160 grams of I-131 were in the original sample if the half-life is 8 days.
What do you mean by half life?In a chemical reaction, the time taken for the concentration of that substance to become half of its initial value is called half-life. This term is used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay .
The amount left N after n half lives of a radioactive element with original amount N₀ is given as:
N= N₀ (1/2)ⁿ
Given, half life of Iodine-131 is 8 days
n= 40/8= 5
5= N₀ (1/2)⁵
N= 32 * 5
= 160 grams
Hence, the original amount amount of I-131 will be 160 grams.
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Please help me solve this USING DIMENSIONAL ANALYSIS! :
Get yourself a snack. Read the nutrition label. How many calories are in the snack? Now convert this into the international unit of energy, the Kilojoule.
How many kJ are in your snack?
1 dietary Calorie = 1000 calories (the dietary Calorie, with a capital C, is what is listed on your nutrition label. This is different than a lower-case c "calorie.")
1 calorie = 4.184 Joules
Complete this sentence: In my ___________, there are _______kJ of energy.
Answer:
Explanation:
Given: 1 dietary Calorie = 1000 calories
1 calorie = 4.184 Joules
But,
1 dietary Calorie = 1 Kcalorie
= 1000 x 4.184 Joules
= 4184 Joules
= 4.184 KJoules
1 dietary Calories contains 4.184 KJ of energy.
A bottle of Coca cola contains 42 Kcalories; thus,
1 Kcalorie = 1000 calories
= 4.184 KJoules
Energy = 42 x 1 dietary Calories
= 42 x 4.184 KJoules
= 175.728 KJoules
Energy ≅ 176 KJ
So that;
In my bottle of coca cola, there are 176 KJ of energy.
PLEASE HELP!!
What elements typically bond with Zinc? include a formula or name.
Cadmium (Cd), Mercury (Hg), and Copernicium (Cn).
Which of the following would you get from playing too much tennis?
A. Cerebral Palsy
B. Muscular Dystrophy
C. Tendonitis
D. ALS
Answer:
cerebral palsy
Explanation:
What are the lowest ratio of coefficients needed to balance the equation below? __ CaCl2 + __Al --> __AlCl3 + __Ca
According to the picture above, which layer contains :
Answer:
a) layer 4
b) layer 1
Explanation:
Older the layer=older the fossils
Newer the layer=newer the fossilss
3. What type of particles move to create electicity?
Electrical energy is caused by moving particles that have a negative or positive charge. These charged particles are called electrons. The faster the electrons are moving, the more electrical energy they carry. Electrical energy commonly moves through a wire in an electrical circuit.
[tex]\huge\boxed{Electrons.}[/tex]
_____________________________________Explanation...Electrons are particles that move to create electricity. In other words, they are responsible for electric currents. Thus, the answer should be Electrons.
_____________________________________[tex]\boxed{Hope\;i\;helped!}\\\\\\\huge\boxed{Thanks,Plip.}[/tex]
How are atoms combined in a mixture?
Answer:
Chemically combined and cannot be separated
Explanation:
1)A minimum of two atoms combine to form a molecule.
2)Atoms are combined via chemical reactions thus chemically combined. Sodium+Chlorine
e.g Na+Cl—>NaCl²
Which of the following minerals scratches
fluorite mineral?
a. talc
b. diamond
c. gypsum
d. calcite
Answer:
b. diamond
Explanation:
Diamond is the hardest known naturally occurring substance. And it will scratch any other minerals below it on the moh's scale of hardness.
Fluorite is below diamond in the scale of hardness and it will readily scratch it. Talc, is the softest mineral, it will not scratch fluoriteBoth gypsum and calcite also below fluorite. They will not scratch this mineral.Which sentence would be inappropriate in an informational piece of writing with a formal tone?
A: People find Shakespeare's Pericles, Prince of Tyre boring and annoying because it's possible that he didn't even write the entire play.
B: Thirty-nine plays, a combination of comedies, histories, and tragedies, are attributed to William Shakespeare.
C: William Shakespeare, a poet, and playwright have generally deemed the greatest writer in the history of the English language.
D: Scholars speculate that Hamlet may have been informed by the relationship between Shakespeare and his son Hamnet, who died at eleven years of age.
Answer:
Its a
Explanation:
i took the quiz
The sentence that is inappropriate in an informational piece of writing with a formal tone is "People find Shakespeare's Pericles, Prince of Tyre boring and annoying because it's possible that he didn't even write the entire play." The correct option is A.
What is a formal tone?In academic or professional settings, a formal writing tone is common. This tone emphasizes thoroughness and directness while remaining respectful.
It emphasizes facts and grammatical correctness and uses full words rather than contractions.
The use of standard English, more complex sentence structures, the infrequent use of personal pronouns, and the absence of colloquial or slang terms characterize formal language.
In informal language, nonstandard English forms, colloquial vocabulary, and typically shorter sentence structures are permitted.
"People find Shakespeare's Pericles, Prince of Tyre boring and annoying because it's possible that he didn't even write the entire play," is an inappropriate sentence in a formal informational piece of writing.
Thus, the correct option is A.
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How can you tell which elements form chemical bonds?
Answer: The number of bonds that an element can form is determined by the number of electrons in its valence shell. Similarly, the number of electrons in the valence shell also determines ion formation.
Explanation:
Examine the diagram of a cell.
Which organelle is marked with an X?
lysosome
nucleus
chloroplast
vacuole
Answer:
chloroplast
Explanation:
i took the test
An element that is malleable and a good conductor of heat and electricity could have an atomic number of
Answer:
Copper (atomic number 29)
Explanation:
Copper is a element that is malleable and a good conductor of heat and electricity.
Which statement best describes a source of new genetic variations in a species? A. Asexual reproduction produces many offspring with a successful set of genes.
B. Sexual reproduction results in offspring that each have a unique set of genes.
C. Lifelong leaming helps offspring with the same parents have different skills.
D. Limited resources cause some offspring to survive longer than others,
Answer:
B. Sexual reproduction results in offspring that each have a unique set of genes.
Explanation:
New genetic variation arises in a species as a result of sexual reproduction which results in offspring having a unique set of genes.
Genetic variation is the differences in the genetic make up of organisms within a population. During sexual reproduction, there is an exchange of materials between sexes and the new combination produces a varied form of the original genetic materials. The main source of genetic variation is mutation.Answer:
B
Explanation:
How is the process of using patterns to predict phases of the moon similar to the process Mendeleev used to predict undiscovered elements?
The characteristic of some repeating property can be used to find the answer is
The periodic table and the moon phases can be ordered according to some repeating property, you can create an ordered table and leave the gaps for the unknown properties.
The periodic table created by Mendeleev was initially based on the atomic weight of the elements, but he realized that the similarities of the atoms were greater if he used the atomic number, so he changed the ordering.
Mendeleev found that elements with the same number of electrons in their last shell had similar properties, when he ordered them he found that there were holes in the table, shortly after the work of many researchers the holes were completed and found numerous new chemical elements.
In the observation of the phases of the Moon around the earth it is found that for short measurements there are four phases, for longer measurements in addition to these four phases there are several higher repetition periods, with repeated observation the phases and periods are found. .
We can see that the two jobs are searched for, which is repeated and a table is created, leaving the spaces that are not known empty, with subsequent jobs filling these holes.
In conclusion, with the characteristics of some repeating property, the answer can be found is
The periodic table and the phases of the moon can be ordered according to some repeating property, you can create an ordered table and leave the gaps for the unknown properties.
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Which of the following elements has the lowest ionic radius?
Answer:Atomic radii vary in a predictable way across the periodic table. As can be seen in the figures below, the atomic radius increases from top to bottom in a group, and decreases from left to right across a period. Thus, helium is the smallest element, and francium is the largest. So the asnwer is helium
Explanation:
THIS is SO easy PLEASE help ME ! ill ALSO mark YOU brainliest !
How many orbitals in iron are half-filled, that is, have only one electron?
(A) 1
(B) 2
(C) 3
(D) 4
Answer:
B.
Explanation:
1 orbital is 4 half of 4 is 2.
Complete the sentences
( solid, liquid or gas)
What do you notice about the temperature?
(increases or decreases)
What do you notice about the movement of the molecules and the spacing between the molecules?
( INCREASES or DECREASES)
1. When you
click on the yellow button,
The solid becomes
Liquid
The temperature
increases
The movement of the molecules ____increases__________________
and the space between molecules __increasing_____________________
2. When you click on the green button
The liquid becomes
Gas
The temperature
increases
The movement of the molecules ______increases________________
and the space between molecules ________________________
3. Click on the yellow button again
And the gas becomes
liquid
The temperature
decreases
The movement of the molecules ______________________
and the space between molecules ________________________
4. Click on the red button,
And the liquid becomes
The temperature
The movement of the molecules ______________________
and the space between molecules ________________________
Answer:
xcvbn
Explanation:
nkj
Answer:
what he said
Explanation:
What is the frequency of a photon whose energy is 5.4 ´ 10-19 J? (h = 6.626 ´ 10-34 J·s)
Answer:
8.15 x 10¹⁴Hz
Explanation:
Given parameters:
Energy of photon = 5.4 x 10⁻¹⁹J
h = 6.626 x 10⁻³⁴J.s
Unknown:
Frequency of the photon = ?
Solution:
The energy of a photon is given as;
E = hf
h is the Planck's constant
f is the frequency
f = [tex]\frac{E}{h}[/tex] = [tex]\frac{5.4 x 10^{-19} }{6.626 x 10^{-34} }[/tex] = 8.15 x 10¹⁴Hz
The Law of Superposition allows us to determine:
a
which rock layers are the oldest
b
the relative age of layers of rocks and the fossils in them
c
the exact or absolute age of rock layers
d
a and b are correct
Answer:
d . a and b are correct
Explanation:
The law of superposition allows us to determine the age of rock layers and also that of the fossils within them.
The law of superposition states that "in an undeformed sequence of strata, the oldest rock layer is at the bottom and the youngest is on top".
Using this law, geochronologists can determine the relative ages of rock layers. The youngest layer will be found on top. The oldest at the bottom of the sequence. The arrangement of the layers and the fossils there in can also tell us about the ages of the fossils themselves.The process by which CO2 gas releases heat energy to become dry ice is called :
evaporation
freezing
deposition
sublimation
i believe its deposition
2.911 grams of ethanol C2H5OH is burned and produces how many grams of water vapor?
Please help me or I'm dead.
Answer:
3.4g
Explanation:
Given parameters:
Mass of ethanol = 2.911g
Unknown:
Mass of water vapor = ?
Solution:
To solve this problem, let us write the balanced reaction equation first;
C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O
Now find the number of moles of ethanol;
Number of moles = [tex]\frac{mass}{molar mass}[/tex]
Molar mass of ethanol = 2(12) + 5(1) + 16 + 1 = 46g/mol
Number of moles = [tex]\frac{2.911}{46}[/tex] = 0.06mole
So;
1 mole of ethanol will produce 3 moles of water vapor
0.06mole of ethanol will produce 0.06 x 3 = 0.19moles of water vapor
Mass of water vapor = number of moles x molar mass
Molar mass of H₂O = 2(1) + 16 = 18g/mol
Mass of water vapor = 0.19 x 18 = 3.4g
POSS
Explain when gold is considered an element and when it is considered a solution.
Answer:
Gold is an element even when it is in a solution
what trends can you see in the melting point and the boiling point of the halogens?
Answer:
The boiling points increase down the group.
Explanation:
The melting and boiling points increase down the group because of the van der Waals forces. The size of the molecules increases down the group. This increase in size means an increase in the strength of the van der Waals forces.
Answer:
Melting and Boiling Points (increases down the group)
The melting and boiling points increase down the group because of the van der Waals forces. The size of the molecules increases down the group. This increase in size means an increase in the strength of the van der Waals forces.
Explanation:
Which is Chemical Equation is Balanced?
CH, +0,------CO,+2H2O
4A1+30,-----2A1,0,
H2+O2-----2H,0
PLease help I need to get this test done and whoever helps first I will mark brainliest Love you!!!!!
Answer:
moon
Explanation:
Answer:
Explanation:
its the moon. the moon covers the sun causing it to be completely blakened out. and if thats not right then lifes a lie cuz i got blinded pretty bad in one of my eyes for looking at it with it
How many moles of SO3
are in 2.4 x 1024
molecules of S03?
Answer:
2457.6
Explanation:
I calculated the answer and got it right.
Which part of the electromagnetic spectrum has a lower frequency than visible light?
gamma rays
x-rays
infrared
ultraviolet
Answer:
Infrared Radiation
Explanation:
Infrared Radiation
The range of infrared frequencies extends up to the lower limit of visible light, just below red.
The answer is infrared.
what is a catalyst?what is the catalyst used for manufacturing ammonia?
Answer:
finely divided iron is used as catalyst in the manufacture of ammonia by haber's process
Melting chocolate (a change of state) is an example of a