Because the oldest rocks with fossilized evidence of life on earth are at least 3.5 billion years old, life on earth must have started at least then.
How did life on Earth look like 3 billion years ago?According to a study, Earth may have been a "waterworld" without continents 3 billion years ago. Without any continents to divide the oceans, Earth may have been entirely submerged in water about 3 billion years ago, resembling a "waterworld." The 3.5 billion year old "stromatolites," which are hard structures made by microbes, also contain evidence of their presence. Stromatolites are produced when microbe-made sticky mats trap and organize sediments into layers. Even as the microbes disappear, minerals precipitate inside the layers, forming strong structures.
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Bobby is at a family reunion and
would like to know what the median
age is, of everyone present. Here
are the ages of everyone at his
reunion:
35, 2, 7, 33, 25, 70, 75, 40, 42, 12,
15, 7, 44, 20, 25, 3, 65, 62
What is the median?
Answer:
Median is 29.
Explanation:
add all them up and divide them
In an experiment, a solution required 30. 05 g of nacl, 50. 0 g of , and 0. 4006 g of mgso4. Using the correct number of significant figures, what is the resulting mass?.
The total mass of the mixture is 80.5 g. The analysis of the calculation shows that there should be three significant figures in the end result.
This is an addition operation, and when dealing with addition and subtraction operations it is necessary to consider the last significant figure for each of the numbers. The result of the addition/subtraction should have the same last significant figure as the number with the leftmost (or highest) last significant figure. When applied to this calculation, the principle looks like this:
30.05 - the last significant figure is 5, and it is in the hundredths
50.0 - the last significant figure is 0, in the tenths
0.4006 - the last significant figure is 6, in the ten thousandths.
Of the three, the leftmost/highest significant figure is 0 in the tenths, so the end result should also have its last significant figure in the tenths.
30.05 g + 50.0 g + 0.4006 g = 80.4506 g, but we round up to the tenths, and because the numbers after 5 are greater than 0, we have to round up to reach the end result of 80.5 g
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27. What pattern in the behavior of gases is shown from Step I through Step 3 of the figure?
Answer:
Boyle's law
Explanation:
If a 5-kg bowling ball is projected upward with a velocity of 2.0m/s. What is the momentum?
What amount of force will that bowling ball have as it falls back to Earth?
The momentum of the bowling ball is projected upward with a velocity of 2.0 m/s is 10 kg m/s.
The amount of force will that bowling ball have as it falls back to earth is 10 N.
We know that,
The mass of the ball is 5 kgVelocity of the ball is 2.0 m/sMomentum is the product of speed of an object and its mass. This means that an object at rest has zero momentum since the velocity is also zero.
It is given as -
Momentum = Mass of an object x speed/ velocity
Momentum = 5 kg x 2.0 m/s
= 10 kg m/s
To calculate amount of force bowling ball have when it falls back to Earth is -
Force exerted by an object is equal to product of its mass and velocity.
The second law of motion states that change in momentum of the object is given by mass multiplied by the velocity, which is equal to force.
F = mv
where,
F = force
m = mass
v = velocity
and,
p = mv
where,
p = momentum
m = mass
v = velocity
Hence, the amount of force that bowling ball have as it falls back to Earth is 10 N.
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What happens after molecules interact with each other
Answer:
I think "they are held together by chemical bonds"
Which element is most likely to experience an increase in radius?
A. Ca changing to Ca2+
B. Fe changing to Fe3+
C. Cl changing to Cl-
D. Li changing to Li+
Answer:
C. Cl changing to Cl-
Explanation:
Cl gains 1 electron, resulting in an increase in radius.
The other 3 give up electrons.
true or false: an object's color is dependent on the chemical composition of its matter, which determines the wavelegnth that is reflected
Answer:
true
Explanation:
The physical and chemical composition of matter determines which wavelength (or color) is reflected.
which one of the following statements is true? the rate of a zero order reaction is independent of concentration. for the first-order reaction a→b, doubling the concentration of a will result in an increase of the half-life. the unit for the rate of a reaction depends on the order of the reaction. for the zero-order reaction a→b, a plot of 1/[a] vs. time will produce a straight line. the rate of a zero-order reaction decreases as the reaction proceeds.
This circumstance frequently arises when an enzyme or a solid surface is used to catalyze a process (heterogeneous catalysis).
What is zero order reactions?The unit for the rate of reaction depends on the odder of the reaction .for the zero order reaction a→b,a plot of 1/⊂a⊃vs.time will produce a straight line. the rate of a zero order reaction decreases as the reaction proceeds
Zero-order kinetics is always a byproduct of the circumstances surrounding the reaction.The term "pseudo-zero-order reaction" is frequently used to describe processes that exhibit zero-order kinetics.Clearly, the exhaustion of a reactant prevents a zero-order process from continuing.Just before this moment, the reaction will switch to a different rate law rather of decreasing to zero as seen in the upper left.Zero-order rates might result from two general circumstances:Only a small portion of the reactant molecules are capable of reacting, and this portion is continuously refilled from the larger pool.This circumstance frequently arises when an enzyme or a solid surface is used to catalyze a process (heterogeneous catalysis).
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Find the concentration of sulfuric acid in mol/dm3 and g/dm3 given
that 25.0 cm3 of this solution reacts with 26.5 cm3 0.100 mol/dm3
sodium hydroxide solution in a titration
H2SO4 + 2NaOH → Na2SO4 + 2H2O
The concentration of sulfuric acid in mol/dm3 and g/dm3 would be 5.194 and 0.053 respectively.
Stoichiometric problemFrom the equation of the reaction, the mole ratio of the concentrated sulfuric acid and sodium hydroxide solution is 1:2.
Recall that: mole = molarity x volume
For 26.5 cm3 0.100 mol/dm3 sodium hydroxide solution, the number of moles of the solute in the solution can be calculated as:
26.5/1000 x 0.100 = 0.00265 moles
The equivalent number of moles of the concentrated sulfuric acid will be:
0.00265/2 = 0.001325 moles
Also, recall that:
Concentration in g/dm3 = mass/volume
concentration in mol/dm3 = mole/volume
For 0.001325, 25.0 cm3 sulfuric acid:
mass = 0.001325 x 98 = 0.12985 g
Concentration in g/dm3 = 0.012985/0.025
= 5.194 g/dm3
Concentration in mole/dm3 = 0.001325/0.025
= 0.053 mol/dm3
Hence, the concentration of the sulfuric acid in mol/dm3 and g/dm3 would be 5.194 and 0.053 respectively.
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Where are chromatids found in a cell?
Answer:
During metaphase, the cell's chromosomes align themselves in the middle of the cell through a type of cellular "tug of war." The chromosomes, which have been replicated and remain joined at a central point called the centromere, are called sister chromatids.
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Two different samples of matter are measured in each of these glass containers. Both of the containers show the same measure for both samples of matter. The samples most likely have which of these in common?.
Two different samples of matter are measured in each of these glass containers. Both of the containers show the same measure for both samples of matter. These samples have volume in common.
In chemistry, volume is defined as the three-dimensional space taken up by matter. Volume is measured in cubic meters.
If you were to put two different samples in a graduated glass container and both of them have the particular digit that shows their volume then it means their volume is the same and they take up the same amount of space irrespective of their chemical composition.
For example, if you pour the sample into a glass container and the number you get is 250 m³.
Then this 250 m³ refers to the volume of the sample.
In general, volume is measured as volume = mass/density and its SI unit is m³.
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1-Bromobutane reacts with water to form 1-butanol according to the following equation.
C4H9Br(aq) + 2 H2O(l) → C4H9OH(aq) + H3O+(aq) + Br−(aq)
The following is a proposed mechanism for the reaction.
C4H9Br(aq) → C4H9+(aq) + Br−(aq) slow
C4H9+(aq) + H2O(l) → C4H9OH2+(aq) fast
C4H9OH2+(aq) + H2O(l) → C4H9OH(aq) + H3O+(aq) fast
Determine the overall rate law for this proposed mechanism. (Rate expressions take the general form: rate = k . [A]a . [B]b.)
1-Bromobutane reacts with water to form 1-butanol according to the following equation overall rate law for this proposed mechanism is rate = k [C₄H₉Br]
The reaction intermediate in the chemical species that is formed in one elementary step and consumed in subsequent step and the slowest step in the reaction mechanism is rate determining step and the rate determining step limit the overall rate and therefore determines the rate law for the overall reaction
Here given reaction
C₄H₉Br(aq) + 2H₂O(l) → C₄H₉OH(aq) + H₃O⁺(aq) + Br⁻(aq)
And the following is a proposed mechanism for the reaction
C₄H₉Br(aq) → C₄H₉⁺(aq) + Br⁻(aq) slow
C₄H₉⁺(aq) + H₂O(l) → C₄H₉OH₂⁺(aq) fast
C₄H₉OH₂⁺(aq) + H₂O(l) → C₄H₉OH(aq) + H₃O⁺(aq) fast
So in that 1st step is the rate determining step means slow step
So rate expressions take the general form: rate = k . [A]a . [B]b
So given equation rate expressions is k [C₄H₉Br]
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how does a forest fire model the energy flow of combustion?
Explanation:
Plenary lecture paper
Combustion dynamics of large-scale wildfires
Author links open overlay panelLiuNaianXieXiaodong
https://doi.org/10.1016/j.proci.2020.11.006
Get rights and content
Under a Creative Commons licenseOpen access
Abstract
A fact often overlooked is that large-scale wildfires, although occurring infrequently, are responsible for the overwhelming majority of fire-related suppression costs, economic losses, and natural resources damages. Fortunately, the increasingly severe problems of large-scale wildfires worldwide have been receiving ever-growing academic attention. The high-intensity burning behaviors in wildfires stem from the significant interaction of combustion with heat transfer and atmospheric flow under complicated fuel, meteorology, and topography conditions. Therefore, mitigating measures against large-scale wildfire disasters have grown into a challenging research focus for combustion scientists. Research over the past century has resulted in incrementally enhanced insights into the mechanisms of combustion dynamics underlying the various erratic behaviors in large-scale wildfires, with theories and models of fire accelerations developed and validated. These advances are expected to improve the efficacy of large-scale wildfire predictions significantly. Nevertheless, the physical interpretation of the acceleration of large-scale wildfires is far from adequate and complete. This paper intends not to make a comprehensive review of the entire wildfire research field, but to depict an overall pattern of the essential factors that lead an initial small-scale spreading flame to a large-scale wildfire beyond control. It is outlined that the complicated transformation of fuel preheating mechanisms determines the growth of surface fire spread, while varied large-size flame fronts and unique spread modes induced in specific fire environments play an essential role in fire spread acceleration. Additionally, multiple fires burning and merging often act as crucial steps for accelerating surface fire spread, generating large-size flames, and triggering unique spread modes. These major potential factors strike the energy balance of a low-intensity wildfire and push it to a high-intensity state. Several issues regarding intensely burning behaviors in large-scale wildfires are selected for in-depth discussions, for which an overview of the progress and challenges in research is presented. It is concluded that the fundamental exploration targeted at developing application tools capable of dealing with large-scale wildfires remains at its early stages. Opportunities for innovation are abundant, yet systematic and long-term research programs are required.
a student proposes the following lewis structure for the azide ion. assign a formal charge to each atom in the student's lewis structure. atom formal charge
Lewis structures are diagrams that illustrate the bonding between atoms in a molecule as well as any lone pairs of electrons that may exist. They are also known as Lewis dot formulae, Lewis dot structures, electron dot structures, or Lewis electron dot structures (LEDs). Lewis structures are diagrams that illustrate the bonding between atoms in a molecule as well as any lone pairs of electrons that may exist. They are also known as Lewis dot formulae, Lewis dot structures, electron dot structures, or Lewis electron dot structures (LEDs). A Lewis structure can represent any covalently attached molecule as well as coordination compounds. who proposed it in his 1916 article The Atom and the Molecule.
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You need to use your separatory funnel for an extraction, but you notice that there is some residual water in it from when it was washed during the previous lab period. What should you do?.
In this situation, wash the separating funnel with soap and water once more before using it for the subsequent experiment and rinse the funnel with acetone into a waste container.
Separating funnels are employed in the extraction process and must be free of contaminants that could reduce the yield of the extraction. The funnel could be placed in a desiccation after being cleaned and rinsed to allow the water on the body to dry before being used for the following extraction procedure. Washing laboratory equipment before use irrespective of its state (whether it is clean or not) contributes to standard laboratory practices.
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just because you don't know your direction doesn't mean you don't know have one.
yes I agree thank you for sharing
what is the definition of electron orbital?
The electron orbit, is the path of an electron around the nucleus of an atom.
Explanation:
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A base has been added to water such that the concentration of hydroxide ions is 2.61 × 10–9 M. The solution has a temperature of 25°C (Kw = 1.0 × 10–14). What's the concentration of hydronium ions present in this solution?
Question 14 options:
3.83 × 10–6
1.79 × 10–8
2.57 × 10–6
4.42 × 10–7
The hydronium ion concentration, [H₃O⁺ ], of the solution is 3.83 * 10⁻⁶.
What is the hydronium ion concentration of a solution?The hydronium ion concentration of a solution is the concentration in mol/dm³ of the hydronium ions of a solution.
The hydronium ion is formed when a water molecule combines with a hydrogen ion as shown below:
H₂O + H⁺ ---> H₃O⁺
The hydronium ion concentration of a solution is also known as the hydrogen ion concentration of the solution or pH.
The product of the hydronium ion concentration of a solution and the hydroxide ion concentration of a solution gives the ion product of water.
[H₃O⁺ ] * [OH⁻] = Kw
where Kw = 1.0 * 10⁻¹⁴ M²
The hydronium ion concentration of the given solution can be calculated as follows:
[H₃O⁺ ] * [OH⁻] = Kw
[OH⁻] = 2.61 * 10⁻⁹ M
Kw = 1.0 * 10⁻¹⁴ M²
[H₃O⁺ ] = Kw / [OH⁻]
[H₃O⁺ ] = 1.0 * 10⁻¹⁴ M² / 2.61 * 10⁻⁹ M
[H₃O⁺ ] = 3.83 * 10⁻⁶
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A volume of 293 mL of oxygen gas was collected at a temperature of 10°C and a pressure of 102 kPa. What
volume of oxygen would be collected at STP?
Volume of oxygen would be collected at STP is 293.3 ml
V1 = 293 mL
V2 = ?
P1 = 102 kPa
P2 = 100 kPa
T1 = 10°C = ( 273 + 10 ) = 283 k
T2 = 273 k
The Combined Gas Law combines Charles Law, Boyle s Law and Gay Lussac s Law. The Combined Gas Law states that a gas pressure x volume x temperature = constant
The combined gas law is an amalgamation of the three previously known laws which are- Boyle's law PV = K, Charles law V/T = K, and Gay-Lussac's law P/T = K. Therefore, the formula of combined gas law is PV/T = K, Where P = pressure, T = temperature, V = volume, K is constant.
P1V1/T2 = P2V2/T2
102 x 293 / 283 = 100 x V2 / 273
105.6 = 0.36 x V2
105.6/0.36 = 293.3
V2 = 293.3 ml
Hence, volume of oxygen would be collected at STP is 293.3 ml
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0.46 g of a metal produced 0.77 g of metal oxide. a. b. 0.805 g of the same metal displaced 760 cc of H₂ gas at NTP from HCI. c. 1.26 g of water was formed by the union of 1.12 g of oxygen with hydrogen. Show that these data illustrate the law of reciprocal proportions.
The given examples depict law of reciprocal proportions.
Jeremias Ritcher put forward the law of reciprocal proportions in 1792. The ratio of the masses in which they do so is either the same or a simple multiple of the mass ratio in which they combine, according to the statement, "If two different elements combine independently with the same weight of a third element."
a. Metal oxide contains
M = 0.46 g.
O = 0.77−0.46 = 0.31 g
Therefore, weight of oxygen that combines with 1g of
Metal = 0.31/0.46 = 0.674 g
b. 0.82g of Metal liberates H₂ = 0.00009 × 760 = 0.068g
Thus, the weight of H₂ that will be liberated by 1g of
Metal = 0.068/0.82 = 0.083 g
According to (a) and (b) the ratio of the weight of O:H that combine with or is displaced by the same weight of metal is 0.674:0.083 or 8:1.
Again according (c ), 1.25g of water contains
O= 1.12g and
H 1.25 − 1.11 = 0.14g
Therefore, The ratio of O:H::1.11:0.14 or 8:1
Hence, that ratio being the same, the law of reciprocal proportions is illustrated.
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4(NO3)2
please explain, will give brainliest!!
_____________________________________________________________________________________________________________________
Match the parts of the following chemical equation to the correct description.
CL2(g)+ALCl3(aq)-->__I2(aq)+___AlCl3(aq)
Column A. Column b
1.Cl2 + AlI3. a. Products
2.I2 + AlCl3. b. Shows which way the reaction progresses
3.(g) or (aq). c. Reactants
4.-->. d. State of Matter
PLEASE ANSWER QUICK
The parts of the chemical equation to the correct description are done below.
Column A Column B
1. Cl₂ + Ail₃ ----------- c. Reactants
2. I2 + AlCl3. ---------- a. Products
3. 3.(g) or (aq) --------- d. State of Matter
4. 4.--> -------------------- b. Shows which way the reaction progresses.
Chemical equations tell us the factors and/or compounds that can be reacting and the product(s) of the response. The coefficients on the materials in the response tell us the mole ratio or molecular ratio of the elements/compounds inside the reaction. A chemical equation is the symbolic representation of a chemical response in the form of symbols and chemical formulation.
Chemical equations are an efficient way to explain chemical reactions. This module explains the shorthand notation used to express how atoms are rearranged to make new compounds at some stage in a chemical reaction. It indicates how balanced chemical equations convey the proportions of each reactant and product concerned.
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If a wave has a frequency of 4.89 x 10^12 Hz, what is the wavelength?
Answer:
4,890,000,000,000
Explanation:
To convert out of scientific notation, you would take the beginning number and move the decimal to the right 12 spaces.
(keep in mind that if the twelve was negative you would move to the left 12 spaces)
two isotopes of gallium are naturally occurring, with 6931ga at 60.11 % (68.93 amu ) and 7131ga at 39.89 % (70.92 amu ). what is the atomic mass of gallium?
Gallium has two naturally occurring isotopes: 69ga with a mass of 68.9256 amu and a natural abundance of 60.11% and 71ga. Using the mass of gallium from the periodic table, the mass of Ga-71 isotope is 70.9246 amu.
There are two naturally occurring isotopes of gallium: Ga-69 isotope having mass 68.9256 and percentage abundance is 60.11%, let say 'X' be the mass of isotope - Ga-71.
Its percentage abundance can be calculated as:
%Ga-71=100-60.11=39.89%
The atomic mass of an element can be calculated by adding the atomic masses of its isotopes multiplied by their percentage abundance.
In this case we have
Atomic mass = m(Ga-69)×%(Ga-69) + X ×%(Ga-71)
The atomic mass of Ga is 69.723 amu.
Now putting the values, we will get
69.723 amu = (68.9256amu)(60.11/100) + X (39.89/100)
Hence,
69.723 amu = 41.431amu + + X (39.89/100)
Now rearranging the above equation we get,
X = 69.723 amu - 41.431amu/0.3989 = 70.9246amu
Thus, the mass of Ga-71 isotope is 70.9246 amu.
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The complete question is:
Gallium has two naturally occurring isotopes: 69ga with a mass of 68.9256 amu and a natural abundance of 60.11% and 71ga. use the atomic mass of gallium from the periodic table to find the mass of gallium-71. express the mass in atomic mass units to two decimal.
Which chemical leads to a pleasurable sensation when released in the brain, such as in response to nicotine?.
One of these neurotransmitters, dopamine, is released in the reward area of the brain and results in pleasurable feelings and an uplifted mood. More nicotine is required to feel good the more you smoke.
What is Nicotine ?The nightshade plant family naturally produces nicotine, an alkaloid that is widely used recreationally as a stimulant and anxiolytic. It is a medication meant to decrease withdrawal symptoms in smokers who desire to quit.
Nicotine is a highly addictive and dangerous drug. It might cause a rise in blood pressure, an increase in heart rate, and arterial constriction (vessels that carry blood). The hardening of artery walls, which may lead to a heart attack, is another potential effect of nicotine.Learn more about Nicotine here:
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draw the structural formula of 2-bromo-3,3,4,4- Tetra methyl hexane
Answer:
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Which choice is an element?
O sodium chloride
O water
O oxygen
O air
Answer:
Oxygen
Explanation:
The 1st 2 are compounds
The last one "air" can be used to say oxygen, however, "air" is not on the periodic table of elements.
Oxygen is on the periodic table of elements
Which property could be used to separate a mixture of salt and sand? Responses solubility in water solubility in water mass mass electrical conductivity electrical conductivity magnetism
Property could be used to separate a mixture of salt and sand is solubility in water
Salt and sand mixture can be separated by filtration followed by an evaporation process
To separate the salt and sugar based on the solubility and the substances is soluble that means it dissolved in solvent and salt is ionic compound that means soluble in water
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When the temperature of a gas decreases (at constant volume), what happens to the pressure in the container?
a: pressure stays the same.
b: pressure decreases.
c: pressure increases.
When the temperature of a gas decrease the pressure also decrease. That is option B.
What is temperature?Temperature is defined as the quantity that measures the degree of how hot or cold an object or medium is.
When the temperature of a medium increases there would be increase in the collision between the molecules that is found in the medium.
The increase in intermolecular collision leads to increase in pressure of the medium. Subsequently, when there is decrease in temperature, the pressure of the medium also falls.
Therefore, it can be said that the temperature of a gas decreases which causes the pressure to also decrease.
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Can someone do questions, 1, 2 and 3 if possible please?
Mass of magnesium ribbon is 0.21 g.
Mass of oxygen gas reacts with magnesium is 0.11 g
Number of moles of magnesium is 0.00875
Number of moles of oxygen is 0.0068.
Ratio of moles of magnesium and oxygen = 1.2 : 1
The number of moles of a substance equals the ratio of its given mass in a chemical reaction to the mass of one mole of that substance. One mole of any substance equals Avogadro's number, that is, 6.023 × 10²³.
we know that mass of crucible and lid = 35.56 g
mass of crucible and lid and magnesium = 35.77 g
Thus mass of magnesium = 35.77 - 35.56 = 0.21 g
mass of crucible and lid and magnesium oxide = 35.88 g
thus, mass of oxygen = 35.88 - 35.77 = 0.11 g
Now, Number of moles of magnesium = 0.21/24 = 0.00875
Number of moles of Oxygen = 0.11/16 = 0.0068
Ratio of Number of moles of magnesium to Number of moles of Oxygen = 0.00875/0.0068 = 1.2 : 1.
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