The radioactivity A of a drop of iodine I-131 if the mass of the drop is 1.5 g and the period is 13h is: 1.29 x 10^(-11) disintegrations/second.
What is radioactivity?Generally, To find the radioactivity of a drop of iodine I-131, you will need to use the following formula:
A = (N/M) * ln(2) / T
where:
N is the number of atoms in the sampleM is the atomic mass of the isotopeln(2) is the natural logarithm of 2T is the half-life of the isotopeTo use this formula, you will need to know the atomic mass of I-131, which is about 130.906 amu, and its half-life, which is about 8.04 days. You will also need to convert the mass of the drop from grams to atomic mass units, which can be done by dividing the mass by the atomic mass of carbon-12 (12 amu).
First, convert the period from hours to seconds:
13 hours = 13 * 60 minutes/hour * 60 seconds/minute
= 5,040 seconds
Then, convert the period from seconds to days:
5,040 seconds = 5,040 seconds / (24 hours/day * 60 minutes/hour * 60 seconds/minute)
= 0.6 days
Then, calculate the half-life in seconds:
8.04 days = 8.04 days * 24 hours/day * 60 minutes/hour * 60 seconds/minute
= 691,840 seconds
Then, use the formula above to calculate the radioactivity:
A = (N/M) * ln(2) / T = (N/130.906 amu) * ln(2) / (691,840 seconds)
= (1.5 g / 12 amu) * ln(2) / (691,840 seconds)
= 0.125 * ln(2) / (691,840 seconds)
= 0.08867 * (1/691,840 seconds)
= 1.29 x 10^(-11) disintegrations/second
So the radioactivity of the drop of iodine I-131 is approximately 1.29 x 10^(-11) disintegrations/second.
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In the balanced equation-aPb(NO3)2(s)heatb PbO(s)+ c NO2(g)+ dO2(g); the values of a,b,c, d are respectively
Answer:
The balance reaction is
2Pb(NO3)2 ----》4NO2+2PbO+O2
hence the value of a,b,c,d are 2,4,2,1 respectively!
7th grade science lol help
Answer:
C) Organic Weathering
Explanation:
Heat and Cold
And if some people start reporting and making fun of me in this answer don't listen to them.
They are hunting me down.
There are approximately 4,600 species of cockroaches that have been discovered and named on the planet. Cockroaches first landed in the Americas in 1625, and about 65 species are currently found in the United States. Below is a table that compares egg production of three different cockroach species that are common pests in Texas.
Answer:
may you include the table and actual question? would love to help but I need clarity on what is being asked.
Explanation:
What is chemical equilibrium?
Question 1 options:
The rearrangement of the constituent atoms to create different substances as products.
A reversible reaction.
The process by which the reactants form products and products form reactants at equal rates.
A process that involves rearrangement of the molecular or ionic structure of a substance, as opposed to a change in physical form or a nuclear reaction.
In the process of photosynthesis, plants take in carbon dioxide (CO2) from the atmosphere and water (H2O) from the soil. Using the energy of sunlight, plants build molecules of glucose (C6H12O6) and oxygen (O2).
Select one:
a.
Plants absorb Carbon Dioxide which increases the amount of carbon in the atmosphere.
b.
Plants produce Carbon Dioxide which increases the amount of carbon in the atmosphere.
c.
Plants absorb Carbon Dioxide which reduces the amount of carbon in the atmosphere.
d.
Plants produce Carbon Dioxide which reduces the amount of carbon in the atmosphere.
Answer:
C
Explanation:
thts the right answwer im sure
Answer:
C
Explanation:
They take in carbon dioxide and make an oxygen. That's why they are encouraging people to plant. Less CO2 more oxygen
Which of the following has had the most negative effect on Earth's ecosystems?
A. establishment of air pollution standards.
B. increase in human population
C. recycling glass, plastic, and metals
D. use of natural predators to control pest insects.
Answer:
B
Explanation:
humans are evil, done a lot of negative effects on ecosystem.
Which of the following statements is true about rain falling from clouds?*
Answer:
Clouds are not made of liquid water but they hold liquid water, and when the pool of liquid water that fills the inside of clouds gets too large for the cloud to hold, the cloud releases the water as rain. ... Rain does not fall from clouds.
Explanation:
please give me brainlist and follow
A solution of nitric acid has a [H3O+] = 2.8 x 10-6 M. What is the pH?
Answer:
5.55
Explanation:
see explanation attached
hope it helps
Approximately 1 mL of two clear, colorless solutions, 0.1 M Ba(NO3)2 and 0.1 M Na2SO4, were combined. Upon mixing, a thick milky white precipitate formed. After centrifugation, the solution above the precipitate was found to be clear and colorless. Based on the these observations, determine if a reaction occurred. If so, what is the net ionic equation for the reaction.
Answer:
Ba²⁺(aq) + SO₄²⁻(aq) ⇒ BaSO₄(s)
Explanation:
Let's consider the molecular equation for the reaction between Ba(NO₃)₂ and Na₂SO₄. This is a double displacement reaction in which BaSO₄ forms a white precipitate.
Ba(NO₃)₂(aq) + Na₂SO₄(aq) ⇒ BaSO₄(s) + 2 NaNO₃(aq)
The complete ionic equation includes all the ions and insoluble species.
Ba²⁺(aq) + 2 NO₃⁻(aq) + 2 Na⁺(aq) + SO₄²⁻(aq) ⇒ BaSO₄(s) + 2 Na⁺(aq) + 2 NO₃⁻(aq)
The net ionic equation includes only the ions that participate in the reaction and insoluble species.
Ba²⁺(aq) + SO₄²⁻(aq) ⇒ BaSO₄(s)
Sulfur and fluorine react to form sulfur hexafluoride according to the reaction shown here. How many mol of F2 are required to react completely with 2.15 mol of S?
S(s)+3F2(g)→SF6(g)
A. 12.9 molF2
B. 6.45 molF2
C. 0.72 molF2
D. 2.15 molF2
6.45 mole of fluorine are required to completely react with 2.15 mole of sulfur according to the stoichiometry of the reaction .
What is stoichiometry?It is the determination of proportions of elements or compounds in a chemical reaction. The related relations are based on law of conservation of mass and law of combining weights and volumes.
Stoichiometry is used in quantitative analysis for measuring concentrations of substances present in the sample.
In the given example the balanced chemical reaction is as follows:
S +3 F₂ [tex]\rightarrow[/tex] SF₆
According to the reaction, 1 mole of sulfur reacts with 3 moles of fluorine to yield 1 mole of sulfur hexafluoride.
∴2.15 mole of sulfur requires 2.15×3=6.45 mole of fluorine.
Hence, 6.45 mole of fluorine are required to completely react with 2.15 mole of sulfur.
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How many moles are in 15.2 grams of Calcium (Ca)?
Answer:
There are 0.379 moles of Ca in the given sample.
Explanation:
Hey there!
We're given that we have 15.2 grams of Ca (Calcium). We need to convert grams to moles.
There are many different conversion types for moles. A few examples are:
grams to molesmoles to gramsgrams to particlesmoles to litersThere are really endless possibilities for conversion factors. Since we want to find the number of moles in a certain sample, we first need to define what a mole is.
Mole - a unit of measurement in chemistryA mole is one unit of a certain item. For instance, one cup would be equivalent to one mole. Moles are simply a hypothetical unit in chemistry that act as a placeholder.
Now, how do we find the number of moles?
We know that a mole of something is one of that substance. In this case, we're referring to one atom of Calcium.
Therefore, we need to reference a periodic table to understand what the mass of one atom of calcium is equivalent to. I'll be using the official AP Chemistry periodic table as issued by the College Board.
When we reference the periodic table, we see the mass of one atom of calcium is equivalent to 40.08 amu (atomic mass units).
We learn in chemistry that we can use the terms amu and grams interchangeably, so we have learned that one mole of calcium is equivalent to 40.08 grams.
How do we work this out?
Now, we need to find out how many moles are in 15.2 grams of calcium. We can use dimensional analysis to work this out.
Our starting unit will be 15.2 grams of Ca.
[tex]\text{15.2 grams Ca}[/tex]We want to convert this into moles, so we need to cancel out our grams value. Additionally, since we know that we have 40.08 grams of Ca in one mole, we can set these up as two ratios:
[tex]\displaystyle \frac{\text{40.08 grams Ca}}{\text{1 mole Ca}}[/tex][tex]\displaystyle \frac{\text{1 mole Ca}}{\text{40.08 grams Ca}}[/tex]These ratios can be used to express the relationship between the moles of calcium and the mass of one calcium atom. However, we need our value of grams to cancel out, so since we will be using cross multiplication in our dimensional analysis, we need to use the ratio with grams on the bottom.
Now that we have selected our ratio, we can set up a multiplication problem of our two ratios:
[tex]\displaystyle \text{15.2 grams Ca} \times \frac{\text{1 mole Ca}}{\text{40.08 grams Ca}}[/tex]
We assume that we have a denominator of 1 below 15.2 grams Ca.
Now, we perform our multiplication.
[tex]\displaystyle \frac{\text{15.2 grams Ca} \ \times \ \text{1 mole Ca}}{\text{40.08 grams Ca}}[/tex]
We see that our remaining unit is going to be mole(s) Ca, so we can go ahead and drop our grams Ca unit.
[tex]\displaystyle \frac{\text{15.2} \ \times \ \text{1 mole Ca}}{\text{40.08}}[/tex]
Now, we need to simplify a little bit.
[tex]\displaystyle \frac{\text{15.2}}{\text{40.08}} = \text{? moles Ca}[/tex]
Finally, let's divide our fraction and evaluate our equation to find the value of moles Ca.
[tex]\displaystyle \frac{15.2}{40.08} = \text{0.379241517 moles Ca}[/tex]
Are we done yet?
Not just yet! To complete our work, we need to find the number of significant figures we can use. We are given two values in which we can use to judge how many significant figures we are limited to.
15.2 -- Three significant figures40.08 -- Four significant figuresIn chemistry, we always use the least number of significant figures for precision calculations, so we need to round our answer to three significant figures.
[tex]0.379241517 \approx 0.379[/tex]
Therefore, there are approximately 0.379 moles of Ca in the given sample.
At the same temperature and pressure, balloons of equal volume always contain
a.equal masses of gas.
b.equal numbers of molecules.
c.equal densities of gas.
d.equal numbers of atoms.
Answer:
B. equal numbers of molecules
Explanation:
The following information is to be used for the next 2 questions. In order to analyze for Mg and Ca, a 24-hour urine sample was diluted to 2.000 L. After the solution was buffered to pH 10, a 10.00 mL aliquot was titrated with 26.23 mL of 0.003474 M EDTA. The calcium in a second 10.00 mL aliquot was isolated as CaC2O4, redissolved in acid, and titrated with 20.49 mL of the EDTA solution. (Note: Normal levels for magnesium are 15 to 300 mg per day and for calcium are 50 to 400 mg per day.)
a. How many mg of Ca were in the original sample?
b. How many mg of Mg were in the original sample?
Answer:
Explanation:
From the given information:
The concentration of metal ions are:
[tex][Ca^{2+}]= \dfrac{0.003474 \ M \times 20.49 \ mL}{10.0 \ mL}[/tex]
[tex][Ca^{2+}]=0.007118 \ M[/tex]
[tex][Mg^2+] = \dfrac{0.003474 \ M\times (26.23 - 20.49 )mL}{10.0 \ mL}[/tex]
[tex]=0.001994 \ M[/tex]
Mass of Ca²⁺ in 2.00 L urine sample is:
[tex]= 2.00 L \times 0.001994 \dfrac{mol}{L} \times \dfrac{40.08 \ g}{1 \ mol}[/tex]
= 0.1598 g
Mass of Ca²⁺ = 159.0 mg
Mass of Mg²⁺ in 2.00 L urine sample is:
[tex]= 2.00 L \times 0.007118 \dfrac{mol}{L} \times \dfrac{24.31 \ g}{1 \ mol}[/tex]
= 0.3461 g
Mass of Mg²⁺ = 346.1 mg
Tam a highly reactive alkali metal in period 3 with only one valence electron
O Sodium (Na)
Beryllium (Be)
Magnesium (Mg)
Answer:
Sodium (Na)
Helium
Magnesium (Mg).
Explanation:
From the periodic table, we will understand that the group 1 metals are the alkali metal. However, the period runs from left to right on the periodic table while the group runs from up to down in the periodic table. In period 3, the alkali metal present there with one valence electron in its outermost shell is sodium (Na).
The only noble gas exists in the last group, group zero of the periodic table. However, the only noble gas with two electrons in its outermost shell is called Helium
The ALkaline earth metals are group 2 metals. They are usually shiny metals and the ability to lose 2 electrons in their outermost electron shell. The alkaline earth metal located in period 3 is Magnesium (Mg).
At conditions of 785.0 torr of pressure and 15.0 °C temperature, a gas occupies a volume of 45.5 mL. What will be the volume of the same gas at 745.0 torr and 30.0 °C?
Answer:
50.4 mL
Explanation:
Step 1: Given data
Initial pressure (P₁): 785.0 torrInitial temperature (T₁): 15.0 °CInitial volume (V₁): 45.5 mLFinal pressure (P₂): 745.0 torrFinal temperature (T₂): 30.0 °CFinal volume (V₂): ?Step 2: Convert the temperatures to Kelvin
We will use the following expression.
K = °C + 273.15
K = 15.0°C + 273.15 = 288.2 K
K = 30.0°C + 273.15 = 303.2 K
Step 3: Calculate the final volume occupied by the gas
We will use the combined gas law.
P₁ × V₁ / T₁ = P₂ × V₂ / T₂
V₂ = P₁ × V₁ × T₂/ T₁ × P₂
V₂ = 785.0 torr × 45.5 mL × 303.2 K/ 288.2 K × 745.0 torr = 50.4 mL
What frequency does a photon of wavelength 4.5 x 10-4 m have?
A. 6.67 x 1011 Hz
B. 1.47 x 10-30 Hz
C. 2.98 x 10-37 Hz
D. 1.35 x 105 Hz
SUBMIT
Answer:
6.67* 1011 Hz
Explanation:
a p e x
Answer:
Awnser above is correct
Explanation:
a. 6.67
Scientists classify organisms into three domains and six kingdoms. In which
kingdom are yeasts classified and why?
A Plantae, because they are eukaryotic.
B Protista, because they are prokaryotic.
Fungi, because they are heterotrophic.
Animalia, because they are autotrophic.
Answer:
c is correct option
according to the question.
Scientists classify organisms into three domains and six kingdoms. In Fungi kingdom are yeasts classified because they are heterotrophic. Therefore, option C is correct.
What do you mean by the term heterotrophic ?An organism is referred to be a heterotroph if it is unable to manufacture food on its own and must obtain it from other sources of organic carbon, primarily plant or animal materials.
All fungi are heterotrophic, which means they draw their energy from other living things.
Since they share some traits with fungi, such as the presence of chitin in their cell walls, extracellular digestion, saprophytic feeding, asexual reproduction by budding, and the ability to store food as glycogen, yeast cells are categorised as fungi.
Thus, option C is correct.
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Consider the aldol condensation between dibenzyl ketone and benzil in strong base. Calculate the molar masses of the reactants and product. (Hydrogens in the structures have been omitted for clarity) Report molar masses to 1 decimal place. g/mol g/mol Molar mass of dibenzyl ketone Molar mass of benzil Molar mass of 2,3,4,5-tetraphenylcyclopentadienone g/mol
Answer:
a) 210.3 g/mol
b) 210.2 g/mol
c) 384.5 g/mol
Explanation:
First step we will calculate the molar masses of ; carbon atom, hydrogen atom and oxygen atom in each .
Molar mass of dibenzyl ketone
Molar mass of dibenzyl ketone = ∑ molar masses of atoms in dibenzyl ketone
= carbon( 15 ) = 15 ( 12.0107 ) + oxygen ( 14 ) = 1 ( 15.999 ) + hydrogen(14) =14(1.00784)
= 210.26926 ≈ 210.3 g/mol
Molar mass of benzil
Molar mass of Benzil = ∑ molar masses of atoms in Benzil
= carbon( 14) = 14(12.0107) + oxygen(2) = 2 ( 15.999) + hydrogen(10) =10(1.00784)
= 210.2262 ≈ 210.2 g/mol
Molar mass of 2,3,4,5-tetraphenylcyclopentadienone
Molar mass = ∑ molar masses of atoms
= carbon ( 29) = 29(12.0107) + oxygen (1) = 1( 15.999 ) + hydrogen(20) = 20(1.00784 )
≈ 384.5 g/mol
48 g of magnesium sulfate are left after dehydration of magnesium sulfate heptahydrate . What was the original weight of the sample before dehydration?
Answer:
98.6g is the mass of the heptahydrate
Explanation:
The hydrated magnesium sulfate contains 7 moles of water per mole of magnesium sulfate. 1 mole of MgSO₄ dehydrated is 1 mole of MgSO₄.7H₂O
To solve this question we must find the moles of MgSO₄. These moles = Moles of MgSO₄.7H₂O. Then, we must convert the moles to mass:
Moles MgSO₄ -Molar mass: 120.366g/mol-:
48g * (1mol / 120.366g) = 0.40 moles MgSO₄ = moles MgSO₄.7H₂O
Mass MgSO₄.7H₂O -Molar mass: 246.47456 g/mol-:
0.40 moles MgSO₄.7H₂O * (246.47456 g / 1mol) =
98.6g is the mass of the heptahydrate
how the proton H gradient is used to make ATP
Answer:
The proton gradient produced by proton pumping during the electron transport chain is used to synthesize ATP. Protons flow down their concentration gradient into the matrix through the membrane protein ATP synthase, causing it to spin (like a water wheel) and catalyze conversion of ADP to ATP.
Name the following alkene:
CH3C = CH2
1
CH3
A. 2-methyl-1-propene
B. 2-methyl-2-propene
C. 1-propyl-2-methene
D. 2-methyl-1-propane
Pls help
The name of the given alkene is 2-methyl-1-propene. The correct option is A.
What are alkenes?
Alkenes are inorganic compounds. They are the series of hydrocarbons, that are formed by carbon-carbon double bonds. To find out alkenes, you have to see that the number of hydrogen atoms is always double the number of carbons.
Propene is an unsaturated compound, which is the second-simplest compound, and it contains a single double bond, and it is a colorless gas and has a texture of petroleum jelly.
CH₃C = CH₂
I
CH₃
Here, the three CH₃ are shown in the diagram, so it will be the methyl because it contains 3 CH₂, and now see the propene means one double bond and four carbon atoms. So it will be the 2-methyl-1-propene.
Thus, the correct option is A. 2-methyl-1-propene.
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What is the coefficient for hydrogen in the balanced equation for the reaction of solid tungsten(VI) oxide with gaseous hydrogen to form solid tungsten and liquid water?
Answer:
2
Explanation:
WO2(s) + 2H2(g) -> W(s) + 2H2O(l)
The strength of an acid is affected by the polarity of the bond connected to the acidic hydrogen. The more highly polarized this bond, the more easily the hydrogen is ionized. Electronegative atoms or groups of atoms present in the structure of an acid can act to withdraw electrons and produce additional polarization. Two common groups of acids to which this principle can be applied are oxoacids and carboxylic acids. In the latter group, the length of the hydrocarbon chain in a carboxylic acid has very little effect on acid strength Longer chains may slightly diminish acidity. Bases act as hydrogen ion acceptors because of the unshared electron pass in their structure. Any group present in a base that withdraws electrons makes these electron pairs less available to accept a hydrogen ion. In contrast, any group that can act as an electron donating group such as hydrocarbon groups (usually represented as II) can increase the base strength. Thus, the addition of electronegative atoms or groups of atoms to the structure of a base decreases the base strength and electron donating groups increase base strength. Many common weak bases are derivatives of ammonia, in which H atom(s) of NH_2 are replaced with other groups.
Arrange the following oxoacids in order of decreasing acid strength. Rank from strongest to weakest acid.
HBrO
HClO
HClO3
HClO2
Answer:
HClO3>HClO2>HClO>HBrO
Explanation:
Hello there!
In this case, in agreement to the given information and the reported acidic dissociation constant (Ka) for these acids, which are shown below:
[tex]Ka_{HBrO}=2x10^{-9}\\\\Ka_{HClO}=3.5x10^{-8}\\\\Ka_{HClO_2}=1.2x10^{-2}\\\\Ka_{HClO_3}>>>>1[/tex]
In such a way, since the Ka of chloric acid, HClO3 is greater than 1, we infer it is a strong acid so it is the strongest, next we have HClO2, then HClO and the weakest would be HBrO as its Ka is the smallest.
Thus, the order would be:
HClO3>HClO2>HClO>HBrO
Best regards!
EDTA is a very common ligand, which like oxalate, binds to many metals. However, unlike oxalate, which forms two bonds, EDTA forms 6 bonds to the metal. A 0.2481g sample of marble was dissolved in 100 mL, and a 10.00 mL aliquot of the solution was titrated to an endpoint with 23.56 mL of 0.01052 M EDTA solution. What is the molecular weight of the marble
Answer:
100 g/mol
Explanation:
The equation of the reaction;
Ca^2+(aq) + EDTA(aq) -----> (CaEDTA)^2-(aq)
Let CA = concentration of EDTA
VA = volume of EDTA
NA= number of moles of EDTA
CB= concentration of marble
VB = volume of marble
NB= number of moles of marble
CAVA/CBVB = NA/NB
CAVANB=CBVBNA
CB = CAVANB/VBNA
CB = 0.01052 * 23.56 * 1/10.00 * 1
CB = 0.02479 M
number of moles = concentration * volume
number of moles = 0.02479 M * 100.00/1000L
number of moles = 2.479 * 10^-3 moles
number of moles = mass/molar mass
molar mass = 0.2481g/2.479 * 10^-3 moles
molar mass = 100 g/mol
How much energy is required to vaporize 1.5 kg of aluminum? (Refer to table
of latent heat values.)
A. 733 kJ
B. 1650 kJ
C. 7095 kJ
D. 600 kJ
Answer:
B 1650
Explanation:
Based on this information, which hypothesis best predicts how a change to the gene could affect people who do not produce enough lactase?
Answer:
B
Explanation:
I had same question
how to make your Go ogle forms look impressive
Lots of fonts, you can also insert those images with the checkered background (they show up clear) and decorate it, also make sure that you have proper spacing a paragraph structure
Day/Night and Seasons (8.7A)
4 Which of the following changes would be most likely to occur if the rate of
Earth's rotation on its axis decreased?
A The length of day would be longer.
B The length of day would be shorter.
C The length of seasons would be longer.
D The length of seasons would be shorter.
The changes that most likely would occur if the rate of Earth's rotation on its axis decreased is the length of day would be longer (option A).
What is Earth's rotation on its axis?Earth's rotation on its axis refers to the movement of the Earth that determine the length of days (i.e. 24 hours), conversely to translation movement that determines the seasons.
Therefore, with this data, we can see that Earth's rotation on its axis determines the length of the day, and thereby a slow movement will produce longer days.
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6. The random motion of the particle in a substance is greatest when the
substance is
Answer:
when the substance is decrease
Explanation:
One of the reactions used to inflate automobile air bags involves sodium azide (NaN₃).
2NaN₃ --> 2Na + 3N₂
Determine the mass of N₂ produced from 250.0 g NaN₃
Answer:
161.54 g of N₂
Explanation:
The balanced equation for the reaction is given below:
2NaN₃ —> 2Na + 3N₂
Next, we shall determine the mass of NaN₃ that decomposed and the mass of N₂ produced from the balanced equation. This is illustrated below:
Molar mass of NaN₃ = 23 + (3×14)
= 23 + 42 = 65 g/mol
Mass of NaN₃ from the balanced equation = 2 × 65 = 130 g
Molar mass of N₂ = 2 × 14 = 28 g/mol
Mass of N₂ from the balanced equation = 3 × 28 = 84 g
SUMMARY:
From the balanced equation above,
130 g of NaN₃ decomposed to produce 84 g of N₂.
Finally, we shall determine the mass of N₂ produced by the decomposition of 250 g of NaN₃. This can be obtained as follow:
From the balanced equation above,
130 g of NaN₃ decomposed to produce 84 g of N₂.
Therefore, 250 g of NaN₃ will decompose to produce
= (250 × 84)/130 = 161.54 g of N₂
Thus, 161.54 g of N₂ were obtained from the reaction.