Answer:
2.322 half-lives have passed to decay down from 150 miligrams to 30 miligrams.
Explanation:
The half of Technetium-99 is approximately 211000 years. The decay of isotopes is represented by the following ordinary differential equation:
[tex]\frac{dm}{dt} = -\frac{m}{\tau}[/tex] (Eq. 1)
Where:
[tex]\frac{dm}{dt}[/tex] - First derivative of isotope mass in time, measured in miligrams per year.
[tex]m[/tex] - Mass of the isotope, measured in miligrams.
[tex]\tau[/tex] - Time constant, measured in years.
Now we proceed to obtain the solution of this differential equation:
[tex]\frac{dm}{m} = -\frac{dt}{\tau}[/tex]
[tex]\int {\frac{dm}{m} } = -\frac{1}{\tau}\int dt[/tex]
[tex]\ln m = -\frac{t}{\tau}+C[/tex]
[tex]m(t) = m_{o}\cdot e^{-\frac{t}{\tau} }[/tex] (Eq. 2)
Where:
[tex]m_{o}[/tex] - Initial mass of the isotope, measured in miligrams.
[tex]t[/tex] - Time, measured in years.
The time passed for isotope is cleared within the equation described above:
[tex]\ln \frac{m}{m_{o}} = -\frac{t}{\tau}[/tex]
[tex]t = -\tau \cdot \ln \frac{m}{m_{o}}[/tex]
In addition, we can obtain the time constant as a function of half-life:
[tex]\tau = \frac{t_{1/2}}{\ln 2}[/tex] (Eq. 3)
If we know that [tex]t_{1/2} = 211000\,yr[/tex], [tex]m_{o} = 150\,mg[/tex] and [tex]m = 30\,mg[/tex], then the time passed is:
[tex]\tau = \frac{211000\,yr}{\ln 2}[/tex]
[tex]\tau \approx 304408.654\,yr[/tex]
[tex]t = -(304408.654\,yr)\cdot \ln \left(\frac{30\,mg}{150\,mg} \right)[/tex]
[tex]t \approx 489926.829\,yr[/tex]
The amount of passed half-lives is that time divided by a half-life. That is:
[tex]n = \frac{489926.829\,yr}{211000\,yr}[/tex]
[tex]n = 2.322[/tex]
2.322 half-lives have passed to decay down from 150 miligrams to 30 miligrams.
When an atom is trying to obtain stability, what part(s) of the atom change(s)?
Answer: If the outer shell is filled, the atom is stable. Atoms with unfilled outer shells are unstable, and will usually form chemical bonds with other atoms to achieve stability.
(hope this helps ^^)
Galium is a metal that can melt in your hand at 302.93 k. what is the temperature in celcius ?
Explanation:
subtract it into 273.15to convert it in to celcius
Refer to the Chemical Compounds table above. How many total elements are in
Ethanol?
Answer:
3 element i.e carbon (C), hydrogen (H) and oxygen.
Explanation:
The following data were obtained from the question:
Subtance >>>>>>>> Chemical Formula
Glucose >>>>>>>>> C₆H₁₂O₆
Methane >>>>>>>> CH₄
Ethanol >>>>>>>>> C₂H₅OH
Hydrogen peroxide >> H₂O₂
From the above table, we can see that ethanol (C₂H₅OH) contains carbon (C), hydrogen (H) and oxygen
Therefore, the total number of elements present in ethanol, C₂H₅OH is 3.
Which one of these is not a characteristic of electromagnetic waves.
amplitude
wavelength
frequency
intensity
Answer:
Amplitude
Explanation:
A person drops two objects from the same height. one object weighs 15 N and the other weighs 10 N
A The 10 N object has the same mass as the 15 N object
B The 15 N object has twice the mass of the 10 N object
C The 15 N object has more mass than the 10 N object
D The 10 N object has more mass than the 10 N object
In chemical reactions, what does the law of conservation of mass mean?
Group of answer choices
Matter is not created nor destroyed.
The total mass of the products is greater than the total mass of the reactants.
The total mass of the reactants is less that the total mass of the products.
Matter is not changed.
Answer
The law of conservation of mass states that mass in an isolated system is neither created nor destroyed by chemical reactions or physical transformations. According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants.
WILL MARK BRAINLIEST please
Answer:
C is the only reasonable answer.. but this is 6th grade science and I'm in 7th, so I'm pretty sure I'm right
How are plants,animals,and bacteria alike
Answer:
They all carry bacteria you have to feed it
Explanation:
Answer:
They all have Organisms.
Explanation:
Hope this helps!
Brainliest Please.
Rank lead, phosphorus, and barium in order of increasing ionization energy.
A) Pb < P < Ba
B) Ba < P < Pb
C) Pb < Ba < P
D) Ba < Pb < P
Answer:
D) Ba < Pb < P
Explanation:
Barium (Ba): 5,2117
Lead (Pb): 7,4167
Phosphorus (P): 10,4867
Increasing order of ionization energy:
Ba < Pb < P
Electronic configurations of given elementsPb: [Xe] 6s² 4f¹⁴ 5d¹⁰ 6p²
P: [Ne] 3s² 3p³
Ba: [Xe] 6s²
All the given elements have stable half-filled subshells. But phosphorus has the smallest atomic size among them, so it will have the lowest tendency to remove an electron from its valence shell and hence will require the highest amount of ionization energy. Barium has a higher atomic size than lead, therefore it has lower ionization energy than lead.How are ionization energy and atomic size related?The force of attraction is stronger when the electron is closer to the nucleus, and as a result, more energy is needed to overcome this attraction and remove the electron.Therefore, the ionization energy increases with decreasing radius and vice versa.Learn more about trends of ionization energy here:
https://brainly.com/question/6842791
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A type of substance containing atoms of two or more different elements that are chemically bonded together is referred to as a
Answer:
Compound
Explanation:
In a mixture of bromine-79 and bromine-81 isotopes. An atom of bromine-79 contains?
Answer:
Bromin-79
Explanation:
The isotope bromine-79 will contain 35 protons, 35 electrons and 44 neutrons.
The state of matter of a material depends on its
O A) density
OB) temperature
O C) volume
OD) weight
Answer:
Tempature
Explanation:
Matter can move between any two states (or phases) of matter depending on the pressure and temperature conditions. ... The temperature of the melting and boiling points depend on the identity of the substance and the atmospheric pressure.
Also apex.
Answer:
temperature
Explanation:
an example here
ice
when its cold ice tends to stay as a solid but as the temperature rises the ice melts and turns into a liquid... with more heat the water will turn into gas
Liquid hexane will react with gaseous oxygen to produce gaseous carbon dioxide and gaseous water . Suppose 17. g of hexane is mixed with 101. g of oxygen. Calculate the maximum mass of carbon dioxide that could be produced by the chemical reaction. Be sure your answer has the correct number of significant digits.
Answer:
52g of carbon dioxide
Explanation:
Liquid hexane + gaseous oxygen --> Carbon dioxide + gaseous water
The balance chemical equation is given as;
C6H12 + 9O2 --> 6CO2 + 6H2O
From the stochiometry of the reaction;
1 mol of hexane (86g) would consume 9 mol of oxygen (144g) to form 4 mol of carbon dioxide (264g)
The limiting reactant in this equation is hexane as it would run out before oxygen. This means hexane determines how much of the carbon dioxide is formed.
86g of hexane = 264g of crbon dioxide
17g of hexane = xg of carbon dioxide
x = 17 * 264 / 86 = 52g of carbon dioxide
what is erotic please answer
Answer:
adjective
Explanation:
relating to or tending to arouse sexual desire or excitement.
Answer:
WARNING: THIS IS NOT FOR THE EYES OF KIDS
Explanation:
Its when a man's penis gets excited around women or other men. This is usually called sexual desire and feelings. This only happens to men in their particular area because they might see someone they like or they might just be masturbating alone.
Which is the electron configuration for boron?
A.1s22s3
B.1s22s23s
C.1s'2s²2p?
D.1s22s²2p?
Answer:
electron configuration for boron is 1s22s22p1
hope this helps :)
Explanation:
Kinetic and potential energy are two types of energy that relate too
Answer:
Option B. A tractor–trailer traveling at 80 kph.
Explanation:
Kinetic energy can be defined as the energy possessed by a body in motion. Mathematically, it is expressed as:
K.E = ½mv²
Where:
K.E is the kinetic energy.
m is the mass of the object.
v is the velocity of the object.
From the equation, K.E = ½mv²,
We can say that the kinetic energy (K.E), is directly proportional to both the mass (m) and square of the velocity (v). This implies that the greater the mass of an object, the greater the kinetic energy and the smaller the mass, the smaller the kinetic energy.
Now, considering the options given in question above, it is evident that the tractor–trailer has a greater mass than the car, cheetah and motor cycle. Hence, the tractor–trailer will have a greater kinetic energy even though they are traveling with the same velocity.
10. What is the change in the boiling point of water at 1000 C per Pa change under atmospheric pressure conditions? The molar enthalpy of vaporization is 40.69 kJ mol-1, the molar volume of liquid water is 0.019 x 10-3 m3 mol-1, and the molar volume of steam is 30.199 x 10-3m3 mol-1, all at 1000 C and 1.01325 bar. (Hint: change in temperature per change in pressure)
Answer:
The answer is [tex]\frac{dT}{dP} = 2.84*10^{-4}\ K/Pa[/tex]
Explanation:
From the question we are told that
The boiling point of water is [tex]T_b = 100^oC = 100 + 273 = 373 \ K[/tex]
The enthalpy of vaporization is [tex]\Delta H_{vap} = 40.69 \ kJ mol-1 = 40.69 *10^{3} \ J/mol[/tex]
The molar volume of liquid water is [tex]V =0.019 * 10^{-3} m^3 mol^{-1}[/tex]
The molar volume of steam is [tex]V_s = 30.199 * 10^{-3} \cddot m^3\cdot mol^{-1}[/tex]
The pressure is [tex]P = 1.01325 \ bar[/tex]
Gnerally from Clausius Clapeyron equation we have that
[tex]\frac{dP}{dT} = \frac{\Delta H_{vap}}{ T * \Delta V}[/tex]
Here [tex]\Delta V = V_s - V[/tex]
=> [tex]\Delta V = [30.199 * 10^{-3} ] - [ 0.019 * 10^{-3}][/tex]
=> [tex]\Delta V = [30.199 * 10^{-3} ] - [ 0.019 * 10^{-3}][/tex]
=> [tex]\Delta V = 0.03018 \ m^3 mol^{-1}[/tex]
So
[tex]\frac{dP}{dT} = \frac{40.69 *10^{3} }{ 373 * 0.03018}[/tex]
=> [tex]\frac{dP}{dT} = 3522.28 \ Pa/K[/tex]
Generally from the we are ask to obtain the change in the boiling point of water at 1000 C per Pa change under atmospheric pressure conditions which is mathematically represented as
[tex]\frac{d T}{dP}[/tex]
So
[tex]\frac{dT}{dP} = \frac{1}{\frac{dP}{dT} } = \frac{1}{3522.28}[/tex]
=> [tex]\frac{dT}{dP} = \frac{1}{\frac{dP}{dT} } = 2.84*10^{-4}\ K/Pa[/tex]
WILL mark Brainliest
Answer:
Ok what question
Explanation:
3. Which of the following most likely describes an isotope? *
O a. Oxygen with 27 electrons.
b. Neon with 10 protons.
O c. Fluorine with 35 neutrons.
O d. Lithium with an atomic mass of 7 amu.
What step will be most effective for a manufacturer that wants to reduce the human costs of extracting the minerals it uses in its smartphones?(1 point)
committing to only mining minerals in the United States
decreasing the prices of its products
switching to using gold instead of tungsten in its products
verifying that child labor was not used in mining these minerals
Please Help ASAP
If you are given 22.990 g of sodium and 12.011 g of carbon, which sample do you expect to have more particles?
Answer:
they are expected to have the same particles because their masses are the same with there molar mass
Which element has more metallic properties?
Lead or Germanium
lead has more metallic properties
What is the mean of the data set [3, 2, 2, 12, 6, 5, 14,4)?
O2
O 7
Answer:
the mean is 6 but you don't have that as an option.
Explanation:
the mean is the average.
to find the mean you have to add all of your data first
3 + 2 + 2 + 12 + 6 + 5 + 14 + 4 = 48
then you have to divide your answer by how many numbers there are in total.
48 / 8 = 6
the mean is 6.
Write the balanced chemical equation for the decomposition of sulfur trioxide to sulfur dioxide and
oxygen.
Answer:
The balanced equation is 2SO2+O2→2SO3 .
What does the presence of a polar covalent bond show about the electronegativity of its two atoms
Answer:
The electronegative of two atoms are not equal.
Explanation:
6-36. Calculate [H ] and pH for the following solutions: (a) 0.010 M HNO 3 (b) 0.035 M KOH (e) (c) 0.030 MHCl
Answer:
a)2
b)12.5
c)1.5
Explanation:
a)
pH = -log [H^+]
pH = -log [0.01]
pH = 2
b)
pOH = -log[OH^-]
pOH = -log [0.035]
pOH= 1.5
But
pH + pOH = 14
pH = 14 - pOH
pH= 14 - 1.5
pH = 12.5
c)
pH = -log[H^+]
pH= -log[0.030]
pH = 1.5
A non polar covalent bond (pure covalent) would form in which of the following pairs of atoms?
A.) H-Cl
B.) Se-Br
C.) Na-Cl
D.) Br-Br
The sulfuric acid–catalyzed reaction of isopentyl alcohol with acetic acid to form isopentyl acetate is performed. This reaction does not proceed to completion. After the reaction is heated under reflux for an hour, the product mixture is washed with aqueous sodium bicarbonate solution, and the organic layer is thoroughly dried. A distillation of the organic layer is then performed. Given the boiling points listed below, select the compound that will distill first.
Compound Boiling point, ℃
acetic acid 118
isopentyl acetate 142
isopentyl alcohol 130
sulfuric acid water 290
Answer:
The correct option is acetic acid
Explanation:
Distillation is the process of separating a mixture of substances based on differences in boiling points. During distillation, the compound with the lowest/least boiling point is distilled and collected first and then the one with the next least boiling point and it goes on like that.
From the explanation above, acetic acid has the least boiling point (in the organic layer) with 118°C and thus will distill first. This is then followed by isopentyl alcohol (130°C) and then isopentyl acetate (142°C) and finally sulfuric acid water (290°C).
How is light emitted
Answer:
The frequencies of light that an atom can emit are dependent on states the electrons can be in. When excited, an electron moves to a higher energy level or orbital. When the electron falls back to its ground level the light is emitted.
Answer:
A Light is produced when an electron moves from a higher to a lower energy level.
Explanation:
How many atoms of N (nitrogen) are there in 1 mole of NH4Cl?
Answer:
In one mole of NH₄Cl 6.022 × 10²³ atoms of N are present.
Explanation:
Given data:
Number of atoms of N = ?
Number of moles of NH₄Cl = 1 mol
Solution:
First we have to calculate the number of atoms in NH₄Cl .
There is only 1 mole of N in 1 mole of NH₄Cl .
Now we will calculate the number of atoms of nitrogen in one mole of N by using Avogadro number.
It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.
The number 6.022 × 10²³ is called Avogadro number.
1 mole of N = 6.022 × 10²³ atoms of N
Thus in one mole of NH₄Cl 6.022 × 10²³ atoms of N are present.