Answer:
Explanation:
Purpose of Case Control Studies
To determine whether or not an association exists between a disease and a particular risk factor. To start with a group of people with disease and work back to see whether a possible risk factor may be the cause. It may be the first step in testing a hypothesis.
helllppp i have a test!!!!
A compound has a molar absorptivity of 40.9 cm ^ - 1 * M ^ - 1 at 293 nm. If a 1.00 cm cuvette is used, and the absorbance found to be 0.111, what is the concentration of the sample ?
Answer:
0.00271 M
Explanation:
To solve this problem we can use the formula:
A = ε * C * lWhere A is the absorbance, ε is the molar absorptivity, C is the molar concentration and l is the optical path length.
We input the data given by the problem:
0.111 = 40.9 cm⁻¹M⁻¹ * C * 1.00 cmAnd solve for C:
C = 0.00271 MThe study of chemicals is called chemistry.
The correct answer is 0.00271 M
To solve this problem the formula is used as follows:-
A = ε * C * l
The data is given as follows:-
A is the absorbance,ε is the molar absorptivity, C is the molar concentration l is the optical path length.
[tex]0.111 = 40.9 * C * 1.00[/tex]
After solving the equation the value of C is as follows:-
[tex]C = 0.00271 M[/tex]
Hence, the correct answer is 0.00271.
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Help!!
Which set of Earth components is arranged in order from solid to liquid to gas?
hydrosphere, atmosphere, lithosphere
hydrosphere, lithosphere, atmosphere
lithosphere, atmosphere, hydrosphere
lithosphere, hydrosphere, atmosphere
Answer:
Lithosphere, Hydrosphere, atmosphere
The set of Earth components that is arranged in order from solid to liquid to gas is D. lithosphere, hydrosphere, atmosphere
Lithosphere refers to the solid, outer part of the Earth. It is also known as the Rocky part of the Earth. It consists of the top part of the upper mantle and the brittle crust.Hydrosphere simply refers to the water on the Earth, underground and those that are in the air. This can be seen in ocean, seas, rivers, etc.Atmosphere refers to the layers of gases that can be found on Earth.ut contains gases like nitrogen, oxygen, etc.Read related link on:
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Four moles of CO2
a mass of how many grams
Answer: = 17.6
Explanation:
Molar mass of CO2 = 44 g mol-1
Mass of 1 mole of CO2 = 44 g
Mass of 0.4 mole = 44 x 0.4
= 17.6g
Answer:
the answer is 17.6 that's what I got
Explain why the pressure of a gas increases when its volume decreases.
HELP
Answer:
The gas pressure is raised by decreasing the volume of a gas. ... The particles can collide more often with the walls of the container because the volume has decreased. They exert force on them each time they collide with the walls. More collisions mean more force, so it will increase the strain.
hope this helped :)
1) How many moles of water does 6.02 x 1023 molecules
represent?
Answer:
1.00 mol
Explanation:
Step 1: Given data
Molecules of water: 6.02 × 10²³ molecules
Step 2: Calculate the number of moles corresponding to 6.02 × 10²³ molecules of water
In order to convert molecules to moles, we need a conversion factor. In this case, we will use Avogadro's number: there are 6.02 × 10²³ molecules in 1 mole of molecules.
6.02 × 10²³ molecules × 1 mol/6.02 × 10²³ molecules = 1.00 mol (we keep 3 significant figures)
What happens as elevation increases?
Answer:
As altitude increases, the amount of gas molecules in the air decreases the air becomes less dense than air nearer to sea level.
Explanation:
Describe why there are places on the curve where the temperature does not rise even though the burner is stil transferring energy to the ice and water.
Answer:
y
Explanation:
Which three observations are caused by plate tectonics?
Answer:
B. HOPE THIS HELPED SENSI
Explanation:
similarities between mole and MOL
How many moles are in 5.34 x 10*21 particles of Nitrogen?
16. Copper is made by the electrolysis of copper sulfate solution
Look at the diagram of the apparatus used in this electrolysis.
6 volt DC
power supply
Copper sufate solution
Carbon (graphtel electrodes
Desenbe what you would see at each of the electrodes
Answer:
SORFRRRRRRRRRRRRY!
Explanation:
As the volume of a gas increases, what happens to the pressure of the gas?
How many moles of magnesium (Mg) are there in 96.3 g of Mg?
Explanation:
number of moles = m/Mr and the process is in the picture
A bone contains 6.25% of Carbon -14 it began with. How old is the bone ?
Answer:
Is there a multiple choice??
Explanation:
How does a limiting reagent affect how much product is formed?
O A. The amount of product will be limited by the molar mass of the
limiting reagent
B. The amount of product will be limited by the sum of the reactant
coefficients.
C. The amount of product will be limited by the number of moles of
the limiting reagent.
D. The amount of product will be limited by leftover amounts of other
reactants.
Answer:
C. The amount of product will be limited by the number of moles of
the limiting reagent.
Explanation:
a p e x :)) i just took the quiz
The amount of product will be limited by the number of moles of
the limiting reagent. Hence, option C is correct.
What is a Limiting reagent?The reactant that gets consumed early in the reaction restricts the quantity of product which will be produced in the chemical reaction. Thus, the reactant that gets consumed early in a chemical reaction is a limiting reagent.
Hence, the amount of product will be limited by the number of moles of the limiting reagent.
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formula for trichlorine tetroxide
How do most animals produce offspring
Answer:
Some animals produce offspring through asexual reproduction while other animals produce offspring through sexual reproduction. Both methods have advantages and disadvantages. Asexual reproduction produces offspring that are genetically identical to the parent because the offspring are all clones of the original parent.
Explanation:
30. The density of an unknown gas at 27°C and 2 atm pressure is equal with density of N2 gas at
52°C and at 5 atm
pressure. Calculate the molar mass of that unknown gas.
pls help guys
Answer:
Molar mass of the unknown gas is 64.6 g/mol
Explanation:
Let's think this excersise with the Ideal Gases Law.
We start from the N₂. At STP conditions we know that 1 mol of anything occupies 22.4L.
We apply: P . V = n . R . T
5 atm . V = 1 mol . 0.082 . 325K
V = (1 mol . 0.082 . 325K) / 5 atm = 5.33 L
It is reasonable to say that, if we have more pressure, we may have less volume.
As this is the volume for 1 mol of N₂, our mass is 28 g. Then, the density of the nitrogen and the unknown gas is 28 g/5.33L = 5.25 g/L
Our unknown gas has, this density at 27°C and 2 atm.
If we star from this, again: 1 mol of any gas occupy 22.4L at STP, we can calculate the volume for 1 mol at those conditions:
P₁ . V₁ / T₁ = P₂ . V₂ / T₂
1 atm . 22,4L / 273K = 2 atm . V₂ / 300K
Remember that the value for T° is Absolute (T°C + 273)
[ (1 atm . 22.4L / 273K) . 300K] / 2 atm = V₂ → 12.3L
This is the volume for 1 mol of the unknown gas at 2 atm and 27°C
We use density to determine the mass: 12.3 L . 5.25 g/L = 64.6 g
That's the molar mass: 64.6 g/mol
pls help
Plot the point (5,9)
a. How many moles of hydrogen would be needed to produce 12 moles of ammonia
8 moles and I hope that this helps
What is the number of orbitals in an atom of radon
En la ecuación: Fe2O3 + CO = Fe + CO2.
El agente reductor es:
a)oxido ferrico
b)dióxido de carbono
c)monóxido de carbono
d)hierro
Answer:
English please
Explanation:
PLEEAASSEE HELP ITS ALREADY WAY PAST DUE AND ILL GIVE BRAINLIEST
Which of the following would be the evidence of a physical change?
A. unexpected change in odor
B. change in state of matter
C. formation of bubbles
D.precipitate was formed
Answer:
A. unexpected change in odor
Explanation: Common physical changes include melting, change of size, volume, color, density, and crystal form. Example the classic baking soda and vinegar reaction provides evidence of a chemical change due to the formation of a gas and a temperature change.
A 18.5 gram sample of metal was added to a graduated cylinder that had
an initial volume of 45.50 mL. The water level raised to 54.10 mL. Using
this information, calculate the density of the metal. *
Answer:
[tex]d=2.15g/mL[/tex]
Explanation:
Hello there!
In this case, since the density of the metal is computed as shown below:
[tex]d=\frac{m}{V}[/tex]
We need to calculate the volume of the solid by subtracting the final volume and the initial volume of water:
[tex]V=54.10mL-45.50mL\\\\V=8.60mL[/tex]
Thus, we obtain:
[tex]d=\frac{18.5g}{8.60mL}\\\\d=2.15g/mL[/tex]
Best regards!
Hot, molten rock deep below Earth’s surface is called lava mantle rock parent rock magma
Answer:
I think it is Magma
Specify the number of possible isomers of bromodimethylbenzene. 6 Write the name of one of these isomers. Abbreviate ortho (o), meta (m) and para (p), no italics, if you elect to use these terms.fill in the blank 2 Specify the number of possible isomers of aromatic compounds with the formula C7H8O. ___ Write the name of one of these isomers. Abbreviate ortho (o), meta (m) and para (p), no italics, if you elect to use these terms. fill in the blank 4
Answer:
Explanation:
See attached file .
The number of possible isomers of Bromodimethylbenze are 6. One of the isomers is 2 Bromo - m -xylene. The number of possible isomers of an aromatic compound [tex]\rm C_7H_8O[/tex] are 5. One of these isomers has been o - cresol.
(a). Bromodimethylbenze has also been known as bromoxylene. The compound has been consisted of 1 benzene ring with 2 methyl groups and a bromine atom.
The possible isomers of bromoxylene are:
4 Bromo - o -xylene3 Bromo - o -xylene2 Bromo - m -xylene4 Bromo - m -xylene5 Bromo - m -xylene2 Bromo - p -xylene(b). Aromatic compound with formula [tex]\rm C_7H_8O[/tex] has been the benzene compound. The compound has been consisted of a benzene ring with 1 methyl group and oxygen atom.
The possible isomers of [tex]\rm C_7H_8O[/tex] are:
Benzyl alcoholAnisolo - cresolp - cresolm - cresolThus, the number of possible isomers of Bromodimethylbenze are 6. One of the isomers is 2 Bromo - m -xylene. The number of possible isomers of an aromatic compound [tex]\rm C_7H_8O[/tex] are 5. One of these isomers has been o - cresol.
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Pls help me I will give you 10 points
What is the concentration of sodium ions in 0.185 M Na2CO3?
Answer:
0.370 M
Explanation:
Step 1: Given data
Molar concentration of the sodium carbonate solution: 0.185 M
Step 2: Write the balanced dissociation equation
Sodium carbonate is a strong electrolyte that dissociates according to the following equation.
Na₂CO₃(aq) ⇒ 2 Na⁺(aq) + CO₃²⁻(aq)
Step 3: Calculate the molar concentration of sodium ions
The molar ratio of Na₂CO₃ to Na⁺ is 1:2.
0.185 mol Na₂CO₃/L × 2 mol Na⁺/1 mol Na₂CO₃ = 0.370 mol Na⁺/L
an atom of which element has the strongest attraction for electons in a chemical bond?cholorine, phosphorus, carbon, sulfur
The number of atoms of any element in the given chemical formula is the number that is written on the foot of the symbol of that element. Therefore, chlorine has the strongest attraction for electrons in a chemical bond.
What is atom?Atom is the smallest particle of any matter. Atom combines to form element and element combine to form molecule or compound.
Atom consists of electron, proton and neutron. The total mass of atom is inside the nucleus. Inside the nucleus proton and neutron is there. So calculate mass of an atom, total mass of all protons is added to the total mass of neutron. Electrons revolve around the nucleus.
Electronegative element have greatest strongest attraction for electrons due to high effective nuclear charge. Among the given molecules, chlorine is the most electronegative element. Chlorine has the strongest attraction for electrons in a chemical bond.
Therefore, chlorine has the strongest attraction for electrons in a chemical bond.
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What happens to the total number of carbon atoms on Earth? Does the total get larger, does it get smaller, or does it stay the same?
Answer:
It stays the same.
Explanation:
