Iodine-131 has a half-life of 8 days. How long would it take for the number of unstable nuclei in the sample to be reduced from 1,000 to 125?
Answer:
After one-half life: 16 mg
After 2-half lives: 8 mg
After 3-half lives: 4 mg
After 4-half lives: 2 mg
After 5-half lives: 1 mg
(5 half-lives) x (8 days/half-life) = 40 days
or doing it the mathematical way: Let z be the number of days to be found:
1 mg = 32 mg x (1/2)^(z / 8 days)
1/32 = (1/2)^(z / 8 days)
log (1/32) = (z / 8 days) x log (1/2)
z / 8 days = log (1/32) / log (1/2)
z = 8 days x log (1/32) / log (1/2) = 40 days
Explanation:
Iodine-131 has a half-life of 8 days, then it would it take for the number of unstable nuclei in the sample to be reduced from 1,000 to 125 is 512 days.
How do we calculate total time?Total time of the reduction of any substance from an initial concentration to a particular concentration will be calculated as:
T = (t)ⁿ, where
n = number of half lives
t = half life time = 8 days
1st half life: 1000 → 500
2nd half life: 500 → 250
3rd half life: 250 → 125
So number of half life times is 3. On putting values we get,
T = (8)³
T = 512 days
Hence total duration of time is 512 days.
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A saturated solution of sulfur dioxide is prepared by dissolving SO2(g) in 100. g of water at 10.°C and standard pressure.
Determine the mass of SO2 in this solution.
A.) 15g to 18g
B.) 40g to 43g
C.) 53g to 56g
D.) 6g to 8g
Answer:
The correct option is;
A.) 15 g to 18 g
Explanation:
The solubility of sulfur dioxide at room temperature = 94 g/L of water forming sulfurous acid as follows;
SO₂ + H₂O ⇄ HSO₃⁻ + H⁺
Which is a partial reversibly association with water molecules
Whereby 1 liter of water weighs 1 kg
9.4 gram of SO₂ will dissolve in 100 g of water at room temperature of 23 to 24°C
The solubility increases as the temperature reduces therefore as shown from the sulfur dioxide solubility chart we have;
At 10°C the solubility of SO₂ (g) is midway between 150 g to 200 g per kg of water
Therefore;
The solubility of SO₂ (g) is between 15 g to 18 g per 100 of water.
The mass of SO2 in the given solution should be an option a 15g to 18g.
Calculation of the mass:Since the solubility of sulfur dioxide at room temperature = 94 g/L of water forming sulfurous acid likewise:
SO₂ + H₂O ⇄ HSO₃⁻ + H⁺
This represents the partial reversibly association along with water molecules
Here 1 liter of water weighs 1 kg
So we can say that
9.4 gram of SO₂ will dissolve in 100 g of water at room temperature of 23 to 24°C
Due to this, there is an increase in solubility this result in decrease in the temperature
Also, At 10°C the solubility of SO₂ (g) is midway between 150 g to 200 g per kg of water
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What are the units of measurement for atomic radius?
Answer:
Units used to measure atomic radius:
Angstroms (Å): This the most common unit used. Equivalent to 1.0 x 10-10 meters.
Nanometer (nm): Equivalent to 1.0 x 10-9 meters.
Picometer (pm): Equivalent to 1.0 x 10-12 meters.
If they are traveling at the same speed, which will have the most kinetic energy?
A. A 5-kilogram ball
B. A 25-kilogram ball
C. A 10-kilogram ball
D. A 1-kilogram ball
Answer: B. (A 25 kg ball)
Explanation:
Since [tex]KE = \frac{1}{2} mv^{2} \\[/tex], and velocity is the same for all four balls, the ball with the greatest mass will have the greatest kinetic energy (since mass and KE are directly related). Below shows these calculations:
A. m = 5
[tex]KE = \frac{1}{2} mv^{2} \\[/tex]
[tex]KE = \frac{1}{2} (5)v^{2} \\[/tex]
[tex]KE = 2.5v^{2} \\[/tex]
B. m = 25
[tex]KE = \frac{1}{2} mv^{2} \\[/tex]
[tex]KE = \frac{1}{2} (25)v^{2} \\[/tex]
[tex]KE = 12.5v^{2} \\[/tex]
C. m = 10
[tex]KE = \frac{1}{2} mv^{2} \\[/tex]
[tex]KE = \frac{1}{2} (10)v^{2} \\[/tex]
[tex]KE = 5v^{2} \\[/tex]
D. m = 1
[tex]KE = \frac{1}{2} mv^{2} \\[/tex]
[tex]KE = \frac{1}{2} (1)v^{2} \\[/tex]
[tex]KE = 0.5v^{2} \\[/tex]
Pressure increases from Earth’s surface toward the center of Earth.
True Or False
Answer:
True
Explanation:
The center receives pressure which is what creates convection currents
Which is the best summary of the kinetic theory?
A. Potential energy is converted to kinetic energy.
O B. Atomic motion is constant at all temperatures.
C. Atoms and molecules are always in motion.
O D. Energy cannot be created or destroyed.
SUBMI
Answer:
C. Atoms and molecules are always in motion.
1. The polymerization of amino acids produces:
organic acids
lipids
proteins
carbohydrates
2. Which group of compounds has a –OH functional group?
aldehydes
esters
carboxyl acids
alcohols
3. Unsaturated compounds _____.
do not readily react
have a high activation energy
require UV light to react
are very reactive
4. Butene would have ____ carbon atoms and a_____ bond.
- 4 - double
- 2 - single
Answer:
1. Proteins
2. Alcohol
3. Unsaturated compounds are very reactive.
4. Butene has 4 carbon atoms and one double bonds attached to it
Explanation:
1. The polymerization of amino acids gives protein.
Polymerization is a process whereby smaller unit molecules of organic compounds combine repeatedly, in a regular fashion to form a larger organic structure or compound.
The smaller units are called monomers while the larger compound formed are called the polymers.
In this case, the smaller units are the amino acids held or linked together by peptide bonds to form a polymer called proteins.
2.
Compounds with functional group of -OH are called alcohols.
Alcohols are also known as alkanols and they belong to a class of organic compounds where -OH functional group is attached to an alkyl group. They have general formula of CₓH₂ₓ₊₁OH where x refers to the number of carbon atom. They're also categorized into primary, secondary and tertiary alcohols based on the type of carbon in the which the functional group (-OH) is attached to.
3.
Unsaturated compounds are very reactive due to the presence of lone pairs of electrons present in them.
4. Butene actually has 4 carbon atoms and several single bonds attached to it.
Butene has a total of 12 bonds and 1π (pi-bond) while several 11σ (sigma bonds) are attached to it.
PLEASEEEE HELP MEEE
For the reaction 2H2 + O2 → 2H2O, how many grams of water are produced from 26.0 mol of hydrogen?
A scuba tank contains air at 2975 psi and 25°C. The tank is left in a car in the
hot sun and the temperature increases to 44°C. What will be the pressure (psi)
in the tank?
Answer:
The new pressure is 3164.58 psi.
Explanation:
We have,
Initial pressure, [tex]P_1= 2975\ psi[/tex]
Initial temperature, [tex]T_1=25^{\circ}=298.15\ K[/tex]
The tank is left in a car in the hot sun and the temperature increases to 44°C, [tex]T_2=44^{\circ} =317.15\ K[/tex]
Let [tex]P_2[/tex] is the final pressure in the tank. Gay Lussac's law,
[tex]P\propto T\\\\\dfrac{P_1}{P_2}=\dfrac{T_1}{T_2}\\\\P_2=\dfrac{P_1T_2}{T_1}[/tex]
Plugging all the values,
[tex]P_2=\dfrac{2975\times 317.15}{298.15}\\\\P_2=3164.58\ psi[/tex]
So, the new pressure is 3164.58 psi.
2 The precipitate formed when sodium hydroxide reacts with solutions
containing metal ions is the corresponding METAL HYDROXIDE.
a Write word equations and symbol equations including state symbols)
to show how the following solutions react with sodium hydroxide:
magnesium sulfate, MgSO4
ii iron(II) sulfate, FeSO4
ili iron(III) chloride, FeCl3
iv copper(ll) chloride, CuCl2
Answer:
Explanation:
MgSO4 + 2NaOH -------> Mg(OH)2 + 2NaSO4
CuCl2 +2NaOH -------> Cu (OH)2 + 2Nacl
FeCl3 + 3NaOH ----> Fe(OH)3 + 3NaCl
based on this can you try for the FeSO4. similar to first reaction showed above
In the reaction:
CO3²- + H+ --> HCO³-
The CO3²- ion is considered a base because it
1) accepts a proton
2) accepts an electron
3) donates a proton
4) donates an electron
Thanks! :)
Answer:
1) accepts a proton
Explanation:
CO₃⁻² is a base here because it is accepting a proton ( H⁺) through coordinate bonding by donating a pair of electron .
So option (1) is correct .
The type of radioactive decay in which the mass number and atomic number remain unchanged is (2 points) Select one: a. beta radiation. b. alpha radiation. c. positron radiation. d. gamma radiation.
Answer:
d.
Explanation:
a. beta radiation - electrons that have negative charge, and when they leave a nucleus , the charge or atomic number of the nucleus will change.
b. Alpha radiation - nuclei of He, atomic number and mass number will be changed.
c. positron radiation - positrons are similar to electrons but have positive charge, so , the charge or atomic number of the nucleus will change.
d. gamma radiation is electromagnetic waves, does not have charge and mass.
Answer:
the answer is d. gamma radiation
Explanation:
How do the HOX genes in the paddlefish match the HOX genes in human
Answer:
Hox are transcription factors that are evolutionarily conserved across bilaterians and, therefore, they share sequence homology between paddlefish and humans .
Explanation:
The Hox genes represent a family of homeodomain transcription factors that play roles in the development of the axial and appendicular skeleton, being therefore critical during embryonic development. In this case, the human Hox genes are homologous to homeobox genes found in the paddlefish. These genes have a DNA-binding domain of 60 amino acids which is evolutionarily conserved in bilaterian species including paddlefish and human species.
How many hours will it take for only 1.5625 mg to remain
Answer:
36 hours
Explanation:
Notice that you are given the actual table of how the isotope reduces , and it shows that for each period of 6 hours the isotope decays to half of the initial number.
EVery 6 hours, the reduction in number of mg of the isotope goes down in half'
100 mg, then 50 mg, then 25 mg, then 12.5 mg, then 6.25 mg, then 3.125 mg and finally (reaching 1.5625 mg
That was 6 periods of 6 hours each, which totals: 6 time 6 hours = 36 hours
Which phase lasts longer, a full moon or a new moon?
Select one: a. Full moon
b. New moon
C. They both last for the same number of days.
Answer: Definitely the answer is C. They both last for the same number of days.
Explanation: This requires the moon to complete a bit more than one orbit to be between the earth and the sun again. The period from new moon to full moon is one half a synodic month of 29.530/2 which is 14.765 days.
I'll give brainliest
In going through the three physical states of matter, water would normally undergo changes in
A) composition.
B) density.
C) mass.
D) weight.
Answer:
COMPOSITION
Explanation:
Brainliest plz
A substance that is made up of more than one atom is called _____.
Answer:
It is called a compound.
Explanation:
A salt is made by adding an excess of an insoluble metal oxide to an acid.
How can the excess metal oxide be removed? *
D filtration
B crystallisation
A chromatography
C distillation
Answer:
Filtration
Explanation:
Filtration is used to separate solid substances from liquids or large molecules from small molecules. Since, Acid is a liquid and metal oxide is solid so Filtration can be used to separate these two.
How does a salt bridge improve a battery
The role of the salt bridge is to assure the neutrality of both compartments.
20. Which of the following is NOT true for the atoms 13N, 14N, and 'N?
a. They all have the same mass number.
b. They are isotopes.
c. They all have the same atomic number.
d. They all have 7 protons.
e. They all have 7 electrons.
Answer:
a ,e
Explanation:
math
They all have the same mass number
Explain how you could use Avogadro's Law given the grams of a known compound and volume.
According to Avogadro's law, volume is directly proportional to number of moles which is in relation with the grams of a compound.
What is Avogadro's law?
Avogadro's law is a gas law which states that the total number of atoms or molecules has a direct proportion to the volume occupied by a gas at a constant temperature and pressure.
It is closely related to ideal gas equation as it links temperature, pressure, volume and the amount of substance.It is given as, V∝n,
The straight line graph of volume versus moles is a straight line passing through the origin which implies that zero moles of gas occupy zero volume.The law was proposed by Amedeo Avogadro in year 1811.
The law can be derived from the assumption of kinetic theory of gases considering their ideal behaviour.
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At a party, you see someone on the floor with grayish skin, having
trouble breathing. This could be a sign of:
AN ALCOHOL OVERDOSE
AN OPIOID OR DEPRESSANT OVERDOSE
A STIMULANT OVERDOSE
ALL OF THE ABOVE
A person having trouble breathing could be a sign of
d. All of the above(alcohol overdose, depressant overdose, or stimulant overdose)
Causes of trouble breathing:Most instances of windedness are because of heart or lung conditions. These organs are engaged with shipping oxygen to your tissues and removing carbon dioxide, and issues with both of these cycles influence your relaxation.
At a party, if a person feels trouble breathing then it can be due to an alcohol overdose, depressant overdose, or stimulant overdose.
Thus, option D is correct.
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Find the Empirical formula for 0.765g Cr, 0.235g O
Answer:
CrO
Explanation:
0.765g Cr
0.235g O
O = 16g/mol
Cr = 52g/mol
O 2-
Cr 2+, 3+, 6+
0.765 + 0.235 = 1
so 76.5% Cr
23.5% O
76.5/52 = 1.47/1.47 = 1
23.5/16 = 1.47/1.47 = 1
CrO
Most scientists recommend reducing carbon dioxide emissions. Less carbon dioxide in the atmosphere would be expected to?
Answer:
the air would be much cleaner and better for us to breath.
Explanation:
A. Element
B. Compound
C homogenous mixture
D heterogenous mixture
Calcium nitrate, Ca(NO3)2 , is a(n) ___________________.
element
compound
heterogeneous mixture
homogeneous mixture
What is the percent by mass in a solution with 10.0 grams of solute and 25.0 grams of solvent?
Answer:
Percent by mass of solute is (10/35) x 100 = 28.57%
Percent by mass of solvent is (25/35) x 100 = 71.43%
Explanation:
10.0 grams of solute
25.0 grams of solvent
Total Mass = 35 grams
percent by mass = (Mass A / Total Mass) x 100
Percent by mass of solute is (10/35) x 100 = 28.57%
Percent by mass of solvent is (25/35) x 100 = 71.43%
Can some one please help?
Neutralization Reactions
PREDICT THE PRODUCTS OF THE FOLLOWING REACTIONS
HNO3+ Ba(OH)2
+
+
H3PO4 + Ca(OH)2
HCI + FelOH)3 –
Answer:
2HNO3 + Ba(OH)2 = Ba(NO3)2 + 2H2O
H3PO4 + Ca(OH)2 = Ca3(PO4)2 + 6H2O
3HCl + Fe(OH)3) = FeCl3 + 3H2O
Explanation:
H+
N3-
O2-
Ba2+
OH-
P 5+, 3+, 3-
Ca2+
Cl-
Fe 2+, 3+
2HNO3 + Ba(OH)2 = Ba(NO3)2 + 2H2O
H3PO4 + Ca(OH)2 = Ca3(PO4)2 + 6H2O
3HCl + Fe(OH)3) = FeCl3 + 3H2O
This part of the nervous system is the decision-
maker for the rest of the nervous system. What is it called?
o Brain
o Sensory Neurons
O Motor Neuron
o Spinal Cord
Please help me thank you
Is the answer B? Help
Answer:
A
Explanation:
Hmm, so we have the following in the diagram
Pt(s)
Cl2(g)
Ag(s)
NaCl(aq)
AgNO3(aq)
Pt 2+, 4+, 6+ Though it states Pt is inert
Cl 2-
Ag 1+
Na 1+
NO3-
Anode definition: the positively charged electrode by which the electrons leave an electrical device.
Electrode definition: a conductor through which electricity enters or leaves an object, substance, or region.
Cations attracted to cathode pick up electrons
Anions attracted to anode release electrodes+
Reduction at Cathode (red cat gain of e)
Oxidation at Anode (ox anode loss of e)
So from the diagram we can see that the charge is being generated through the 2 metal plates.
So the answer is A, the anode material is Pt and the half reaction is 2Cl- = Cl2 + 2e-
