A sample of polonium-210 has an initial mass of 390 milligrams (mg). If the half-life of polonium-210 is 36 days, how many mg of the sample remains after 72 days?

A.
392 mg

B.
195 mg

C.
97.5 mg

D.
48.75 mg

Answers

Answer 1

Answer: D. 48.75

Explanation: just took the test

Answer 2

Answer:

D

Explanation:

I got this question right on my test.


Related Questions

How many grams of potassium carbonate are needed to make 300ml of a 4.5M solution?

Answers

Answer:

186.3g

Explanation:

4.5moles of K₂CO₃  is in 1000ml

? moles of K₂CO₃ is in 300 ml

(4.5 × 300)/ 1000 = 1.35 moles of K₂CO₃

1 mole of K₂CO₃ = (39 × 2) + 12 + (16 × 3) = 78 + 12 + 48 = 138g

1.35 moles of K₂CO₃  = ?

= (1.35 × 138)/1 = 186.3g

What unit should you think of when using coefficients?

Answers

Answer:

Far as I know coefficients are unitless. sorry if this don't help ;)

Which of the following is NOT true regarding sexual reproduction?

It requires only one parent.

It requires only one parent.

Offspring show genetic variability.

It produces few offspring.

Answers

Answer: I think it’s B

explanation

Answer:

I believe it would need more then one parent so therefore the wrong answer would be It requires only one parent

Explanation:

What is true of an earthquake that causes major damage to buildings in an area?

It has a high magnitude.
It has a high frequency.
It has a low frequency.
It has a low magnitude.

Answers

The correct option is :

=》It has a high magnitude.

the damage caused by an earthquake is proportional to its magnitude, as much the magnitude is, that much damage will be caused by it.

The term used to indicate and earthquake that causes major damage to buildings in an area is called a high magnitude earthquake. Hence, option a is correct.

What is high magnitude earthquake?

The most typical way to gauge an earthquake's size is by its magnitude. No matter where you are or how violent the shaking is, it is the same number since it represents the size of the earthquake's source.

The USGS no longer uses the outmoded Richter scale to determine the magnitude of major, teleseismic earthquakes. Several magnitude scales measure various aspects of the earthquake, but the Richter scale measures the biggest wobble (amplitude) on the recording.

Currently, the USGS uses the Moment Magnitude scale to report earthquake magnitudes, however many different magnitudes can be calculated for comparison and research. Therefore, option a is correct.

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Please help me on 6 and 8 thanks

Answers

Answer:

6.) 3, 12, 1, and 4   8.) 4, 1, and 3

Explanation:

By multiplying subscripts inside and outside of the parentheses you can count the number of atoms that are present. I recently answered a question for you and I did the math wrong I am going to go back and comment so you know which one and I will correct my errors. Sorry for the inconvenience!

the number of atoms in number 6:

N: 3

H: 12

P: 1

O: 4

the number of atoms for number 8:

Ca: 4

C: 1

O: 3

hope I clarified my mistake and helped you! :)

A reaction occurs in which carbon combines with sulfur to form carbon
disulfide. Is this a chemical reaction or a nuclear reaction, and how do you
know?
A. This is a nuclear reaction, because mass was conserved.
B. This is a chemical reaction, because only the electrons were
rearranged.
C. This is a nuclear reaction, because there was a change in the
atoms' nuclei.
D. This is a chemical reaction, because mass was not conserved.

Answers

The reaction in which carbon combines with sulfur to form carbon

disulfide. Is

B. This is a chemical reaction, because only the electrons were rearranged.

What is a chemical reaction?

In a chemical reaction, bonds between molecules of the reactant are broken and new bonds between molecules of the product are established to create a new substance.

Chemical reactions occur all around us, including in our body's digestion of food and the creation of the sunlight's light. Understanding physical and chemical changes is crucial before starting any chemical reactions.

Sulfur and carbon combine to form carbon disulfide in an endothermic reaction that absorbs 92 kJ/mol of heat.

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Which of the following is an advantage of asexual reproduction compared to sexual reproduction?

Both will produce genetically identical offspring from the parent.

Sexual reproduction will increase genetic variability within a species.

Asexual reproduction requires less energy and will produce more offspring over time.

Sexual reproduction has minimal changes of mutations compared to asexual reproduction.

Answers

Explanation:

sexual reproduction has minimal changes of mutations compared to asexual reproduction

Answer:

sexual reproduction has minimal changes of mutations compared to asexual reproduction

I hope this helps

Consider the balanced equation Zn + 2HCl ZnCl2 + H2 How many
moles of ZnCl2 will be produced if 2 moles of HCl are used?

Answers

Answer:

1 mole of ZnCl₂

Explanation:

Just from the stoichiometric equation/ balanced equation:

            Zn(s) + 2HCl(aq) → ZnCl₂(s) + H₂(g)

            1 mole   2 moles    1 mole       1 mole

Therefore: 2 moles of 2HCl produce 1 mole of ZnCl₂

HELPP ASAP I WILL MARK BRAINIST


Answers

Answer:

I'm thinking ethier D or A

Explanation:

Bears stop coming to a river ecosystem where they have been eating many fish each day. The fish the bears eat normally eat smaller fish, which eat plants along the river bottom.

What happens to the ecosystem?


Both the larger and the smaller fish populations grow quickly but then die out because the plant life is insufficient for them all to eat.

The larger fish population will drop first, and the smaller fish population will grow quickly. The plants will die off because too many of the smaller fish are eating them.

The larger fish population explodes at first, and the smaller fish population begins to drop. Eventually, the river runs out of smaller fish so larger fish die out, and the plant population grows.

The smaller fish population begins to eat more plants and to grow. The larger fish have more food to eat so their population is able to grow, too.

Answers

Answer:

The larger fish population explodes at first, and the smaller fish population begins to drop. Eventually, the river runs out of smaller fish so larger fish die out, and the plant population grows.

Explanation:

At 47c a gas has a pressure of 140kpa. The gas is cooled until the pressure decreases to 105kpa. If the volume remains constant, what will the final temperature be in kelvin’s? In degrees Celsius

Answers

Answer:

The final temperature is equal to 240 K or -33.15°C

Explanation:

Given that,

Initial temperature of the gas, T₁ = 47°C = 320 K

Initial pressure, P₁ = 140 kpa

Final pressure, P₂ = 105 kpa

We need to find the final temperature if the volume remains constant.  The relation between temperature and pressure is given by :

[tex]P\propto T[/tex]

or

[tex]\dfrac{P_1}{P_2}=\dfrac{T_1}{T_2}\\\\T_2=\dfrac{P_2T_1}{P_1}\\\\T_2=\dfrac{105\times 320}{140}\\\\T_2=240\ K\\\\T_2=-33.15^{\circ} C[/tex]

So, the final temperature is equal to 240 K or -33.15°C.

To achieve the highest return during recrystallization of a given solid, one must: Group of answer choices Add the minimum amount of boiling solvent necessary to dissolve the solid to be crystallized. Add an excess amount of cold solvent necessary to dissolve the solid to be crystallized. Add the minimum amount of cold solvent necessary to dissolve the solid to be crystallized. Add an excess amount of boiling solvent necessary to dissolve the solid to be crystallized.

Answers

Answer:

Option A

Explanation:

Addition of too much of solvent will make the solution dilute due to which the crystals will not form. Hence option D is incorrect

On the other hand adding a minimum amount of boiling solvent will give a saturated solution for recrystallization. Hence, option A is incorrect

Addition of cold solvent will lower the rate of formation of crystals. Hence, both option B and C are incorrect

What happens to the entropy when a solution is made?
A. The entropy increases.
B. The entropy decreases.
C. The entropy goes to zero.
D. The entropy is unaffected.

Answers

Answer:

The entropy increases

Explanation:

Just took the quiz

Which of the following is a characteristic shared by all living things?
A. They have tissues and organs,
B. They take in oxygen.
C. They make more individuals of the same kind.
D. They move.​

Answers

Answer; it’s either d or a. If it was be I would pick A. Not sure

During energy conversions, some energy is always lost as _____.

heat
electricity
chemical energy
light

Answers

Answer:

electricity

Explanation:

I know this because I am currently learning about this and remember doing it

heat because in a machine heat must come out to follow the law of conservation of energy. I hope i can help

5.0 g of copper was heated from 20°C to 80°C. How much energy was used to heat Cu?

Answers

Answer:

100 J of energy are needed to heat the copper from 20∘C to 80∘C .

Here are the atomic masses of hypothetical elements:
X = 13.25 amu
Y = 69.23 amu
Z = 109.34 amu
3.8 moles of X2Y5Z3 is equivalent to how many grams?
Enter your answer to zero decimal places (round to the ones place). Do
not include the units of "g", just the numerical answer.

Answers

Answer:

2663 g

Explanation:

We'll begin by calculating the molar mass Of X₂Y₅Z₃. This can be obtained as follow:

Molar mass of X₂Y₅Z₃ = (13.25×2) + (69.23×5) + (109.34×3)

= 26.5 + 346.15 + 328.02

= 700.67 g/mol

Finally, we shall determine the mass of 3.8 moles of X₂Y₅Z₃. This can be obtained as follow:

Molar mass of X₂Y₅Z₃ = 700.67 g/mol

Mole of X₂Y₅Z₃ = 3.8 moles

Mass of X₂Y₅Z₃ =?

Mass = mole × molar mass

Mass of X₂Y₅Z₃ = 3.8 × 700.67

Mass of X₂Y₅Z₃ = 2663 g

Therefore, the of 3.8 moles of X₂Y₅Z₃ is

2663 g

How many grams are there in 1.8055 x 10^25 molecules of sodium sulfate? Hint: Convert to moles first

Answers

Answer:

4258.82 g of Na₂SO₄

Explanation:

From the question given above, the following data were obtained;

Number of molecules of Na₂SO₄ = 1.8055x10²⁵ molecules.

Number of mole of Na₂SO₄ =?

From Avogadro's hypothesis,

6.02×10²³ molecules = 1 mole

Therefore,

6.02×10²³ molecules = 1 mole of Na₂SO₄

Next, we shall determine the mass of 1 mole of Na₂SO₄. This can be obtained as follow:

1 mole of Na₂SO₄ = (23×2) + 32 + (16×4)

= 46 + 32 + 64

= 142 g

Thus,

6.02×10²³ molecules = 142 g of Na₂SO₄

Finally, we shall determine the mass of Na₂SO₄ that contains 1.8055x10²⁵ molecules. This can be obtained as follow:

6.02×10²³ molecules = 142 g of Na₂SO₄

Therefore,

1.8055x10²⁵ molecules

= (1.8055x10²⁵ × 142) / 6.02×10²³

= 4258.82 g of Na₂SO₄

Thus, 4258.82 g of Na₂SO₄ contains 1.8055x10²⁵ molecules

PLZ HELP *NO LINKS*
1) How many moles of gaseous arsine (AsH3) occupy 0.372 L at STP?
In sig fig 4
2) What is the density of gaseous arsine?
In sig fig 4
Thanks!

Answers

Answer: (1). There are  0.0165 moles of gaseous arsine (AsH3) occupy 0.372 L at STP.

(2). The density of gaseous arsine is 3.45 g/L.

Explanation:

1). At STP the pressure is 1 atm and temperature is 273.15 K. So, using the ideal gas equation number of moles are calculated as follows.

PV = nRT

where,

P = pressure

V = volume

n = number of moles

R = gas constant = 0.0821 L atm/mol K

T = temperature

Substitute the values into above formula as follows.

[tex]PV = nRT\\1 atm \times 0.372 L = n \times 0.0821 L atm/mol K \times 273.15 K\\n = 0.0165 mol[/tex]

2). As number of moles are also equal to mass of a substance divided by its molar mass.

So, number of moles of Arsine [tex](AsH_{3})[/tex] (molar mass = 77.95 g/mol) is as follows.

[tex]No. of moles = \frac{mass}{molar mass}\\0.0165 mol = \frac{mass}{77.95 g/mol}\\mass = 1.286 g[/tex]

Density is the mass of substance divided by its volume. Hence, density of arsine is calculated as follows.

[tex]Density = \frac{mass}{volume}\\= \frac{1.286 g}{0.372 L}\\= 3.45 g/L[/tex]

Thus, we can conclude that 0.0165 moles of gaseous arsine (AsH3) occupy 0.372 L at STP and the density of gaseous arsine is 3.45 g/L.

a) How do you prepare %3 (w/v) Na2CO3 solution from Na2CO3⸱2H2O? (15p) Na2CO3 MW=106 g/mol

Answers

Answer:

4.02g of Na2CO3⸱2H2O must be added completing the volume of the solution to 100mL

Explanation:

A 3%(w/v) solution contains 3g of solute (In this case, Na2CO3) in 100mL of solution.

Assuming we require 100mL of solution we must add 3g of Na2CO3. The reactant that is available is its dihydrate, with molar mass:

106g/mol + 2*MW H2O

106g/mol + 2*18g/mol = 142g/mol

That means the mass of Na2CO3.2H2O that must be added to prepare the solution is:

3g Na2CO3 * (142g/mol Na2CO3.2H2O / 106g/mol Na2CO3) =

4.02g of Na2CO3⸱2H2O must be added completing the volume of the solution to 100mL


8. Which of the following elemental gases would have properties closest to an ideal gas?
a. hydrogen
argon
b. helium
d. fluorine

Answers

Answer:

Helium

Explanation:

Please tell me if it was right

15.
A tank containing 173 grams of methane, CH (9), registers 15.1 atmospheres at 298 Kelvin. What is the volume of the tank (assuming the entire volume is available to the gas)?
A 3,410L
B. 213
C.O 175L
D. 280.
Chemistry 4/28 5454
Copyright © 2021 Illuminate Education, Inc. All Rig

Answers

Answer: The volume of tank is 17.5 L.

Explanation:

Given: Mass of methane = 173 g

Pressure = 15.1 atm

Temperature = 298 K

Molar mass of methane is 16.04 g/mol.

Therefore, moles of methane are calculated as follows.

[tex]No. of moles = \frac{mass}{molar mass}\\= \frac{173 g}{16.04 g/mol}\\= 10.78 mol[/tex]

Now, ideal gas equation is used to calculate the volume as follows.

PV = nRT

where,

P = pressure

V = volume

n = no. of moles

R = gas constant = 0.0821 L atm/mol K

T = temperature

Substitute the values into above formula as follows.

[tex]PV = nRT\\15.1 atm \times V = 10.78 mol \times 0.0821 L atm/mol K \times 298 K\\V = \frac{10.78 mol \times 0.0821 L atm/mol K \times 298 K}{15.1 atm}\\= 17.5 L[/tex]

Thus, we can conclude that volume of the tank is 17.5 L.

What's you're favorite year?

Answers

Answer:

2020 cause of the lockdown

Explanation:

If a substance has a density of 0.123 g/mL, 10.0 dL would weigh in g? ​

Answers

Answer:

123 g

Explanation:

First, we convert 10.0 dL into mL, keeping in mind that:

1 dL = 100 mL; then10.0 dL * 100 = 1000 mL

Now we can multiply the density by the volume in order to calculate the mass:

Density = mass / volumeDensity * volume = mass0.123 g/mL * 1000 mL = 123 g

10.0 dL of a substance with a density of 0.123 g/mL would weigh 123 grams.

What volume will 28 grams of nitrogen gas occupy at 27 Celsius and a
pressure of 785 mm Hg?

Answers

Answer: [tex]2.49\ m^3[/tex]

Explanation:

Given

Mass of nitrogen present [tex]m=28\ g[/tex]

Temperature [tex]T=27^{\circ}C\equiv 300\ K[/tex]

Pressure [tex]P=785\ mm\ \text{of}\ Hg\ \text{or}\ 1.032\ atm[/tex]

The molar mass of Nitrogen [tex]M=28\ g/mol[/tex]

No of moles of nitrogen present

[tex]n=\dfrac{m}{M}\\\\n=\dfrac{28}{28}\\\\n=1[/tex]

Using [tex]PV=nRT[/tex]

[tex]\Rightarrow 1.032\times V=1\times 8.314\times 300\\\\\Rightarrow V=\dfrac{2494.2}{1.032}\\\\\Rightarrow V=2494.2\ L\ \text{or}\ 2.49\ m^3[/tex]

Oil is
so it will
dissolve in water.

Answers

Answer:

liquid, and of course

Explanation:

How many grams of N2 is needed to produce 2000 grams NH3?

Answers

Answer:

1644 g

Explanation:

Step 1: Write the balanced equation

N₂ + 3 H₂ ⇒ 2 NH₃

Step 2: Calculate the moles corresponding to 2000 g of NH₃

The molar mass of NH₃ is 17.03 g/mol.

2000 g × 1 mol/17.03 g = 117.4 mol

Step 3: Calculate the moles of N₂ needed to produce 117.4 moles of NH₃

The molar ratio of N₂ to NH₃ is 1:2. The moles of N₂ needed are 1/2 × 117.4 mol = 58.70 mol

Step 4: Calculate the mass corresponding to 58.70 moles of N₂

The molar mass of N₂ is 28.01 g/mol.

58.70 mol × 28.01 g/mol = 1644 g

Jerry is trying to classify cells by their physical characteristics. He discovers a multicellular organism containing cells that have a nucleus and a cell wall as well as the ability to conduct photosynthesis. Into which of the three domains would this organism most likely fit? A. Archaea B. bacteria C. Eukarya D. Viral​

Answers

Turn on will turn on will turn on both turn on mobile

Domains eukarya  would this organism most likely fit.

The domain eukarya comprised of eukaryotes or organisms whose cells contain true nucleus.

What is a domain?

It is  the largest of all groups in the classification of life. There are three domains:-

Archaea domainBacteria domainEukarya domainWhat is Eukarya?

It is the domain of organism called eukaryotes. These are the organism who have a well defined nucleus and membrane bound organelles.

Hence, C) option is correct.

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The Swedish chemist Karl Wilhellm was the first to produce chlorine in the lab
2NaCl + 2H2SO4 + MnO2 -----> Na2SO4 + MnSO4 + H2O + Cl2
If Dr. Wilhellm started with 50.0 g of each reactant, which reactant is the limiting reactant?

Answers

Answer:

Explanation:

Remark

Interesting que8stion. You have to figure out how many mols are present in each reactant. Since all periodic tables are different, I'm going to use rounded numbers. If it is too close, I will go further.

NaCl

Na = 23

Cl = 35.5

1 mol = 58.5 grams

given = 50.0 grams

Mols for the reaction = 50/58.5 = 0.855

H2SO4

H2       =    2*1        2

S          =   1 * 32   32

O4       =   4*16     64

1 mol  =               98   grams

mols  present = 50/98 = 0.510

MnO2

Mn     = 1 * 55    = 55

O2   =   2*16      = 32

1 mol =                  87 grams

mols available    = 50/87 = 0.5747

Discussion

Na Cl and H2SO4 both require 2 moles for every mol of Cl2 produces.

H2SO4  has 0.51 mols available for a reaction

NaCl has  0.855 moles available for a reaction

MnO2 has 0.575 moles available for a reaction.

Given those numbers 0.510 mols of H2SO4 will only produce 0.255 mols of chlorine and the rest will be reduced in a similar manner. H2SO4 is the limiting reagent (reactant).

In other words only 0.510 moles of NaCl will be used and 0.855 - 0.510 moles will be left over on the reactants side.

only 0.575 moles of MnO2 will be used and 0.065 moles will be left over.

The oddity in the result shows up because the balance numbers in the equation give a ratio of 2 to 1 for H2SO4 and NaCl The 2 belongs to the reactants and the 1 for the chlorine.

131.39 g/mol C2HCl3
find the molecular formulas

Answers

Answer:

Find the mass of 1 mole.

mass of

1

mole of

131.39

g

m

o

l

C

2

H

C

I

3

=

37.04000067

g

Explanation:

hope it helps make brainlliest ty

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