(OH)₂ is 0.000004 mole

Molarity is defined as the mole of solute per unit litre of solution. Mathematically, it can be expressed as:

Molarity = mole / Volume

With the above formula, we can determine the number of mole present in the solution. Detail below:

Molarity = mole / Volume

Cross multiply

Mole = Molarity × volume

Mole of solute = 0.004 × 0.001

Mole of solute = 0.000004 mole

Thus, the mole of the solute in the solution is 0.000004 mole

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If I study, I will pass the exams.

Answer:

C.) 42 grams NaOH

Explanation:

To find the mass of NaOH, you need to (1) find the moles (using the molarity equation) and then (2) convert moles to grams (using the molar mass).

(Step 1)

250.0 mL / 1,000 = 0.2500 L

Molarity = moles / volume (L)

4.2 M = moles / 0.2500 L

1.05 = moles

(Step 2)

Molar Mass (NaOH): 22.990 g/mol + 15.998 g/mol + 1.008 g/mol

Molar Mass (NaOH): 39.996 g/mol

1.05 moles NaOH           39.996 g
-----------------------------  x  ------------------  =  42 grams NaOH
                                           1 mole

Answer:

The answer is Oxygen

The oxygen has the most electronegativity.

The rate of the forward reaction equals the rate of the reverse reaction.

When it comes to chemical reactions, a dynamic equilibrium is a condition in which a reversible reaction produces products and reactants at an equal rate.

Dynamic equilibrium can only be achieved in a closed system. That is, a system in which there are no external influences in form of energy, material, or pressure.

For example, consider the following reversible reaction:

[tex]A + B < --- > C + D[/tex]

If the reaction is in dynamic equilibrium, there will not be a net production of reactants and products. In other words, the rate of production of A and B will be the same as the rate of production of C and D.

This is as opposed to static equilibrium in which the production of both reactants and products stops completely after reaching equilibrium.

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The correct name for the compound is written as lead II trioxonitrate V.

We know that a compound is formed when atoms are bonded together. The bond that holds atoms together could be ionic, metallic or covalent. We know that in  Pb(NO3)2, there is both ionic and covalent bonding.

This is because, the kind of bond between the lead II ion and the nitrate ion is an ionic bond while the bond between the nitrogen and the oxygen atoms in the nitrate ion is  covalent bond.

Hence, the correct name for the compound is written as lead II trioxonitrate V.

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Answer:

a.) 1+

Explanation:

Potassium (K) is located in the first column of the periodic table.

These elements have 1 valence electron. As such, in order to obtain a full octet (8 valence electrons), these elements are likely to lose 1 electron. When this occurs, the element gains an overall charge of 1+ because the positively-charged protons now outnumber the negatively-charged electrons by 1.

The two compounds that are the correct enol tautomers of 2-butnone are the structures shown in Option B.

Isomerism is a situation in which two compounds have the same molecular formula but do not have the same structural formula. This occurs because the atoms in the molecule are arranged differently in space. One of the types of isomerism that we have is the Keto Enol Tautomerism. The Keto Enol Tautomerism occurs between the Keto and the enol forms of a compound via the movement of electrons. It is common in ketone compounds.

In this case, we can see that the compound 2-butanone can give rise to two enol compounds that have the same molecular formula as the 2-butanone.

The two compounds that are the correct enol tautomers of 2-butnone are the structures shown in Option B.

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The concentration of carbon monoxide at equilibrium is 0.209 M.

CO2 = 2 mol/5 L = 0.4

H2 = 1.5 mol/5L = 0.3

Create ICE table as shown below

        CO2(g)    +     H2(g) ↔       CO(g)    +     H2O(g)

I          0.4               0.3                0                  0

C        - x                 - x                 x                   x

E        0.4 - x           0.3 - x           x                   x

Kc = [CO][H₂O] / [CO₂][H₂]

2.5 = (x²)/(0.4 - x)(0.3 - x)

x² = 2.5(0.4 - x)(0.3 - x)

x² = 2.5(0.12 - 0.7x + x²)

x²  = 0.3 - 1.75x + 2.5x²

0 = 1.5x² - 1.75x + 0.3

solve the quadratic equation using formula method;

x = 0.209

Thus, the concentration of carbon monoxide at equilibrium is 0.209 M.

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The true statements are;

We define a redox reaction as one in which a specie is oxidized and another is reduced.

Now;

Eo cell = cell potential = -0.13 V - (+0.34 V) = -0.47 V

n =number of moles of electrons = 2 mole of electrons

K = equilibrium constant

ΔG = change in free energy

Eo cell = 0.0592/n log K

-0.47 =  0.0592/2 log K

log K =  -0.47  * 2/0.0592

K = 1.3 * 10^-16

ΔG = -nFEo cell

ΔG = -(2 * 96500 * -0.47)

ΔG = 90.7kJ

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Answer:

52.57 Celsius

Explanation:

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Gay-Lussac's law

P1/T1 = P2/T2

pressure 1 / temperature1 = pressure2 / temperature2

temperature has to be in kelvin

20 degrees Celsius is 293.15

1.8 / 293.15 = 2.0 / temperature2

1.8 / 293.15 = 2.0 / x

293.15 * 2.0 = 586.3

586.3 divided by 1.8 =

325.722222222 kelvin which is

52.57222222200005 Celsius

chemlibretextsorg

The oxidation number of chlorine in KClO3 is +5 (option A).

The oxidation number of an element is the hypothetical charge of an atom within a molecule.

The oxidation number of an element like chlorine in a compound like Pottasium chlorate can be calculated as follows:

The oxidation number of the elements in KClO3 is as follows:

1 + x - 2(3) = 0

x - 5 = 0

x = +5

Therefore, the oxidation number of chlorine in KClO3 is +5.

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Answer:

D

Explanation:

Ideal gas law    PV = n RT     R = .082057      T   must be in Kelvin  

                                               n = moles

V = n RT / P

  = 1.5 (.082057) ( 27+ 273.15) / 2 = 18.5 liters

Vinegar pH 3.2: Weak acid

Battery acid pH 0.5: Strong acid

Shampoo pH 7.0: Neutral

Ammonia pH 11.1 Strong base

Answer:

1.2   ( two significant digits)

Explanation:

5.4 - 4.21        answer should only have the the number of significant digits as the number in the equation with the least number of significant digits... in this case   5.4   is only two significant digits....so the answer should only have two significant digits

5.4 - 4.21 = 1.19     round to two digits = 1.2    

Taking into account the definition of dilution, the answer is "The volume of stock solution used is less than 3 Liters."

When it is desired to prepare a less concentrated solution from a more concentrated one, it is called dilution.

Dilution is the process of reducing the concentration of solute in solution, which is accomplished by simply adding more solvent to the solution at the same amount of solute.

In a dilution the amount of solute does not change, but as more solvent is added, the concentration of the solute decreases, as the volume (and weight) of the solution increases.

A dilution is mathematically expressed as:

Ci×Vi = Cf×Vf

where

In this case, you know:

Replacing in the definition of dilution:

10 M× Vi= 1 M× 3 L

Solving:

Vi= (1 M× 3 L)÷ 10 M

Vi= 0.3 L

In summary, to prepare 3 Liters of 1 M solution, you need 0.3 L of the 10 M concentration stock solution and dilute to 3 L. Therefore, the answer is "The volume of stock solution used is less than 3 Liters."

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Answer:

9.10% dextrose

Explanation:

To find the mass percent, you need to use the following equation:

                               mass (g) of solute
Mass Percent  =  ---------------------------------  x  100%
                              mass (g) of solution

You can plug the given values into the equation and solve to find the mass percent of dextrose. But first, you need to calculate the mass of the solution.

Mass (solute): 25.0 g

Mass (solution): 250.0 g + 25.0 g = 275 g

                                25.0 grams
Mass Percent  =  ------------------------  x  100%
                                 275 grams

Mass Percent  =  0.0909 x 100%

Mass Percent  =  9.10%

A solution of dextrose contains 25.0 g solute in 250.0 g water. 9.10% is the percentage by mass of dextrose in this solution.

A component's concentration in a combination or compound can be expressed as a mass percent, also known as a weight percent. It shows how much of the total mass of the solution or mixture is made up of the solute's (component's) mass. In chemistry, mass percent is frequently employed and stated as a percentage.

Mass Percent  =     mass (g) of solute/       mass (g) of solution x  100%

Mass (solute): 25.0 g

Mass (solution): 250.0 g + 25.0 g = 275 g

Mass Percent  =25.0 grams /    275 grams x  100%

Mass Percent  =  0.0909 x 100%

Mass Percent  =  9.10%

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Based on periodic trends, the most probable value for the ionic radius of K⁺ is 133 pm.

Periodic trends are the observation which are seen in the chemical and physical elements found in the periodic table.

Periodic trends is based on the periodicity of elements.

Periodicity is the variation seen in the chemical and physical properties of the elements in the period table in a regular pattern, both down the groups and across the periods.

The periodic trends observed in metallic ions is that ionic radius of metallic ions increase down a group but decreases across a period.

Based on this periodic trend, the most likely size of the potassium ion, K⁺ is 133 pm.

In conclusion, the ionic radius of metallic ions increase down a group and decrease across a period.

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Answer:

C. zero 0

Explanation:

single elements will always possess an oxication number of zero

Answer:

You can never have above 100% yield under any circumstance

To solve such this we must know the concept of chemical reaction. Therefore, the correct option is option D that is  you can never have above 100% yield under any circumstance.

Chemical reaction is a process in which two or more than two molecules collide in right orientation and energy to form a new chemical compound. The mass of the overall reaction should be conserved. There are so many types of chemical reaction reaction like combination reaction, double displacement reaction.

You can never have above 100% yield under any circumstance for any chemical reactions. Option D is the correct options among all the given options.

Therefore, the correct option is option D that is  you can never have above 100% yield under any circumstance.

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Answer:

B.) their electrons are assigned to the s and p orbitals only

Explanation:

Once you get to the fourth row on the periodic table, the transition metals are introduced. The transition metals are located in the d-block and their electrons fill up d orbitals. When an element in the p-block (the right side of the table) is in one of these rows, the d-block has to fill up first.

The volume of ethyne, C₂H₂ required to produce 12 moles of CO₂ assuming the reaction is at STP is 134.4 L

2C₂H₂(g) + 5O₂(g) --> 4CO₂(g) + 2H₂O(g)

From the balanced equation above,

4 moles of CO₂ were produced by 2 moles of C₂H₂

From the balanced equation above,

4 moles of CO₂ were produced by 2 moles of C₂H₂

Therefore,

12 moles of CO₂ will be produce by = (12 × 2) / 4 = 6 moles of C₂H₂

At standard temperature and pressure (STP),

1 mole of C₂H₂ = 22.4 L

Therefore,

6 moles of C₂H₂ = 6 × 22.4

6 moles of C₂H₂ = 134.4 L

Thus, we can conclude that the volume of C₂H₂ needed for the reaction at STP is 134.4 L

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As we know that the equivalency point of moles of added base will be equal to the moles of original acid, this allows to determine the number of moles of original acid.

At the equivalency point the moles of added base will be equal to the moles of original acid, this allows the determination of the number of moles of original acid. This can be combined with the original volume of the analyte solution in order to determine its concentration.

So we can conclude that at the equivalence point the moles of added base will be equal to the moles of original acid, this allows the determination of the number of moles of original acid.

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The change to the experimental design that would improve the reliability of the engineers' measurements is C. testing single samples from more than three locations

It should be noted that experimental design is the process of carrying out research in an objective as well as a controlled fashion in order for precision to be maximized and specific conclusions can be drawn from the hypothesis statement.

Based on the information, the locations selected are only three. Also, an area must have more types of soil with variable porosity. Hence, the collection of more soil samples may provide more accurate results than collecting soil samples from only three regions.

Therefore, change to the experimental design that would improve the reliability of the engineers' measurements is the testing single samples from more than three locations.

In conclusion, the correct option is C.

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Complete question:

Which change to the experimental design would improve the reliability of the engineers' measurements?

A. using a liquid other than water to determine porosity

B. using flasks instead of beakers

C. testing single samples from more than three locations

D. testing more samples from each location

Answer:

X = ¹₀n

Explanation:

The mass number is the total amount of neutrons and protons in the element. The atomic number is the total protons in the element. The mass number is the superscript and the atomic number is the subscript. The mass and atomic numbers must be balanced on both sides of the equation. The element can be identified by the atomic number.

In the event that we have an atomic number of zero, there is no element this represents, so the letter "n" should be used.

²³₁₁Na + ¹₁H  →  ²³₁₂Mg + X

Mass Number:

Reactants = Products

23 + 1 = 23 + ?

24 = 23 + ?

1 = ?

Atomic Number:

Reactants = Products

11 + 1 = 12 + ?

12 = 12 + ?

0 = ?

The complete equation is:

²³₁₁Na + ¹₁H  →  ²³₁₂Mg + ¹₀n

Direct titration of aspirin with NaOH have a side reaction simply because aspirin is a weak acid

Direct titration can simply be defined as a type of titration in which a titrant of known concentration and volume is added to a substance in order to analyze it.

As the name implies, it is called direct titration simply because the one approaches the endpoint of the experiment directly.

Furthermore, the significance of direct titration is that it is used to find the quantity of a substance within a solution with chemical reactions.

So therefore, direct titration of aspirin with NaOH have a side reaction simply because aspirin is a weak acid

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Answer:

C.) PV = k

Explanation:

Boyle's Law is a variation of the Ideal Gas Law when all variables, except for pressure and volume, are held constant.

Pressure is represented by "P" and volume is represented by "V". In the Ideal Gas Law, pressure and volume are inversely proportional (if one goes up, the other goes down). That being said, the equation which best represents Boyle's Law is PV = k.

Answer:

[tex]\boxed{\sf no.\ of \ molecules = 7.13 \times 10^{22} \ molecules}[/tex]

Explanation:

Mass in g = m = 5.68 g

Molar mass = M = (16)3 = 48 g/mol

Avogadro's number = [tex]N_A[/tex] = 6.023 × 10²³

No. of molecules = ?

[tex]\displaystyle no.\ of \ molecules = \frac{m}{M} \times N_A[/tex]

Put the givens in the above formula

[tex]\displaystyle no. \ of \ molecules =\frac{5.68}{48} \times 6.023 \times 10^{23}\\\\no. \ of\ molecules = 0.12 \times 6.023 \times 10^{23}\\\\no. \ of \ molecules = 0.713\times 10^{23}\\\\no.\ of \ molecules = 7.13 \times 10^{22} \ molecules\\\\\rule[225]{225}{2}[/tex]

The common word on the outside of a shipping container that will alert you to the fact that the material inside is hazardous is caution.

Hazardous statements are those words or phrases that are labelled against chemicals which shows the degree of how dangerous the chemical are.

The common words that are used as hazardous statements which shows that a chemical is dangerous include the following:

Therefore, the common word on the outside of a shipping container that will alert you to the fact that the material inside is hazardous is caution.

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Symbol  "X" represents Nitrogen, phosphorus, and arsenic.as they have five valence electrons in their valance shell.

A Lewis form is a completely simplified illustration of the valence shell electrons in a molecule. it's miles used to expose how the electrons are organized round man or woman atoms in a molecule. Electrons are proven as dots or for bonding electrons as a line between the 2 atoms.

Lewis systems, also known as electron-dot structures or electron-dot diagrams, are diagrams that show the bonding between atoms of a molecule, and the lone pairs of electrons that can exist within the molecule.A Lewis form is based totally at the idea of the octet rule, wherein atoms percentage electrons in order that every atom has 8 electrons in its outer shell. for example, an oxygen atom has six electrons in its outer shell.

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