Iodine-131 half life 8.040 how long will it take for a 40 gram sample of iodine-131 to decay to 0.75 grams
Answer:
See explanation below
Explanation:
To get this, we need to apply the general expression for half life decay:
N = N₀e(-λt) (1)
Where:
N and N₀ would be the final and innitial quantities, in this case, masses.
t: time required to decay
λ: factor related to half life
From the above expression we need λ and t. To get λ we use the following expression:
λ = t₁₂/ln2 (2)
And we have the value of half life, so, replacing we have:
λ = 8.04 / ln2 = 11.6
Now, we can replace in (1) and then, solve for t:
0.75 = 40 exp(-11.6t)
0.75 / 40 = exp(-11.6t)
ln(0.01875) = -11.6t
-3.9766 = -11.6t
t = -3.9766 / -11.6
t = 0.34 daysWill lithium become a cation or anion?
Answer:
Lithium Cation is a monovalent cation that is metabolized much like sodium and is important in many cellular functions inside or on the surface of cells. lithium has a single valence electron that is easily given up to form a cation. Because of this, lithium is a good conductor of heat and electricity as well as a highly reactive element, though it is the least reactive of the alkali metals
calculate the ph of the solution [oh-] = 1x 10-11 m
a. 11.0
b. 12.0
c. 2.7
d. 3.0
Answer:
d. 3.0
Explanation:
First we calculate the pOH of the solution, using the following formula:
pOH = -log[OH⁻]pOH = -log[1x10⁻¹¹ M]pOH = 11.0Using the pOH we can calculate the pH of the solution, keeping in mind the relationship between pH and pOH:
pH = 14.0 - pOHpH = 14.0 - 11.0pH = 3.0The answer is option d.
A 125.0-g sample of a metal heated to 100.0 ∘C and placed in a calorimeter that contains 250.0 g of water. The temperature rises from 24.3 ∘C to 27.2 ∘C. What is the specific heat capacity of the metal? Ignore the calorimeter in your analysis. Group of answer choices
Answer:
0.333J/g°C is the specific heat of the metal
Explanation:
The heat that the metaal gives is equal to the heat that water is absorbing. The equation is:
S(metal)*ΔT(metal)*Mass(metal) = S(H2O)*ΔT(H2O)*Mass(H2O)
Where S is specific heat, ΔT is change in temperature and mass the mass in grams of the metal and water.
Replacing:
S(metal)*(100.0°C-27.2°C)*125.0g = 4.184J/g°C*(27.2°C-24.3°C)*250.0g
S(metal) = 4.184J/g°C*(27.2°C-24.3°C)*250.0g / (100.0°C-27.2°C)*125.0g
S(metal) = 0.333J/g°C is the specific heat of the metal
PLSSS HELP WITH THIS ASAP
Answer:
the property of air shown in the figure describe A.mass
Describe the law of conservation of mass in your own words *DO IT IN YOUR OWN WORDS PLEASE*
Answer:
Chemical reactions and physical transformations do not create or destroy mass in an isolated system, according to the law of conservation of mass. The mass of the products in a chemical reaction must equal the mass of the reactants, according to the conservation of mass law. The law of conservation of mass can be used to solve for unknown masses, such as how much gas is consumed or produced during a reaction.
what is zinc chemical formula?
Answer:
Zn+2
Explanation:
I'm sorry if its wrong but have a good one!
How many days does it take the moon to orbit the Earth once.
Answer:
27.3 days
Explanation:
I really have no explanation lol.
Answer:
Hope thia helps
Explanation:
it takes 27.3 days!!!
A substance has a boiling point of 78 °C. Which of the following is true about the substance? (5 points) a It will also change from a gas to a solid at 78 °C while the gas loses energy. b It will also change from a gas to a solid at 78 °C while the gas gains energy. c It will also change from a gas to a liquid at 78 °C while the gas loses energy. d It will also change from a gas to a liquid at 78 °C while the gas gains energy.
Answer: If a substance has a boiling point of [tex]78^{o}C[/tex] then it is true that it will also change from a gas to a liquid at 78 °C while the gas loses energy.
Explanation:
The temperature at which vapor pressure of a liquid substance becomes equal to the atmospheric pressure is called boiling point of substance.
At the boiling point, liquid phase and vapor phase remains in equilibrium.
This means that as liquid phase changes into vapor phase and also vapor phase changes into liquid phase at the boiling point.
Thus, we can conclude that if a substance has a boiling point of [tex]78^{o}C[/tex] then it is true that it will also change from a gas to a liquid at 78 °C while the gas loses energy.
how do some plants grow and survive in the harshest environments like the dessert or under water
Answer:
Adaptation
Explanation:
Some plants grow and survive in the harshest environments like the desert or underwater by adapting to the environment. For example, some plants in the desert have thick, waxy skin to reduce loss of water and to reflect heat. They also have large, fleshy stems to store water. Also, specific plants like cacti in the desert have spikes to protect them from animals wishing to use stored water. These adaptations help them to grow and survive in the desert.
In the ocean, plants have adapted to absorb all the water and carbon dioxide they need from the water they live in. Just as cacti have adapted to live in brutally hot deserts, ocean plants have adapted to deal with things like ocean tides and the salinity (or salt levels) of the water around them. Many ocean plants cling tightly to rocks in order to avoid being swept away by ocean tides.
Hope this helps! Can I have brainliest?
How many moles are in a solution with a concentration of 5 M and a volume of 0.25 L?
Answer:
160 mL
Explanation:
How many formula units (particles of AgNO3) are in 5.50
grams of AgNO3?
a 1.93 x 1022 molecules
b 8.67 x 1021 molecules
C 0.032 molecules
d 6.14 1022 molecules
e, 3.22 x 1022 molecules
Answer:
2.0 X 10²² molecules of AgNO₃Explanation:
Given 5.50 grams of AgNO₃, how many formula units of AgNO₃ are contained in the 5.50 grams of AgNO₃? (formula wt. of AgNO₃ = 169,87 g/mole).
Solution:
1st convert grams to moles => moles AgNO₃ = 5.50 g AgNO₃ / 169.841g AgNO₃ = 0.032377 mole AgNO₃ 2nd calculate number of particles in 0.032377 mole AgNO₃ . Number AgNO₃ molecules in 0.032377 mole AgNO₃ = 0.032377 mole AgNO₃ X 6.023 x 10²³ molecules of AgNO₃ /1.0 mole AgNO₃ = 1.95007 X 10²² molecules of AgNO₃ in 5.50 grams of AgNO₃. The appropriate form of the answer should contain 2 Sig,Figs. based on the data point having the least number of sig.figs. in the given data. This then is 5.50 grams of AgNO₃ which has 2 sig.figs. Therefore, the number of AgNO₃ molecules in 5.5 grams of AgNO₃ = 2.0 X 10²² molecules of AgNO₃. (Note: 1.95 rounds to 2.0).The number of molecules of silver nitrate in 5.5 grams has been [tex]1.93\;\times\;10^2^2[/tex]. Thus, option A is correct.
The formula unit has been given as the number of molecules of the compound. The number of molecules in a mole of compound has been given by the Avogadro law.
According to the Avogadro law, the number of molecules in a mole of sample has been equivalent to the Avogadro number, i.e. [tex]6.023\;\times\;10^2^3[/tex].
Computation for formula unit of Silver nitrateThe given mass of silver nitrate has been 5.50 grams.
The molar mass of silver nitrate has been 169.84 g/mol.
The moles of silver nitrate has been:
[tex]\rm Moles=\dfrac{Mass}{Molar\;mass} \\\\
Moles=\dfrac{5.5}{169.84}\;mol\\\\
Moles=0.032\;mol[/tex]
The moles of silver nitrate in the sample has been 0.032 mol.
The number of molecules of silver nitrate has been:
[tex]\rm 1\;mole=6.023\;\times\;10^2^3\;molecules\\ 0.032\;mol=0.032\;\times\;6.023\;\times\;10^2^3\;molecules\\ 0.032\;mol=1.93\;\times\;10^2^2\;molecules[/tex]
The number of molecules of silver nitrate in 5.5 grams has been [tex]1.93\;\times\;10^2^2[/tex]. Thus, option A is correct.
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describe how to calculate the relative atomic mass
Would an alkali metal make a good replacement for tin in a tin can? Explain.
Answer:
No
Explanation:
If tin is heated, it can react with alkalis' with the release of hydrogen.
Tin is a great metal that is used for packaging purposes.
It does not react with any acid that may be present in the food material stored inside the tin can which makes it a useful metal. It keeps the food safe.However, if the tin in the tin can is replaced with alkali metals then they will readily react with the acid present in the food materials stored inside, thereby rendering the food unsafe.
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Select the correct structure that
corresponds to the name.
4-bromo-5-chlorocyclohexene
Answer: a
Explanation:
If 36g of Al react with 34L of Oz, how many moles of Al2O3 are produced?
4Al +302 --> 2Al2O3
145 moles
0.667 moles
0.165 moles
101 moles
Answer:
.........................................................................................................................................................................................................................................................................................................................................................................................................................................................
Explanation:
If 36g of Al react with 34L of Oz, 0.667 moles of Al2O3 are produced. The correct option is b, 0.667 moles
What are moles?The mole is a SI unit of measurement that is used to calculate the quantity of any substance.
[tex]\rm 4Al +3O_2 -- > 2Al_2O_3[/tex]
Step1- calculate the moles of aluminum
The mass of Al is 36 g
The molar mass of Al is 27
[tex]\rm Number\;of \;moles= \dfrac{mass}{molar\;mass}\\\rm Number\;of \;moles\;of\;Al = \dfrac{36}{27} = 1.33\;mol[/tex]
Step2- calculate the moles of oxygen
The mass of O₂ is 34 L
[tex]\rm 1 L = \dfrac{1}{22.4 }[/tex]
[tex]\rm Number\;of \;moles\;O_2= \dfrac{34}{22.4} = 1.51[/tex]
The limiting reagent is 1.33 MOL. By the rule of stoichiometry, four moles of Al produced 2 moles of Al.
[tex]\rm \dfrac{1.33}{2} = 0.665 \;moles[/tex]
Thus, the correct option is b. 0.667 moles.
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Which of the following is an example of a molecular element?
a.NaCl b. CO2 c. Na d. O2
Answer:
oxygen (O2) is a molecular element
Explanation:
Molecular compound are chemical compounds that take the form of discrete molecules.
atomic element is an element which occurs independently as atoms and can react with other elements to form a compound
Ionic compounds are the compound which on dissolution form ions in solution
Mixture is the composition of different compounds
During a combustion reaction, 9.00 grams of oxygen reacted with 3.00 grams of CH4.
What is the amount of the leftover reactant?
0.74 grams of methane
0.89 grams of methane
1.22 grams of oxygen
1.45 grams of oxygen
Answer:
0.74
Explanation:
this is the correct answer. I followed a correct answer that had the same probelm with different values, swithxed it with mine, and got 0.75. So its basically 0.74
How is a radioactive element different from a stable element?
Radioactive elements are the elements into which an atom is very unstable or highly reactive because it is having more energy in its nucleus. stable elements are those who have stable and there shell are properly filled with electrons.
What are radioactive elements and stable elements?Most radioactive chemical elements have one or more radioactive isotopes on the other hand some chemical elements only have one type of radioactive isotopes.
A radioactive element has an unstable nucleus that emits particles in the form of alpha, beta, or gamma radiation and stable element have stable nucleus with no effect of any radiation or energy due to fully filled orbitals.
Bombarding of these radiations has to be done in the nucleus of the element after this the desired element will become a radioactive element. And there is no effect of these rays on stable elements beacuse they are unreactive to this.
The ray of alpha beta and gamma consists of some charges within them and they are radioactive radiations harmful to human eyes.
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What is a jet stream. in your own words but be more detailed about what you say.
(don't send a link)
Name the sub atomic particles in part Z of a boron atom give the relative charges of these sub atomic particles
Answer:
Neutrons and protons
Explanation:
There are three fundamental subatomic particles, these are;neutrons protons and electrons.
Ernest Rutherford successfully showed that every atom does possess a central core that contain positively charged particles (protons) called the nucleus. Chadwick later discovered the existence of neutrons.
Both protons and neutrons are found in the nucleus. Z represents the nucleus of the boron atom and houses the neutrons and protons of the boron atom.
In 2Fe+3Cl2=2FeCl3, how much iron (Fe) is needed to produce 4 moles of FeCl3?
In 2Fe+3Cl2=2FeCl3, how much FeCl3 is produced when 5 moles of Fe react in excess chlorine?
Answer:
4 mol Fe
5 mol FeCl₃
Explanation:
Step 1: Write the balanced equation
2 Fe + 3 Cl₂ ⇒ 2 FeCl₃
Step 2: Calculate how much iron (Fe) is needed to produce 4 moles of FeCl₃
According to the balanced equation, the molar ratio of Fe to FeCl₃ is 2:2.
4 mol FeCl₃ × 2 mol Fe/2 mol FeCl₃ = 4 mol Fe
Step 3: Calculate how much FeCl₃ is produced when 5 moles of Fe react in excess chlorine
According to the balanced equation, the molar ratio of Fe to FeCl₃ is 2:2.
5 mol Fe × 2 mol FeCl₃/2 mol Fe = 5 mol FeCl₃
What is the acceleration of a 7 kg
mass being pulled by a 56 N force?
Answer:
8 meters per second per second
Explanation:
Newton's second law: [tex]f=ma[/tex], force = mass multiplied by acceleration.
Therefore 56 / 7 = acceleration = 8
Collisions only result in a reaction if the particles collide with a certain maximum energy called the activation energy of the reaction.
Answer: The statement collisions only result in a reaction if the particles collide with a certain maximum energy called the activation energy of the reaction, is false.
Explanation:
Activation energy is the minimum amount of energy required to initiate a chemical reaction.
So, when activation energy for a reaction is lower then molecules with lower energy can also participate in the reaction. As a result, more number of collisions will take place due to which an increase in the rate of reaction will takes place.
When activation energy for a reaction is larger then molecules with higher energy will not be able to participate in the reaction. As a result, less number of collisions will take place due to which a decrease in rate of reaction will occur.
Therefore, we can conclude that the statement collisions only result in a reaction if the particles collide with a certain maximum energy called the activation energy of the reaction, is false.
Answer:
true
Explanation:
particularly must collide with energy equal to or greater the
The best way to increase the amount of a solid solute dissolved in a saturated solution would be to
Answer:
The solubility of a saturated solution can be increased by increasing the temperature.
Explanation:
Temperature -- Generally, an increase in the temperature of the solution increases the solubility of a solid solute. For example, a greater amount of sugar will dissolve in warm water than in cold water. A few solid solutes, however, are less soluble in warmer solutions.
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C.
Show that the results of these dulys
Calculate the oxidation state of Manganese in the following
i. KMnO4 ii. Mno4-
i) KMnO4
lets calculate using x method
1+x+ 4(-2) = 0
1+x-8 =0
x= 7
ii)MnO4‐
x+4(-2) = -1
x-8 = -1
x = 7
If a book has a weight of 23.2 N on Earth, what is its mass?
Answer: Mass is 2,37 kg
Explanation: Weight G = mg, and g = 9.81 m/s² on Earth.
m = W/g = 23.2 N / 9.81 m/s²
Please help is for my final An example of a chemical change is-
evaporation of seawater
о
sublimation of dry ice (CO2)
melting of aluminum
burning wood reducing it to ashes
Explanation:
Souring of milk
Baking of cake
a concentrated solution of sulfuric acid, H2SO4, has a concentration of 18.0 M. How many mL of the concentrated acid would be required to make 250. mL of a 1.00 MH2SO4 solution?
Answer: A 13.88 mL of the concentrated acid would be required to make 250. mL of a 1.00 M [tex]H_{2}SO_{4}[/tex] solution.
Explanation:
Given: [tex]M_{1}[/tex] = 18.0 M, [tex]V_{1}[/tex] = ?
[tex]M_{2}[/tex] = 1.00 M, [tex]V_{2}[/tex] = 250 mL
Formula used to calculate the volume of concentrated acid is as follows.
[tex]M_{1}V_{1} = M_{2}V_{2}[/tex]
Substitute the values into above formula as follows.
[tex]M_{1}V_{1} = M_{2}V_{2}\\18.0 M \times V_{1} = 1.00 M \times 250 mL\\V_{1} = \frac{1.00 M \times 250 mL}{18.0 M}\\= 13.88 mL[/tex]
Thus, we can conclude that 13.88 mL of the concentrated acid would be required to make 250. mL of a 1.00 M [tex]H_{2}SO_{4}[/tex] solution.
M
Mass can be measured in local units like dharni pau eto. Discuss the advantages of using
standard units of mass over the local units of mass. (Any two points)
N2 Points)
soup answer
Answer:
1.They are reliable.
2.They dont vary from person to person