A sample contains 2.2 g of the radioisotope niobium-91 and 15.4 g of its daughter isotope, zirconium-91.

If the half-life of niobium-91 is 680 years, how long will it take for the decay described in the previous question?

680 years
1,360 years
✓2,040 years (correct answer)
2,720 years

Answers

Answer 1

Time to decay : 2040 years

Further explanation  

The atomic nucleus can experience decay into 2 particles or more due to the instability of its atomic nucleus.  

Usually radioactive elements have an unstable atomic nucleus.  

The main particles are emitted by radioactive elements ,so that they generally decay, are alpha (α), beta (β) and gamma (γ) particles  

General formulas used in decay:  

[tex]\tt Nt=No.\dfrac{1}{2}^{\dfrac{T}{t\frac{1}{2} }[/tex]  

T = duration of decay  

t 1/2 = half-life  

N₀ = the number of initial radioactive atoms  

Nt = the number of radioactive atoms left after decaying during T time  

moles zirconium :

[tex]\tt \dfrac{15.4}{91}=0.169[/tex]

moles niobium :

[tex]\tt \dfrac{2.2}{91}=0.0242[/tex]

the half-life of niobium-91 is 680 years

Reaction

⁹¹₄₁Nb ⇒⁹¹₄₀Zr + ₁⁰e

Amount of Nb from reaction : 0.169

Amount of initial Nb = 0.0242 + 0.169 = 0.1932

Time to decay (T) :

[tex]\tt 0.0242=0.1932.\dfrac{1}{2}^{\dfrac{T}{680}}\\\\0.1252=\dfrac{1}{2}^{\dfrac{T}{680}}\\\\\dfrac{1}{2}^{3}=\dfrac{1}{2}^{\dfrac{T}{680}}\\\\T=680\times 3=2040[/tex]

Answer 2

Answer:

It’s CCCCCCCCCCCCCCC

Explanation:

I just took the instruction and yes its “C.”


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2. How have observations of the natural world helped
in the development of calendars?

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Answer:

just wanted points

Explanation:

i wasted your time srry

There are well over 100 __________________ that exist on Earth

Answers

Answer:

species like plants, animals , human etc

Answer:

Dogs, Chocolate, Tvs, Phones.

Explanation:

Water, H20, is a molecule made of oxygen and hydrogen. The bonds that hold water
bonds.
molecules together are due to shared electrons, and known as _______ bonds

Answers

Answer:

the answer is convalent bonds

Explanation:

Strong linkages—called covalent bonds—hold together the hydrogen (white) and oxygen (red) atoms of individual H2O molecules. Covalent bonds occur when two atoms—in this case oxygen and hydrogen—share electrons with each other.

i hope this helped

how many grams are there in 0.6 moles of beryllium iodide, Bel2?​

Answers

Convert mole to gram multiply it by the molar mass of BeI2

BeI2 molar mass = 262.8122g

0.6 moles x 262.8122g = 157.68g BeI2

Sharing or transfer of electrons from one atom to the other to attain stable octet
configuration follows
————-theory

Select one:

O a. Einstein's

O b.
Bohr's

O c. Newton's

O d. Candella's

Please help me with this question


Answers

Answer:

C newton's..................

1.8 L of a 2.4M solution of NiCl2 is diluted to 4,5 L. What is the resulting concentration of the diluted solution?

Answers

Hope this helps :) all you need to do is use the C1V1=C2V2 formula

A pipet is used to transfer 5.00 mL of a 1.25 M stock solution in flask "S" to a 25.00-mL volumetric flask "B," which is then diluted with DI H2O to the calibration mark. The solution is thoroughly mixed. Next, 3.00 mL of the solution in volumetric flask "A" is transferred by pipet to a 50.00-mL volumetric flask "B" and then diluted with DI H2O to the calibration mark. Calculate the molarity of the solution in volumetric flask "B."

Answers

Answer:

The answer is "0.015 M ".

Explanation:

[tex]M_1 = 1.25 \ M\\\\M_2 = M_2\\\\V_1 = 5.00 \ mL\\\\V_2 = 25.00 \ mL \\\\\bold{\text{Formula:}}\\\\\to M_1 \times V_1 = M_2\times V_2\\\\\to M_2 = \frac{ M_1 \times V_1}{V_2}\\\\=\frac{( 1.25 \times 5.00 )}{ 25.00}\\\\=\frac{( 6.25 )}{ 25.00}\\\\= 0.25 \ M \\\\[/tex]

If the volume [tex]V_2 = 3.00 \ mL[/tex]

[tex]M_3=M_3 \\\\V_3 = 50.00 \ mL\\[/tex]

Formula:

[tex]M_3 = \frac{M_2 \times V_2}{V_3}[/tex]

     [tex]= \frac{ 0.25 \times 3.0}{50.0}\\\\ = \frac{ 0.75}{50.0}\\\\ = 0.015 \ M \\\\[/tex]

Show the reaction : Phenol to benzene

Answers

The reaction is given by

[tex]\\ \rm\Rrightarrow C_6H_5OH+Zn\longrightarrow C_6H_6+ZnO[/tex]

Answer:

See below ~

Explanation:

Element X has 2 following stable isotopes, X-23 (relative abundance 41.9%) and X-25 (relative abundance is [100-41.9]%). What is the average atomic mass of Element X? Record the numerical answer to the hundredths place (2 places after the decimal).

Answers

Further explanation

Isotopes : the same atomic number, but different mass numbers  

Atomic mass is the average atomic mass of all its isotopes  

avg atomic mass = m1.%m1 + m2.%m2....mn.%mn

You did not include the mass of each isotope

Element X :

X-23 = 41.9%

X-25 = 58.1%

The average atomic mass of Element X :

[tex]\tt =0.419\times mass~X-23+0.581\times mass~X-25[/tex]

What is the Atomic weight Of Neon/ Ne in elements.

Answers

Look it up on google bruv

Answer:

20.1797 u or g/mol

Explanation:

I looked it up.

DEFINE -_-

ATOMIC MASS
&
MOLECULAR MASS​

Answers

Answer:

atomic mass is the mass of an atom compared to that of carbon 12 isotope while molecular mass is the mass of a given molecule

Explanation:

Can some inherited traits be changed by an organism's environment?

Answers

Some inherited traits can be changed by an organism's environment because environment has a direct impact on organisms.

Can inherited traits be changed by environment?

Traits allow a plant, animal, or other organism to survive and reproduce in its environment which is known as adaptations. Natural selection occurs when there is some variation in the inherited traits of organisms within a species.

So we can conclude that some inherited traits can be changed by an organism's environment because environment has a direct impact on organisms.

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how to create a particle model that would be more dense than a depicted one?​

Answers

Answer:

make the particles close together (eg a solid is more dense than liquids as it has a fixed shape)

A rod of iron of uniform density has a thickness such that a one-inch-long segment of it weighs 3. 88 ounces. Given that there are 0. 035273 ounces in a gram and 2. 54 centimeters in an inch, how many grams would a 14. 79 cm length of the same iron rod weigh? a. 73. 30 g b. 274. 49 g c. 640. 51 g d. 1,626. 89 g.

Answers

The number of grams of iron present in 14.79 cm length of the same iron rod is 640.51 g.

What is ounces?

Ounces is a unit of mass which is used to define a very little amount of anything.

In the question, given that:

In one inch of iron rod whose weighs is 3.88 ounces = 2.54 cm long

In 1 g = 0.035273 ounces present

So we can calcuylate the number of grams in which 3.88 ounces present as:
x = (3.88 ounces) / (0.035273 ounces/g)

x = 110g

So, in 110g = 3.88 ounces present

And in 2.54 cm = 110g of iron present

In 14.79 cm, present grams of iron can be calculated as:

y = (14.79cm x 110g) / 2.54cm

y = 640.51 g

Hence option (c) is correct i.e. 640.51 g.

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https://brainly.com/question/24505595

The weight of the iron rod with 14.79 cm length with same density is given by: Option C; 640.51 g

How are density, volume and mass of a substance related?

Suppose that a finite amount of substance is there having its properties as:

mass of substance = m kgdensity of substance = d kg/m³volume of that substance = v m³

Then, they are related as:

[tex]d = \dfrac{m}{v}[/tex]

We know that:

1 ounce = 28.3495 g approx

Now, from the facts given in the problem, we have:

The weight of first iron rod which is one inches long = 3.88 ounces

The new rod is 14.79 cm long. And 1 cm = 0.3937 inches approx, thus the new rod is: [tex]14.79 \times 0.3937 \approx 5.8228 \: \rm inches[/tex]

As for 1 inch long rod, there is  weight of 3.88 ounces, thus:

for 5.8228 inch rod, the weight of the rod would be [tex]5.8228 \times 3.88 \approx 22.5924 \: \rm ounces[/tex]

And since 1 ounce = 28.3495 g approx

Thus, weight of the new rod in grams would be [tex]22.5924\times 28.3495 \approx 640.485 \approx 640.51\: \rm g[/tex]

Thus, the weight of the iron rod with 14.79 cm length with same density is given by: Option C; 640.51 g

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SOMEONE PLEASE HELP LIKE ASAP ITS DUE IN A COUPLE MINUTES AND I MARK BRAINLIEST

Answers

first one: like charges

second one: opposite charges

third one: opposite charges

fourth one: opposite charges

yw :)

How does heat transfer? *

cold object to cold object
cold object to hot object
hot object to cold object
hot object to hot object

Answers

Answer:

hot object to cold object

who was the first person to create the periodic table

Answers

Answer:

Dmitri Ivanovich Mendeleev

Explanation:

A Russian chemist Dmitri Ivanovich Mendeleev gave the framework of the periodic table in 1869

Answer:

the first person was Dimitri mendeleev

how does energy transfer from computer to speaker plz help fasttt​

Answers

Answer:

As the coil moves through the magnetic field, created by the magnet, an electric current flows through it. The electric current flows out from the microphone to a computer or other recording device, and you can hear it. Aspeaker works in almost the same way, except that the process isreversed.

an object with a mass of 40g has a volume of 80cm3.will the object float or sink in water? why?

Answers

The substance will not sink in water, as it Dencity is (0.5)is less than the density of water (1gcm).

Which method of finding slope do you prefer? Why?
(slope formula, table, other)

Answers

I prefer using the slope formula because it’s easy to pick two numbers on a graph and solve for the slope with a simple equation.

What causes the move from one era to another era?​

Answers

Answer:

most likely climate changes and or mass extinction

Explanation:

Answer:

Look below

Explanation:

Climate changes.

For problems 1-9, use rectangle QUAD. Treat each problem independently

Answers

The value of DP in the rectangle QUAD can be gotten by equating DP and DA which will be 17 units.

How to solve the rectangle?

From the complete question, DP = 4x + 1, and PA = x + 13. In this case, the value of DP will be calculated thus:

DP = DA (property of rectangle)

4x + 1 = x + 13

Collect like terms

4x - x = 13 - 1

3x = 12

Divide both side by 3

3x/3 = 12/3

x = 4

Therefore, DP will be:

= 4x + 1

= 4(4) + 1

= 16 + 1 = 17

Learn more about rectangles on:

https://brainly.com/question/25292087

What occurs during a solar eclipse?

Earth is closest to the Sun.
There are small tides across Earth.
The moon’s shadow falls on Earth.
The moon is covered in Earth’s shadow.

Answers

Answer:

Explanation:

option C is correct

Answer:

The moon is covered in Earth’s shadow.

Explanation:

When the moon goes behind the earth to the shadow it becomes a solar eclipse.

PS, Can you mark me brainlyest please.

What happens during an El Nino event?
o
All of the Above
Droughts and Tropical Storms are stronger
O
The water of the Pacific Ocean gets warmer
O
The trade winds reverse the direction they normally blow in

Answers

The answer is All of the above

Based on your answer in part F, what must happen to the sodium acetate for it to dissolve in the water again? Safely test your method using only those materials available in the equipment list. Does the sodium acetate dissolve again with your chosen method?

Answers

When sodium acetate is dissolved in water, it is hydrolyzed into ions.

What happen when sodium acetate dissolved in water?

When a salt of weak acid or base is dissolved in water, this salt hydrolysis in it. Water ionises into hydroxide and hydrogen due to addition of sodium acetate. In water, sodium acetate splits into sodium and acetate ions.

So we can conclude that when sodium acetate is dissolved in water, it is hydrolyzed into ions.

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What is
metal refinning

Answers

Answer:

It is the way of cleaning of impurities present in metals

Anyone know the answer to this question

Answers

Answer:

Construction

Explanation:

Buildings
Hope this helps

an element (gas) used to make colorfully lit advertising signs

Answers

The correct answer is neon

Neon element which is in gaseous form is used in lit advertising signs as it emits reddish orange glow on passage of current through it.

What is an element?

It is defined as a substance which cannot be broken down further into any other substance. Each element is made up of its own type of atom. Due to this reason all elements are different from one another.

Elements can be classified as metals and non-metals. Metals are shiny and conduct electricity and are all solids at room temperature except mercury. Non-metals do not conduct electricity and are mostly gases at room temperature except carbon and sulfur.

The number of protons in the nucleus is the defining property of an element and is related to the atomic number.All atoms with same atomic number are atoms of same element.

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#SPJ2

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