Cobalt 60 is a radioactive source with a halflife of about 5 years, 15 years will the activity of a new sample of cobalt 60 be decreased to 1 8 its original value.
Cobalt-60 is a radioactive isotope with a half-life of approximately 5 years. To determine when the activity of a new sample will decrease to 1/8 of its original value, we need to use the concept of half-life. After one half-life, the activity of the sample will be reduced by half, and after each subsequent half-life, the activity will be reduced by half again.
To reach 1/8 (or 0.125) of the original activity, we need to calculate how many half-lives this represents. Since 1/2^3 equals 1/8, we know it takes three half-lives for the activity to reduce to 1/8 of its original value.
As each half-life is 5 years, we can multiply the number of half-lives (3) by the duration of each half-life (5 years): 3 x 5 = 15 years. Therefore, the activity of the new sample of Cobalt-60 will be decreased to 1/8 of its original value after 15 years. The correct answer is option d) 15 years.
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what is used to make the dry cells ????
Answer: The parts of a dry cell battery are as follows: at the center is a carbon rod called a cathode. The cathode is surrounded by an electrolyte paste. The paste and cathode are surrounded by a separator before finally being sealed within a zinc cylinder.
Explanation: A diagram is show below
what's the answer? please help
Answer:
a usually reversible change in the physical properties of a substance, as size or shape
For example:
Freezing a liquid is a physical change.
Answer:I like bread
I like ya cut G
So that's step by step solution to get to the answer
How many moles of xenon gas are necessary to exert a 0.64atm pressure in an 8.5L container at 300.0K?
0.026 moles is the right answer.
We have that for the Question "How many moles of xenon gas are necessary to exert a 0.64atm pressure in an 8.5L container at 300.0K?" it can be said that moles of xenon gas is
n=0.22moles
From the question we are told
How many moles of xenon gas are necessary to exert a 0.64atm pressure in an 8.5L container at 300.0K?
Generally the equation for the ideal gas is mathematically given as
[tex]n=\frac{Pv}{RT}\\\\n=\frac{0.64*8.5}{0.08206*300}[/tex]
n=0.22moles
Therefore
How many moles of xenon gas are necessary to exert a 0.64atm pressure in an 8.5L container at 300.0K is
n=0.22moles
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What happens when a cold drink sits in a hot room? A) It remains coldincorrect answer B) It gets warmerincorrect answer C) It starts boilingincorrect answer D) It starts freezingincorrect answer
Answer:
its B
Explanation:
4 description of meteor showers
Answer:
A meteor shower are defined as the celestial event in which a meteor comes from one point in the sky and visible in night sky.
Meteors are also known as Shooting stars as they glow when enters in the Earth surface as glowing streaks, where tail point to the origin in the sky and face faces the Earth surface.
Meteor showers take place when meteoroids entering Earth's atmosphere.
Meteor showers can repeat themselves because it depends on the comet orbits which can take place at the same time each year.
I have no idea what to put, pls help, due tmr
(science)
Answer:
It traveled for 4 seconds at a distance of about 4.1 meters. With a velocity of 10%.
Explanation:
In the reaction 2CO2+ 2H2O -> C2H4 + 3O2 , the mole ratio of water to oxygen is
I'm gonna guess 2:3 because you have two moles of water and three moles of oxygen
If sperm and egg cells have half of the number of chromosomes found in other body cells, how do gametes form?
The Sun appears to move across the sky each day. What causes this?
A.the spinning of Earth on its axis
B. the path of the Sun around Earth
C. the production of nuclear energy by the Sun
D. the tilt of Earth on its axis
Answer:
a
Explanation:
as the earth rotate around the sun it appears to be moving across the sky
Answer:
The answer is option A
Explanation:
From Earth, the Sun looks like it moves across the sky in the daytime and appears to disappear at night. This is because the Earth is spinning towards the east. The Earth spins about its axis, an imaginary line that runs through the middle of the Earth between the North and South poles.
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Which statement best compares the melting points of magnesium and sodium?
a
Magnesium has a higher melting point because it contributes one additional electron per atom than sodium in the electron sea.
b
Sodium has a higher melting point because it contributes one fewer electron per atom than magnesium in the electron sea.
c
Sodium has a higher melting point because it contributes two fewer electrons per atom than magnesium in the electron sea.
d
Magnesium has a higher melting point because it contributes two additional electrons per atom than sodium in the electron sea.
A because according to electron sea theory magnesium shares two valence electrons in electron sea while sodium shares one suggesting that magnesium has stronger metallic bond than sodium so breaking metallic bond in magnesium will require more energy as compared to breaking metallic bond in sodium
The melting point of magnesium is higher than the melting point of sodium because it contributes two additional electrons per atom than sodium in the electron sea. Thus option d is correct.
What is melting point?Melting point of a substance is the temperature at which it converts from solid state to liquid state where, the two phases are in equilibrium. Melting point is affected by the bond type, molecular weight, temperature and pressure.
Melting point of elements increases along a period because the atomic size is decreasing along the period and molecular weight is increasing. Thus, the nuclear attractive pull increases resulting in higher energy needed to break the attractive force.
Magnesium is 12th element and sodium is 11th element. Thus magnesium is smaller than sodium and have one more electron than sodium. Thus magnesium have high molecular weight and high nuclear attraction leads to its higher melting point.
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What will happen to the temperature
when KCI is added to water?
Answer:
As potassium chloride (KCl) dissolves in water, the ions are hydrated. ... Ion-dipole forces attract the positive (hydrogen) end of the polar water molecules to the negative chloride ions at the surface of the solid, and they attract the negative (oxygen) ends to the positive potassium ions.
Examine the layers of rock. Which layer shown contains the youngest fossils, and why?
Answer:
Layer A is the youngest
It is at the top, it has all of the dinosaur bones which got buried after earth got hit with an asteroid and they went extinct. Layer D started it and all of these years dirt, soil, and fossils have been gathering making each layer before older and older.
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Explanation:
Answer:
The youngest fossils would be the "upmost" ones
Explanation:
Logically speaking, in order for fossils to be newer they have to be lied down first, think of it as folding laundry. The clothes that you folded first would be on the bottom, and the newer clothes you would lay ontop of the previous clothing.
Periodic law states that elements show a
A. repetition of their physical and chemical properties when arranged according to increased atomic number
B. repetition of their physical and chemical properties when arranged according to increased atomic mass
C. repetition of their physical and chemical properties when arranged according to increased atomic size
D. repetition of their physical and chemical properties when arranged according to increased atomic radius
Answer:
A. repetition of their physical and chemical properties when arranged according to increased atomic number
Explanation:
There are various kind of elements that are present in periodic table. Some elements are harmful, some are radioactive, some are noble gases. Therefore, option A is correct option.
What is periodic table?Periodic table is a table in which we find elements with properties like metals, non metals, metalloids and radioactive element arranges in increasing atomic number.
Periodic table help a scientist to know what are the different types of elements are present in periodic table so that they can discover the new elements that are not being discovered yet.
Periodic law states that elements show a repetition of their physical and chemical properties when arranged according to increased atomic number.
Therefore, the correct option is option A out of given options.
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What is the difference between a chemical symbol and a chemical formula?
Answer: A chemical symbol is a one- or two-letter designation of an element. Compounds are combinations of two or more elements. A chemical formula is an expression that shows the elements in a compound and the relative proportions of those elements. Many elements have symbols that derive from the Latin name for the element
Can someone help me please. chem.
Answer:
linar
Explanation:
balance Ca(NO3)2 + NaCl ---> NaNO3 + CaCl2
Answer:
Ca(NO3)2 + 2 NaCl = 2 NaNO3 + CaCl2
Explanation:
On the left you have an original balance of Ca - 1, N - 2, O - 6, Na - 1, and Cl - 2, and on the right you have a balance of Ca - 1, N - 1, O - 3, Na - 1, Cl - 2.
Ca - 1 Ca - 1
N - 2 N - 1
O - 6 O - 3
Na - 1 Na - 1
Cl - 1 Cl - 2
In order to balance these, you'll have to make both sides equal. To get the N on the right to be equal to the N on the left, you'll have to multiply NaNO3 by 2, thus making it 2NaNO3. By doing this, you will offset the balance of both Na and O.
Ca - 1 Ca - 1
N - 2 N - 2
O - 6 O - 6
Na - 1 Na - 2
Cl - 1 Cl - 2
To balance the rest of the equation, you'll have to multiply both Na and Cl by 2. This will change NaCl to 2NaCl, making the balance look like this:
Ca - 1 Ca - 1
N - 2 N - 2
O - 6 O - 6
Na - 2 Na - 2
Cl - 2 Cl - 2
You will now be left with your final equation Ca(NO3)2 + 2 NaCl = 2 NaNO3 + CaCl2.
Which of these best describes the relationship between the inner core, outer core, mantle, crust, asthenosphere, and lithosphere?
The question is incomplete, the complete question is;
Which of these best describes the relationship between the inner core, outer core, mantle, crust, asthenosphere, and lithosphere?
A: The coolest layers are farthest from the core.
B: The least dense layers are closest to the core.
C: The layers with the highest concentration of metals are closest to the crust.
D: The layers that remain in a molten state are closest to the crust.
Answer:
The coolest layers are farthest from the core.
Explanation:
When we talk about the internal structure of Earth, we mean the subdivisions of the solid Earth, that is, the concentric spherical layers that marks out the structure of the solid Earth.
The inner core is the innermost part of the earth's core and is known to have extremely high temperature. This high temperature steadily decreases as you approach the earth's surface.
Hence, the coolest layers are farthest from the core.
What is the name of this molecule?
O A. 1-methylpentane
O B. 1-pentyne
C. cis-1-pentene
O D. Pentane
Answer:
The name of that molecule should be 1-pentyne
so your answr should be B
Explanation:
Molecules are species made up of atoms. The given molecule in the figure is 1-pentyne. Thus, option B is correct.
What is 1-pentyne?1-Pentyne is a chemical compound with the formula C₅H₈, and an internal alkyne group between the first and the second carbon atom.
The molecules consist of twelve bonds including the bonds between the carbon-carbon, and carbon-hydrogen. There is one triple or the alkyne bond present and five carbon hence the name of the molecule is 1-Pentyne.
Therefore, the molecule is option b. 1-Pentyne.
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What are the characteristics of electromagnetic waves?
Answer: Electromagnetic waves are transverse in nature as they propagate by varying the electric and magnetic fields such that the two fields are perpendicular to each other.
Accelerated charges are responsible to produce electromagnetic waves.
Explanation:
calculate the volume occupied by 10g of propane gas, under normal conditions of temperature and pressure
Answer:
5.5 L
Explanation:
First we convert 10 g of propane gas (C₃H₈) to moles, using its molar mass:
10 g ÷ 44 g/mol = 0.23 molThen we use the PV=nRT formula, where:
P = 1 atm & T = 293 K (This are normal conditions of T and P)n = 0.23 molR = 0.082 atm·L·mol⁻¹·K⁻¹V = ?1 atm * V = 0.23 mol * 0.082 atm·L·mol⁻¹·K⁻¹ * 293 K
V = 5.5 LDo temperature and air pressure change in a smooth, gradual way as your balloon flies higher?
Answer:
yes ?
Explanation:
from what I have learned so far, the hair gradually gets thinner and thinner with less oxygen which would change the pressure
if you need 2.5 moles of of aluminum, how many atoms of aluminum is this?
Answer:
This can be found by my multiplying number of moles with avogadro number
So we have:
2.5 × 6.022 × 10²³
= 15.055 × 10²³
Therefore there are 15.055 × 10²³ atoms in 2.5 moles of Aluminium
Write the formula for potassium nitride?
(show work)
CAN SOMEONE PLEASE HELP?
Answer:
It should b KNO3
Explanation:
one Potassium (K) and three Nitrite (NO3)
The breaking down or wearing away of rock and soil is known as... A. earthquake
B. global shift C. weathering D. deposition
Answer:
the breaking down of rock is known as weathering
Particles of a suspension will settle while particles of a colloid do not. Why dose this happen?
Answer:
The dispersed particles are spread evenly throughout the dispersion medium, which can be a solid, liquid, or gas. Because the dispersed particles of a colloid are not as large as those of a suspension, they do not settle out upon standing.
Explanation:
What is the temperature at 11:59 pm?
how many atoms of alumminum are in 3.9 mol of aluminum
Answer:
2.35 x 10²⁴ atoms Al
Explanation:
Given 3.9 moles of aluminum (Al), determine number of aluminum atoms in that quantity of substance.
By definition a mole is the mass of substance containing one Avogadro's Number (N₀) of particles. That is, 1 mole = 1 N₀ = 6.023 x 10²³ particles*.
So, if 1 mole aluminum contains 6.023 x 10²³ atoms of aluminum then
3.9 moles Al = 3.9 moles Al x 6.023 x 10²³ atoms Al/mole Al = 2.35 x 10²⁴ atoms Al.
________________
*The complete equivalent relationship is ...
1 mole (atoms or compounds) = 6.023 x 10²³ atoms or molecules = 1 formula weight of the substance = 22.4 Liters (if in gas phase at STP conditions (0°C and 1atm pressure).
________________
Sure hope this is understandable ... if not, kick back a note. Doc
14. How many liters would 5 moles of oxygen gas take up?
a.0.22L
b.112
c.27.4L
d.55L
Answer:
a 0.22L
Explanation:
Answer:
A
Explanation:
1 moles of oxygen is 0.044L
A boat at rest on the ocean moves up and down as water moves past it. What can be concluded about the nature of the water particles in the waves from rl this observation
How many mL of a 1.00 M HCl solution would need to be added to 100 mL of 0.263 M ammonia to produce a buffer with a pH of 10.00. The pKa of ammonia is 9.25.
Answer:
3.97mL of 1.00M HCl must be added
Explanation:
The buffer of ammonia and ammonium ion follows the equation:
pH = pKa + log [NH₃] / [NH₄⁺] (1)
Where pH is the pH we want to obtain: 10.00
pKa is the pKa of the buffer: 9.25
[NH₃] could be taken as moles of ammonia
And NH₄⁺ moles of ammonium ion
When NH₃ reacts with HCl:
NH₃ + HCl → NH₄⁺ + Cl⁻
NH₄⁺ is produced. That means moles of ammonia are Initial moles of ammonia - Moles of HCl added
Moles of HCl added = Moles of ammonium ion
The total moles of the buffer are:
0.100L * (0.263mol / L) = 0.0263moles = [NH₄⁺] + [NH₃] (2)
Rewriting (1):
10.00 = 9.25 + log [NH₃] / [NH₄⁺]
0.75 = log [NH₃] / [NH₄⁺]
Replacing (2) in (1):
0.75 = log 0.0263 - [NH₄⁺] / [NH₄⁺]
5.6234 = 0.0263 - [NH₄⁺] / [NH₄⁺]
5.6234[NH₄⁺] = 0.0263 - [NH₄⁺]
6.6234[NH₄⁺] = 0.0263
[NH₄⁺] = 0.00397 moles = Moles HCl
To obtain these moles we must add:
0.00397 moles HCl * (1L / mol) = 0.00397L =
3.97mL of 1.00M HCl must be added