A freshly prepared sample of radioactive isotope has an activity of 10 mCi. After 4 hours, its activity is 8 mCi. Find: (a) the decay constant and half-life T1/2; (b) How many atoms of the isotope were contained in the freshly prepared sample? (c) What is the sample's activity 30 hours after it is prepared?
Answer:
(a). The decay constant is [tex]1.55\times10^{-5}\ s^{-1}[/tex]
The half life is 11.3 hr.
(b). The value of N₀ is [tex]2.38\times10^{11}\ nuclei[/tex]
(c). The sample's activity is 1.87 mCi.
Explanation:
Given that,
Activity [tex]R_{0}=10\ mCi[/tex]
Time [tex]t_{1}=4\ hours[/tex]
Activity R= 8 mCi
(a). We need to calculate the decay constant
Using formula of activity
[tex]R=R_{0}e^{-\lambda t}[/tex]
[tex]\lambda=\dfrac{1}{t}ln(\dfrac{R_{0}}{R})[/tex]
Put the value into the formula
[tex]\lambda=\dfrac{1}{4\times3600}ln(\dfrac{10}{8})[/tex]
[tex]\lambda=0.0000154\ s^{-1}[/tex]
[tex]\lambda=1.55\times10^{-5}\ s^{-1}[/tex]
We need to calculate the half life
Using formula of half life
[tex]T_{\dfrac{1}{2}}=\dfrac{ln(2)}{\lambda}[/tex]
Put the value into the formula
[tex]T_{\dfrac{1}{2}}=\dfrac{ln(2)}{1.55\times10^{-5}}[/tex]
[tex]T_{\dfrac{1}{2}}=44.719\times10^{3}\ s[/tex]
[tex]T_{\dfrac{1}{2}}=11.3\ hr[/tex]
(b). We need to calculate the value of N₀
Using formula of [tex]N_{0}[/tex]
[tex]N_{0}=\dfrac{3.70\times10^{6}}{\lambda}[/tex]
Put the value into the formula
[tex]N_{0}=\dfrac{3.70\times10^{6}}{1.55\times10^{-5}}[/tex]
[tex]N_{0}=2.38\times10^{11}\ nuclei[/tex]
(c). We need to calculate the sample's activity
Using formula of activity
[tex]R=R_{0}e^{-\lambda\times t}[/tex]
Put the value intyo the formula
[tex]R=10e^{-(1.55\times10^{-5}\times30\times3600)}[/tex]
[tex]R=1.87\ mCi[/tex]
Hence, (a). The decay constant is [tex]1.55\times10^{-5}\ s^{-1}[/tex]
The half life is 11.3 hr.
(b). The value of N₀ is [tex]2.38\times10^{11}\ nuclei[/tex]
(c). The sample's activity is 1.87 mCi.
In a food chain, consumers gather energy by _______. a. consuming organisms at a lower trophic level b. consuming organisms at a higher trophic level c. decomposing dead organic matter d. absorbing sunlight directly Please select the best answer from the choices provided A B C D
Answer:
a. consuming organisms at a lower trophic level.
Explanation:
A food chain shows how various organisms are related to each other as per the food they eat. Each level of a food chain refers to a distinct trophic level.
Food chain is basically related to transfer of matter and energy from organism to organism in the form of food.
In a food chain, consumers gather energy by consuming organisms at a lower trophic level
Answer:
a. consuming organisms at a lower trophic level.
Explanation: took the unit test
witch element is the most prevalent in the human body a)nitrogen,b)hydrogen,c)carbon,d)oxygen
I will give you more points if you want!!! :)
But first please answer the following question!
Answer:
thank you very much for giving me points.
Explanation:
I really appreciate it so muchhhhh so muchhhh thanks again
matter makes up all ? and ?
which other team sport basketball is the most like.
hi
Answer: mmm... If you mean most like Basketball it's net ball but i don't know much about Basket ball teams
Explanation:
Giving brainlist so plz help
What were John Locke's 3 big ideas
A. Natural rights, consent of the people, and moral obligation to rebel.
OR
B. Life, Liberty, and property
Answer:
Among these fundamental natural rights, Locke said, are "life, liberty, and property." Locke believed that the most basic human law of nature is the preservation of mankind. To serve that purpose, he reasoned, individuals have both a right and a duty to preserve their own lives.
Explanation:
From Google
Can I have brainliest
Write a brief summary of table tennis or tennis
Answer:
A point is won by a player when the opponent cannot hit the ball with a racket over the net and onto the other side of the table. Each game is won by being the first player to win 11 points, and be at least 2 points ahead of their opponent. The equipment needed to play table tennis would be a table, rackets, and balls. Some of the rules are no hand-on table (even leaning your hands on the table is not allowed!) Also, if the ball hits the net, you have to serve again.
Most _________ rely on sellers offering their goods or services in exchange for money from buyers
Answer:
Businesses
Explanation:
I think not sure tho
A chestnut-colored horse mates with a white-colored horse to produce a roan-colored offspring. What type of inheritance pattern does this genetic expression represent? A. Artificial selection B. Codominance C. Incomplete dominance D. Multiple alleles E. Polygenic inheritance
Answer:
The correct option is B.
Codorminance.
Explanation:
The type of inheritance pattern is codorminance because in codorminance the two alleles in the gene are expressed, no allele was able to masked the express on the other allele. The chestnut colored horse allele is expressed likewise the white
colored allele too is expressed none of the two alleles mask the Expression of the other, the two are expressed to give offsprings roan colored which is an indication of the two expression.
Answer:
Codominance
Explanation:
Calculate the slope of the line on the graph.
Answer: 5
Explanation: rise over run. 25/5 = 5
state the various use of a periscope
Answer:
the periscope is an instrument for observation over, around or through the object, obstacle or condition that prevents direct line-of-sight observation from the observer's current position.
Explanation:
the periscope is used to monitor the dangerous chemical reactions in the laboratory and they are used in observing the nuclear.
Answer:
A periscope is used to see objects over the heads of a crowd.It is used by soldiers sitting in a bunker to observe and view the opponents' activities over the ground.It is used by a navy officer sitting in a submarine to see ships over the surface of the water in the sea.It is also useful in submarines to determine the distance of the torpedo and decide the right time for an attack.4. A cylindrical tube has a length of 14.4cm and a radius of 1.5cm and is filled with a colorless gas. If the density of the gas is known to be 0.00123g/cm', what is the mass of the gas in the tube in mg?
Answer:
Mass, m of gas is 0.2504 grams.
Explanation:
First, we need to solve for the volume of the cylindrical tube.
Volume of cylinder is given by the formula;
[tex] V = 2\Pi r^{2}h[/tex]
Where, V represents volume.
π represents pie
r represents radius.
h represents height or length.
Given the following data;
Radius, r = 1.5cm
Length, h = 14.4cm
Density, d = 0.00123g/cm³
Substituting into the equation;
[tex] V = 2 * 3.142 * (1.5)^{2}14.4[/tex]
[tex] V = 2 * 3.142 * 2.25 * 14.4[/tex]
[tex] V = 203. 6016[/tex]
Therefore, the volume of the cylindrical tube is 203. 6016cm³
Density can be defined as mass all over the volume of an object.
Simply stated, density is mass per unit volume of an object.
Mathematically, density is given by the formula;
[tex]Density = \frac{mass}{volume}[/tex]
[tex] Mass = density * volume [/tex]
Substituting into the equation, we have;
[tex] Mass = 0.00123 * 203. 6016 [/tex]
Mass = 0.2504g.
A rocket is fired vertically upwards with initial velocity 92 m/s at the ground level. Its engines then fire and it is accelerated at 4m/s2 until it reaches an altitude of 1200 m. At that point the engines fail and the rocket goes into free-fall. Disregard air resistance.
Answer:
The rocket above the ground is in 44 sec.
Explanation:
Given that,
Initial velocity = 92 m/s
Acceleration = 4 m/s²
Altitude = 1200 m
Suppose, How long was the rocket above the ground?
We need to calculate the time
Using equation of motion
[tex]s=ut-\dfrac{1}{2}at^2[/tex]
Put the value into the formula
[tex]1200=92t+\dfrac{1}{2}\times4t^2[/tex]
[tex]2t^2+92-1200=0[/tex]
[tex]t=10\ sec[/tex]
We need to calculate the velocity
Using equation of motion
[tex]v=u+at[/tex]
Put the value into the formula
[tex]v=92+4\times10[/tex]
[tex]v=132\ m/s[/tex]
When the rocket hits the ground,
Then, h'=0
We need to calculate the time
Using equation of motion
[tex]h'=h+ut-\dfrac{1}{2}at^2[/tex]
Put the value into the formula
[tex]0=1200+132t-\dfrac{1}{2}\times9.8t^2[/tex]
[tex]4.9t^2-132t-1200=0[/tex]
[tex]t=34\ sec[/tex]
When the rocket is in the air it is the sum of the time when it reaches 1000 m and the time when it hits the ground
So, the total time will be
[tex]t'=34+10[/tex]
[tex]t'=44\ sec[/tex]
Hence, The rocket above the ground is in 44 sec.
A racehorse coming out of the gate accelerates from rest to a velocity of 12.0
m/s due west in 2.30 s. What is its average acceleration?
27.6 m/s^2
5.22 m/s^2
-5.22 m/s^2
-27.6 m/s^2
-0.19 m/s^2
O 0.19 m/s^2
Answer:
5.22 m/s²
Explanation:
From the question given above, the following data were obtained:
Initial velocity (u) = 0 m/s
Final velocity (v) = 12 m/s
Time (t) = 2.3 s
Acceleration (a) =.?
Acceleration is defined as the change of velocity with time. Mathematically, it is expressed as:
Acceleration (a) = final velocity (v) – initial velocity (u) / time (t)
a = (v – u) /t
With the above formula, we can obtain the acceleration of the racehorse as follow:
Initial velocity (u) = 0 m/s
Final velocity (v) = 12 m/s
Time (t) = 2.3 s
Acceleration (a) =.?
a = (v – u) /t
a = (12 – 0) / 2.3
a = 12 /2.3
a = 5.22 m/s²
Therefore, the average acceleration of the racehorse is 5.22 m/s²
Describe a circumstance where you want friction to work against Newton’s First Law.
Answer:
If I was riding my bicycle, and there was no friction to work against Newton's First Law, I'd give a first push, and I would never be able to turn or stop.
Explanation:
When the white ball strikes the other colored balls, what can you say about the total momentum of all of the balls combined?
Momentum is never created or destroyed. It is conserved.
The cue stick gave the cue ball all the momentum there is on the table. There's nothing on the table that can pour in any more momentum.
After the strike, with 15 or 16 balls rolling every which way around the table, the total momentum of all of them combined will be the same as the cue ball's momentum right now, before the strike.
Help mee what molecule is this
how am I supposed to know
The gradual change in a species over time is called
a.
mutation.
b.
evolution.
c.
migration.
d.
variation.
PLZ HURRY WILL GIVE BRAINLIEST
Answer: B. Evolution
Explanation:
As species grow older over time they will gradually evolve through natural selection and evolution.
The gradual change in a species over time is known as evolution (b).
The process of evolution occurs through several mechanisms, including mutation, migration, and natural selection.
Mutation (a) is the spontaneous change in the genetic material of an organism. These changes can result in new traits that may be advantageous, disadvantageous, or neutral for survival. When mutations occur, they can introduce genetic variation within a population, which serves as the raw material for evolution.
Natural selection is a crucial factor driving evolution. Individuals with advantageous traits that better suit their environment are more likely to survive and reproduce, passing on these advantageous traits to their offspring. Over generations, the frequency of beneficial traits increases in the population, leading to the adaptation and evolution of the species.
Variation (d) encompasses the differences in physical traits and genetic makeup among individuals within a population. This variation is essential for evolution to occur since it provides the raw material for natural selection to act upon.
To know more about species here
https://brainly.com/question/9506161
#SPJ6
witch of the following questoons would you expect to see on an interest inventory
Answer: Do you like science experiments ? 1)
Would You enjoy reading a fashion magazine? 2)
Explanation:
What must be true for a hypothesis to become generally accepted by
scientists?
A. It must involve lots of complicated math.
B. It must have been tested by many scientists.
O O O O
C. It must be presented by a famous scientist.
D. It must be proven true by one experiment.
Answer:
B It must have been tested by many scientists.
Explanation:
trust me :)
For a hypothesis to become generally accepted by scientists, It must have been tested by many scientists. Hence option B is correct.
What is hypothesis ?A hypothesis is a theory put up to explain a phenomena. A hypothesis must be testable according to the scientific method for it to be considered a scientific hypothesis. Scientific hypotheses are often based on prior findings that cannot be adequately explained by the current body of knowledge. Despite the fact that the terms "hypothesis" and "theory" are sometimes used interchangeably, they are not the same thing. A working hypothesis is an acknowledged theory that has been tentatively supported and is put up for further investigation.
In formal logic, the term "hypothesis" is used to refer to the antecedent of a statement, or in the proposition, in a different sense.
Hence option B is correct.
To know more about hypothesis :
https://brainly.com/question/29519577
#SPJ5.
Cacao beans arrive in a factory from the areas where they grew. At the factory, the best beans are sorted and put into bags. After quality-control workers check the bags, a large truck transports the cacao beans to a commercial chocolate-producing company. Which organelle plays a similar role inside a cell?
A. cytoplasm
B. Golgi body
C. mitochondrion
D. ribosome
E. vacuole
Answer:
B. Golgi body
Explanation:
The Golgi body is the region where proteins are modified, packaged, and transported to the appropriate location, usually outside of the cell.
The cytoplasm is the intracellular fluid/space, the mitochondrion produces energy, the ribosome produces proteins, and the vacuole is a storage organelle.
The Answer is B , Because the golgi body stores stuff for later use.
hope this helps
What groups of animals are heterotrophs?
a.) herbivores
b.) carnivores
c.) omnivores
d.) all the above
Answer:
All of the above.
Explanation:
As a review, remember that carnivores eat other animals and omnivores eat both plants and animals. There is yet another term used when talking about food chains, the word heterotroph. Anything that is not an autotroph is a heterotroph. The word means “other feeding” or feed off of others.
What theory explains the main cause of mountain building, earthquakes, and volcanic eruptions on Earth?
Group of answer choices
the scientific theory of Earth's shift
the scientific theory of magnetism
the scientific theory of Earth's layers
the scientific theory of plate tectonics
Answer:the scientific theory of plate tectonics I believe
Explanation:
An object has an acceleration of 6m/s/s. If the net force was tripled and the mass was doubled, then the new acceleration would be
What are the SI units for distance and time?
Answer:
distance is meters, time is seconds
Answer:
distance is meters(m)
time is seconds (s)
Explanation:
list 3 lessons we learned from history to handle pandemic
Answer:
1- impact
2. Inequalities
4. Controllability
Explanation:
Why does sound travel slower at a cold temperature?
Sound moves faster in warmer air than colder air the way bends away from the warm air and back towards of air.
Answer:
Sound travels slower in cold temperatures than in hot temperatures because the particles in cold air are more closely compacted together and move slower compared to the particles of hot air. Thus the sound, vibrations of particles in the atmosphere, will travel slower.
What is the design process (Engineering Design Process) 5 sentences
what are three effects of using only non-renewable resources? please help