Ninety-seven years is the half-life of 90Sr. A sample of 90Sr would still have 0.015 of its original atoms after 175 years. The duration needed for a quantity to fall to half its starting value is known as the half-life.
The phrase is frequently employed in nuclear physics to indicate how rapidly unstable atoms decay radioactively or how long stable atoms last. One or more electrons are attached to the nucleus of every atom, which is made up of a nucleus. Protons and neutrons, in various numbers, make up the nucleus. Neutrons exist only in the most prevalent type of hydrogen. Atoms that are neutral or ionised are the building blocks of all solids, liquids, gases, and plasma.
[A]t=[A]o/[A]t=4.18 [A]o/[A]t=e4.18=65.5
[A]o = 1.5%[A]o], where [A]t = 0.015
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The air pressure from the atmosphere measures 0. 5atm at an altitude of 18,000 ft. How much pressure is this in pounds per square inch?
At an altitude of 18,000 feet, where the atmospheric pressure is 0.5 atm, the pressure is 7.5 pounds per square inch.
At sea level, what is the calculation?One square inch of any surface has 15 pounds of air sitting on top of it at sea level. That same square inch is only under 7.5 pounds per square inch of pressure at 18,000 feet.
The atmospheric pressure rises with increasing altitude. Contrary to popular belief, the graph shows that pressure decreases as altitude rises (moving to the right on the graph).
At sea level, the atmospheric pressure is 14 pounds per square inch. If we assume that the altitude is zero, we can see that the pressure is equal to 14 pounds per square inch. The atmospheric pressure rises as the altitude gets closer to sea level.
We observe that the pressure value rises as the altitude gets closer to sea level. As the altitude rises, the atmospheric pressure approaches 14 pounds per square foot. Only when the elevation is 0 miles above sea level does the pressure equal 14 pounds per square inch.
The pressure will therefore be 7.5 pounds per square inch if the air pressure in the atmosphere measures at 18,000 feet or 0.5 atm.
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The reaction of ethane gas C2H6 with chlorine gas produces C2H5Cl as its main product along with HCl. (In addition, the reaction invariably produces a variety of other minor products, including C2H4Cl2, C2H2Cl3, and others. Naturally, the production of these minor products reduces the yield of the main product.) (a) Write out the complete, balanced chemical reaction of main reaction taking place. (b) Calculate the percent yield of C2H5Cl if the reaction of 300. grams of ethane with 650. grams of chlorine produced 490. grams of C2H5Cl.
a) The balanced equation is :
C₂H₆ + Cl₂ ---> C₂H₅Cl + HCl
b) The percent yield is the 83.0 % %.
a) The balanced equation is given below :
C₂H₆ + Cl₂ ---> C₂H₅Cl + HCl
b) mass of the ethane = 300 g
molar mass of the ethane = 30 g/mol
moles of the ethane = 300 / 30
= 10 mol
mass of chlorine = 650 g
molar mass of the chlorine = 71 g /mol
moles = 650 / 71
= 9.15 mol
it is clear the the chlorine is the limiting reactant.
1 mole of the chlorine produces the 1 mole of the C₂H₅Cl
moles of the C₂H₅Cl = 9.15 mol
mass of the C₂H₅Cl = 9.15 × 64.5
= 590.175 g
The percent yield = (experimental yield / theoretical yield ) × 100 %
= ( 490 / 590 .175 ) × 100 %
= 83.0 %
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Which of these are involved in creating
new technologies?
A. engineering only
B. science only
C. math only
D. science, engineering, and math
The rate of effusion of a particular gas was measured and found to be 21.0 mL/min. Under the same conditions, the rate of effusion of pure methane (CH4) gas is 47.0 mL/min. What is the molar mass of the unknown gas
the particular gas effusion was 21.0. and the methane effusion rate is 47.0 The molar mass of the unknown gas is approximately 28.6 g/mol
The process through which a gas manages to escape through with a small hole or highly permeable barrier is known as effusion. A gas's rate of effusion is inversely proportional to its molar mass squared. The following equation describes this relationship: rate1 / rate2 = (sqrt(molar mass2) / sqrt(molar mass1)). where rate1 and rate2 are the rates of effusion of the two gases and molar mass1 and molar mass2 are the molar masses of the two gases.Given the rate of effusion of the unknown gas is 21.0 mL/min, and the rate of effusion of pure methane (CH4) is 47.0 mL/min, we can use the above equation to find the molar mass of the unknown gas:
(21.0 mL/min) / (47.0 mL/min) = sqrt(molar mass unknown) / sqrt(16.04 g/mol)
Squaring both sides of the equation, we get:
(21.0 mL/min)^2 / (47.0 mL/min)^2 = (molar mass unknown) / (16.04 g/mol)
Solving for molar mass unknown we get:
molar mass unknown = (16.04 g/mol) * (21.0 mL/min)^2 / (47.0 mL/min)^2
The molar mass of the unknown gas is approximately 28.6 g/mol
Please note that the above calculation is based on the assumption that the temperature and pressure are the same for both gases and that the gases are ideal
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A compound is composed of carbon and hydrogen and has an empirical
formula of CH. The molar mass of the compound is experimentally
determined to be 78.12 g/mol. What is the molecular formula for the
compound?
The supplied statement indicates that the compound's molecular formula is (CH)ₙ = CH₆ = C₆H₆
What is the purpose of hydrogen?Fuel cells may produce energy, power, and heat using hydrogen. The two industries where hydrogen is now most widely employed are urea manufacturing and petroleum refining, with the developing markets of utilities and transportation.
Briefing:The lowest half figure ratio of a compound is revealed by the empirical formula for that molecule.
Empirical weight formula: 12 + 1 Equals 13.
Molecular weight = 78
n = Molecular weight/Empirical formula weight
n = 78.12/13
n = 6.00
Molecular formula = (CH)ₙ = CH₆ = C₆H₆
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In a reaction between vinegar and antacid tablets, the antacid is the limiting reagent. At constant pressure and temperature, three tablets produce 600 cm³ of gas.
What volume will six tablets produce?
The volume of gas produced by six tablets would be twice the volume produced by three tablets, or 600 cm³ x 2 = 1200 cm³.
Definition of a gas's volumeUntil they are enclosed in a container, gases lack a definite shape or volume. Gases can expand and contract as they are forced into various container sizes and shapes because of the way their molecules spread out and move randomly.
The volume of the container in which a gas is contained can be used to define the volume of the gas itself.
The volume of a gas reduces as the molecules are crammed closer together when it is compressed. A gas's volume rises when it expands.
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Answer:
1200 cm³.
Explanation:
How do you calculate number of molecules?
Determine the substance's molecular weight in units of one mole, then divide the molar mass value by the molecular mass, and multiply the result by the Avogadro constant to get the required number of molecules.
It is possible to determine the number of molecules by using the relationship between the number of moles and Avogadro's number, which is provided by;
1 mole = Avogadro's constant (NA)
The number of molecules will equal the product of the number of moles and Avogadro's number, which is determined after the number of moles has been determined
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Describe how you would prepare a pure sample of barium sulfate using barium chloride as one of the starting materials
Answer:
See explanation
Explanation:
Barium sulphate is easily prepared by means of a double replacement reaction. A double replacement reaction is one in which the ions in each of the reactants exchange partners in the products.
For instance, we can decide to prepare barium sulphate by a double replacement reaction between sodium sulphate and barium chloride. The both starting materials are soluble compounds. However, the barium sulphate formed is an insoluble white precipitate. The precipitate is recovered by filtration, washed and dried.
The reaction equation is shown below;
Na2SO4(aq) + BaCl2(aq) -------> BaSO4(s) + 2NaCl(aq)
Why are bacteria necessary for life on Earth to exist? Select three options.
Bacteria help produce the oxygen that plants and animals need.
Bacteria help produce some of the foods we eat.
Bacteria put atoms together to form water that plants and animals need.
Bacteria are required for plants and animals to reproduce.
Bacteria decompose rotting plant and animal material.
Answer:
Bacteria decompose rotting plant animal material.
Explanation:
Theres good bacteria, and theres bad bacteria. some helps, and some makes things worse. so really, in some sense all of the above.
Hope that helps.
Bacteria are necessary for life because they help produce oxygen for plants and animals. Similarly bacteria decompose rotting plant and animal materials.
What are bacteria?Bacteria are a type of organism which are classified as a kingdom of life. Bacteria are prokaryotic microbes that can spread diseases in animals and plants.
Some of the bacteria are very useful in for our life. Some of them are autotrophs thus, produce energy and oxygen. For example cyanobacteria release oxygen which is used animals and plants to respire.
Bacteria are very essential to degrade wastes and remove them from the surface. They consume the decomposing plants and animals and make them biodegradable. Some bacteria living in plants helps in nitrogen cycle as well.
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helpp!!
1.) How many protons?
2.) How many neutrons?
3.) How many electrons?
Answer:
1) 33
2)47
3)33
Explanation:
The atomic number 33 is the same for both protrons and electrons.
The filtration technique is used to separate
O two solids
O two liquids
o all of the above
O liquid from a solid
Answer:
Liquid from a solid
Explanation:
If a bond forms between calcium and chlorine, the bond is covalent.
True or False
Answer:
False
Explanation:
there should be sharing of electrons between two of the atoms to be a covalent bonding. but there is no linkage of electron between them
PLEASE ANSWER FAST!!!!!!!!!!!!!!!
What is light?
A. a wave of vibrating electric and magnetic energy
B. a wave that travels by compressions
C. a wave that travels by rarefactions
D. a state of matter
Answer:
The answer is A. a wave of vibrating electric and magnetic energy.
Iodine, I2, is a solid at room temperature but sublimes (converts from a solid into a gas) when warmed. What is the temperature in a 83.3-mL bulb that contains 0.392 g of I2 vapor at a pressure of 0.562 atm
Answer:
T = 3.75 K
Explanation:
As we know
PV = nRT
R =8.3144598 J. mol-1. K-1
P = 0.562 atm
V = 83.3 mL
moles in 0.392 g of I2 = 0.392/mass of I2 = 0.392 grams/253.8089 g/mol = 0.0015 moles
Substituting the given values, we get
0.562 atm * 83.3 *10^-3 L = 0.0015 moles * 8.3144598 J. mol-1. K-1 * T
T = 3.75 K
13. The equation used to find acceleration is a =
1. vf- vilt
b. v/t
a.
C. Vi - vlt
d. vit vflt
Acceleration represented by the equation = Δv/Δt.
J.J Thomson's experiments provided what evidence about atoms?
a) atoms are the smallest particles of matter
b) atoms contain negatively charged particles
c) atoms have a negative charge
d) atoms have a positive charge
is the specific heat capacity of gaseous ethanl greater than. less thean or equal to the speciifc heat captity of liquid ethanol
The specific heat capacity of the gaseous ethanol is less than the specific heat capacity liquid ethanol.
The specific heat capacity is given as :
Q = mc ΔT
where ,
Q = heat
m = mass
c = specific heat capacity
ΔT = temperature change
The heating curve represented the temperature , T in the y axis and the heat added at the x - axis. the slope is given as :
T / Q = 1 / C
T is the temperature and the c is the specific heat capacity.
Thus, the heat capacity of the gaseous ethanol is low as compared to the liquid ethanol.
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ill mark u brainlest if u answer me wit no links!
Which of these best describes the brainstorming stage of the engineering design process?
identifying a need to be addressed
gathering feedback about prototypes
collecting information from a variety of background sources
using group input to discuss and prepare preliminary designs
Answer: I believe it would be using group input to discuss and prepare preliminary designs
Explanation:
Explain how the following two processes alter the percentage of carbon dioxide in the
atmosphere
(1) combustion
We burn the things that have previously grown in the sunlight-carbohydrates. Hydrogen in the carbohydrates burns to form water which is very harmless. The carbon can be recycled into many different compounds.
The carbon in this material becomes carbon monoxide carbon dioxide, (Poisonous to us mammals) and the carbon or char which can be a nutrient into the soil. Other things that can be burning in the waste will be toxic. Plants will absorb some worst things that humans will spill out so carelessly like: lead, cadmium, and the other toxic metals—and these toxins are very dangerous in the atmosphere
So we can indeed to alter the composition of our atmosphere by burning things. Once our planet had a carbon dioxide in the atmosphere. It was a hell-hole here. It was very hot and the atmosphere was poisonous to higher life forms. Gradually life on the planet primarily plant life has been changed this atmosphere into something clean and wonderful. But we by our careless behaviour could return it into its original poisonous luckily the huge coniferous forests clean our air of carbon and the other pollution. We are eroding one factor of this margin after the another. Glaciation, wetlands, oceans, coral reefs, wild areas—these are our safeguards and one after another they are being lost.
--The given question is incomplete, the complete question is
"Explain how the following two processes alter the percentage of carbon dioxide in the atmosphere. I. Combustion (3) II. Respiration (3)".
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A seismograph measures the size of a volcano eruption.
O True
O False
(This is for Science btw)
Answer:
This is true. A seismograph measures the size of a volcano eruption by detecting the vibrations that are produced by the volcanic activity. The vibrations can then be converted into a numerical value that represents the magnitude of the eruption.
Explanation:
28. How many formula units are found in 0.250 moles of potassium nitrate?
2.41 x 1024 formula units
O 1.5x1023 formula units
4.15x10-25 formula units
O 6.022 x 1023 formula units
Answer:
[tex]\boxed {\boxed {\sf B. \ 1.5 *10^{23} \ formula \ units}}[/tex]
Explanation:
1 mole of any substance contains the same number of particles. The particles can vary (atoms, molecules, formula units), but there are always 6.022*10²³ particles. In this case, the particles are formula units of potassium nitrate or KNO₃.
Let's create a ratio.
[tex]\frac {6.022*10^{23} \ formula \ units \ KNO_3}{1 \ mol \ KNO_3}[/tex]
Since we are trying to find the formula units in 0.250 moles, we multiply by that number.
[tex]0.250 \ mol \ KNO_3 *\frac {6.022*10^{23} \ formula \ units \ KNO_3}{1 \ mol \ KNO_3}[/tex]
The units of moles of potassium nitrate cancel.
[tex]0.250 *\frac {6.022*10^{23} \ formula \ units \ KNO_3}{1 }[/tex]
The denominator of 1 can be ignored, so we can make a simple multiplication problem.
[tex]0.250 *{6.022*10^{23} \ formula \ units \ KNO_3}[/tex]
[tex]1.5055 * 10^{23} \ formula \ units \ KNO_3[/tex]
If we round to the nearest tenth, the 0 in the hundredth place tells us to leave the 5 in the tenth place.
[tex]1.5 *10^{23} \ formula \ units \ KNO_3[/tex]
0.250 moles of potassium nitrate is approximately equal to 1.5*10²³ formula units of potassium nitrate and choice B is correct.
Calculate the final pressure in the cylinder of a car engine if the original volume was 450
mL at a pressure of 0.80 aim, and the final volume is 120 mL. Assume no change in the
number of molecules or ternperature.
According to the Boyle's law, the final pressure of gas in cylinder is 3 atmospheres.
What is Boyle's law?Boyle's law is defined as an experimental gas law which describes how the pressure of the gas decreases as the volume increases. It's statement can be stated as, the absolute pressure which is exerted by a given mass of an ideal gas is inversely proportional to its volume provided temperature and amount of gas remains unchanged.
Mathematically, it can be stated as,
P∝1/V or PV=K. The equation states that the product of pressure and volume is constant for a given mass or amount of gas and the equation holds true as long as temperature is maintained constant or does not change.
According to the equation the unknown pressure and volume of any one gas can be determined if two gases are to taken in consideration.That is,
P₁V₁=P₂V₂
∴P₂=0.8×450/120=3 L.
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the goal of the light reaction is to make ___, an high energy electron transporter, and ____, an energy storing molecule
The goal of the light reaction is to make NADH an high energy electron transporter and ATP an energy storing molecule.
The energy storage molecule ATP and the reduced electron carrier NADPH are produced by the light-dependent processes using light energy, which is required for the subsequent stage of photosynthesis. Light reactions in plants occur in the thylakoid membranes of organelles referred to as chloroplasts.
The light reactions are largely controlled by photosystems, sizable complexes of proteins and pigments (light-absorbing molecules) that are designed to capture light. Photosystem I (PSI) and Photosystem II are the two different types of photosystems (PSII).
Both photosystems have a variety of pigments that aid in the absorption of light energy as well as a unique pair of chlorophyll molecules at the reaction center. P700 denotes the special pair of photosystem I, while P600 denotes the unique pair of photosystem II.
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Describe the physical properties of matter using the graphic organizer below
indicate whether each property can be used to identify a substance, $6.6.864
Mass
Weights
Mass and Weight
Magnetism
Density
Physical properties such as mass, weights , density can be common for one or more substances hence cannot be used for identification while magnetism is unique for each substance ,hence used for identification.
What are physical properties?Any property which describes the state of a physical system is called as a physical property.Changes in physical properties are used to describe changes between the states. They are often related to as observable properties.
Physical property which can be quantified is a physical quantity. These are also classified further with respect to their directionality. Physical properties are differentiated from chemical properties by the way they determine how a substance behaves in a chemical reaction.
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consider three identical flasks with different gases. in which flask will the molecules have the greatest average velocity
The flask A, flask B, flask C, all have equal average kinetic energy at 0°C.
What is the average kinetic energy?The average kinetic energy of the particles in a gas is inversely related to its temperature. These particles must move more quickly as the gas warms because their mass is constant.
KE avg = 3/2RT
As a result, it is possible to state that average kinetic energy depends on temperature. As a result, as the temperature rises, the gas molecules become more energetic and move at a faster rate.
The average kinetic energy also stays the same because, in accordance with the question, the temperature is constant across all flasks.
Therefore, the average kinetic energy of flasks A, B, and C at 0°C is the same.
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Complete question is " Consider three identical flasks with different gases:
Flask A: CO at 760 torr and 273 K
Flask B: N₂ at 250 torr and 273 K
Flask C: H₂ at 100 torr and 273 K
In which flask will the molecules have the greatest average kinetic energy per mole?
magine a population of rabbits in the woods.
What would happen if the rabbit population continued to decrease?
CHOOSE ALL THAT APPLY
Lesson 5.06
Question 17 options:
Animals that prey on rabbits would begin to prey on other organisms.
none of the choices
Animals that prey on rabbits would starve.
Animals that prey on rabbits would leave the area in search of more rabbits.
Answer:
A.) They would have to prey on other organisms
Explanation:
The answers are.....
Animals that prey on rabbits would begin to prey on other organisms.
And...
Animals that prey on rabbits would starve.
And...
Animals that prey on rabbits would leave the area in search of more rabbits.
My son attends K12 and had this question on his unit 5 test. These were his answer choices and they were correct.
How many days does it take 16.Og of Gold-198 to decay to 1.0g? (each half-
life = 2.69 days) *
O 10 days
0 2.69 days
O 10.76 days
16 days
PLZ HELP NOW
Answer:
10.8 days (3 sig.figs.)
Explanation:
All radioactive decay is 1st order decay defined by the expression A = A₀e^-kt
which is solved for time of decay (t) => t = ln(A/A₀) / -k
A = final weight = 1.0 gram
A₀ = initial weight = 16.0 grams
k = rate constant = 0.693/t(1/2) = 0.693/2.69 days = 0.258 days⁻¹
t = ln(1/16) / -0.258da⁻¹ = (-2.77/-0.258) days = 10.74646792 days (calculator)
≅ 10 days (1 sig. fig. based on given 1 gram mass)
When the equation 4. 78X^2-2. 14x-1. 60=0 is solved the two values of unknown x are ____ and _____
x has the values (2.14 + √(23.288)) / 9.56 and (2.14 - √(23.288)) / 9.56.
What Is a Quadratic Equation?Quadratic equations are the degree two, one-variable polynomial equations of the form f(x) = ax^2 + bx + c = 0 with a, b, c, and R R and a 0 being the variables. In its most basic form, it is a quadratic equation where "a" denotes the leading coefficient and "c" is the absolute term of f(x). The values of x that satisfy the equation (, ) are the quadratic equation's roots.
The name "quadratic equation" is for what?Intricate relationships exist between square and quadrangle (another name for rectangle) difficulties and quadratic equations.
The Latin term quadratus, which means square, is where the word "quadratic" originates.
The quadratic formula or factoring can be used to get the solution to the problem 4.78x^2-2.14x-1.60=0.
x = (-b (b^2 - 4ac)) / (2a) where a = 4.78, b = -2.14, and c = -1.60 is the quadratic formula.
Plugging in the values we get:
x = (-(-2.14) ± √((-2.14)^2 - 4(4.78)(-1.60)) ) / (2(4.78))
x = (2.14 ± √(4.6016 + 18.688)) / 9.56
x = (2.14 ± √(23.288)) / 9.56
So the two values of x are:
x = (2.14 + √(23.288)) / 9.56 and x = (2.14 - √(23.288)) / 9.56
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The sum of three consecutive odd numbers is 69. Find the numbers of P is the largest
number
Answer:
The correct answer is - 25.
Explanation:
Given:
Sum of the 3 consecutive odd numbers = 69
solution:
Let’s assume the initial number - 2X+1
Let's say the second number is -‘2X+3’ and
Let's say the largest number is- ‘2X+5’.
Sum of the numbers = 69
(2X+1) + (2X+3) + (2X+5) = 69
6X+9 = 69
6X = 69–9
6X = 60
X = 60/6
X= 10
So, x value would be 10. Putting value of X in 2X+5
= 2(10)+5
=25
= 25 (Answer)
Ammonium chromate is named the way it is based on being
Answer:
Ammonium dichromate is an inorganic compound with the formula (NH4)2Cr2O7. In this compound, as in all chromates and dichromates, chromium is in a +6 oxidation state, commonly known as hexavalent chromium. It is a salt consisting of ammonium ions and dichromate ions.