In toxicology, the median lethal dose, LD₅₀, LC₅₀ or LCt₅₀ is a measure of the lethal dose of a toxin, radiation, or pathogen. The value of LD₅₀ for a substance is the dose required to kill half the members of a tested population after a specified test duration.
What are the 3 most valuable metals in the United States? A. Lead b. Gold c. Iron d.Copper e.Coal f.Silver g.Titanium
Answer:
Gold, Silver and Titanium
Explanation:
The most valuable metals in the list are:
Gold:
Its value makes it a good investment option. Gold can be used in many different ways, like in jewelry, electronics, medicine, etc.
Silver:
Similar to the case of gold, besides the common value of silver in jewelry, it can be also used in other ways, because it has a large thermal and electrical conductivity.
Finally, the titanium: It's price is actually close to the copper one, but for the cost of work with titanium (Titanium has a really large melting point, then melting it into ingots needs a lot of energy), the price of titanium is increased.
how many moles in 200 grams of Br
The pressure of a 980.0 mL sample of gas at a constant temperature is increased from 0.4620 atm to
0.6320 atm. What is the final volume of the gas?
Answer:
P
1
V
1
T
1
=
P
2
V
2
T
2
Explanation:
P
1
V
1
T
1
=
P
2
V
2
T
2
, given a constant quantity of gas.
And thus,
P
1
×
V
1
×
T
2
V
2
×
T
1
=
P
2
, even given this format, we can see the problem is dimensionally sound. We do need to use
absolute temperature.
P
2
=
1.00
⋅
a
t
m
×
250
⋅
m
L
×
313
⋅
K
500
⋅
m
L
×
293
⋅
K
≅
1
2
⋅
a
t
m
.
Explanation:
2.3g of lithium chloride in 500cm3 of solution
Answer:
0.109M
Explanation:
Find molarity of the solution:
Molarity is defined as the ratio between the moles of the solute (Lithium Chloride in this case) per liter of solution. To solve this question we have to find the moles of LiCl and its volume as follows:
Moles LiCl -Molar mass: 42.394g/mol-
2.3g * (1mol / 42.394g) = 0.0543 moles
Volume in liters:
500cm³ * (1L / 1000cm³) = 0.500L
Molarity:
0.0543 moles / 0.500L =
0.109M
Find the molality of a solution of 58.5 g NaCl dissolved in 0.556 kg of water
Answer:lmk
Explanation:
during prophase a group of fibers called what forms the cell
Answer:
During prophase, the nucleus disappears, spindle fibers form, and DNA condenses into chromosomes ( sister chromatids ). During metaphase, the sister chromatids align along the equator of the cell by attaching their centromeres to the spindle fibers.
Explanation:
How much energy is required to raise the temperature of a 300.0
gram block of lead from 22.3°C to 59.9°C? The specific heat of lead is
0.129 J/gºC.
Answer:
Q = 1455.12 Joules.
Explanation:
Given the following data;
Mass = 300 grams
Initial temperature = 22.3
Final temperature = 59.9°C
Specific heat capacity = 0.129 J/gºC.
To find the quantity of energy;
[tex] Q = mcdt[/tex]
Where,
Q represents the heat capacity.
m represents the mass of an object.
c represents the specific heat capacity of water.
dt represents the change in temperature.
dt represents the change in temperature.
dt = T2 - T1
dt = 59.9 - 22.3
dt = 37.6°C
Substituting the values into the equation, we have;
[tex] Q = 300*0.129*37.6 [/tex]
Q = 1455.12 Joules.
PLS HELP ME WILL GIVE BRAIN THINGYYYYY
Answer:
C, when the ball lands it will have the least amount potential energy.
Explanation:
here is a picture that should help you.
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!!!
H2O2 is what type of compound?
13) Which "conversion tool" below would you use to complete this
conversion?
if 26.8g of copper (ll) chloride are dissolved in sufficient water to make 4.00 L of solution, what is the molarity of the solution? & what is the solvent?
Answer: Molarity of the solution is [tex]4.97 \times 10^{-2} M[/tex] and water is the solvent.
Explanation:
Given: Mass of solute = 26.8 g
Volume = 4.00 L
Now, moles of copper (II) chloride (molar mass = 134.45 g/mol) are calculated as follows.
[tex]No. of moles = \frac{mass}{molar mass}\\= \frac{26.8 g}{134.45 g/mol}\\= 0.199 mol[/tex]
Molarity is the number of moles of a substance divided by volume of solution in liter.
Therefore, molarity of given solution is calculated as follows.
[tex]Molarity = \frac{no. of moles}{Volume (in L)}\\= \frac{0.199 mol}{4.00 L}\\= 0.04975 M\\= 4.97 \times 10^{-2} M[/tex]
Solvent is defined as a component which is present in higher amount in a solution. Generally, a solvent is present in liquid state but it can also be a solid or gas.
In the given solution, copper (II) chloride is dissolved in water so copper (II) chloride is the solute and water is the solvent.
Thus, we can conclude that molarity of the solution is [tex]4.97 \times 10^{-2} M[/tex] and water is the solvent.
5 points
How many moles are in 3.5 L solution with a concentration of 2.5 M?
O 8.75 moles
O .71 moles
1.4 moles
100 POINTS!!! AND BRAINLIEST!!!
This tree species was preserved as a fossil in the Arizona desert. The species is now extinct. Describe what the environment was like when the tree lived and how it is different now. Then, infer why this type of tree and other living things that lived with it are extinct.
Which of the following processes is not an example of physical weathering?
A. acidification
B. abrasion
C. frost action
D. exfoliation
Answer:
acidification
Answer:
I think its A
Explanation:
Hope this helps: )
1) Escribe oraciones coherentes que incluyan los siguientes términos con los conceptos correspondientes:
CARBÓN-PETRÓLEO-GAS NATURAL-RECURSO NO RENOVABLE-
COMBUSTIBLES FÓSILES-HIDROCARBUROS-RESERVAS-CONTAMINACIÓN-
MAREAS NEGRAS
La respuesta correcta para esta pregunta abierta es la siguiente.
Estas son las oraciones apropiadas.
El carbón, el petróleo, y el gas natural son recursos naturales no renovables.
Estos generadores naturales de energía son considerados combustibles fósiles que produce la mayor parte de hidrocarburos que se usan en el mundo. Sin embargo, estas reservas energéticas se están agotando porque son recursos naturales no renovables. Además, estos combustibles son altos generadores de contaminación como es el caso de las mareas negras.
Independientemente de estas ideas, es apropiado decir que los combustibles fósiles han sido fuertemente cuestionados por los ambientalistas y los científicos porque son causantes del llamado calentamiento global y del cambio climático.
Por esa razón, la sociedad y los expertos ambientalistas están pidiendo que los gobiernos comiencen a utilizar más energías alternativas y renovables como la energía solar y las turbinas de viento o energía eólica.
DIRECTIONS: Underline the selected word item that best completes the statements.
1. (Climate, Weather) is an overall atmospheric condition of a place of 30 years
and more while (Climate, Weather) is a condition for a short period of time.
2. (Climate, Weather) is influenced by latitude, altitude, ocean current, and
topography.
3. The (higher, lower) the altitude, the (colder, warmer) the climate.
4. (Windward, Leeward) area of the mountain forms precipitation while (Windward,
Leeward) gives dry air and warm weather.
5. Ocean currents bring (cold, warm) water and rain from the equator to the
poles and (cold, warm) water from the poles toward the equator
Explanation:
(Climate, Weather) is an overall atmospheric condition of a place of 30 years and more while (Climate,Weather) is a condition for a short period of time.
2. (Climate, Weather) is influenced by latitude, altitude, ocean current, and topography.
3. The (higher, lower) the altitude, the (colder, warmer) the climate.
4. (Windward, Leeward) area of the mountain forms precipitation while (Windward,Leeward) gives dry air and warm weather.
5. Ocean currents bring (cold, warm) water and rain from the equator to the poles and (cold, warm) water from the poles toward the equator
The enthalpy (AH) is +624.7 kJ for the following reaction. How would you classify this reaction? (Explain)
SiO2(g) + 3C(s) --> SIC(s) +2CO(g)
A.exothermic: heat is lost by the system
B.endothermic: heat is gained by the system
C.endothermic: heat is lost by the system
D.exothermic: heat is gained by the system
Answer: The reaction [tex]SiO_{2}(g) + 3C(s) \rightarrow SiC(s) + 2CO(g); \Delta H = +624.7 kJ[/tex] is classified as endothermic: heat is gained by the system.
Explanation:
A process or reaction in which heat is absorbed is called endothermic reaction.
For example, melting of ice is an endothermic process.
For an endothermic reaction the sign of [tex]\Delta H[/tex] is positive which means heat is gained by the system.
Here, the given reaction is as follows.
[tex]SiO_{2}(g) + 3C(s) \rightarrow SiC(s) + 2CO(g); \Delta H = +624.7 kJ[/tex]
A process or reaction in which heat is released is called exothermic reaction.
For example, combustion reaction, freezing of water etc are exothermic process.
For an exothermic reaction the sign [tex]\Delta H[/tex] is negative which means heat is lost by the system.
Thus, we can conclude that the reaction [tex]SiO_{2}(g) + 3C(s) \rightarrow SiC(s) + 2CO(g); \Delta H = +624.7 kJ[/tex] is classified as endothermic: heat is gained by the system.
A leaking underground storage tank or wastewater pouring into a river from a pipe would be examples of
Answer:
Water pollution.
Explanation:
This is because water pollution refers to the release or disposal of harmful substances called contaminants which contaminate water bodies which include rivers, oceans, lakes e.t.c.. These harmful substances affect aquatic organisms and make water unfit for good use. This can lead to the death if aquatic lives in the water bodies, release of bad smells and make the water bad . A leaking underground storage tank or wastewater pouring into a river from a pipe can be a source of water pollution.
What is the number of moles of solute in 250 mL of a 0.4M solution?
a. 0.1 mol
c. 0.62 mol
b. 0.16 mol
d. 1.6 mol
Explanation:
Answer. There are 0.1 moles of solute in 250 mL of 0.4 M solution.The tetrahedral arrangement of bonds formed by carbon and its relevance In the interaction of biomolecules
Answer:
Due to the presence of 4 valence electrons.
Explanation:
The tetrahedral arrangement of bonds formed by carbon and its relevance In the interaction of biomolecules occurs because the carbon atom has four electrons in their outermost shell and the four hydrogens has one electron each which result is a total of eight electrons distributed in four bonding orbitals making the structure of tetrahedral and the bond angles between these carbon atoms is approximately 109.5 degree.
Can someone please help me with science.
Answer:
The tendency of an object to resist changes in its state of motion varies with mass. Mass is that quantity that is solely dependent upon the inertia of an object. The more inertia that an object has, the more mass that it has. A more massive object has a greater tendency to resist changes in its state of motion.
If a system is left to change spontaneously, in what state will it end?
A. The state with the lowest possible energy consistent with the state of maximum disorder
B. the state with lowest possible energy
C. The same state in which it began
D. The state with the maximum disorder
Answer:
The state with the lowest possible energy consistent with the state of maximum disorder
so letter A
If a system is left to change spontaneously then, the state with the lowest possible energy is consistent with the state of maximum disorder. option A is correct.
what is spontaneous change?A spontaneous change may be so fast or rapid or in a fraction of time that it is essentially instantaneous or fast or so slow that it cannot be observed over any practical time of period.
A is the spontaneous change is one in which the system happening into which the A an increase or boost in internal energy B lowering decline in entropy C lowering in energy D no energy change Medium.
The time-evolution or change of a system in which it releases free energy and it moves to a lower, or decreased more thermodynamically stable energy state, closer to attend the thermodynamic equilibrium.
Therefore, the system is left to change spontaneously then, and the state with the lowest possible energy is consistent with the state of maximum disorder. option A is correct.
Learn more about spontaneous change, here :
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Help i’m taking a test!!
What new element is formed from the equation below? (Answer form is
MN:, AN: , S)
Answer:
Element Z
Explanation:
I hope this is correct and helps you!
6. What is the atomic number of the element?
7. How many neutrons does this element have?
8. What is the atomic mass of this element?
9. How many electrons does this element have?
Answer:
For O: atomic number = 8 # neutrons = 8
For Al: atomic mass = 27, # electrons = 13
why do different people have differently shaped proteins?
The sequence of amino acids in the chain determines how the chain will fold up to make the protein, so different proteins have different three-dimensional shapes. ... This is because proteins form attachments and interact with many other molecules and structures inside organisms.
(This is rly for science but there’s no category for that) Which statement best describes how scientists and engineers work together
in the research and development cycle?
O A. Engineers come up with scientific questions when they are
developing their design, and scientists do research to answer
them.
O B. Scientists test designs made by engineers and then use the
results to improve the designs.
C. Scientists develop a new technology, and then engineers test it by
doing experiments.
D. Engineers make a scientific discovery, and then scientists perform
research to verify it.
Answer:
A. Engineers come up with scientific questions when they are developing their design, and scientists do research to answer them.
Give examples of how land resources are used in a city setting
Answer:
Land resources such as gravel and bedrock are used to construct buildings, roads, and sidewalks. Land is also where city structures—such as buildings, roads, and sidewalks—are constructed. People use land resources such as bedrock and aggregate to construct buildings, roads, and sidewalks.
I hope this answer helps
How are radar and an approaching siren different? How are they similar?
A. Radar uses sound waves, and the siren uses radio, but both exhibit
the Doppler effect
B. Radar uses radio, and the siren uses sound waves, but both exhibit
the Doppler effect
C. The Doppler effect can be observed only with radar, but both
devices use sound waves.
D. The Doppler effect can be observed only in the approaching siren,
but both devices use radio.
Answer:
b
Explanation:
Radar uses radio, and the siren uses sound waves, but both exhibit the Doppler effect. Therefore, option (C) is correct.
What is Doppler's effect?Radar operates by emitting radio waves and measuring the reflected waves to detect objects and determine their velocity. On the other hand, an approaching siren emits sound waves that propagate through the air.
Both radar and an approaching siren exhibit the Doppler effect. The Doppler effect is the change in frequency or pitch of waves (sound or electromagnetic) when the source of the waves and the observer are in relative motion. In the case of radar, the Doppler effect is used to measure the velocity of objects based on the frequency shift of the reflected radio waves. Similarly, the Doppler effect is observed with an approaching siren as the sound waves compress and the frequency appears higher as the source approaches the listener.
Therefore, both radar and an approaching siren differ in the type of waves they use (radio waves vs. sound waves), but they share the characteristic of exhibiting the Doppler effect.
Learn more about Doppler effect. here:
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Is this correct??Pls help!!!
Answer:
C
Explanation:
Answer:
Yes, your answer is correct. B is correct :3