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.
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
Identify 3 pieces of safety equipment commonly found in the science lab.
Answer: googles, fire extinguisher, fire blanket
Explanation:
PLEASE HELP ME ASAP!
Which of the following elements has the highest electronegativity?
A. Ar
B. Ga
C. Ag
D. S
Answer:
its S
Explanation:
1. What is the mass of a rock that has a density of 2.5 grams per cubic centimeter and a volume of 4.0
cubic centimeters?
What is the mass
Answer:
Explanation:
d =
m
V
m = d×V
V =
m
d
DENSITY
Density is defined as mass per unit volume.
d =
m
V
Example:
A brick of salt measuring 10.0 cm x 10.0 cm x 2.00 cm has a mass of 433 g. What is its density?
Step 1: Calculate the volume
V = lwh = 10.0 cm × 10.0 cm × 2.00 cm = 200 cm³
Step 2: Calculate the density
d =
m
V
=
433
g
200
c
m
³
= 2.16 g/cm³
MASS
d =
m
V
We can rearrange this to get the expression for the mass.
m = d×V
Example:
If 500 mL of a liquid has a density of 1.11 g/mL, what is its mass?
m = d×V = 500 mL ×
1.11
g
1
m
L
= 555 g
VOLUME
d =
m
V
We can rearrange this to get the expression for the volume.
V =
m
d
Example:
What is the volume of a bar of gold that has a mass of 14.83 kg. The density of gold is 19.32 g/cm³.
Step 1: Convert kilograms to grams.
14.83 kg ×
1000
g
1
k
g
= 14 830 g
Step 2: Calculate the volume.
V =
m
d
= 14 830 g ×
1
c
m
³
19.32
g
= 767.6 cm³
The mass of rock is 10 g.
We have sample of rock.
We have to determine its mass.
How is density and mass of body related ?The density and mass of body are related as follows -
D = M / V
where -
V - volume of the body.
M - mass of the body.
D - density of the body.
According to the question →
Using the formula discussed above -
D = M / V
M = D x V
M = 2.5 x 4 = 10 g
Hence, the mass of rock is 10 g
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Calcium reacts with oxygen to make calcium oxide, CaO. What is the theoretical yield (g) of CaO(s) that could be prepared from 7.75 g of Ca(s) and 2.44 g of O2(g)
Answer:
Explanation:
2Ca + O₂ = 2CaO
80 g 32 g 112 g
given amount of Ca = 7.75 g
it will require oxygen = 32 x 7.75 / 80 = 3.1 g
but available oxygen = 2.44 so oxygen is the limiting reagent .
32g oxygen reacts with calcium to give 112 g of calcium oxide
2.44 gram of oxygen reacts with calcium to give 112 x 2.44 / 32 of CaO .
= 8.54 gram .
Theoretical yield of CaO = 8.54 gram.
please help me i don’t know the answer to this!!!!!!
Answer: Lithium and Ethanol
Explanation: As lithium and ethanol both have a density of under
1.000g/ml, they can be supported by the water. Blood and Magnesium are denser than the water and will therefore sink as the water can not support it them.
Help me this, I only have 10 minutes to answer!!!!
Answer:sedimentary
Explanation:
1.What do you call the rate of doing work?
A. Energy
B. Time
C.Power
D. Work
2.What is the unit of power?
A. Joule
C. Newton
B. Second
D. Watt
3.How much power is required to lift a 30ON chair, as high as 0.20 in 2s?
A.1 W
C. 3 W
B. 7W
D. 15 W
4.How much power is required to raise a 30 kg crate with a vertical distance of 6m in a time of 4
Seconds?
A. 45 WV
C 52.5 W
B. 385 W
D. 441 W
5. A job is done slowly, and an iden tical job is done quickly. Both jobs require the same amount of_______
but different amounts of_________
A. energYy, work
B. work, energy
Choose the correct two words respectively.
C. power, work
D. work, power
6.What is work?
A. Force muitiplied by time
C. Force multiplied by distance
B. Force per unit of time
D. Force divided by distance
7.What is the unit of work?
A Joule
B. Second
C. Newton
D. Watt
8.Power can be increased by______
A. decreasing the force applied by an object.
B. decreasing the work done on the object
C.inereasing the time in which the work is done.
D. decreasing the time in which the work is done.
Please help
Answer:
1. c
2. d
3. c
4. d
5.
6. a
7. a
8.
A chef fills a 60 mL container with 52.2 g of cooking oil. What is the density of the oil?
Answer:
The answer is 0.87 g/mLExplanation:
The density of a substance can be found by using the formula
[tex]density = \frac{mass}{volume} \\ [/tex]
From the question we have
[tex]density = \frac{52.2}{60} \\ [/tex]
We have the final answer as
0.87 g/mLHope this helps you
1. A camper named Bob ran into aliens on a trail. Bob made friends with the aliens so he could
steal their treasure of 1 zygot.
1 zygot = 3 trigots
3 trigots = 2 bigots
4 bigots = 1 gram gold
How many grams of gold did Bob take from the aliens?
Answer : The number of grams of gold Bob take from the aliens will be 0.5.
Explanation :
As we are given that:
1 zygot = 3 trigots
3 trigots = 2 bigots
4 bigots = 1 gram gold
Now we have to determine the number of grams of gold Bob take from the aliens.
The number of grams of gold Bob take from the aliens will be equal to:
[tex]\frac{1\text{ zygot}}{1}\times \frac{3\text{ trigots }}{1\text{ zygot}}\times \frac{2\text{ bigots }}{3\text{ trigots }}\times \frac{2\text{ gram gold}}{4\text{ bigots }}[/tex]
= [tex]\frac{6}{12}[/tex] gram gold
= [tex]\frac{1}{2}[/tex] gram gold
= 0.5 gram gold
Hence, the number of grams of gold Bob take from the aliens will be 0.5.
What is the unbalanced force on a 1/2 kg object that causes it to accelerate 3 m/s2 to the right
Answer:
The answer is 1.5 NExplanation:
The force acting on an object given it's mass and acceleration can be found by using the formula
force = mass × accelerationFrom the question we have
force = 0.5 × 3
We have the final answer as
1.5 NHope this helps you
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 protons does Hydrogen contain?
Answer:
1
Explanation:
1. Which of the following pairs of elements is most likely to share one or more pairs of electrons between
their nuclei?
a. Lithium and iodine
b. Sodium and lead
c. Copper and oxygen
d. Sulfur and chlorine
Answer:
d. Sulfur and chlorine.
Explanation:
A covalent bond is formed by two non-metals with similar electronegativities. As a consequence, they share one or more pairs of electrons between their nuclei.
Which of the following pairs of elements is most likely to share one or more pairs of electrons between their nuclei?
a. Lithium and iodine. NO. Lithium is a metal and iodine a non-metal.
b. Sodium and lead. NO. Both sodium and lead are metals.
c. Copper and oxygen. NO. Copper is a metal and oxygen is a non-metal.
d. Sulfur and chlorine. YES. Both are non-metals.
If a feather and in Marble are dropped at the same time from the same height explain. Which object would hit the floor first based on air resistance?
Answer:
the marble would hit the floor first because the feather would be effected by air resistance
Which statement best Describe the people in Mississippi period
Answer:Explanation:
The statement that best describes the people of the Mississippian Period is that they were farmers who used simple tools to grow their food in small gardens. They would also fish and gather food such as muscles, in order to create a large enough food supply in addition to produce from these gardens and farms.
what is the relationship between netforce and acceleration based on the situation?
Answer:
The net force is greater at the second situation as well as the acceleration due to the contribution of the second guy.
Explanation:
Hello.
In this case, since the net force is computed via adding all the exerted forces on a body, for the first situation we can see that the net force equals the force provided by that guy when pulling, whereas in the second situation the net force equals the force of both of the guys pulling the car:
[tex]F_N_1=F_1\\\\F_N_2=F_1+F_2[/tex]
For the acceleration, we can see that applying an extra force (due to the second guy) turns out into a greater acceleration, that is why the car at the second situation reaches the tree whereas the other one does not.
Best regards.
Please helpppp!!!!!! It's 6th-grade thermal energy science.
Answer:
b?
Explanation:
The answer is C: Radiant energy from the sun travels through the glass, is absorbed by the black pot, and reflected by the aluminum foil.
How many grams of Al are needed to react with 91.8 grams of FeO
3FeO + 2Al —> 3 Fe +Al2O3
Answer:
Ans : 22.86 gm of Aluminium
Solution,
3FeO + 2Al ---> 3 Fe + [tex]Al_{2}O_{3}[/tex]
Given 3 2
Find 1.27 x
By the given gms of FeO find its mole and put the moles in the find,
[tex]n = \frac{given mass}{molecular mass}[/tex]
Given mass of FeO is 91.8
Molecular mass of FeO is 71.8
n = [tex]\frac{91.8}{71.8}[/tex]
n = 1.27 moles of FeO
Now solve for x,
[tex]x = \frac{2 x 1.27}{71.8}[/tex]
x = 0.85 moles
These are just moles of Aluminium that we need to react with FeO, so to find Grams of Aluminium we need,
Mass = moles x molecular mass
Mass = 0.85 x 27(atomic mass of Al)
Mass = 22.86 grams of aluminium is what we need
Which part of a flower can make eggs
Answer:Within the flower, sperm cells are produced by pollen at the tips of stamens, while egg cells develop in ovules, tiny structures embedded in the ovary at the base of the pistil.
I didn't realize the person up top had the same answer give them the brainliest! :)
The force of 20 N acts upon a 5kg block. What is the acceleration of the block?
100 m/s/s
4 m/s/s
O 25 m/s/s
O 0.25 m/s/s
Answer:
The answer is 4 m/s²Explanation:
The acceleration of an object given it's mass and the force acting on it can be found by using the formula
[tex]a = \frac{f}{m} \\ [/tex]
where
a is the acceleration
f is the force
m is the mass
From the question
f = 20 N
m = 5 kg
We have
[tex]a = \frac{20}{5} \\ [/tex]
We have the final answer as
4 m/s²Hope this helps you
what always forms between two large air masses of different moisture and air temperature?
Answer:
"What always forms between two large air masses of different moisture and air temperature?"
Explanation:
When a cold air mass replaces a warm air mass the boundary between the two air masses is called a cold front. ... Fronts form at the boundary between air masses of different temperatures and moisture. Warm air always slopes upward over colder air.
The boundary between two air masses of different density such when it can not move called “stationary” “warm” when warmer air replaces cooler air.
What is density ?The density can be defined as the mass per unit volume which means that it is the ratio between mass and volume, that means the object has the stuff in a unit volume.
Density is determined by the matter where it shows how the matter is tightly crammed together and it was put forwarded by the Greek scientist Archimedes
To calculate the density of an object, the mass (m) can be divided by the volume (v)
Density = Mass/Volume
The different units include SI unit of density which is kilogram per cubic meter (kg/m3) or in cgs unit of grams per cubic centimeter (g/cm3).
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Which elements is the most reactive on this table?
Answer:
alkali metals
Explanation:
alkali metals only have one valence electron, meaning they are extremely reactive. they are considered the most reactive on the periodic table.
i need help please help me now please
Which of the following substances will dissolve in water? Check all that apply.
Magnesium Sulfate
Methane
Butane
Sodium nitrate
Answer:
The answers are A. and D.
According to the concept of solubility and properties of ionic compounds, magnesium sulfate and sodium nitrate dissolve in water.
What is solubility?Solubility is defined as the ability of a substance which is basically solute to form a solution with another substance. There is an extent to which a substance is soluble in a particular solvent. This is generally measured as the concentration of a solute present in a saturated solution.
The solubility mainly depends on the composition of solute and solvent ,its pH and presence of other dissolved substance. It is also dependent on temperature and pressure which is maintained.Concept of solubility is not valid for chemical reactions which are irreversible. The dependency of solubility on various factors is due to interactions between the particles, molecule or ions.
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Velocity is
is a given
O distance, time
O speed, displacement
O speed, direction
3. What noble gas would be part of the electron configuration notation for Mn?
Answer:
Argon {Ar}
Explanation:
The noble gas used for a condensed electron configuration is the one before the element which you are configuring.
In this case, the element (Mn) is manganese
The noble gas that is before this element is Argon which is the row above it
so your configuration would be {Ar} 3d^5 4s^2
If the reaction yield is 88.2%,what mass in grams of hydrogen is produced by the reaction of 7.73 g of magnesium with 1.31 g of water
Mg + 2h2o >>mg(oh)2+h2
Answer:
Mass of hydrogen produced is 0.07g.
Explanation:
Given data:
Mass of magnesium = 7.73 g
Mass of water = 1.31 g
Reaction yield = 88.2%
Mass of hydrogen produced = ?
Solution:
Chemical equation:
Mg + 2H₂O → Mg(OH)₂ + H₂
Number of moles of water:
Number of moles = mass/ molar mass
Number of moles = 1.31 g / 18 g/mol
Number of moles = 0.07 mol
Number of moles of magnesium:
Number of moles = mass/ molar mass
Number of moles = 7.73 g / 18 g/mol
Number of moles = 0.43 mol
Now we will compare the moles of water and magnesium with hydrogen.
Mg : H₂
1 : 1
0.43 : 0.43
H₂O : H₂
2 : 1
0.07 : 1/2×0.07 = 0.035
Mass of hydrogen:
Mass = number of moles × molar mass
Mass = 0.035 mol × 2 g/mol
Mass = 0.07 g
Answer: 0.064 grams is the answer
Explanation:
at the end you must multiply 88.2/100*0.073=0.064
An enzyme can catalyze a reaction with either of two substrates, S1 or S2. The Km for S1 was found to be 2.0 mM, and the Km, for S2 was found to be 20 mM. A student determined that the Vmax was the same for the two substrates. Unfortunately, he lost the page of his notebook and needed to know the value of Vmax. He carried out two reactions: one with 0.1 mM S1, the other with 0.1 mM S2. Unfortunately, he forgot to label which reaction tube contained which substrate. Determine the value of Vmax from the results he obtained:
Tube number: 1
Rate of formation of product:0.5
Tube number: 2
Rate of formation of product: 4.8
Answer:
100.5 ≈ 101
Explanation:
Km for S1 = 2.0 mM
Km for S2 = 20 mM
Given that : S1 = S2 = hence Vmax for either S1 or S2 can represent
The Vmax can be calculated using the data Given and equation below
Vo = Vmax [s] / ( Km + [s] ) ------ (1)
Vo = 0.5
[s] = 0.1 mM
km = 20 mM
making Vmax subject of equation 1
Vmax = 0.5 ( 20.1 mM) / (0.1 mM )
= 100.5 ≈ 101
How much space does 2 x 1022 atoms of copper take up?
How much space do 2 x 1022 copper pennies take up, using examples from the animation?
Answer:
2044
Explanation: