Rubidium-86 (86Rb) undergoes beta decay. A 9.52 x 10^−5 mol sample of 86Rb emits 8.87 x 10^16 beta particles in one hour. Calculate the half-life (in hours) for 86Rb
The half-life (in hours) for 86Rb is mathematically given as
half-life= 447.1 hr
This is further explained below.
What is the half-life (in hours) for 86Rb?Generally, the equation for k is mathematically given as
k = (1/t)ln(a/x)
Where
No of mol of Beta particle
β= (8.87*10^16/(6.023*10^23))
β = 1.47*10^-7 mol
Therefore
k = (9.52*10^-5)-(1.473*10^-7)
= 9.50527*10^-5 mol
Hence
k = (1/1)ln((9.52*10^-5)/(9.50527*10^-5))
k = 0.693/t0.5
t0.5=half lifetime
t0.5= 0.693/(0.00155)
half-life= 447.1 hr
In conclusion, the half-life (in hours) for 86Rb
half-life= 447.1 hr
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A solution, which at a given temperature dissolves as much solute as it is capable of dissolving,is said to be a-
(A) super saturated solution
(C) unsaturated solution
(B) semi saturated solution
(D) saturated solution
How many grams of sodium hydroxide will be formed when 200 g of sodium react completeyl with water?
347.8 grams of sodium hydroxide will be formed.
Balanced chemical equation for reaction of sodium with water:
2Na + 2H₂O → 2NaOH + H₂
m(Na) = 200 g; mass of sodium
M(Na) = 23 g/mol; molar mass of sodium
n(Na) = m(Na) ÷ M(Na).
n(Na) = 200 g ÷ 23 g/mol.
n(Na) = 8.695 mol; amount of sodium.
From chemical equation: n(Na) : n(NaOH) = 1 : 1.
n(NaOH) = 8.695 mol; amount of sodium hydroxide
M(NaOH) = 40 g/mol; molar mass of sodium hydroxide
m(NaOH) = 8.695 mol × 40 g/mol
m(NaOH) = 347.8 g; mass of sodium hydroxide
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__________ could be the formula of an alkene. a. c3h8 b. c2h8 c. c6h6 d. c3h6 e. c17h36
The general formula for alkenes is CnH2n, the formula with hydrogen count double the carbon count should be the correct formula for alkene and that is d. C3H6.
What are alkenes?
Alkenes, commonly known as olefins, are organic unsaturated hydrocarbons that have one or more carbon-carbon double bonds in their chemical structure and are composed of carbon and hydrogen atoms.
Alkenes are unsaturated hydrocarbons with a double bond between the carbon atoms. Carbon atoms are connected by at least one double bond. The general formula for alkenes is C n H 2n. Olefin is frequently substituted with alkenes. The word "olefin" comes from the Greek phrase "olefin gas," which denotes the production of oil.
Since, their general formula is CnH2n, the formula with hydrogen count double the carbon count should be the correct formula for alkene and that is d. C3H6.
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What mass of nitrogen gas is required to react completely with excess hydrogen gas to produce 13.6 g of ammonia?
Taking into account the reaction stoichiometry, 11.2 grams of nitrogen gas is required to react completely with excess hydrogen gas to produce 13.6 g of ammonia.
Reaction stoichiometryIn first place, the balanced reaction is:
3 H₂ + N₂ → 2 NH₃
By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:
H₂: 3 molesN₂: 1 mole NH₃: 2 molesThe molar mass of the compounds is:
H₂: 2 g/moleN₂: 28 g/moleNH₃: 17 g/moleThen, by reaction stoichiometry, the following mass quantities of each compound participate in the reaction:
H₂: 3 moles×2 g/mole= 6 gramsN₂: 1 mole ×28 g/mole= 28 gramsNH₃: 2 moles ×17 g/mole= 34 gramsMass of N₂ requiredThe following rule of three can be applied: If by reaction stoichiometry 34 grams of NH₃ are produced by 28 grams of N₂, 13.6 grams of NH₃ are produced by how much mass of N₂?
mass of N₂= (13.6 grams of NH₃× 28 grams of N₂)÷ 34 grams of NH₃
mass of N₂= 11.2 grams
Finally, 11.2 grams of nitrogen gas is required to react completely with excess hydrogen gas to produce 13.6 g of ammonia.
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Calvin was being bullied by a coworker. That night, he dreamed that the coworker had a terrible accident. According to sigmund freud, his dream was most likely an example of?.
According to Sigmund Freud, his dream was most likely an example of wish fulfillment when he dreamt about the coworker having a terrible accident.
What is Wish fulfillment?This is defined as the process in which a desire is fulfilled through and involuntary thought process such as dreams etc.
Sigmund Freud is regarded as the father of psychoanalysis which was used to treat various types of mental illnesses and he was involved in the study of wish fulfillment.
Wish fulfillment is the process in which desire is fulfilled through involuntary process such as dream and in this scenario, Calvin was being bullied by a coworker and he night he dreamed that the coworker had a terrible accident which therefore means that he depicted wish fulfillment in this category.
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why is it important and be able to identify chemical and physical changes
Answer: because without them we can't produce any type of substances as for producing new products physical or chemical change is necessary
Explanation:
Write equation for the following acid-base reaction.
f3ccoona + br3ccooh
express your answer as a chemical equation.
[tex]Br_{3} CCOOH[/tex]+[tex]F_{3} CCOONa[/tex] → [tex]F_{3} CCOONaH + Br_{3} CCOO^{-}[/tex]
What is the significance of chemical equations?Chemical equations show us the products of reactions as well as how they form. They can be used to predict the outcomes of a reaction. We can predict what will happen if magnesium (a metal) reacts with hydrochloric acid (an acid, of course!) using this rule.When one or more chemicals are converted into one or more other chemicals, a chemical reaction occurs. Examples include iron and oxygen reacting to form rust, and vinegar and baking soda reacting to form sodium acetate, carbon dioxide, and water.A chemical equation is a symbolic representation of a chemical reaction in the form of symbols and formulae, with the reactant entities on the left and the product entities on the right, with a plus sign between the entities in both the reactants and the products and an arrow pointing towards the products and indicating the direction of the reaction. The absolute values of the stoichiometric numbers are represented by the coefficients next to the symbols and formulae of entities. Jean Beguin drew the first chemical equation in 1615.
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What is the ph of a solution of 1.699 l of 1.25 m hcn, ka = 6.2 x 10-10, and 1.37 moles of nacn?
The pH of a solution is 9.02.
c(HCN) = 1.25 M; concentration of the cyanide acid
n(NaCN) = 1.37 mol; amount of the salt
V = 1.699 l; volume of the solution
c(NaCN) = 1.37 mol ÷ 1.699 l
c(NaCN) = 0.806 M; concentration of the salt
Ka = 6.2 × 10⁻¹⁰; acid constant
pKa = -logKa
pKa = - log (6.2 × 10⁻¹⁰)
pKa = 9.21
Henderson–Hasselbalch equation for the buffer solution:
pH = pKa + log(cs/ck)
pH = pKa + log(cs/ck)
pH = 9.21 + log (0.806M/1.25M)
pH = 9.21 - 0.19
pH = 9.02; potential of hydrogen
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What would happen to the
Moon if the Earth's mass
increased?
When the Earth's mass is increased moon would spiral toward Earth.
The Moon, the fifth-largest moon in the solar system, is the sole natural satellite of Earth. Our planet's wobble is lessened and our climate is moderated by the moon's existence. The Moon is approximately 240,000 miles away from Earth (385,000km). The exosphere, the Moon's extremely thin atmosphere,
Earth's gravitational pull is influenced by its mass. The moon would move towards earth if the mass increased since the gravitational force would likewise increase.Likewise,The moon would move farther away if the mass reduced since the gravitational force would likewise decrease.The moon is close to the earth and visible at night because of gravity.
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Ivr Which order shows the levels of organization from largest to smallest? organism, organ system, cell, organ, tissue organism, tissue, organ system, organ, cell organism, organ, organ system, cell, tissue organism, organ system, organ, tissue, cell
The levels of organization from largest to smallest are - organism, organ system, organ, tissue, and cell.
Therefore, option (D) is correct.
The cell is the basic or fundamental unit of life of an organism.
A Group of cells with similar shapes and functions combines to form tissues.
Then the tissues organize to form organs.
A group of organs with similar functions combine to form an organ system.
A group of organ systems organizes to form an organism.
Hence, the correct order of levels of organization from largest to smallest is - organism, organ system, organ, tissue, and cell.
Option (D) is correct.
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7.39 mmol of base was used when titrating 432 mg of a monoamine monocarboxylic amino acid from ph 0.8 to 12.0. what is the name of the amino acid?
Answer:
Valine
Explanation:
A molecule with 4 single bonds (and any number of lone pairs) could have which type of molecular geometry?
A molecule with 4 single bonds (and any number of lone pairs) could have the tetrahedral geometry.
For example carbon(IV) chloride (CCl₄). There are four single covalent bonds between one carbon atom and four chlorine atoms (see the picture below).
Carbon has sp3 hybridization (hybridize one s-orbital and three p-orbitals) and four chlorine atoms are positioned symmetrically as corners in a tetrahedral configuration. Because of symmetrical geometry, carbon tetrachloride is non-polar molecule.
Electron configuration of carbon: ₆C 1s² 2s² 2p².
Electron configuration of chlorine: ₁₇Cl 1s² 2s² 2p⁶ 3s² 3p⁵.
The ammonium ion has exactly the same shape as methane, because it has exactly the same electronic arrangement, ammonium ion is tetrahedral (sp3 hybridized).
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What happens to the pressure of an ideal gas if its volume is doubled and its kelvin temperature is halved, assuming the moles of gas does not change?
By ideal gas approximation, the final pressure is 4 times greater than the initial pressure.
We need to know about the ideal gas theory to solve this problem. The ideal gas is assumed that there is no interaction between particles in a gas. It can be determined by the equation
P . V = n . R . T
where P is pressure, V is volume, n is the number of moles gas, R is the ideal gas constant (8.31 J/mol.K) and T is temperature.
From the question above, we know that
V2 = 2V1
T2 = 1/2 . T1
n1 = n2 = n
When the initial and final temperature is the same, we can use the ratio of pressure as
P1 / P2 = (n1 . R . T1 / V1) / (n2 . R . T2 / V2)
P1 / P2 = (n . R . T1 / V1) / (n . R . (1/2.T1) / 2V1)
P1 / P2 = 4
Hence, the final pressure is 4 times greater than the initial pressure.
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Would you expect higher or lower conductivity from a solute that does not dissolve well in solution?
It will be lower conductivity from a solute that does not dissolve well in solution.
The conductivity of the solution will be lower than that of entirely dissociating compounds if an ionic compound does not completely dissociate.Ions are created when an ionic substance dissociates in water and dissolves. As is well knowledge, the degree of an ionic compound's dissociation directly relates to the conductivity of an ionic solution. An ionic compound's conductivity will be high if it dissociates more.The compound's conductivity will be lower if it dissociates less.The ionic compound with less dissociation would thus have lower conductivity, as may be deduced.To know more about conductivity visit : https://brainly.com/question/1336689
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What is the major organic product that is obtained from the reaction at the right?
a) cyclohexanol
b) cyclohexene
c) 2-cyclohexene-1-one
d) cyclohexanone
e) 1,3-cyclohexanedione
The major organic product that is obtained from the reaction is (a) cyclohexanol.
What is a major product?
Chemical reactions take place all around us, including during food digestion in our bodies and the production of light from the sun. Before beginning any chemical processes, it is essential to comprehend physical and chemical changes. A burning candle serves as the best example of a physical and chemical transformation.
The main product of a reaction would be the one that is more stable and hence most likely to form. Propene added electrophilically to HBr would be one instance.
The major organic product that is obtained from the reaction is (a) cyclohexanol. The ketone is reduced to alcohol via proper reagents and conditions.
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At the start of a certain reaction, only reactants are present; no products have been formed. what is the value of qc at this point in the reaction? enter your answer numerically.
At the start of the reaction, value of reaction quotient is zero as no product is being formed.
How is reaction quotient calculated?The reaction quotient is a measure which signifies the relative amounts of reactants and products present in a reaction at any given time.
For any reversible reaction, the value of reaction quotient can be calculated by multiplying the product concentration raised to their moles and then dividing it by the product of reactant concentration which is also raised to their moles.
At the start of the reaction, as no product is formed so its concentration is zero and thereby this concentration divided by the reactant concentration gives a value of zero as the value of reaction quotient.Reaction quotient is closely related to equilibrium constant .
Unlike equilibrium constants which are always calculated when a reaction is at equilibrium reaction quotients can be calculated irrespective of the nature of equilibrium of a reaction.
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what do we call the temerature at which all substance will turn into a solid ?
Answer:
freezing point, i think.
Explanation:
freezing point is the point at which all substances turn solid, this varies based on what you have, but this characteristic temperature is freezing point.
What is the ph of a 0.0100 m sodium benzoate solution? kb (c7h5o2-) = 1.5 x 10-10
The pH of a 0.0100 M sodium benzoate solution is 8.09.
c(C₆H₅COONa) = 0.0100 M; concentration of the salt sodium benzoate.
Balanced chemical equation for reaction of benzoate ion (from the salt sodium benzoate) with water:
C₆H₅COO⁻(aq) + H₂O ⇄ C₆H₅COOH(aq) + OH⁻(aq)
Kb = 1.5 × 10⁻¹⁰; constant of base
Kb = c(C₆H₅COOH) × c(OH⁻) / c(C₆H₅COO⁻)
c(C₆H₅COOH) = c(OH⁻) = x
1.5 × 10⁻¹⁰ = x² ÷ 0.0100 M
x = c(OH⁻) = 1.225 × 10⁻⁶ M
pOH = -log c(OH⁻)
pOH = -log (1.225 × 10⁻⁶ M)
pOH = 5.91
pH = 14 - 5.91
pH = 8.09
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The diameter of the he atom is approximately 0.10 nm. calculate the density of the he atom in g/cm3 (assuming that it is a sphere).
The density of the He atom is 12.69 g/cm³.
d(He) = 0.1 nm = 1 × 10⁻⁸ cm; a diameter of helium atom
V(He) = 1/6 × (1 × 10⁻⁸ cm)³ × 3.14
V(He) = 5.23 × 10⁻²⁵ cm³; volume of helium atom
m(He) = 4 amu; mass of helium atom
d(He) = m(He) / V(He)
d(He) = 4 × 1.66 × 10⁻²⁴ g / 5.23 × 10⁻²⁵ cm³
d(Cr) = 12.69 g/cm³; density of the helium atom
Volume of the helium is the measure of the amount of space occupied by the helium.
Diameter or the atomic radius of an atom is a measure of the size of that atom. It is distance from the center of the nucleus to the outermost isolated electron of an atom.
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___________ is a dangerous concept because toxic chemicals concentrate as they pass up the food chain. group of answer choices
Biomagnification is a dangerous concept because toxic chemicals concentrate as they pass up the food chain. group of answer choices
What is biomagnification?
Biomagnification is defined as the accumulation of a particular substance in the body of the organisms at different trophic levels of a food chain. An example for biomagnification is the accumulation of insecticide DDT which gets accumulated in zooplanktons. Zooplanktons are those which consumes small fishes.In the entire food chain or in the predators, the chemical toxic will gets increased.It makes all the animals to get more impact and also it makes the food chain to the higher toxic.Biomagnification can be also known as the biological magnification.Also in plants, if a farmer sprays pesticides on the crops which enters the food chain from crops these pesticides enter into the organisms that feed on it.Learn more about Biomagnification,
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Which of the following is an example of an element? a water b air c sugar d oxygen
Answer:
d. Oxygen
Explanation:
- Water is not an element but a compound made of hydrogen and oxygen elements
- Air is a compound made of gases such as oxygen, nitrogen, rare gases and carbondioxide...
- Sugar is an organic compound (sucrose) made of carbonyl carbons and hydrocarbons
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PLEASE HELP ME IM ALMOST DONE WITH MY TEST
Which of the following statements about polyatomic ions is false?
Select one:
a. Polyatomic ions act like a single atom.
b. Each polyatomic ion has a single oxidation number.
c. Polyatomic ions are found in nature.
d. Polyatomic ions do not combine with ions of the opposite charge to form chemical compounds.
Answer:
D
Explanation:
Opposite charge
Drag each number to the correct location on the equation. Each number can be used more than once, but not all numbers will be used. Balance the equation with the correct coefficients. 2 3 4 5 Reset Next
The balanced equation is as follows:
2KClO3 → 2KCl + 3O2
A chemical equation is said to be balanced when there are an equal number of atoms on both the reactant and product sides.first we will calculate number of atoms in reactant as well as product side.
In the given reaction,
KClO3 → KCl + O2
Number of atoms on reactant side are as follows:
K = 1
Cl = 1
O = 3
Number of atoms on product side are as follows:
K = 1
Cl = 1
O = 2
Here, we can see that number of oxygen atom on reactant side is not equal to the number of oxygen atom on product side.
Hence to balance the equation we will multiply KClO3 by 2 on reactant side and KCl by 2, O2 by 3 on product side.
(KClO3)2 → (KCl)2+ (O2)3
Therefore the balanced equation will be:
2KClO3 → 2KCl + 3O2
Now, number of atoms on reactant side are equal to the number of atom on product side.
The coefficient used to balance out the equation are 2 and 3.
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Enzymes are specific or picky. So the enzyme that works with a chemical reaction of triglycerides will.
Enzymes are specific or picky. So the enzyme that works with a chemical reaction of triglycerides will work with more triglycerides.
In living organisms, enzymes are kinds of proteins that work as catalysts and accelerate the rate of chemical reactions without consuming themselves.
Enzymes are essential ingredients for humans as they are responsible for respiration, nerve function, and food digestion.
Moreover, these proteins are also vital for catabolic and anabolic reactions as they build and break substances.
These are found in all living things and are synthesized naturally in the human body.
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Mercury has a specific weight of 133 kn/m^3 when the temperature is 20C. Determine the density and specific gravity at this temperature.
Mercury has a specific weight of 133 kn/m^3 when the temperature is 20C.
Density of given mercury = 133kg/m3
Density of water = 1000 kg/m3
specific gravity of mercury = Density of Hg/ Density of H20
= 133/1000 = 0.133
0.133 is the specific gravity of given Hg.
What is specific gravity?
The ratio of the densities of two different objects or substances is known as specific gravity. The ratio of the substance's density to the density of water is the most common way to define specific gravity.
Given, specific weight of 133 kg/m^3
Thus, Density of given mercury = 133kg/m3
Density of water = 1000 kg/m3
Thus, specific gravity of mercury = Density of Hg/ Density of H20
= 133/1000 = 0.133
0.133 is the specific gravity of given Hg.
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Observing and
How could you prove that your inference about the acidity of the paper is true?
By doing scientific experiment we can prove inference about the acidity of the paper is true.
what is the basic requirements of an experiment ?The experiment is nothing but to do the test of the hypothesis and are the main foundation of the scientific method, the steps include Make an observations, form hypothesis, conduct experiment, evaluation of result.
Then accept or reject the hypothesis from the evaluated result, if rejected make new hypothesis; Another important factor is variable which is compulsorily added to the experiment.
Three major types of variables included like dependent, independent and controlled variables.
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Which part of the atom change the mass number 
Protons, neutrons, electrons
Answer: Atomic number is the number of protons
Atomic mass subtract
atomic number is the number of neutrons
Atomic number is the number of electrons in a neutral atom
Explanation:The atomic number is assigned based on the number of protons, so the atomic number is always the same as the number of protonsAtomic mass is the sum of protons and neutrons. Protons and neutrons both have masses of 1 amu, but the mass of electrons is negligible so it is left out. The atomic mass of an element is never a round number because it's a weighted average of all the isotopes of the element. Just round the number to the nearest integer get the most likely atomic mass. In a neutral atom number of protons = number of electrons since there is no overall charge. In an ion, add an electron for every negative charge and subtract an electron for every positive charge (ex. Mg2+ has 10 electrons because its atomic number is 12 and you subtract two electrons for the 2+ charge)
Law of Conservation of Mass Practice
1. 3Na + Cl₂ → 3NaCl
30g ? 76g
What is the mass of Cl₂?
What are the reactants?
What are the products?
Are the reactants elements or compounds?
Is the product an element or compound?
A compound has an empirical formula of ch2o with a molar mass of 60.0 g/mol. what is the molecular formula of the compound?
The molecular formula becomes [tex]C_{2}H_{4}O_{2}[/tex]
A compound is a substance made of two or more elements in fixed proportions.
the empirical formula tells us the relative ratios of different atoms in a compound. The ratios hold true on the molar level as well. Thus, [tex]H_{2}O[/tex] is composed of two atoms of hydrogen and 1 atom of oxygen.
The empirical formula is [tex]C_{}H_{2}O[/tex]
Molar mass is 60 g/mol
x*C + 2x*H + x*O = 60
Where x is the number of atoms of the element
12*x + 2*x + 16*x =60
30*x = 60
x = 60 / 30
x= 2
Thus the molecular formula becomes C2H4O2
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