The half-life = 10hrs.
Solution:
We know, activity after 'n' half-lives R=RO (1/2)n
125= 500 (1/2) n
= (1/2)n = (125/500) = 1/4 = (1/2)
n = 2
now,
nty2 = 20 hrs
2ty₂ = 20 hrs
ty₂ = 10 hrs
∴ half-life = 10 hrs
Half-life is the time it takes a given amount of a radioactive element to decay to half its original value. This also means that half-life is the time it takes for the activity of a source to decay to half its original value. Become. Isotope half-life is used to describe the rate at which the isotope decays and emits radiation. Half-life can be used to predict the amount of radioactive material remaining after a certain period of time.
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carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur are considered multiple choice minor elements. major elements. neutral elements. acidic elements.
These elements like carbon, oxygen, nitrogen, etc are called the major elements.
Major elements are those elements that are found more than 1% in the atmosphere. These elements are higher in quantity than the other elements.
These are also known as major elements because they are majorly found in the genetic material of living beings.
It can be said that these are the element by which the living beings are formed. Genetic material like DNA or RNA have these materials and are abundant in the body.
They are also known as CHON elements in short.
Hence, with all that we can conclude that these elements are the major elements.
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which of the following ions has the same ground-state electron configuration as the nearest noble gas?
group of answer choices
fe3+
pb4+
zn2+
zr2+
ce4+
Answer:
i think it might be zr2+ i may be wrong but lets try that
Explanation:
A student is conducting a lab investing solutions. The student starts by adding a set amount of sugar to water. After stirring, all of the sugar has dissolved. The student adds more sugar but does not dissolve. He continues to stir, but the sugar will not dissolve. The student correctly concludes that the first amount of sugar added caused the solution to be.
Sugar dissolves in water because intermolecular connections between the slightly polar sucrose molecules and the polar water molecules release energy.
The weak bonds that form between the solute and the solvent compensate for the energy needed to disrupt the structure of both the pure solute and solvent. When sugar dissolves in a liquid, the sugar molecules take up the space between the water molecules.
As a result, they don't contribute any extra room. Thus, the volume of the solution does not change. Sugar dissolves more quickly in hot water than it does in cold water because hot water has more energy. The molecules of water move more swiftly and energetically when it is heated.
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I have this chemistry exam tomorrow and im revising but i don’t understand this question
what process occurs in box a? what process occurs in box a? electron transport and oxidative phosphorylation oxidative phosphorylation electron transport
oxidative phosphorylation occurs in a box ,Carbon dioxide and water are by-products of cellular respiration.
what is oxidative phosphorylation ?
During oxidative phosphorylation, electrons derived from NADH and FADH2 combine with O2, and the energy released from these oxidation/ reduction reactions is used to drive the synthesis of ATP from ADP.Oxidative phosphorylation or electron transport-linked phosphorylation or terminal oxidation is the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing chemical energy in order to produce adenosine triphosphate. In eukaryotes, this takes place inside mitochondriaOxidative Phosphorylation StepsDelivery of Electrons by NADH and FADH2. Reduced NADH and FADH2 transfer their electrons to molecules near the beginning of the transport chain. ...Electron Transport and Proton Pumping. ...Splitting of Oxygen to form Water. ...ATP Synthesis.Oxidative phosphorylation provides most of the ATP that higher animals and plants use to support life and is responsible for setting and maintaining metabolic homeostasis.In the mitochondrion, what the proton gradient does is facilitate the production of ATP from ADP and Pi. This process is known as oxidative phosphorylation, because the phosphorylation of ADP to ATP is dependent on the oxidative reactions occurring in the mitochondriato know more about oxidative phosphorylation follow
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what force was applied to an object if 35 j of work was done and the object moved 7 m?
5N force was applied to an object if 35 j of work was done and the object moved 7 m
A force is an effect that can alter an object motion according to physics and an object with mass can change its velocity or accelerate as a result force and also force is as push or pull and work done by the force on an object means assuming that direction of the force is parallel to the displacement of the object
Then the formula is
W = f × d
Where f is the magnitude of force and d is the displacement of the object
Then W = 35 J is the work done and
d = 7m is the displacement of the object
So rearrange the equation then
F = 35/7 = 5N
5N force was applied to an object if 35 j of work was done and the object moved 7 m
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A reaction that has two molecules involved at the rate determining step normally has an overall reaction order equal to?.
The total number of molecules responding in an elementary step determines the reaction's overall order. The reaction in the example below is referred to as first order.
Can there be two rate-determining phases in a reaction?Accordingly, a chemical system must always have either a single rate-controlling step (the RDS) or many rate-controlling steps, as well as potentially one or more rate-inhibiting processes. To sum up: Although not every overall chemical reaction contains a rate-determining step (RDS), all chemical reactions should have at least one.
What does order of reaction mean?Definition. The power dependence of the rate on the concentration of each reactant is referred to as the order of reaction. As a result, the rate of a first-order reaction depends on the concentration of a single species.
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identify each material as a compound or a mixture. coffee is a solution of organic substances in water. mixture compound
The material as a compound or a mixture. coffee is a solution of organic substances in water is mixture.
Mixture can be defined as the combination of different substances and they can be separate by the different types methods. like salt water , salad is a mixture. coffee comes under the category of solution , a mixture and a homogenous mixture. A homogeneous mixture is defined as the mixture of substances that can be mixed thoroughly that cannot be seen as individual substance.
Thus, The material as a compound or a mixture. coffee is a solution of organic substances in water is mixture.
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Answer:
mixture for both
Explanation:
carbohydrates and fats are considered high-energy foods because they . carbohydrates and fats are considered high-energy foods because they . have no nitrogen in their makeup. have a lot of electrons associated with hydrogen. have a lot of oxygen atoms. are easily reduced. request answer
Because they contain a large number of hydrogen-related electrons, carbohydrates and fats are regarded as high-energy foods. Carbohydrates include the sugar, starch, and fibre present in everyday.
One of the three micronutrients that the human body uses to produce energy is this one. At the molecular level, carbon, hydrogen, and oxygen atoms are characteristics of carbohydrate biology. The first element encountered throughout the tour of the periodic table of elements is hydrogen, which is represented by the chemical symbol H. Of all the elements in the universe, it is the most fundamental and first. Ninety percent of all atoms in the universe are hydrogen atoms, making it the periodic table's lightest element.
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After comparing the 20% cranberry juice absorption spectrum to the 20% apple juice absorption spectrum, do you think that apple juice contributes to the color of cranberry-apple juice at the λmax you selected? why or why not?.
Color of apple and cranberry juice is yellow and red respectively as the two colors of juices are different each color has it's own λ max according to Beer's law and hence apple juice contributes to color of cranberry-apple juice .
What is Beer's law?The Beer's law states that the absorbance is directly proportional to the concentration of a solution that is,A∝C .Most substances follow Beer's law from low to moderate temperature ranges only.It is not followed well in case of saturation effects which are present in highly concentrated samples.
Due to the direct relation between absorbance and concentration , absorbance is preferred over transmittance for recording the spectra.
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what alkane, with molecular formula c5h12 , forms only one monochlorinated product when it is heated with cl2 ?
The alkane with the molecular formula C₅H₁₂ , which forms the only one monochlorinated product when it is heated with Cl₂ is 2,2 dimethyl propane or neo-pentane.
The alkane with the molecular formula C₅H₁₂, forms only one monochlorination product is given as follows :
C(CH₃)₃- CH₃ + Cl₂ -----> C(CH₃)₃- CH₂ - Cl
2,2 dimethyl propane 2,2 dimethyl 1 chloro- propane
( neopentane)
thus, the 2,2 dimethyl 1 chloro- propane is formed when the neopentane or the 2,2 dimethyl propane with undergoes mono chlorination. in the mono chlorination the , in the alkane the one hydrogen atom is replaced by the chlorine atom,. this is the process of chlorination.
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Which of the following 10-g samples of a radio-isotope will decay to the greatest extent in 28 days? Show all work and explanation
A. P-32
B. Kr-85
C. Fr-220
D. I-131
The radioisotope that would decay the most ought to be Fr-220. Option C
What is the half life?The term half life of the radioactive isotope has to do with the time that it would take for us to have only half of the number of the original radioactive atoms to be left. We have to find the half life of each of the isotopes so that we can be able to get the one that has decayed the most.
For P - 32
Half life = 14.3 days
Using;
N/No = (1/2)^t/[tex]t_{\frac{1}{2} }[/tex]
N = amount present at time t
No = initial amount
t = time taken
[tex]t_{\frac{1}{2} }[/tex] = half life
Hence;
N/10 = (1/2)^28/14.3
N = (1/2)^28/14.3 * 10
N = 2.6 g
For Kr-85
Half life 10.76 years or 3927.4 days
N/10 = (1/2)^3927.4/28
N = (1/2)^3927.4/28 * 10
N = 5.97 * 10^-47 g
For Fr-220;
27.40 seconds or 0.00032 days
N/10 = (1/2)^0.00032 days/28 days
N = (1/2)^0.00032 days/28 days * 10
N = 10 g
For I-131
Half life = 8 days
N/10 = (1/2)^8/28
N = (1/2)^8/28 * 10
N = 8.2 g
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The amount of energy needed to apply a force of 1 newton over a distance of 1 meter is also called a.
Answer:
Joule
Explanation:
This is the answer
When preparing a buret for use in lab, the buret must always be cleaned thoroughly. Prior to being filled with solution, the buret is rinsed one last time. What is the buret rinsed with, and why?.
The titrant must be used to ensure that when added to the buret it will not be diluted with water.
How to clean a buret for use in lab?Rinse with distilled water: With the tap closed, add distilled water to the burette. Tilt and roll the burette so that the water contacts all internal surfaces. Open the stopcock to let the water run. If the sides are dry and the water is gone, repeat the rinse two more times before proceeding to step 2. If water droplets remain on the inner surface, clean the burette with cleaning solution, rinse several times with tap water, and then three times with distilled water.Rinse with solution: After draining the last rinse with distilled water, close the stopcock and add approx. 5 ml of solution from the burette. Rotate and tilt the burette again so that the solution contacts all internal surfaces. Open the stopcock and drain the solution. Repeat this two more times. Discard the rinse solution.As with pipettes, burettes should be rinsed with distilled water followed by the filling solution to avoid contamination problems.
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a large rainstorm hits your town and it rains all day. how does this event relate to the water cycle?
When a large rainstorm hits your town and it rains all day, is a stage of water cycle known as precipitation.
What is water cycle?
The water cycle shows the continuous movement of water within the Earth and atmosphere.
There are three main parts to the water cycle and they are listed below:
Evaporation, Condensation PrecipitationThe evaporation of water occurs when the water on earth surface such as lakes, rivers, ocean, etc, gains heat, turn into water vapour and escapes into the atmosphere.
The next stage after evaporation in water cycle is condensation, the warmer water vapour comes in contact with cooler air in the atmosphere or clouds, lose heat and form water droplets which accumulates in the cloud.
The last stage in the water cycle is precipitation; when the condensed water droplets in the cloud saturates the cloud, it precipitates in form of rain fall, and the process continues to infinite.
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What is the noble gas electron configuration for sulfur, S?
Answer:
below
Explanation:
From periodic table the shell electrons are 2 8 and 6 so:
1s2 2s2 2p6 3s2 3 p4 for sulfur
the noble gas config is then (neon + 6) =
[Ne] 3s2 3p4
based on the tests in this lab, what anion is most likely present if you add acid to a solution and then bubbles form vigorously?
HCO₃⁻ is most likely present if you add acid to a solution and then bubbles form vigorously.
Define bicarbonate (HCO₃)?The body uses bicarbonate, an electrolyte and negatively charged ion, to assist keep its acid-base (pH) balance. In order to maintain electrical neutrality at the cellular level, it also collaborates with the other electrolytes (sodium, potassium, and chloride). This examination examines the total concentration of blood carbon dioxide (CO₂), which primarily takes the form of bicarbonate (HCO₃⁻). The majority of the CO₂is a byproduct of many metabolic activities.
The main organs responsible for controlling blood pH by eliminating extra bicarbonate are the lungs and kidneys.
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Which brain region or part of the brain is responsible for hearing the sounds of a crowd in a baseball game?
Answer:
I think it's the auditory cortex or the temporal lobe
If 30. 0 l of oxygen gas is cooled from 473 k to 274 k at constant pressure, what is the new volume of oxygen ?.
The new volume of oxygen is 17.378 L.
Charles's law“If a gas is contained in a closed chamber with constant mass and pressure, then its volume is directly proportional to its absolute temperature"
The relationship between volume and absolute temperature in the Charles equation is directly proportional. That is, if the temperature increases, the volume also increases. Conversely, if the temperature decreases, the volume of gas also decreases.
Thus, the simplest Charles law equation can be expressed as:
K = V/T
With,
V = gas volume (m³)
T = absolute temperature (K)
k : constant
So, Charles' law equation can be written as:
V₁/T₁ = V₂/T₂
Where:
V₁ = initial volume of gas = 30 L
T₁ = initial temperature of gas = 473 K
V₂ = new volume of gas = ?
T₂ = new temperature of gas = 274
On putting all these values on the above equation, we get
V₂ = (30)(274) / 473 = 17.378 L
So, the new volume of oxygen is 17.378 L.
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What is the correct lewis electron-dot structure for the compound made of magnesium fluorine after forming an ionic bond?.
In the Lewis structure of MgF₂, each magnesium atom and each fluorine atom has two single bonds. Two fluorine atoms flank the magnesium atom. There are no lone pairs present on magnesium ion however there are three lone pairs on each of the fluorine atoms.
What is lewis electron-dot structure?Each element has a certain number of electrons in its atomic orbitals. Of these electrons, only those involved in bond formation with other atoms are present in the outermost shell of the atom. These electrons in the outermost orbital of the atom are called valence electrons.
MgF₂ is an ionic compound consisting of a magnesium cation and a fluoride anion. To draw the electron dot or Lewis diagram of this compound, you must first draw the electron configuration of the atoms.
Electronic configurations:
Mg : 1s²2s²2p⁶3s²
F : 1s²2s²2p⁵
By donating two electrons, magnesium has a full octet in its outer shell, and fluorine lacks only one electron to complete its octet, so two fluorine atoms bond with magnesium. Forms stable MgF₂ compounds. Thus an ionic bond is formed.
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a mixture with h2 and he exerts a total pressure of 0.480 atm. if there is 1.00 g of h2 and 1.00 g of he in the mixture, what is the partial pressure of the helium gas? round the answer to three significant figures.
A mixture with H₂ and He exerts a total pressure of 0.480 atm. If there is 1.00 g of H₂ and 1.00 g of He in the mixture, the partial pressure of the helium gas is 0.158 atm.
The partial pressure of a gas is defined as the pressure exerted by a individual gas in the gas mixture. The partial pressure for individual gas is calculated using the formula
P(gas)=P(total)×X(gas) (i)
Where, X(gas)- Mole fraction of the gas
mole fraction is calculated using the formula
mole fraction=(moles of individual compound/total moles)
The molar mass of H₂ is 2 g/mol and of He is 4g/mol. Hence moles of H₂ and He is
mol of H₂=1 g×(1 mol/2 g)
=0.50 mol
mol of He=1 g×(1 mol/4 g)
=0.25 mol
Total number of moles are
total mole=(0.50+0.25) mol
=0.75 mol
The mole fraction of He gas is
mol fraction of He=(0.25 mol/0.75 mol)
=0.33
Hence, the partial pressure of He gas after plugging value in equation(i) is
P(He)=0.480 atm×0.33
P(He)=0.1584 atm
P(He)=0.158 atm
Therefore, the partial pressure of helium(He) gas is 0.158 atm.
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A colorimeter is an instrument used to measure the amount of ____________ absorbed by a solution. This absorbance is proportional to the ________ of the solute in solution.
A colorimeter is an instrument used to measure the amount of heat absorbed by a solution. This absorbance is proportional to the concentration of the solute in solution.
A calorimeter is a device used in calorimetry, a procedure for calculating heat capacity and measuring the heat of chemical processes or other physical changes. Among the most popular kinds are differential scanning calorimeters, isothermal micro calorimeters, titration calorimeters, and accelerated rate calorimeters. A straightforward calorimeter is basically a metal container with a thermometer positioned above a combustion chamber. It is one of the measuring tools used in the research of chemistry, biochemistry, and thermodynamics.
To calculate the enthalpy change per mole of substance A in a reaction involving two compounds A and B, the substances are individually introduced to a calorimeter and the beginning and final temperatures (before and after the reaction) are recorded. The mass and specific heat capacity of the substances multiplied by the temperature change provide a figure for the amount of energy released or absorbed during the reaction. The enthalpy change of the reaction is calculated by dividing the energy change by the quantity of A that was present.
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a chemistry student found the density of freon-11 (cfcl3) to be 5.58 g/l under her experimental conditions. her measurements showed that the density of an unknown gas was 4.38 g/l under the same conditions. what is the molar mass of the unknown? a. 96.7 g/mol b. 108 g/mol c. 127 g/mol d. 165 g/mol e. 175 g/mol
The molar mass of the unknown gas is 96.7g/mol so the correct option is (a).
The molar mass of a synthetic compound is delineated as the mass of a sample of that compound detached from a piece amount relevant that is the number of blemishes within the sample, calculated in moles. The molar mass is a size, not microscopic, characteristic of wealth. Molar mass is of excellent importance when starting an experiment.
Molar mass can be calculated by the under-mentioned:
Density = M*P/R*T ---------->(1)
Density = 4.38g/L
Where,
M = molar mass of gas
P = pressure of the gas
R = universal gas constant
T = temperature (273K)
Therefore,
Molar mass = density * universal gas constant * temperature /pressure
Molar mass = 4.38g/L*.0821 L atm/mol K *273K / 1atm
= 97g/mol
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predict the charge that an ion formed from sulfur would have. question 21 options: a) 1- b) 2- c) 6 d) 4 e) 3-
The charge of the ion from the sulfur atom would have 2- ionic state.
Sulfides/sulfur ions are inorganic sulfur anions of the formula S2- or compounds containing one or more S2- ions. Solutions of sulfide salts are corrosive. Sulfides also refer to a large family of chemical compounds, inorganic and organic compounds. Lead sulfide and dimethyl sulfide. Hydrogen sulfide and disulfide are conjugate acids of sulfides.
However, the name sulfide is also used in IUPAC nomenclature for compositions that do not assume the type of bond involved. Examples of such names are selenium disulfide and titanium sulfide, which do not contain sulfide ions.
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Which of the following is a physical change?
A) density of ice
B) oxidation of rust
C) reactivity with water
D) flammability of propane
The following is a physical change flammability of propane. Option D.
Properties that can be obtained without changing the composition of a substance are called physical properties. A chemical property is a property that can be measured or observed only when a substance changes into a completely different kind of substance. These include reactivity flammability and the ability to rust.
Density is the mass per unit volume of matter. Density is a concentrated property. That is, the density does not change as the amount of matter present changes. Physical properties are properties of matter that are not related to changes in chemical composition. Well-known examples of physical properties are density color hardness melting and boiling points and electrical conductivity.
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if a solution has a very low concentration of h , it will have a ph in what range? group of answer choices
If a solution has a very low concentration of H⁺ , The pH in of the solution increases.
The pH is inversely proportional to the concentration of H⁺ ion. the strong acid is one which produces more H⁺ ion in the solution. the weak acid produce less concentration of H⁺ ion. if the concentration of H⁺ ion decreases the pH of the solution increases. the pH below 7 is acidic and pH above 7 is basic. the pH increase mean solution shifts to basicity.
Thus, If a solution has a very low concentration of H⁺ , The pH in of the solution increases.
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what instruments, special equipment, and procedures are used in the calibration of flowmeters that are used for measuring the flow of single-phase liquids
Instruments used for calibrating flowmeters for single-phase liquids include:
Volumetric proversFlow computersControl valvesFlow metersThe special equipment and procedures used in the calibration of flowmetersSpecial equipment used may include a:
Flow loopFlow calibration rigPressure gaugesFlow nozzlesProcedures used in the calibration process may include:
Measuring the flow at different pressures.Measuring the flow rate at different points in the flow loop. Verifying the accuracy of the flow meter against a known reference.Adjusting the meter to the desired flow rate.Verifying the accuracy of the meter by measuring the flow rate at different points in the flow loop.Learn more about flow meters for single-phase liquids:
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The amount of water flowing through a channel over a given amount of time is called its ______.
Answer:
Discharge
Explanation:
this is the answer
it takes 2.00 l pure oxygen gas at stp to react completely with a certain sample of aluminum. what is the mass of aluminum reacted?
64.6 g of Al2O3 are created from 30.4 g of O2. The highest amount of aluminum oxide that may be produced in this reaction is 57.4 g, with aluminum acting as the limiting reagent.
The mass of an object can be calculated by multiplying its density by its volume because density is a measure of mass per unit of volume. For aluminum products, high pressure die casting is a quick and effective method of mass production. A steel mold is heavily pressurized as molten aluminum is poured into it, producing 1,000 to 1,000,000 pieces of high pressure die casting aluminum annually. Sodium aluminate and water are created when aluminum oxide interacts with sodium hydroxide. The temperature where this reaction occurs is between 900 and 1100 °C.
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7. The tendency of sound waves to bend when they pass from one medium to a different medium is known as A. refraction C. resonance B. reflection D. interference
The tendency of sound waves to bend when they pass from one medium to a different medium is known a refraction.
What is refraction ?In diffraction, a sound wave is bent or stretched out in a single medium where the sound speed remains constant. Refraction is a crucial instance in which sound waves arc or diffuse. Due to variations in the wave's speed, a sound wave bends in this occurrence.
A wave bends as it travels along the edge of an object or through an aperture. It is referred to as diffraction. When a wave transitions from one medium to another at an angle, it also bends. It's known as refraction.
Thus, The option A is correct.
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