a 150- mgmg sample of technetium-99 mm is used for a diagnostic test. if technetium-99 mm has a half-life of 6.0 hh , 19 milligrams of the technetium-99 mm sample remains active 18 hh after the test.
Decay of radioactive substances follows first-order kinetics. First order rate equation is A = Ao e-kt. Ao = Intial active amount of substances .
A = Active amount of substance after certain time (t), K = Decay constant. k = ln2 / t½, k = 0.693 / 6.0 hr, k = 0.1155 / hr. A = Ao e-kt A = 150 mg x e-0.1155 hr?¹ x 18.0 hr. A = 18.758 mg.So Answer = 19 g of remains active 18 h after the test.The half-life of a quantity is the time it requires to decrease to half of its original value. In nuclear physics, the term is usually used to describe how rapidly atoms undergo radioactivity or how long stable atoms live. The term is also used to describe any kind of exponentially decaying in general.
Learn more about half-life here:
https://brainly.com/question/24710827
#SPJ4
Explain how you find the instantaneous speed or velocity of an object
I dont want to know WHAT it is I want to know HOW to find it
Answer:
divide the distance by the average
Explanation:
ash QC ok
A sample of chromium oxide is 76.5hromium by weight. what is the simplest formula of the oxide?
CrO and Cr₂O₃ make up the simplest chromium oxide formula.
What name does Cr₂O₃ use?
Chromium oxide (Cr₂O₃)sometimes referred to as chromium sesquioxide or chromic oxide, is a compound in which chromium is oxidized to a +3 state. Sodium dichromate is calcined with either carbon or sulfur to produce it.Eskolaite, a mineral that bears the name of the Finnish geologist Pentti Eskola, is a kind of chromium oxide green that may be found in nature. The metallic glassy green surface of this unusual material has an unsettling moss-like look that may be used to conceal oneself in the environment.Studies on humans have conclusively shown that chromium (VI) breathed is a potential carcinogen, increasing the likelihood of developing lung cancer. According to animal studies, chromium (VI) exposure by inhalation can result in lung cancers.Learn more about chromium here:
https://brainly.com/question/15588080
#SPJ4
A donut has a density of 0.75 g/cm cubed and a mass of 100.0g. What is the volume of the donut?
Answer:
133.333333333 cm^3
Explanation:
Volume = Mass/Density
a 275.0 ml sample of o2 is collected over water at 60.0oc. the total pressure is 755. torr. what is the volume of the o2 at stp? (the vapor pressure of water at 60.0oc is 149. torr).\
a 275.0 ml sample of o2 is collected over water at 60.0oc. the total pressure is 755 torr is
Ptot = PH20+ P02
P02 = 766-149 torr= 606 torr
V2 = 180ml
What is torr?
A torr is a unit of pressure based on an absolute scale, defined as exactly 1/760 of standard atmospheric pressure. Therefore, 1 Torr corresponds exactly to 101325/760 Pascals. Historically, torr was thought to be the same as "millimeter of mercury", but later he was redefined by the two units to be slightly different.
Therefore, Ptot = PH20+ P02
P02 = 766-149 torr= 606 torr
V2 = 180ml,
A torr is a unit of pressure based on an absolute scale, defined as exactly 1/760 of standard atmospheric pressure.
To learn more about torr refer the given link:-
https://brainly.com/question/13893899
#SPJ4
how many moles and numbers of ions of each type are present in the following aqueous solution? 76.3 ml of 1.55 m magnesium chloride:
the number of moles of MgCl2 in the given solution is 0.1184 moles and the number of ions of MgCl2 in the given solution is 0.2368 moles.
Given, The volume of the solution = 76.3 mL The concentration of the solution = 1.55 M The formula of magnesium chloride = MgCl2 Number of moles of MgCl2 = (Concentration of MgCl2 x Volume of solution in L)Number of moles of MgCl2 = (1.55 mol/L) x (76.3 mL/1000 mL/L) = 0.1184 moles Number of ions of MgCl2 = 2 ions per one formula unit * number of formula units= 2 * 0.1184 moles = 0.2368 moles (1 mole MgCl2 contains 2 moles of ions)Therefore, the number of moles of MgCl2 in the given solution is 0.1184 moles and the number of ions of MgCl2 in the given solution is 0.2368 moles.
To learn more about moles visit
brainly.com/question/30892840
#SPJ11
Which of the following transitions (in a hydrogen atom) represent absorption of the smallest frequency photon? A. n = 5 to n = 6 B. n = 1 to n = 3 C. n = 5 to n = 4 D. n = 1 to n = 2 E. n = 4 to n = 1
The smallest frequency photon corresponds to the smallest energy difference between the initial and final states. This energy difference is given by the formula E = hc/λ, where h is Planck's constant, c is the speed of light, and λ is the wavelength of the photon. Since frequency is inversely proportional to wavelength (ν = c/λ), the smallest frequency photon corresponds to the longest wavelength photon, which has the smallest energy.
Using the formula for the energy levels of hydrogen (E = -13.6 eV/n^2), we can calculate the energy differences for each transition:
A. n = 5 to n = 6: ΔE = (-13.6 eV/6^2) - (-13.6 eV/5^2) = 0.377 eV
B. n = 1 to n = 3: ΔE = (-13.6 eV/3^2) - (-13.6 eV/1^2) = 10.2 eV
C. n = 5 to n = 4: ΔE = (-13.6 eV/4^2) - (-13.6 eV/5^2) = 0.194 eV
D. n = 1 to n = 2: ΔE = (-13.6 eV/2^2) - (-13.6 eV/1^2) = 3.4 eV
E. n = 4 to n = 1: ΔE = (-13.6 eV/1^2) - (-13.6 eV/4^2) = 10.2 eV
From these calculations, we can see that the transition with the smallest energy difference (and hence the smallest frequency photon) is C. n = 5 to n = 4.
To know more about smallest frequency visit:-
https://brainly.com/question/31386030
#SPJ11
Which of the following extremophiles has evolved in conditions
of extreme drought or extreme salt, respectively?
Group of answer choices
halophile; xerophile
xerophile; thermophile
xerophile; psychrop
The extremophile that has evolved in conditions of extreme drought is the xerophile, while the extremophile that has evolved in conditions of extreme salt is the halophile.
Extremophiles are organisms that thrive in extreme environments, where most other life forms cannot survive. They have developed unique adaptations to withstand and thrive in these extreme conditions. Two types of extremophiles specifically adapted to different extreme environments are xerophiles and halophiles.
Xerophiles are extremophiles that have evolved to survive in conditions of extreme drought. They are adapted to environments with very low water availability or high water stress. These organisms have developed mechanisms to prevent water loss, such as efficient water retention and protection of cellular structures. Xerophiles can be found in desert environments and other arid regions.
On the other hand, halophiles are extremophiles that have evolved to live in conditions of extreme salt concentration. They are adapted to environments with high salinity, such as salt flats, salt lakes, and hypersaline environments. Halophiles have specialized adaptations to cope with the osmotic stress caused by high salt concentrations. They have enzymes and transport proteins that function in high-salt environments and can maintain osmotic balance within their cells.
In summary, xerophiles have evolved in conditions of extreme drought, while halophiles have evolved in conditions of extreme salt. These extremophiles showcase remarkable adaptations to thrive in their respective harsh environments.
To learn more about Extremophiles click here: brainly.com/question/30627815
#SPJ11
The more bonds an atom can make, the more likely it is to combine with other atoms in different ways Which element is most likely able to make the greatest variety of bonds? a. nitrogen b. hydrogen c. oxygen d. carbon
Answer:
D. Carbon.
Explanation:
Carbon can be mixed with Many things. for example, YOU are mostly made out of carbon. Other things include furniture, clothing, plastics, charcoal, pencil led, diamonds, and gas.
Answer:
b xplanation:
Question 6 of 10
What does it mean when a reaction is spontaneous?
O
A. The reaction requires added energy.
B. The reaction goes to completion.
C. The reaction occurs rapidly.
O O
D. The reaction happens by itself.
SUBMIT
Answer:
D
Explanation:
Does not require energy ...may be slow or fast....
What is the mass percent of nitrogen in NH4Cl?
Answer:
Explanation:I believe the mass percent of nitrogen in NH4Cl N H 4 C l is 26.19%. I might be right but I had this same question on my eoc
Answer:
So, 53.49 g (M) of NH4Cl N H 4 C l contains 14.01 g (m) of N . So, the mass percent of nitrogen in NH4Cl N H 4 C l is 26.19%.
Explanation:
the answer is 26.19%
WHAT IS NH4CH
It was reborn in the united states people used it for equants
Learn more: brainly.com/question/20838718
A substance such as a frozen sample of carbon dioxide, CO, does not melt into a liquid
form but rather transitions directly to vapor, a gas. This form of physical change is called?
Answer:heat caused an increase in gas production
Explanation:
You're paid $25 per hour for your job. How much would you earn in cents per second?
Answer:
0.694 cents per second
Explanation:
25x100=2500 cents per hour, 2500/60 = 41.67 per minute and 41.67/60=0.694 cents per second
WHOEVER ANSWERS FIRST GETS THE BRAINLIST
Answer:
Choose 2 identical plants. Put one in the dark and one near sunlight; use the same amount of water; water both regularly.
Explanation:
You want to keep everything the same except for one thing.
The ionization constant for water is 2.9x10-14 at 40°c. calculate (H3O+.) (OH), pH and pOH for pure water at 40°c.
Answer
O 1.7O3x10-7
O 1.7O3x10-7
O 6.7689
O 6.7689
Given that ionization constant of water (Kw) at 40°C is 2.9x10^-14 .
We need to calculate H3O+, OH-, pH and pOH for pure water at 40°C.
The ionization of water can be given as:
2H2O ⇌ H3O+ + OH-Kw = [H3O+][OH-]
Putting the values:Kw = [H3O+][OH-]2.9x10^-14 = [H3O+][OH-]
Let [H3O+] = [OH-]= x
∴ Kw = x2∴ x = √2.9x10^-14x = 1.7x10^-7mol/L
Hence, [H3O+] = [OH-] = 1.7x10^-7mol/LpH = -log[H3O+]pH = -log(1.7x10^-7)pH = 6.7689pOH = -log[OH-]pOH = -log(1.7x10^-7)pOH = 6.7689
Therefore, pH and pOH of pure water at 40°C are 6.7689.
Learn more about ionisation constant:
https://brainly.com/question/30639622
#SPJ11
Why we need to use the archetorien principle in lab report
This principle is important in laboratory reports because it can be used to determine an object's or material's density, which is an important physical property used in many applications.
The Archimedes' principle is a fundamental physics principle that states that the buoyant force acting on an object submerged in a fluid equals the weight of the fluid displaced by the object. It is critical to use the Archimedes' principle in a lab report to accurately and precisely determine the density of the object or material being studied. This principle provides a dependable and accurate method for calculating density, which is useful in many scientific and engineering fields. By including the Archimedes' principle in a lab report, you show that you considered all relevant factors and used appropriate methods to determine the physical properties of the materials being studied.
learn more about Archimedes' principle here:
https://brainly.com/question/787619
#SPJ4
do all of the glassware measure with the same degree of accuracy? explain
All of the glassware do not measure with the same degree of accuracy.
What is a glassware?A glassware is an apparatus that could be used for measurement. Most of the glassware are used for the measurement of fluids. In this case, we can see that the kinds of glass ware that could be used for measurement in the laboratory are; Burette, pipette, measuring cylinder etc.
The calibration of all the glassware are not the same, recall that there must always be a measure of uncertainty that goes with the instrument that is used in measurement.
Having known this, we can see that all of the glassware do not measure with the same degree of accuracy.
Learn more about laboratory glassware:https://brainly.com/question/14728750
#SPJ1
Which term names a metamorphic change in rocks over a wide area from tectonic forces in earth's crust and mantle?
The term that names a metamorphic change in rocks over a wide area from tectonic forces in Earth's crust and mantle is regional metamorphism.
Regional metamorphism occurs when rocks undergo significant changes due to high pressure and temperature over a large geographic area. This process is typically associated with the collision of tectonic plates or the subduction of one plate beneath another. As the rocks are subjected to immense pressure and heat, they undergo physical and chemical changes, resulting in the formation of new minerals and the transformation of existing ones. Regional metamorphism can lead to the formation of rocks such as gneiss, schist, and marble. It plays a crucial role in the creation of mountain ranges and the formation of new geological features.
In summary, regional metamorphism is the term used to describe the metamorphic changes that occur in rocks over a wide area due to tectonic forces in the Earth's crust and mantle.
Learn more about tectonics from the following link:
https://brainly.com/question/1162125
#SPJ11
presented with two tubes: one tube with a buffered solution + acid and one tube with water + acid, how will you know which tube has the buffer and which tube does not have the buffer?
One tube has a buffered solution + acid and the other tube has water + acid. To decide whether or not the solution is buffered, a simple pH test can be done. An acid-base indicator can be used to determine the pH of each solution.
A buffered solution is defined as a solution that can withstand minor changes in pH upon the addition of small amounts of an acid or base.
Consider the following steps:
To both tubes, add a small amount of acid-base indicator. Determine the pH of each solution by observing the color change of the acid-base indicator when it is added to it. The pH of the solution is determined by the color of the acid-base indicator after it has been added to it. Compare the pH of the two solutions. The solution with the lower pH is likely to have a buffer, whereas the solution with the higher pH is unlikely to have a buffer. This is due to the fact that the addition of an acid to a buffered solution would result in a lower pH, whereas the addition of an acid to an unbuffered solution would result in a higher pH. To find out which tube has the buffer and which does not, one has to compare the pH of each solution.Learn more about buffer: https://brainly.com/question/9458699
#SPJ11
A volumetric pipette has one marked line that indicates a specific volume. Considering polar substances dip downward in a glass volumetric pippette creating a concave meniscus, what is the correct way to read a volumetric pipette to have the most accurate measurement?.
The best way to make an accurate measurement of the height of a polar liquid is to take the reading from the lowest point of the meniscus.
What is the meniscus of a liquid?The meniscus of a liquid is a curved that occurs at the top of a liquid placed in a container as a result of the attractive forces between the molecules of a the liquid.
Polar substances such as water have a concave meniscus as they dip downwards.
Therefore, the best way to make an accurate measurement of the height of a polar liquid is to take the reading from the lowest point of the meniscus.
Learn more about meniscus at: https://brainly.com/question/10868896
#SPJ1
Your teacher takes a candle and cuts some wax from the bottom of it. She puts a bit of wax in a beaker and places it on a hot plate. Eventually, the wax melts and becomes a liquid. Do you think this a physical or a chemical change? Explain.
Answer:
It is a chemical change
Explanation:
Melting of wax is temporary and wax can settle again on cooling and turns into a solid. ... Hence it is a chemical change.
Answer:
physical
Explanation:
the wax is changing it's physical state by becoming a liquid, it isn't changing it's chemical makeup
which is more flammable hexane or potassium sulfate
Answer:
Between the two compounds, hexane and potassium sulphate, hexane is the more flammable compound.
Explanation:
Among hexane and potassium sulfate, hexane is more flammable.
What is Flammability?Flammability may be defined as a type of physical property of an element or compound which determines the ability to support combustion. Due to this, it is also known as Combustibility.
This property defines the capability of any chemical element in order to ignite and continue it a very long time after coming or exposing it to direct contact with a flame or any source of ignition.
The characteristic of flammability relies on the volatility of the compound. This means that the higher the volatility of the compound greater or high the flammability.
So, when we compare hexane or potassium sulfate on the basis of volatility, hexane is more volatile and thus possesses high flammability.
Therefore, among hexane and potassium sulfate, hexane is more flammable.
To learn more about Flammability of chemical compounds, refer to the link:
https://brainly.com/question/14214497
#SPJ2
What's the specific heat of water?
Answer:
4,186 joules
Explanation:specific heat, the quantity of heat required to raise the temperature of one gram of a substance by one Celsius degree. The units of specific heat are usually calories or joules per gram per Celsius degree. For example, the specific heat of water is 1 calorie (or 4,186 joules) per gram per Celsius degree.
What is the correct chemical formula of lead (II) oxide?
Answer:
PbO
Explanation:
Question 2 of 30
A television commercial shows happy people while describing some medical
symptoms. These symptoms include feeling tired and sad. The medication
being advertised by the commercial was approved by the FDA to treat a
disease that causes these symptoms. The narrator says that it is available by
prescription only and contains 1% of the active ingredient. What can you infer
about this medication?
OA. The people in the commercial are happy because they were
treated by the medication.
B. The medication would be more effective if it contained 10% of the
active ingredient.
C. Anyone who has the symptoms should request a prescription
from his or her doctor.
D. The medication can treat people who have the disease described.
The medication can treat people who have the disease described. According to the commercial, the drug has FDA approval to treat a condition whose symptoms are listed.
Additionally, the narrator notes that the medication only comes with a prescription and has 1% of the active substance. We can deduce from this information that the drug can effectively treat persons who have the condition generating these symptoms, but obtaining it requires a prescription. The commercial provides no support for the other possibilities.
Therefore, the correct option is D.
Learn more about Medication, here:
https://brainly.com/question/11098559
#SPJ1
science subject.(please help me giving out points) A scientist wants to determine how a solvent’s properties affect its ability to dissolve a solute. The scientist decides to perform an experiment to see if the temperature of water impacts its ability to dissolve salt. The diagram below shows the experimental setup.
can someone help me find the independent, and dependent variable. I need a constant,a hypothesis,and an experimental question that was in the question and try and find a procedure for this.(giving max 100 points).
Based on the data provided:
Independent variable - temperatureDependent variable -solubility of a soluteConstant variable - solvent (water), water volume, etc.Hypothesis - the temperature of water affects the ability of salt to dissolve.Research question: Does the temperature of water affects the ability of salt to dissolve?Procedure - Dissolve the salt in water at various temperatures ad determine the maximum amount of salt that dissolves at each temperature.What are the variables in an experiment?The variables in an experiment are those factors or quantities that can be changed or controlled by the researcher while conducting the research.
There are three types of variables in an experiment:
Independent variable - this is the variable that does not depend on any other variable but which when changed by the researcher brings about changes in another variable known as the dependent variable.Dependent variable - this is the variable that changes when another variable known as the independent variable changes. The dependent variable is usually the variable that is being tested. Hence, it is also called the test variableConstant variable - this variable is kept constant and not altered.An experiment usually states a hypothesis that is tested.
Learn more about independent and dependent variables at: https://brainly.com/question/25223322
#SPJ1
Question 4 of 5
Suppose a disease wipes out most of the fox population in
the food web shown.
Mountain
lion
Deer
Hawk
Fox
Rabbit
Owl
Snake
Green
plant
Mouse
Which two populations are most likely to increase as a
result?
Answer:
Rabbit and Mouse
Explanation:
The rabbit and mouse are the prey of foxes.
What type of reaction occurs without the addition of heat?
A. An endothermic reaction
B. A reaction at equilibrium
C. A nonspontaneous reaction
D. A spontaneous reaction
Answer:
A.an endothermic reaction
16. The poisonous gases were not __ in the air
A. able to float
B. visible
C. able to evaporate
D. invisible
E. able to condense
Answer:
able to evaporate
Explanation:
gas is evaporated liquid...... the process cannot take place again
Children exposed to high concentrations of manganese (>0.4mg/L ) in drinking water have worse intellectual functioning than children with lower exposure. It is thus critical to remove Manganese (Mn) from drinking water. As an engineer, you know that the following reaction can be used as a first step toward removing Mn from groundwater. Chlorine dioxide (ClO2) reacts rapidly with Manganese oxidizing it to Manganese Dioxide (MnO2). Mn+2+2ClO2+4OH−MnO2+2ClO2−+2H2O Laboratory test has indicated that the pollutant concentration is 1.8mg/L 1) Confirm whether the above equation is balanced and provide your rationale 2) Calculate the amount of O2 required to make water safe for human consumption. (10) 3) Calculate the amount of MnO2 Produced during the process
1) The number of atoms of Mn is 1, Cl is 2, O is 6, and H is 4 on both sides of the reaction equation.
2) The required amount of O2 in moles = 0.06557 * 10^-3 moles
3) The amount of MnO2 produced during the process is 0.00285 g.
1) The above reaction equation is balanced. This is because both sides of the reaction have the same number of atoms of each element.The number of atoms of Mn is 1, Cl is 2, O is 6, and H is 4 on both sides of the reaction equation.
2) The equation is given as:
Mn+2+2ClO2+4OH−MnO2+2ClO2−+2H2O
According to the balanced equation, 2 moles of ClO2 is needed to oxidize 1 mole of Mn.
The molecular weight of Mn is 54.9 g/mole, and the concentration of Mn in water is 1.8 mg/L, so;
the number of moles of Mn in 1 L of water
= 1.8 mg / 54.9 g/mole
= 0.03278 * 10^-3 moles
The required moles of ClO2 for this amount of Mn are;
2 * 0.03278 * 10^-3= 0.06557 * 10^-3 moles
To calculate the amount of O2, the following balanced chemical equation can be used:
ClO2+2NaClO+H2O → 2NaCl+2HClO3+O2
Therefore, 1 mole of ClO2 produces 1 mole of O2.So,
the required amount of O2 in moles = 0.06557 * 10^-3 moles
3) The stoichiometric ratio shows that 1 mole of Mn produces 1 mole of MnO2.
The molecular weight of MnO2 is 86.9 g/mole.
So, the amount of MnO2 produced is;
0.03278 * 10^-3 moles * 86.9 g/mole
= 0.00285 g (to 3 significant figures).
Hence, the amount of MnO2 produced during the process is 0.00285 g.
To know more about moles visit:
https://brainly.com/question/15209553
#SPJ11
if poison expires is it more poisonous or less poisonous?
Depending on the toxin, yes. Many things, including proteins, will surely be denatured or degraded and finally turn harmless if we adopt the colloquial definition of the word and include toxins and poisons.
For instance, ricin, botulinum, tetrodotoxin, etc. They are rather delicate, so I'm hoping this toxin has the lowest shelf life.
For a poison, "not up to quality" might indicate anything. It might be more harmful or less toxic. It might be more toxic than before, which would make it less effective against the intended target but extremely harmful to other species. It only indicates that a single chemical may have begun to breakdown, and the final result of that deterioration may be something entirely else.
Small organic molecules make up a lot of other toxins. These include nerve agents like nicotine, sarin, and VX, all of which are capable of being broken down through air oxidation, UV exposure, hydrolysis, and other processes. Numerous nerve agents have a shelf life of several years, and studies have been done to extend their use in weapons.
Lead, mercury, and cadmium are just a few examples of metals that are hazardous because they are toxic not only in their elemental forms but also as inorganic and organic compounds. Although the toxicity of the various forms can varies substantially (see, for example, methylmercury and elemental mercury), the majority of them are nevertheless at least harmful.
These can persist for a very long period since the reactions that can happen under usual circumstances might not be safe, such as a sizable piece of cinnabar left on a desk even throughout the course of a geological time scale. any substantial modification to ensure safety.
To learn more about poison from given link
https://brainly.com/question/21019313
#SPJ4