Answer:
4.80×10³ years
Explanation:
Let the original amount (N₀) of ²²⁶Rn = 1 g
Therefore,
12.5% of the original amount = 12.5% × 1 = 12.5/100 × 1 = 0.125 g
Next, we shall determine the number of half-lives that has elapse. This can be obtained as follow:
Original amount (N₀) = 1
Amount remaining (N) = 0.125 g
Number of half-lives (n) =?
N = 1/2ⁿ × N₀
0.125 = 1/2ⁿ × 1
0.125 = 1/2ⁿ
Cross multiply
0.125 × 2ⁿ = 1
Divide both side by 0.125
2ⁿ = 1/0.125
2ⁿ = 8
Express 8 in index form with 2 as the base
2ⁿ = 2³
n = 3
Thus, 3 half-lives has elapsed.
Finally, we shall determine the time taken for only 12.5% of the original sample of ²²⁶Rn to remain.
This can be obtained as follow:
Half-life (t½) = 1.60×10³ years
Number of half-lives (n) = 3
Time (t) =?
t = n × t½
t = 3 × 1.60×10³
t = 4.80×10³ years.
Thus, it will take 4.80×10³ years for 12.5% of the original sample of ²²⁶Rn to remain.
The ratio of ducks to chickens in our backyard is 2:3. The total number of ducks and chickens together is 30. If mother gave away 3 chickens to our neighbor, what is the new ratio of ducks to chickens now?
Answer:
4:5
Explanation:
No. of chickens before giving away 3 chickens = 30 x 3/5 = 18
No. of ducks before giving away 3 chickens = 30 - 18 = 12
After giving away 3 chickens,
No. of chickens = 15
No. of ducks = 12
New ratio = 12:15 = 4:5
What is the atomic mass of hafnium if, out of every 100 atoms, 5 have a mass of 176, 19 have a mass of 177, 27 have a mass of 178, 14 have a mass of 179, and 35 have a mass of 180.0? Answer with 2 decimals
Answer:
178.36 a.m.u
Explanation:
5 have a mass of 176,
5/100 * 176 = 8.8
19 have a mass of 177
19 / 100 * 176 = 33.44
27 have a mass of 178
27 / 100 * 178 = 48.06
14 have a mass of 179
14 / 100 * 179 = 25.06
35 have a mass of 180.0
35 / 100 * 180 = 63
Atomic Mass = 8.8 + 33.44 + 48.06 + 25.06 + 63
Atomic Mass = 178.36 a.m.u
If 5.00 g of O2 gas has a volume of 7.20 L at a certain temperature and pressure, what volume does 15.0 g of O2 have under the same conditions?
The volume 15.0 g of O₂ has at a certain temperature and pressure is 2.16 L.
What is volume?Volume is the space occupied by a three-dimensional object.
By the law of dilution
M₁/V₁ = M₂/V₂
Mass 1 is 5.00
Volume 1 is 7.20 L
Mass 2 15.0 g
Volume 2 is to find
Putting the value in the equation
5.00/ 7.20 = 15.0 / V₂
V₂ = 7.20 × 15.00/ 5.00 = 21.6
Thus, the volume will be 21.6 L.
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what is heterogenous mixture
Answer:
heterogeneous mixture is a mixture that is non-uniform and contains smaller component parts.
Answer:
heterogenous mixture is type of mixture
Explanation:
it is one type of mixture involve in the mixture of different or hetro substance and can also easely separated or seen by naked eye example mixture of water and sand
Help please it is due soon
Answer:
it's the amount of energy released by an earthquake
Select the correct answer.
The presence of which ion will not affect the pH of a solution?
A.
OH-
B.
H3O+
C.
H+
D.
Na+
Answer:
D. Na+
Explanation:
Na+ is the only ion here that is not related to pH. Adding OH- increases pH, and adding H3O+ or H+ (the two are interchangeable) decreases pH.
In general, what is the effect of increased temperature on the solubility of a gas?
A. It is uniform
B.The solubility increases.
C. The solubility decreases
D.The saturation increases
E. The effect cannot be determined
Answer:
C. The solubility decreases.
Explanation:
Took the plato test!
4.50 g of Nacl react with 10.00 g of Agno3 to produce 7.93 g of Agcl.if the theroretical amount of agcl that can be formed is 8.43 g what is the percent yield
What tides are at the points on Earth indicated by the letters?
A. high tide (A,C)
B. high tide (B,D)
C. Low tide (B,C)
D. Low tide (A,C)
Answer:
it is A tide (A,C)
Explanation:
i just took the test and tried c and it was a plzzzzz put a btw it was my test lol
Precipitation that falls to earth sometimes soaks into the soul and becomes____.
Answer:
not sure but i think the answer is A
Chlorine and hydrogen gas react to form hydrogen chloride as shown in the following reaction Cl 2 ( g)+H 2 (g)--->2HCl (g) Given a 7.10 g sample of chlorine (MM =71.0 g/mol) , how many grams of hydrogen chloride (MM =36.5 g/mol) is produced, assuming the reaction goes to completion? a. 7.10 g 6.3.65 9 c. 5,68 g d 7.300
Answer:
it should be 7.300 sorry if I am wrong
Answer:
The answer is 115
Explanation:
Teacher walked me through it.
How does temperature affect the rate constant for a reaction?
Answer:
d
Explanation:
increasing the temperature the fraction of molecules which collide with energy greater than Ea increase and hence the rate constant
A sample of calcium fluoride was decomposed into the constituent elements. If the sample produced 294 mg of calcium, how many g of fluorine were formed?
Answer:
Approximately [tex]279\; \rm mg[/tex] of fluorine would be produced.
Explanation:
Look up the relative atomic mass of these calcium and fluorine on a modern periodic table:
[tex]\rm Ca[/tex]: [tex]40.078[/tex].[tex]\rm F[/tex]: [tex]18.998[/tex].In other words, the mass of each mole of calcium atoms is (approximately) [tex]40.078\; \rm g[/tex]. Similarly, the mass of each mole of fluorine atoms is (approximately) [tex]18.998\; \rm g[/tex].
Calculate the number of moles of calcium atom that were produced:
[tex]\begin{aligned} &n({\rm Ca}) \\ &= \frac{m({\rm Ca})}{M({\rm Ca})} \\ &= \frac{294\; \rm mg}{40.078\; \rm g \cdot mol^{-1}} \\ &= \frac{0.294\; \rm mg}{40.08 \; \rm g \cdot mol^{-1}}\\ & \approx 7.3357 \times 10^{-3}\; \rm mol\end{aligned}[/tex].
Every formula unit of calcium fluoride, [tex]\rm CaF_2[/tex], contains twice as many fluorine atoms as calcium atoms.
Hence, if the sample contained approximately [tex]7.33570 \times 10^{-3}\; \rm mol[/tex] calcium atoms, it would contain twice as many fluorine atoms:
[tex]\begin{aligned}n({\rm F}) &= 2\, n({\rm Ca}) \\ &\approx 2 \times 7.33570\times 10^{-3}\; \rm mol \\ &\approx 1.4671 \times 10^{-2}\; \rm mol\end{aligned}[/tex].
Calculate the mass of that many fluorine atoms:
[tex]\begin{aligned}& m({\rm F}) \\ &= n({\rm F}) \cdot M({\rm F}) \\ &\approx 1.4671 \times 10^{-2}\; \rm mol \times 18.998\; \rm g \cdot mol^{-1} \\ &\approx 278.72 \times 10^{-3}\; \rm g \\&\approx 279\; \rm mg\end{aligned}[/tex].
279 mg of Fluorine was formed in the decomposition reaction
The equation of the reaction is;
CaF2 -----> Ca + 2F
Mass of calcium formed = 294 mg
Number of moles of Ca in 294 mg = 294 × [tex]10^-3[/tex] g/40 g/mol = 0.00735 moles
From the equation, the products are in ration 1 : 2
Since 1 mole of Ca is to 2 moles of F
0.00735 moles of Ca is to 0.00735 moles × 2 moles/1 mole
= 0.0147 moles of F
Mass of F = 0.0147 moles × 19 g/mol
= 0.279g or 279 mg of F
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Question 17 of 20
The reactants of a chemical equation have 1 Satom and 40 atoms. Which
set of atoms must also be found in the equation's products so that the
equation models the law of conservation of mass?
A. 4 S and 40
B. 1 S and 40
C. 1 S and 10
O D. 4 S and 10
Answer:
B) 1S and 40
hope it helps
Answer:
b is ur answer
Explanation:
1S and 4O
What is the molality of a 10.0 % by mass solution of NaCl?
(molar mass of NaCl = 58.44 g/mol)
mol/kg
On CK-12 all of these answers are correct
1.9
1.888
1.89
1.88
The molality of a 10.0 % by mass solution of sodium chloride (NaCl) is 1.7M.
How do we calculate molarity?Molarity of any solution will be calculated as number of moles of solutes present in per litre of the solution.
Moles of the substance will be calculated as:
n = W/M, where
W = given mass
M = molar mass
Given that percent mass of NaCl = 10% i.e. 10g of NaCl is present in 100 g of solution.
We know that 1 g = 0.001 L
100 g = 0.1 L
Moles of NaCl = 10g / 58.44g/mol = 0.17 mol
Molarity of NaCl = 0.17 / 0.1 = 1.7M
Hence required molarity is 1.7 M.
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A 20.0 L container at 303 K holds a mixture of two gases with a total pressure of 5.00 atm. If there are 2.00 mol of Gas A in the mixture, how many moles of Gas B are present?
The number of moles of Gas B in the gas mixture is equal to 2.00 mol.
What is the ideal gas equation?The ideal gas equation can be explained as an equation that describes the state of an ideal gas. This equation gives the product of the volume and pressure of ideal gas equal to the multiplication of the universal gas constant, absolute temperature, and moles of gas.
The mathematical form of the ideal gas equation mentioned below:
PV = nRT
Where P is the pressure, V is the volume, n is the moles, and R is the gas constant.
Given, the volume of the gas mixture, V = 500 ml = 0.5 L
The temperature of the gas mixture, T = 303 K
The pressure of the gas mixture = 5 atm
The value of gas constant, R =0.082 atmL/K mol
Substituting the values R, V, P, and T in the ideal gas law, we get:
The number of moles of the gas mixture, n = PV/RT
n = 5 ×20/(0.082 × 303)
n = 4.00 mol
The total number of moles of gas mixture = 4.00 mol
The moles of Gas A = 2.00 mol
The moles of Gas B = 4 - 2 = 2.00 mol
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A student uses a sample of KOH stock solution and dilutes it to a total of 120 mL. If the diluted solution is 0.60 M KOH and its original concentration was 2.25 M, what was the volume of the original sample? *
1.4 mL
89 mL
32 mL
5.5 mL
(DON'T POST LINKS PLEASE)
Answer:
5.5
Explanation:
i think so?????????
The diluted solution of volume 120 ml has the molarity of 0.60 M. Then, the volume of the original solution with a molarity of2.25 M is 32 ml.
What is molarity ?The molarity of a solution is the ratio of the number of moles of its solute particles to the volume of solution in liters.
To solve the given problem, we can use the formula for dilution:
C1V1 = C2V2
where C1 is the initial concentration, V1 is the initial volume, C2 is the final concentration, and V2 is the final volume.
We are given that the diluted solution has a concentration of 0.60 M and a total volume of 120 mL. We are also given that the original concentration was 2.25 M, and we want to find the original volume.
Using the formula for dilution, we can write:
2.25 M x V1 = 0.60 M x 120 mL
Simplifying, we get:
V1 = (0.60 M x 120 mL) / 2.25 M
V1 = 32 mL
Therefore, the original volume of the KOH stock solution was 32 mL.
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what is the molecular formula of a compound with the empirical SO and molecular weight 96.13?
Answer:
Explanation: A compound with the empirical formula SO has a molecular weight of 96.13
Based on the graph, which statement about human use of natural resources is most likely false?
Hey love! <3
Answer:
C. Resource use by humans has gone up and down over the years is a false statement
Explanation:
In the graph you can make an observation on how the increase of human population is directly positive.
The resource use either has a positive or negative correlation, making it impossible for the usage to fluctuate over the years.
Hope this brightens up your day a little! ❀‿❀ Sincerely, Kelsey from Brainly.
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the form of EMR that has less energy per photon than microwaves is ____?
Answer: radio wave frequencies have longer wavelengths and smaller
Energies per photon
How many grams of CaCl 2 are in .48 moles ?
Answer:
We assume you are converting between moles CaCl2 and gram. You can view more details on each measurement unit: molecular weight of CaCl2 or grams This compound is also known as Calcium Chloride. The SI base unit for amount of substance is the mole. 1 mole is equal to 1 moles CaCl2, or 110.984 grams.
The mass of calcium chloride is 53.27 grams.
Given:
Moles of CaCl₂ = 0.48 moles
Molar mass of CaCl₂ = 110.98 g/mol
To find:
Mass of CaCl₂ = ?
Number of moles:It is defined as given mass over molar mass.
Number of moles = Mass / Molar mass
Mass = Number of moles * Molar mass
Mass = 0.48 moles * 110.98 g/mol
Mass = 53.27 grams
Thus, the mass of calcium chloride is 53.27 grams.
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Which superpower would you have for the rest of your life?
The ability to fly
Teleportation
Super speed
Super strength
Invisibility
Time travel
Or be normal and have nothing special
time travel is the best option
g You are given a 1.25 gram mixture of calcium nitrate and calcium chloride. You dissolve this mixture in 200.0 mL of water and add an excess of 0.300 M silver nitrate. You collect and dry the white precipitate which forms and find it has a mass of 0.535 grams. Calculate the percent calcium chloride by mass in the original mixture.
Answer:
16.51%
Explanation:
The reaction that takes place is
CaCl₂(aq) + 2AgNO₃(aq) → 2AgCl(s) + Ca(NO₃)₂(aq)Meaning that the white precipitate that formed is AgCl. Now we convert 0.535 g of AgCl into moles, using its molar mass:
0.535 g ÷ 143.43 g/mol = 0.00373 mol AgClThen we convert 0.00373 moles of AgCl into moles of CaCl₂, using the stoichiometric coefficients:
0.00373 mol AgCl * [tex]\frac{1molCaCl_2}{2molAgCl}[/tex] = 0.00186 mol CaCl₂We convert moles of CaCl₂ into grams, using its molar mass:
0.00186 mol CaCl₂ * 110.98 g/mol = 0.206 gFinally we calculate the percent of CaCl₂ by mass in the original mixture:
0.206 g / 1.25 g * 100% = 16.51%The percent calcium chloride by mass in the original mixture is 16.4%
The equation of the reaction between calcium nitrate and silver chloride is:
[tex]\mathbf{CaCl_2 + 2AgNO_3 \to 2 AgCl+Ca(NO_3)_2}[/tex]
Given that;
the weight mass of the white precipitate formed is = 0.535 gramsthe number of moles of the precipitated AgCl is:
= 0.535 g / 143.32 g/mol
= 0.0037 moles
From the above reaction, If 2 moles of AgCl are formed by 1 mole of CaCl2
Then, 0.0037 moles of AgCl will form (0.0037 × 1)/2 moles of CaCl2.
0.0037 moles of AgCl will form 0.00185 moles of CaCl2.
Now, we can say that the number of moles of CaCl2 present in the mixture is = 0.00185 moles
Mass amount of CaCl2 present = 0.00185 moles × 110.98 g/mol
Mass amount of CaCl2 present = 0.205 grams
Finally, the mass percentage [tex]\mathbf{=\dfrac{0.205}{1.25}\times 100\%}[/tex]
= 16.4%
Therefore, we can conclude that the percent calcium chloride by mass in the original mixture is 16.4%
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can u identify a chemical equation for the saponification of olive oil as per your experiment?
I
Convert 2.024 kilocalories to calories I need to know ASAP
Explanation:
kcal = 1000 cal
2.024 Kcal to cal
= 2.024 × 1000
= 2024 cal
#CMIIWphenol used in DNA extractiom
Answer:
This is thought to aid in the extraction, as this dissolved phenol helps denature proteins while they are still in the aqueous solution. ... Phenol/Chloroform – This is a mixture of buffer-saturated phenol and chloroform, usually close to 1:1 for DNA purification with other ratios sometimes used for RNA purification
Explanation:
Hope it helps!
If you dont mind can you please mark me as brainlest?
Answer:
This is thought to aid in the extraction, as this dissolved phenol helps denature proteins while they are still in the aqueous solution. ... Phenol/Chloroform – This is a mixture of buffer-saturated phenol and chloroform, usually close to 1:1 for DNA purification with other ratios sometimes used for RNA purification
ASAP pleas
Which of the following pair of elements are found as diatomic gaseous molecules in nature?
a)carbon and chlorine
b) sulfur and oxygen
c) oxygen and hydrogen
d) Nitrogen and Neon
what climate is Colorado in?
A.Most Subtropical Mid-Latitude
B.Polar
C.Moist ContinentaMid-Latitiude
D.Dry
Answer:
b
Explanation:
Answer:
D. Dry
Explanation:
Colorado's combination of high elevation, midlatitude, and continental interior geography results in a cool, dry climate.
The second law of thermodynamics can be worded in different ways, such as a.) heat can flow spontaneously from a hot object to a cold object, or b.) the total entropy of any system plus that of the environment increases as a result of natural processes. Why are these statements equivalent
Answer:
Explanation:
The principal reason why these statements are equivalent and identical is that there can be a progressional flow of heat from a hot object item to a cold object because of this entropy is increasing and expanding Δg < 0 but stream flow from cold to hot is nonspontaneous as Δg > 0.
e.g [tex]dS = \dfrac{\delta Q}{T}[/tex]
As found in heat engines and refrigerators.
Practice: A gas reaction is allowed to take place in a canister while submerged in water at a temperature of 25oC. The gas expands and does P-V work on the surroundings equal to 385 J. At the same time, the temperature of the water decreases to 20oC as the energy in the gas reaction reaches 364 J. What is the change in energy of the system
Answer:
change in energy of the system = - 21 J
Explanation:
Δu = q + w
q = 364 J
w = - 385
Temperature of system drops from 25°c to 20°c
hence
Δu ( change in energy ) = q - w
= 364 - 385
= -21 J