Answer: A
Explanation: Potassium is a metal.
Practitioners of the branch of alternative medicine known as homeopathy claim that very dilute solutions of substances can have an effect. Is the claim plausible? To explore this question, suppose that you prepare a solution of a supposedly active substance, X, with a molarity of 0.10 molL1 . Then you dilute 10. mL of that solution by doubling the volume, doubling it again, and so on, for 90 doublings in all. How many molecules of X will be present in 10. mL of the fi nal solution? Comment on the possible health benefi ts of the solution.
Answer:
a. 4.865 × 10⁻⁷ molecules. b. The possible health benefits of the drug might be minimal or non-existent.
Explanation:
a. Since we have 0.10 mol/L and 10 mL of solution, the number of moles in 10 mL of solution is n = CV where C = concentration and V = Volume. C = 0.10 mol/L and V = 10 mL = 0.01 L.
So n = CV = 0.10 mol/L × 0.01 L = 0.001 mol.
Since the initial volume of the solution is 10 mL and doubled, it is 2 × 10 mL = 20 mL. It is doubled again to 2 × 20 mL = 40 mL. It is doubled again to 2 × 40 mL = 80 mL. Our third doubling is thus 80 mL = 2 × 2 × 2 × 10 mL = 2³ × 10 mL. So the volume for our nth doubling is V = 2ⁿ × 10 mL. So four our 90 th doubling, the volume is V = 2⁹⁰ × 10 mL = 2⁹⁰ × 10 mL
Since we have 0.001 mol present, the concentration in this new volume is thus C' = 0.001 mol/2⁹⁰ × 10 mL.
So the number of moles in 10 mL of this solution is thus n = 0.001 mol/(2⁹⁰ × 10 mL) × 10 mL = 0.001/2⁹⁰ mol
To find the number of molecules of X present we use, number of moles, n = number of molecules, N/Avogadro's number of molecules, N'
n = N/N'
N = nN'
= 0.001/2⁹⁰ mol × 6.022 × 10²³ molecules/mol
= 8.078 × 10⁻³¹ × 6.022 × 10²³
= 48.65 × 10⁻⁸
= 4.865 × 10⁻⁷ molecules.
b. Since the number of molecules of X present in 10 mL solution of the final diluted solution is 4.865 × 10⁻⁷ molecules, this shows that the number of molecules of X is very little so, the possible health benefits of the drug might be minimal or non-existent.
2.
What did five different witnesses see in the area where Mary Lou Arruda
disappeared?
A. Mary Lou talking to an unknown man.
B. A green car driven by an unknown man.
C. Mary Lou's bicycle in the trunk of a green car.
D. An unknown man on foot following Mary Lou .
Answer:
c
Explanation:
I believe its c but i could be wrong sorry if I am
Distinguishing Types of Waves through Examples
A 2-column table with 3 rows. The first column labeled mechanical waves has entries ocean water, light waves, earthquake waves. The second column labeled electromagnetic waves has entries sound waves, radiation waves, X-ray waves.
How should the table be changed to correctly distinguish between mechanical and electromagnetic waves?
Earthquake waves and radiation waves need to change places.
Light waves and X-ray waves need to change places.
Ocean waves and X-ray waves need to change places.
Sound waves and light waves need to change places.
Answer:
Sound waves and light waves need to change places.
Explanation:
Given table:
Mechanical waves Electromagnetic waves
Ocean water Sound waves
Light waves Radiation waves
Earthquake waves X-ray waves
From the given table, to be correct, light and sound waves must change their position.
Light wave is an electromagnetic wave
Sound wave is a mechanical wave
An electromagnetic wave does not require a material medium for propagation.
Mechanical waves require material medium for their propagation.
Mechanical waves Electromagnetic waves
Ocean water Light waves waves
Sound waves Radiation waves
Earthquake waves X-ray waves
Answer:
Sound waves and light waves need to change
Explanation:
Gas laws mad question under it
Answer:
what are you asking tho?
Explanation:
Thx for the Free points tho.
please help me anyone its due today thank you !
true
Explanation:
Ecothermic reactiions are reactions or processes that release energy. From heat or light.
A.True
Explanation:
Reactants+Products+Energy
When does nuclear fusion start during the life of a star?
Answer:
Try searching this on google
Explanation:
I might have an answer but I am not entirely sure sorry I really tried to help but there is also an app called socractic it also helps with questions
Once the temperature reaches 15,000,000 levels Celsius, nuclear fusion takes location in the center, or core, of the cloud. The high-quality heat given off by means of the nuclear fusion technique motives the gasoline to glow creating a protostar. This is the first step in the evolution of a star.
The reaction K(s) + 2H2O(l) → 2KOH(aq) + H2(g) is a decomposition reaction.
True
False
Answer:
Yes it is true reaction
Answer: yes it is true
Explanation: i took the test
Which of the following set of atoms has the largest electronegativity difference?
a. H and P
b. N and C
c. Li and O
d. Cl and Ca
Answer:
C
Explanation:
Li has an electronegativity of 0.98, O has an electronegativity of 3.44. 3.44-0.98= 2.46 electronegativity differnece :)
P4 (s) + Cl2 (g) → 4PCl3 (l)
4-How does the concentration of ions in a strong acid differ from a weak acid?
O Previous
4 v
Next
Scientific Models and Measurements: Mastery Test
What type of scientific model does the flow chart represent?
Make
observations
Ask
questions
Construct a
hypothesis.
Repeat the
process.
Test the hypothesis with
an Investigation
Analyze the data.
Explain the
results
The hypothesis
Is true.
The hypothesis
Is not true.
Communicate
the results.
Answer:
what is scientific model
Explanation:
What sport was used to demonstrate Newton's 3 Laws?
Most earthquakes and volcanoes occur in areas of the Pacific Ocean called "The Ring of Fire." What is the main reason for this?
Group of answer choices
Large numbers of people live in this area.
That area of the Earth is hotter than any other area.
Lithosphere plate boundaries are found in that area.
The weight of the ocean water forces magma to the surface.
Answer:
Lithosphere plate boundaries are found in that area.
Explanation:
Answer:
C is the right answer
Explanation:
2 The substance has a mass of 0.50 kg.
34 000 J of energy is transferred to the substance to completely melt it.
The temperature of the substance does not change during this time.
Calculate the specific latent heat of fusion of the substance.
Use an equation from the Equations List.
Answer:
68000J/kg
Explanation:
Given parameters:
Mass of the substance = 0.5kg
Quantity of heat transferred to the body = 34000J
Unknown:
Specific latent heat of fusion = ?
Solution:
The specific latent heat is usually involve in phase changes;
H = mL
H is the quantity of heat supplied
m is the mass
L is the specific latent heat
Insert the parameters and solve;
34000 = 0.5 x L
L = [tex]\frac{34000}{0.5}[/tex] = 68000J/kg
What does it mean when a compound is 'soluble in water?
A. It does not dissolve in water.
OB. It dissolves in water.
O C. It forms a precipitate in water.
O D. It has water molecules attached to it.
B. It dissolves in water.
<33
Answer:
B it dissolves in water
Explanation:
Their molecules bond to water molecules
NEED ANSWER NOW WILL GIVE BRAINLIEST!!!! What is the mass of an object that has an acceleration of 5.8m/s2 when a force of 18N is applied?
Answer:
The answer is 3.10 kgExplanation:
The mass of an object can be found by using the formula
[tex]m = \frac{f}{a} \\ [/tex]
f is the force
a is the acceleration
From the question we have
[tex]m = \frac{18}{5.8} \\ = 3.103448...[/tex]
We have the final answer as
3.10 kgHope this helps you
Answer:
i think it would be 35
Explanation:
r
aluminum oxide is an ionic substance with formula al2o3. explain what this formula means.
Answer:
the 2 means there are 2 al and the 3 means there are 3 o
Explanation:
I hope this helps
WILL GIVE BRAINLIEST how many moles are in 1.42x10^22 molecules of AlCl3?
3 is a subscript.
Answer: Many argue that modern chemical science began when scientists started ... Figure 3.2 The average mass of a chloroform molecule, CHCl3, ... 5.00gCu(molCu63.55g)(6.022×1023atomsmol)=4.74×1022atoms of copper
Explanation: hope this helps
please help it’s due today
does formaldehyde classified as a pure substance or a mixture
Answer:
pure substance
Explanation:
it is a naturally occuring compound
Answer:
Formaldehyde is a mixed substance. It is made up of Carbon, 2 Hydrogen, and an Oxygen.
Explanation:
The formula is CH2O
what is polling in chemistry?
Answer:
Polling is a method used for the purification of copper or tin which contains oxide impurities
Answer:
Polling is used for the purification of copper or tin which contains oxide impurities. The impure metal is melted and stirred with green logs of wood. The heat of molten metal makes the green logs to liberate hydrocarbon gases which in turn reduce the metal oxide into metal.
:answer question number 2
Explanation:
this question was answered in a couple weeks with the same question I did u do not want me and my dad did it all over and u just said it is not going well and you don't want me and my mom and dad don't mind if I can come up to the mall and pick them out on my own and I can come
Ozone consists of three oxygen atoms (O3) and water consists of two hydrogen atoms and one oxygen atom (H2O). Would you consider both products to be molecules?
Answer:
Yes, both are molecules
Explanation:
A molecule is the smallest particle of a substance that can exist alone and still retain the chemical properties of that substance.
Molecules are usually made up of two or more atoms of the same or different elements chemically combined together. for example, two atoms of hydrogen will combine to form a molecule of hydrogen gas. Similarly, an atom of hydrogen can combine with an atom of chlorine to form hydrogen chloride gas molecule.
Ozone is a molecule which consists of three atoms of oxygen chemically combined together.
Similarly, water is a molecule composed of two atoms of hydrogen and an atom of oxygen chemically combined together.
For an object to remain at rest which of the following statements must be true
Answer:
An object that is at rest will stay at rest unless a force acts upon it. An object that is in motion will not change its velocity unless a force acts upon it. This is known as uniform motion. An object continues to do whatever it happens to be doing unless a force is exerted upon it.
Explanation: NEWTONS laws of motion
The diagram shows a transform fault. What is a likely result of slippage along
this fault?
Fault
O.
A. Pyroclastic flow
B. Shield volcano
C. Earthquake
D. Crater
Answer:
C. Earthquake
Explanation:
Earthquake is a likely result of the slippage along this fault boundary.
At a transform margin, rocks are moving parallel to one another. This often causes a slippage that leads to the generation of earthquakes.
An earthquake is a sudden displacement within the earth that leads to a sudden release of energy in all direction. The slippage on the surface of a transform fault often lead to earthquakes.Answer:
C
Explanation:
One litre of hydrogen at STP weight 0.09gm of 2 litre of gas at STP weight 2.880gm. Calculate the vapour density and molecular weight of gas.
Answer:
we know, at STP ( standard temperature and pressure).
we know, volume of 1 mole of gas = 22.4L
weight of 1 Litre of hydrogen gas = 0.09g
so, weight of 22.4 litres of hydrogen gas = 22.4 × 0.09 = 2.016g ≈ 2g = molecular weight of hydrogen gas.
similarly,
weight of 2L of a gas = 2.88gm
so, weight of 22.4 L of the gas = 2.88 × 22.4/2 = 2.88 × 11.2 = 32.256g
hence, molecular weight of the gas = 32.256g
vapor density = molecular weight/2
= 32.256/2 = 16.128g
hence, vapor density of the gas is 16.128g.
Explanation:
what does light emission(color) tell us about elements?
Answer:
The color of the light emitted depends on the energies of the photons emitted, which are in turn are determined by the energies required to move electrons from one orbital to another. Those colors are as distinctive to each element as fingerprints are to people. Hope this helps
Answer:
The color of the light emitted depends on the energies of the photons emitted, which are in turn are determined by the energies required to move electrons from one orbital to another. Depending on the element you put in the flame, various different energies of photons (colors) will appear. Those colors are as distinctive to each element as fingerprints are to people.
Explanation:
What is the pressure of 64 grams of O2 in a 1L container at a temperature of 10°C?
Which compound in the picture has a central atom with four outside atoms and has at least one nonpolar bond.
Answer:
The answer is:
B
Explanation:
The compound in Option B is Methane.
Methane is known to be a compound which has two elements, carbon and hydrogen. It has a central atom which is surrounded by four hydrogen atoms. It's chemical formula is CH4.
Methane's outer atoms are dipoles and are in the same direction. This makes the overall molecule non-polar. The compound itself has non-polar bonds and it is non-polar itself.
How are elliptical galaxies different from spiral galaxies?
a. They contain older stars and less gas and dust.
b. They contain younger stars and more gas and dust.
c. They are bigger than spiral galaxies.
d. They are smaller than spiral galaxies.
Answer:
A. They contain older stars and less gas and dust.
Explanation:
There are three types of galaxies:
elliptical galaxiesspiral galaxieslenticular galaxiesElliptical galaxies are galaxies shaped like an ellipse, while spiral galaxies consist of a flat, rotating disk that contains stars, gas, and dust, and a central concentration of stars called the bulge.
The difference between elliptical and spiral galaxies is in the amount of gas and dust they contain. Spiral galaxies contain large amounts of gas and dust, which means that new stars are born very often. This makes them brighter than relatively dim elliptical galaxies, which contain less gas and dust. This is why fewer new and brighter stars are born in elliptical galaxies, leaving them with older, dimmer stars.