Answer:
[tex]2.82\cdot 10^9 y[/tex]
Explanation:
A radioactive isotope is an isotope that undergoes nuclear decay, breaking apart into a smaller nucleus and emitting radiation during the process.
The half-life of an isotope is the amount of time it takes for a certain quantity of a radioactive isotope to halve.
For a radioactive isotope, the amount of substance left after a certain time t is:
[tex]m(t)=m_0 (\frac{1}{2})^{\frac{t}{\tau}}[/tex] (1)
where
[tex]m_0[/tex] is the mass of the substance at time t = 0
m(t) is the mass of the substance at time t
[tex]\tau[/tex] is the half-life of the isotope
In this problem, the isotope is uranium-235, which has a half-life of
[tex]\tau=7.04\cdot 10^8 y[/tex]
We also know that the amount of uranium left in the rock sample is 6.25% of its original value, this means that
[tex]\frac{m(t)}{m_0}=\frac{6.25}{100}[/tex]
Substituting into (1) and solving for t, we can find how much time has passed:
[tex]t=-\tau log_2 (\frac{m(t)}{m_0})=-(7.04\cdot 10^8) log_2 (\frac{6.25}{100})=2.82\cdot 10^9 y[/tex]
Based on its location on the periodic table, how many electrons does oxygen have in its outer energy level?
03
04
05
06
Answer:
The number of electrons in the outer energy level of oxygen is 6.
Explanation:
Oxygen is present in the group 16 of the periodic table. The electronic configuration of group 16 element is [tex]ns^{2}np^{4}[/tex]. The number of electrons in outer energy level of group 16 element is always found to be 6.
The addition of the number of the electrons present in the valence shell orbitals of oxygen will give the total number of electrons present in the outer energy level.
The number of electron in the outer energy level of oxygen is (2 + 4) = 6.
4. The type of society that has the greatest energy needs is the __
A hunting society
B agricultural society
C industrial society
D gathering society
Ethyl alcohol is prepared industrially by the reaction of ethylene, C2H4, with water. What is the percent yield of the reaction if 4.6 g of ethylene gives 4.7 g of ethyl alcohol?
C2H4(g) + H2O(l) = C2H6O(l)
Answer:
% yield = 62.21 %
Explanation:
C2H4(g) + H2O(l) → C2H6O(l)∴ mass C2H4(g) = 4.6 g
∴ mass C2H6O(l) = 4.7 g
% yield = ((real yield)/(theoretical yield))×100theretical yield:
∴ molar mass C2H4(g) = 28.05 g/mol
⇒ mol C2H4(g) = (4.6 g)*(mol/28.05 g) = 0.164 mol
⇒ mol C2H6O(l) = (0.164 mol C2H4)*(mol C2H6O(l)/molC2H4(g))
⇒ mol C2H6O(l) = 0.164 mol
∴ molar mass C2H6O(l) = 46.07 g/mol
⇒ mass C2H6O(l) = (0.164 mol)*(46.07 g/mol) = 7.55 g
⇒ theoretical yield = 7.55 g
⇒ % yield = (4.7 g)/(7.55 g))*100
⇒ % yield = 62.21 %
The percent yield of the reaction is 62.7%.
Explanation:The percent yield of a chemical reaction is the ratio of the actual yield to the theoretical yield, multiplied by 100. To calculate the percent yield, you need to determine the theoretical yield and the actual yield. The theoretical yield is the maximum amount of product that can be obtained based on stoichiometry, while the actual yield is the amount of product obtained in the reaction. In this case, you are given that 4.6 g of ethylene produces 4.7 g of ethyl alcohol. To find the percent yield, divide the actual yield by the theoretical yield and multiply by 100.
First, determine the moles of ethylene and ethyl alcohol. The molar mass of ethylene (C2H4) is 28 g/mol, and the molar mass of ethyl alcohol (C2H6O) is 46 g/mol.
Moles of ethylene = mass / molar mass = 4.6 g / 28 g/mol = 0.164 mol
Moles of ethyl alcohol = mass / molar mass = 4.7 g / 46 g/mol = 0.102 mol
The molar ratio between ethylene and ethyl alcohol is 1:1, meaning that 1 mol of ethylene produces 1 mol of ethyl alcohol.
Since the moles of ethylene and ethyl alcohol are equal, the theoretical yield of ethyl alcohol is 0.164 mol. Convert this to grams using the molar mass: theoretical yield = 0.164 mol * 46 g/mol = 7.5 g.
Finally, calculate the percent yield:
Percent yield = (actual yield / theoretical yield) * 100
Percent yield = (4.7 g / 7.5 g) * 100 = 62.7%
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Do you think precipitation has a greater impact on the rate of chemical weathering or mechanical weathering ?
Answer:
Chemical weathering.
Explanation:
Chemical weathering has more to do with weathering things with acid, water, and air. Mechanical weathering happens without water most of the time. Yes they both have water weathering but Chemical weathering has a higher rate of impact.
Precipitation greatly impacts both mechanical and chemical weathering, but due to its role in driving chemical reactions, it is generally more impactful on the rate of chemical weathering. Other factors, including climate, temperature, and biological activity, also influence precipitation's effects on weathering.
Explanation:Precipitation can have a great impact on both mechanical and chemical weathering, but the extent of its impact depends on other factors such as temperature and wind. For example, in the context of climate, temperature, moisture, and wind shape different patterns of weathering. Mechanical weathering can be accelerated by moisture as it causes expansion and contraction in rocks, while chemical weathering often occurs when moisture combines with substances in the atmosphere to produce acids that can break down rock over time.
The role of precipitation is also evidenced in chemistry. The process of selective precipitation is used to remove contaminants from wastewater before it's released back into natural water bodies. Further, precipitation reactions in nature can lead to the formation of solid products through a process called metathesis reactions. So, while precipitation indirectly contributes to mechanical weathering, its role in driving chemical reactions that can lead to chemical weathering is more direct and thus it generally has a greater impact on the rate of chemical weathering.
The impact of precipitation can also be seen in biology. Changing conditions such as temperature and precipitation affect the geographic distribution and phenology of plants and animals. For example, moisture levels affect the biological activity in soil, promoting the development of microorganisms and the decomposition of plant materials, which can contribute to soil weathering.
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A box rests on the floor. If you pull sideways on the box with a 300 N force,
but can't move it, what is the net force on the box?
Ο Α) 0 N
O B) less than 300 N
OC) more than 300 N
Answer:
more than 300 N
Explanation:
you have to have more than 300 N of force to move an object that already requires 300 so 301 N would push it but very slowly
In the past all living things were classified as
Answer:
Modern scientists base their classifications mainly on molecular similarities. They group together organisms that have similar proteins and DNA. Molecular similarities show that organisms are related. In other words, they are descendants of a common ancestor in the past.
Explanation:
4 Sodium metal, Na, reacts with water to form a solution of
sodium hydroxide, NaOH, and gives off hydrogen gas, H.
Write a balanced symbol equation, including state symbols,
for this reaction.
Answer:
2Na(s) + 2H2O(l) ---> 2NaOH(aq) + H2(g)
Explanation:
In the reaction above, solid pieces of sodium metal, Na, is dissolved in liquid water to form a solution of its alkali
(sodium hydroxide, NaOH) and gives off hydrogen gas, H.
The reaction occurs vigorously giving off hydrogen gas due to the highly reactive nature of alkali metals like sodium with water.
How many moles of NO gas are formed from 2.25 moles of nitrogen?
Hey there!
A mole is measured in atoms, molecules, particles. It's kind of a loose sort of measurement, just unit of the substance.
Since there is a ratio of 1 to 1 nitrogen to oxygen, there will be the same amount of molecules as atoms of nitrogen.
2.25 moles of NO gas are formed from 2.25 moles of nitrogen.
Hope this helps!
Given the following equation: Zn + 2HCI - H2 + ZnCl2
How many moles of HCl are needed to react with 0.50
moles of Zn?
Answer:
To react with 0.5 moles of Zn 1 mole of HCl is required
Explanation:
Given data:
Number of moles of Zn = 0.50 mol
Number of moles of HCl = ?
Chemical equation:
Zn + 2HCl → H₂ + ZnCl₂
Now we will compare the moles of Zn and HCl through balance chemical equation.
Zn : HCl
1 : 2
0.50 : 2×0.5 = 1 mol
In order to react with 0.5 moles of zinc 1 mole of HCl is required.
Final answer:
To react with 0.50 moles of Zn, following a 1:2 molar ratio based on the provided equation, 1.0 mole of HCl is required.
Explanation:
The question you've asked is about how many moles of hydrochloric acid (HCl) are needed to react with 0.50 moles of zinc (Zn), based on the chemical equation: Zn + 2HCl → H2 + ZnCl2. From this equation, it's clear that zinc reacts with hydrochloric acid in a 1:2 molar ratio, meaning that for each mole of zinc, two moles of HCl are required for the reaction to proceed to completion.
Therefore, to react with 0.50 moles of Zn, you need 2 * 0.50 = 1.0 mole of HCl.
wood with a mass of 3.0 grams was burned in an open dish. The ashes weighed 1.2 grams.
What happened to the rest of the wood? B
A
The rest of the wood was burned into gases of equivalent weight.
Explanation:
The rest of the wood was burned into gases of equivalent weight.
When wood is burnt in the open air, with the help of oxygen and heat, it is transformed into carbon dioxide, water vapor, and ashes. Ignition and combustion of wood mainly depend on pyrolysis which is also known as thermal combustion.The loss in weight of the ashes is due to the fact that gases and water vapor are also formed due to the combustion of wood.e the letters of the correct answers on the lines at left.
1.
it kinds of mixtures at school. While
lan has been learning about different kinds of mixtures at so
he was helping prepare dinner for his family, he noticed that some o
the food they were making were different kinds of mixtures. What kind
of mixture was their dinner if they were having spaghetti and meatballs
A. heterogeneous
B. homogeneous
C. solute
D. suspension
Suspension mixture was their dinner if they were having spaghetti and meatballs. The right option is D.
Explanation:
Properties of suspension mixture are:
Bigger particles are seen in suspension, and they are visible by naked eye.
Suspension is a heterogenous mixture of either two or more substances.
Solute particles are not dissolved in solvent instead they are suspended as it is or in bulk.
Exhibits Tyndall effect.
Solid particles get sedimented easily.
A mixture of spaghetti and meatballs are suspension because two paricles are not dissoved, and they have separate phases on sphagetti and meat ball where liquid in meat ball drizzles to bottom and meatball remians on top.
Electron Configuration of Mercury?
Answer: Mercury (Hg)
Atomic no.= 80
Electronic Configuration= 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6 5s^2 4d^10 5p^6 6s^2 4f^14 5d^10. The shortened form of the electronic configuration is: [Xe] 4f14 5d10 6s2.
I hope that this helps you !
Calculate the percent by volume of a solution that has 75 mL of solute dissolved in 375 mL of solution. Show your work and round your answer to the nearest whole percent.
Answer:
The answer is 20 % V/V
Explanation:
We use this formula for calculate the %V/V:
%V/V= (ml solute/ml solution) x 100= (75ml/375 ml)x 100 = 20 % V/V
The% V / V represents the amount of ml of solute dissolved in 100 ml of solution
How many moles are in 135g of Teflon?
1.34 moles are in 135g of Teflon.
Explanation:
Molecular formula of teflon is (C2H4)n
mass of teflon = 135 grams
atomic mass of teflon = 100.01 gram/mole
number of moles of teflon = ?
Formula used to calculate number of moles in a substance is given as:
number of moles = [tex]\frac{mass}{atomic mass of 1 mole}[/tex]
putting the values in the above equation:
number of moles = [tex]\frac{135}{100.01}[/tex]
number of moles = 1.34 moles
Teflon is polymer which is used for making non-stick coating, in 135 grams of teflon there are 1.34 moles in it.
Using the formula for calculating moles (mass/molar mass), we find that there are roughly 0.27 moles in 135g of Teflon.
Explanation:To calculate the number of moles in a given mass of a substance, we use the formula:
Number of moles = Mass (in grams) / Molar Mass (in g/mol).
Teflon is also known as polytetrafluoroethylene (PTFE), and its molar mass is roughly 500 g/mol. So, to find the number of moles in 135g of Teflon, we divide:
Number of moles = 135 g / 500 g/mol = 0.27 moles.
Therefore, there are around 0.27 moles of Teflon in a 135g sample.
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What would happen to Earth’s tides if the distance between Earth and the Moon increased?
Answer:
The tides wouldn't go sicko mode
Explanation:
The tides would be weaker, hence no sicko mode
Ben and Sam were conducting experiments on physical and chemical changes in science class. First they added some salt to water and stirred it up until the salt dissolved. "That's a physical change" Ben said. "And that's a solution which is a mixture", added Sam. Next they added an anti-acid tablet to some water. The water began to fizz and bubble. The beaker got cooler. "That's a physical change too," Ben noted. "No, it's not," responded Sam. Who is correct and where should the contents of the beaker be placed in the Venn diagram?
A) Sam is correct. It is not a physical change and it should be placed in A
B) Sam is correct. It is a chemical change and the contents should be in D. for compound.
C) Ben is correct. It is a physical change and it is a solution, placing it in B. as a mixture.
D) They are both correct. It is a mixture and a compound and the contents should be placed in C.
Answer:
b
Explanation:
hi from 2022
Ben and Sam were conducting experiments on physical and chemical changes in science class. Sam is correct. It is a chemical change and the contents should be in D. for compound. Therefore, option B is correct.
What is meant by chemical and physical change ?In a physical change the visual aspect or form of the matter changes but the kind of matter in the substance does not. However, in a chemical change, the kind of matter changes and at least one new matter with new properties is produced.
Some of the processes that makes physical changes include cutting, bending, dissolving, freezing, boiling, and melting.
Examples of chemical changes are baking soda and vinegar creating carbon dioxide, iron rusting, and wood burning.
Thus, Sam is correct. It is a chemical change and the contents should be in D. for compound, option B is correct.
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1. Which of the following particles are free to drift in metals?
O neutrons
O cations
O electrons
O protons
Answer:
electrons
Explanation:
metals do what is called metallic bond
An electron is the particles are free to drift in metals.
What is metals?The elements having tendency to lose electron and having properties like lustrous, malleable, ductile, opaque, denser and good conductor of heat and electricity is called metals
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Which reaction is exothermic?
A.) cellular respiration
B.) photosynthesis
C.) baking soda + vinegar
D.) melting ice
Answer: D.) melting ice
Explanation:
An exothermic reaction is a chemical reaction that releases energy through light or heat
hope this helps :D
A flask containing 155cm^3 of hydrogen was collected under a pressure of 22.5kPa. What pressure would have been required in order for the volume of the gas to have been 90.0 cm^3 at constant temperature ?
Answer:
38.75KPa
Explanation:
The following were obtained from the question:
V1 = 155cm^3
P1 = 22.5kPa
V2 = 90cm^3
P2 =?
The new pressure can obtain by doing the following:
P1V1 = P2V2
22.5 x 155 = P2 x 90
Divide both side by 90
P2 = (22.5 x 155) /90
P2 = 38.75KPa
Which is a process that causes an organism’s poorly suited characteristics to disappear?
death rate
adaptation
natural selection
Choose the words that make each statement true.
A6.0 M solution contains 6.0
of solute
dissolved in one of solution. The Min
6.0 M refers to
. The
concentration of a 6.0 M solution may also be
expressed as
Answer:
moles, liter, concentration, and 6.0 mol/L
Explanation:
Answer:
First Question:
Moles, liter, concentration, 6.0 mol/L
Second Question:
C. [HCl]
Third Question:
C. molarity.
Fourth Question:
A. M = mol solute/liter solution
Explanation:
Got it right
C. Balance the following equations.
1 H2O2(1)→ H,00) + O2(8)
Hey there!
H₂O₂ → H₂ + O₂
This equation is already balanced.
We count 2 hydrogen atoms on the left, and 2 hydrogen atoms on the right.
We count 2 oxygen atoms on the left, and 2 oxygen atoms on the right.
This means the equation is balanced.
Hope this helps!
Lists ways that a bike’s motion can change
Answer: Check explanation
Explanation:
Then bike can't get hit. They can turn the wheel. They can hit the brake
Gina was given an irregularly shaped piece of metal and was told that the density of the metal was 10 g/cm3. She measured the mass of the piece to be 210 g. What was the volume of the piece of metal Gina was given?
Answer:
The volume of the piece of the metal Gina is found to be 21 [tex]cm^{3}[/tex]
Explanation:
Given density of the metal = 10 g/[tex]cm^{3}[/tex]
Given mass of the piece of the metal = 210 g
Assuming volume of piece of metal to be V [tex]cm^{3}[/tex]
The expression for the density is shown below
[tex]\textrm{Density} = \displaystyle \frac{\textrm{Mass of piece of metal}}{\textrm{Volume of piece of metal}}\\10 \textrm{ g/cm}^{3} = \displaystyle \frac{210 \textrm{ g}}{V} \\V = 21 \textrm{cm}^{3}[/tex]
Volume of the piece of metal = 21 [tex]cm^{3}[/tex]
Balance this chemical equation please
Answer:
CH4 + 2O2 (excess) → CO2 + 2H2O + EnergyExplanation:
Combustion of methane gas molecules in abundance of O2 can follow the above reaction, product expected carbon dioxide, water and energy only.
But, when the O2 is not sufficiently available for perfect methane combustion, then there are many other products from the methane combustion reaction in above the product with CO and C.
The molar ratio of [C]: [CO] :[CO2] will depend on the availability of O2 for combustion of methane . In the high deficiency of oxygen conditions: monoxide and black carbon will be the major products of the combustion of methane.
According to a weather map, a cold air mass is moving into a given area where a warm air mass is currently located. What type of weather should be expected as the cold air mass approaches? A. rain, accompanied by cooler weather B. clear skies, accompanied by cooler weather C. rain, accompanied by warmer weather D. clear skies, accompanied by warmer weather
Answer:
Rain,accompanied by cooler weather
Answer:
Rain and cooler weather
Explanation:
An iron nail (Fe) is placed into a solution of copper(II) sulfate (CuSO4). After some time, the blue color of the copper(II) sulfate disappears and some copper-colored solid (Cu) is found on the surface of the nail. The solution now contains iron(II) sulfate (FeSO4 ), and the container feels warmer than before the reaction.
1. What do the color changes indicate?
2. List the reactants
3. List the products.
4. Explain what is meant by a balanced chemical equation.
5. How can you determine the rate of a chemical reaction?
Answer:
1. The colors changes mean the reaction took place.
2. Fe and CuSO4
3. FeSO4 and Cu
4. This means that the electrons on both the reactants and the products have to be balance or need to be the same.
5. When you get the products meaning after the reaction takes place
The color change from blue to colorless indicates copper ions are being reduced to metallic copper in a chemical reaction, where iron and copper(II) sulfate are reactants, and iron(II) sulfate and copper are products. A balanced chemical equation has equal numbers of each type of atom on both sides, and reaction rate can be measured by changes in reactant/product concentration over time.
The color changes indicate a chemical reaction is taking place. Specifically, the disappearance of the blue color suggests the reduction of copper ions (Cu2+) to metallic copper (Cu) and their removal from the solution.
The reactants in this reaction are iron (Fe) and copper(II) sulfate (CuSO4).
The products are iron(II) sulfate (FeSO4) and copper (Cu).
A balanced chemical equation means that the number of atoms for each element is the same on both sides of the equation. This follows the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction.
To determine the rate of a chemical reaction, one approach is to measure the change in concentration of a reactant or product over time. For example, for the reaction Fe(s) + CuSO4(aq) → FeSO4(aq) + Cu(s), you might measure how quickly the blue color of CuSO4 fades or how quickly metallic copper forms on the iron nail.
According to the graph, which of the following substances is least soluble in 100 grams of water at 50°C?
1. KCI
2. Nacl
3. NHACI
4. HCI
Answer:2) NaCl
Explanation:
The least soluble substance at 50°C would be the one with the lowest point on a typical solubility graph at this temperature. However, a specific answer cannot be provided without the graph.
Explanation:Without the graph, it's not possible to provide a definitive answer. In general, solubility depends on the specific substance and temperature. However, assuming a typical solubility graph, you would find the least soluble substance at 50°C by looking for the compound which has the lowest point on the graph at this temperature. This is because solubility graphs usually show the amount of a substance that can be dissolved in 100 grams of water at various temperatures.
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What happens when an amorphous solid breaks?
O
A. The solid breaks at predictable places.
O
B. The solid breaks at random places.
O
C. The break follows a crystal pattern.
O
D. The solid shears in flakes or planes.
Answer:
IT BREAKS AT RANDOM PLACES!!!!
An amorphous soild breaks at the random places
Which is an amorphous solid?
Amorphous solid, any noncrystalline solid in which the atoms and molecules are not organized in a definite lattice pattern. Such solids include glass, plastic, and gel.
Which of the following is a property of the amorphous solid?These solids are stabilized by the regular pattern of their atoms. Their characteristic properties include distinct melting and boiling points, regular geometric shapes, and flat faces when cleaved or sheared.
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What is sublimation?
Answer:
Solid -> Gas
Explanation:
Sublimation is when a solid directly transitions to a gas, skipping the liquid form.
Explanation:
sublimation is a changing of a solid directly into vapour on heating and of vapour into solid on cooling .
hope it helps