Three factors that describe the movement of surface water in streams and rivers are the river's gradient, flow, and stream load.
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The half-life of a radioactive substance is 15 days. After 10 days a sample of the substance has been reduced to a mass of 4 mg. A. What was the inital mass (in mg) of the sample? B. Using your answer from above, after how many days will there only be 0. 3 mg of substance left?.
A. The initial mass of the sample is 6.35
B. The time taken for 0.3 mg of the sample to remain is 66 days
A. Determination of the initial mass of the sample
We'll begin by calculating the number of half-lives that has elapsedHalf-life (t½) = 15 days
Time (t) = 10 days
Number of half-lives (n) =?n = t / t½
n = 10 / 15
n = ⅔Finally, we shall determine the initial mass of the sample.Number of half-lives (n) = ⅔
Amount remaining (N) = 4 mg
Initial amount (N₀) =?[tex]N_0 = N \times {2}^{n} \\ N_0 = 4 \times {2}^{2 \div 3} \\ N_0 = 6.35 \: mg[/tex]
Therefore, the initial mass of the sample is 6.35 mg
B. Determination of the time
We'll begin by calculating the number of half-lives that has elapsedAmount remaining (N) = 0.3 mg
Initial amount (N₀) = 6.35 mg
Number of half-lives (n) =?[tex]{2}^{n} = \frac{N_0}{N} \\ \\ {2}^{n} = \frac{6.35}{0.3} \\ \\ {2}^{n} = 21.167 \\ take \: the \: log \: of \: both \: side \\ log \: {2}^{n} = log \: 21.167 \\ nlog2 = log \: 21.167 \\ divide \: both \: side \: by \: log2 \\ \\ n = \frac{log \: 21.167}{log2} \\ \\ n = 4.4[/tex]
Finally, we shall determine the timeNumber of half-lives (n) = 4.4
Half-life (t½) = 15 days
Time(t) =?t = n × t½
t = 4.4 × 15
t = 66 daysTherefore, it will take 66 days for 0.3 mg of the sample to remain.
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If the absorbance of the mixture is 0.20 at 453 nm, how many moles of Fe3 (aq) were present in the 100. mL sample
Despite this problem misses out crucial information for its solution, it turned out possible to come up with the attached absorbance graph, which shows the behavior of the absorbance of the sample with respect to the concentration at 453 nm.
As you can see, there is a red line and circle pointing out the concentration at which the sample has an absorbance of 0.20 (y-axis) which turns out to be 4x10⁻⁵ M (x-axis).
Now, since we require the moles of the iron (III) ions present in 100. mL of the sample, we recall the concept of molarity, which requires moles and volume in liters:
[tex]M=\frac{n}{V}[/tex]
Thus, since all the Fe⁺² in FeSCN⁺² is converted to Fe⁺³ we can find out the moles as shown below:
[tex]n=4x10^{-5}\frac{mol}{L} *0.100L\\\\n=4x10^{-6}mol[/tex]
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https://brainly.com/question/5650600https://brainly.com/question/13490034An ameba absorbs oxygen from its environment and releases carbon dioxide into its environment. This process is known as
Answer:
Respiratory gas exchange
Explanation:
State the term used for the light that is transmitted when complex ions absorb wavelengths of visible light. Give the answer using two words only (and be careful with spelling).
Answer:
complementary colour
Explanation:
The complementary colors are used for the light that is transmitted when complex ions absorb wavelength of visible light.
What is complementary colors?
Complementary colors are color pairs that cancel each other whenever combined and mixed, resulting in a grayscale color either white or black. They offer the most contrast for the those two hues when put adjacent to each other. Colors that are complementary are sometimes known as "opposite colors."
What is light?Light, often known as visible light, is electromagnetic radiation that falls within the region of the electromagnetic spectrum which the human eye can perceive.
Therefore, the complementary colors are used for the light that is transmitted when complex ions absorb wavelength of visible light.
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A chemistry teacher adds red food coloring to water and students observed the dye spreading out to fill the container. Is the teacher
demonstrating a physical or chemical change?
Answer:
its obviously a chemical change
Explanation: Facts
The addition of the food color in water only causes the change in the cor of water but no new substance is formed. Therefore, the teacher is restarting the physical change.
What is a physical change?A physical change can occur when the characteristics of the matter change but the identity does not. Physical changes are classified as: reversible and irreversible. For example, the melting of water is reversible in nature since the melted ice cube will be refrozen.
Physical change can be described as a kind of change where only physical properties of matter such as odor, color, solubility, etc. can change. During physical changes, there is no chemical bonds are broken or formed between atoms of the substance.
The chemical composition as well as the chemical nature of the substance remains unchanged during a physical change. The molecules of matter can rearrange without changing the internal composition of matter.
Therefore, adding food color to water is a physical change as no new substance formed.
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How do erosions affect land forms?
Erosion is the only cause of land form changes.
Land forms can be created by erosion.
Erosion can prevent land forms from being built.
Land forms can only be created through erosions.
Answer:
the anwser is landforms can be created by erosion
Explanation:
Use the periodic table to identify the number of core electrons and the number of valence electrons in each case below.
Can you please add a picture of the case??
What number should be placed in front of Fe to balance this chemical
equation?
_Fe+302>2Fe2O3
A. 8
B. 2
C. 1
D. 4
the answer is B. 2
because there is 2 iron on the right side so you need another two on the left side to balance it out
How are polypeptides and proteins similar?
A. They are both made of amino acids.
B. They are both polysaccharides.
O C. They are both nucleic acids.
D. They are both made of carbohydrates.
Answer is A
Answer:
The answer is A.
Explanation:
They are both made of amino acids.
Which two factors will improve the efficiency of an inclined plane?
the answer is using rollers in conjunction with inclined plane.
DO the postulates of daltons atomic theory explain the law of consrevetion of mass and thelaw of constant composition
Answer:
see answer
Explanation:
DO the postulates of Daltons atomic theory explain the law of conservation of mass and the law of constant composition.
Dalton's Atomic Theory Postulates1. Everything is composed of atoms, which are the indivisible building blocks of matter and cannot be destroyed or divided any further.
2. All atoms of a single pure element are the same in size and mass
3. Atoms of different elements vary from each other in size and mass.
4. Compounds are produced through different simple whole-number combinations of atoms to produce molecules.
5. Anywhere a compound exists, it will have the same atoms in the same ratio.
6. A chemical reaction between compounds is a re-arrangement of atoms
The law of conservation of mass is shown in 2, 4. and 5.
The law of constant co,position is shown in 2, 4, 5, and 6
What defines an element?
Explanation:
each of more than one hundred substances that cannot be chemically interconverted or broken down into simpler substances and are primary constituents of matter. Each element is distinguished by its atomic number, i.e. the number of protons in the nuclei of its atoms.
Complete the sentence.
Atoms form chemical bonds to satisfy the ______
rule and to become _______
michela and simone are camping in a ent during some hot weather
Is krypton a good or poor conductor of electricity? Why? I
Answer:
No it is not a good conductor
Explanation:
Krypton is classified as a gas and nonmetal. Like many nonmetals and gases, krypton is an insulator, so it is a relatively poor conductor of heat and electricity.
what happened if you poured lava on snow
Answer:
This is what could happen:
Explanation:
When lava meets ice, the resulting mess can cause flooding, destroy valuable resources and even produce explosions.
Answer: When lava meets ice, it neither explodes nor tunnels through; rather, it forms strange-looking bubbles.
Explanation:
Question 2
20 pts
What types of elements make up salt and what type of compound is it?
nonmetals only and covalent
metals only and ionic
metals and nonmetals and ionic
The structure of the periodic table is based on the distribution of
in each element. The elements are arranged in horizontal and vertical
Answer:
B- electrons, A- periods, B- groups
Explanation:
Which product in the reaction forms a precipitate? PbSO4 MgCl2 PbMg no precipitate formed
MgCl2 product in the reaction forms a precipitate because it is solid an insoluble salt and not dissolve in solution and precipitate on the bottom surface of the solution.
What is precipitation reaction?The chemical reaction in which two ionic bond combine to form an insoluble salt in a aqueous solution is called precipitation reaction.
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What is atomic mass? the mass of the atom based on the mass of an atom of hydrogen-1 the mass of an atom based on the mass of an atom of carbon-12 the mass of the atom based on the mass of an atom of oxygen-16 the mass of an atom based on the number of electrons
Answer:
The mass of an atom based on the mass of an atom of carbon-12
Explanation:
an empty aerosol can at 25°c still contains gas at 1.00 atmosphere pressure. if an empty can is thrown into a 475°c fire, what is the final pressure in the heated can?
The final pressure in the heated can is 2.51 atm
From the question given above, the following data were obtained:
Initial temperature (T₁) = 25 °C = 25 + 273 = 298 K
Initial pressure (P₁) = 1 atm
Final temperature (T₂) = 475 °C = 475 + 273 = 748 K
Final pressure (P₂) =?The final pressure can be obtained as illustrated below:
[tex] \frac{P_1}{T_1} = \frac{P_2}{T_2} \\ \\ \frac{1}{298} = \frac{P_2}{748} \\ \\ cross \: multiply \\ \\ 298 \times P_2 = 1 \times 748 \\ \\ divide \: both \: side \: by \: 298 \\ \\ P_2 = \frac{748}{298} \\ \\ P_2 = 2.51 \: atm[/tex]
Therefore, the final pressure in the heated can is 2.51 atm
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4. One gram of of ............... contains one type of atoms. a. iron b. ammonia c. hydrogen chloride d. water
Answer: hydrogen chloride.
Explanation:
put these atoms in order of increasing radius: Na, Mg,Cl, P
Answer:
Cl < P < Mg < Na
Explanation:
Cl must have the smallest radius because it is located to the right of the remaining elements on the same row. P must have the second smallest radius because it is located to the right of the remaining elements on the same row. Mg must have the Third smallest radius because it is located to the right of Na on the same row. Therefore, Na has the Largest radius.
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Why can Marco hear the music, even though he is not in the same room as the speaker?
Answer:
Sound Travels
Explanation:
Sound waves can travel, and that makes it so that even though Marco is in a different room, he can hear the music. Depending how loud the music is and how thick the walls car, the sound can travel through the walls.
what type of bacteria use the enzyme nitrate reductase to metabolize nitrogen oxides and transform them back to nitrogen gas?
Denitrifying Bacteria such as Pseudomonas aeruginosa is the type of bacteria that use enzyme nitrate reductase to metabolise nitrogen oxides to nitrogen gas.
Denitrification is the process whereby nitrites or nitrogen oxides is converted to nitrogen gas by a denitrifying Bacteria such as Pseudomonas.
Pseudomonas aeruginosa uses enzyme nitrate reductase to reduce nitrate to nitrite.
Then nitrite is then converted back to nitrogen gas.
Therefore, Pseudomonas aeruginosa is a type of bacteria that uses enzyme nitrate reductase.
Shanika is an engineer at an amusement park who is experimenting with changes to the setup for a magnetic roller coaster ride. In one ride, there are two identical roller coaster cars (orange and green) that start on opposite sides of a large magnet located at the center of a station. Shanika wants to get the largest increase in potential energy she can by moving one car one space to the left or the right. Shanika can move the orange car to point A or point B, or she can move the green car to point C or point D. Which movement should she make? Why will that movement result in the largest increase in potential energy? Describe the magnetic force that will act on the roller coaster car she moves. What should I do for the Green cart?
The orientation of the poles of the magnet on the cars and the large
magnet are like poles.
The correct responses are;
First question
Move the orange car from A to B Move the green car from D to CSecond question:
The reason is reducing the distance increases the magnetic field strengthThird question:
It pushes the cars away in the opposite direction.
Fourth question:
Place the green car at point C to get the largest potential energyReasons:
Potential energy is the energy an object has due to its location.
Energy is a product of force and distance, and therefore, if the force,
experienced by the object increase, the potential energy of the object
increases.
The strength of a magnetic field, B, is given by the formula;
[tex]\displaystyle B = \frac{\mu_0 \cdot I}{2 \cdot \pi \cdot d}[/tex]
Where;
B = The magnetic field strength
I = Current
d = The distance from the source of the magnet
μ₀ = The permeability of free space = 4·π × 10⁻⁷ T m/A
Therefore, the strength of the magnet is higher closer to the source.
First question
In a magnet, like poles push each other back, and given that the poles of the magnet adjacent to each other are like poles, to get the largest increase in she should move the cars towards the large magnet.
Move the orange car from A to B Move the green car from D to CSecond question:
The reason why the movement will result in the largest increase in potential energy is because like polls repel each other and the strength of a magnetic field increases closer to the magnet
Third question:
The magnetic force that will act on the roller coaster car moved towards the large magnet, pushes the car in the opposite direction.
Fourth question:
The green cart should be moved from point D to point C to get the largest potential energy
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All the members of this family (inner transition metals) are both ______________ and _____________.
(HURRY PLS)
Answer:
The actinides and the lanthanides
when the corporation issuing the bonds has the right to redeem the bonds prior to the maturity, the bonds are
Answer:
Callable or redeemable bonds
Explanation:
"..are bonds that can be redeemed or paid off by the issuer prior to the bonds' maturity date."
- A beam of electrons has.....
(A) Wave properties.
(B) Particle properties.
(C) Both of these
(D) Neither of these
Answer:
(C) Both of these
Explanation:
A beam of electrons has both of these Wave properties and Particle properties.
If Temperature 25 C and volume is 117.5 cm³. Explain volume temperature relationship using Charles’s law.
(No links or else I'll report.
Don't answer if u dont know.)
Thank You.
Explanation:
According to Charles law : V/T=k (constant).
the volume temperature relationship will be
V/T = 117.5/25 = 4.7
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