What is the percentage of oxygen in air?

Answers

Answer 1
21% becuase air is mostly gas.

It’s a mixture of different gases. The air in Earth’s atmosphere is made up of approximately 78 percent nitrogen and 21 percent oxygen.

Related Questions

An aqueous solution has 124 g of a salt dissolved in 1000 g of solution. What is the concentration of the salt in units of %?​

Answers

Answer: 12.4%

Explanation:

124/1000 * 100 = 12.4%

According to the concept of percent solution,the concentration of salt in percent units is 12.4 %.

What is percent solution?

Percent solution is defined as a convenient way to record concentration of solution.It is a expression which relates solute to solvent as,mass of solute/mass of solution ×100.There are two types of percentage solutions percent weight by volume and percent volume by volume .Advantages of using percent solutions is that molecular weight of compound is not required.

Percent solutions are of important use in industries and laboratories for measuring concentration of solutions.

In the given example, percent concentration is found out as, mass of solute/ mass of solution ×100 thus substitution of values gives 124/1000×100=12.4%.

Thus, the percent concentration is 12.4%.

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Which of the following statements is correct for precipitation
reaction?

A. All the products must be insoluble.
B. At least one of the products is insoluble.
C. All the reactants must be insoluble.
D. At least one of the reactants must be insoluble.

Answers

Answer:

B. At least one of the products is insoluble.

Explanation:

Precipitation reaction :

A chemical reaction occurring in an aqueous solution where two ionic bonds combine, resulting in the formation of an insoluble salt. These insoluble salts formed in precipitation reactions are called precipitates.

I need help please help

Answers

Answer:

I don't know the help you are talking about.

2C₂H₂(g) + 5O₂(g) —> 4CO₂(g) +2H₂O(g)

b. How many moles of H₂O are produced when 64.0g C₂H₂ burns in oxygen?

Answers

I think it’s 2.46 moles of H2O, unless the ‘burns in oxygen’ is relevant to the equation. i hope this helps.

64.0g C2H2 X 1 mol C2H2 over 26.04g C2H2 X 2 mol H2O over 2 mol C2H2

The first step of the equation is a basic diversion factor showing that for ever C2H2, there’s one mole. I got the number 26.04 grams of C2H2 by calculating their combined mass. To do that, I added them from the periodic table for and multiplied it by the amount of each that I had. Which was displayed as 12.01(2) + 1.01(2)

The second step to the equation is the mole conversion factor. In this step, I took the number of moles from the equation. That just shows that for every 2 moles of C2H2, there will be 2 moles of H2O.

After setting it up, you can ignore any ones in the problem as they won’t make any difference in the answer. And since, in this equation, the moles in the mole conversion factor are equal, you may ignore those too as they will divide down to one and not have any significance.

Now, to find the answer I divided 64.0g C2H2 by 26.04g C2H2 since everything else cancelled out. It equals 2.457757296 moles of H20. But, to get get credit for the sig-figs, you’ll have to change the numbers before submitting.

The beginning number has three placements (64.0) so the answer must also have three. If we look at the long decimal we got in the calculator, we can go over three and round the last number either up or down depending on the fourth number.

Aspirin is one of the Aesthetic Values of biodiversity

true
false

Answers

Answer:

true

Explanation:

Answer:

its true

Explanation:

you know Aspirin is one of the Aesthetic Values of biodiversity is true

hope it help to you and goodluck next time

name the covalent compound:

I8P

Answers

There are certain rules to follow when naming covalent compounds. But first, let us look at the definition of Covalent Compounds.

What are Covalent Compounds?

When covalent bonds aid the creation of a molecule, in which the atoms have at least one similar pair of valence electrons, a covalent compound is said to have been formed.

A very common example is water (H₂O)

How are Covalent Compounds named?

To name a covalent compound, simply list the first element in the formula using the name of the element, then name the second element by adding the suffix "ide" to the stem of the second element's name.

If there is only one atom in the molecule of the first element, then no prefix should be added.

It is to be noted that if the second element in the compound is oxygen, then we should say:

monoxide instead of monooxide andtrioxide instead of troxide, all depending on how many atoms that are involved.

See the attached for the prefixes related to the various number of atoms in the compounds.

It is to be noted that the covalent compound to be named here is not stated hence the general answer.

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What kind of property is melting point? an atomic property , , , an atomic property , , a physical property , a physical property , , an acidic property , an acidic property , , a chemical property

Answers

Answer:

physical property has a melting point

PLEASE HELP: You have been given 0.507 moles of cesium fluoride (CsF), determine the mass in grams of cesium fluoride that you have.

Answers

Answer:

C because 77.0 CsF

Explanation:

That is the correct answer because I have that homework and i got it right

Determine the number of moles of water that could be produce
from 10.0 mols of hydrogen gas and 6.0 mols of oxygen gas.

If 10.0L of hydrogen gas, and 6.0L of oxygen gas were used in
problem 1, how many liters of water vapor would be produced?
PLEASE HELP <3

Answers

From the mole ratio of the gases, 10 moles of hydrogen will produce 10 moles of water, and if 10.0 L of hydrogen and 6.0 L of oxygen were used, 10.0 L of water will be produced.

What is the mole ratio of reactants in the formation of water?

The mole ratio of the reactants in the formation of water can be shown from the equation below:

[tex]2H_2 + O_2 \rightarrow 2H_2O[/tex]

Mole ratio of hydrogen to oxygen is 2:1

10 moles of hydrogen will require 5 moles of oxygen, therefore hydrogen is the limiting reactant.

10 moles of hydrogen will produce 10 moles of water.

1 mole of a gas has a volume of 22.4 L.

If 10.0 L of hydrogen and 6.0 L of oxygen were used, 10.0 L of water will be produced.

Therefore, the volume ratio of gas equals mole ratio of gas.

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8) F2(g) + CaBr2(g) -> CaF2(g) + Brz(g)
What type of reaction is shown above?
A) synthesis
B) decomposition
C) single replacement
D) double replacement

Answers

i’m pretty sure it’s single replacement

When you calculate the Ksp of calcium fluoride, CaF2, and the concentration of the F- ion is 4.2 x 10-4M, what is the concentration of the Ca2 ion

Answers

Calculate its molar solubility in a saturated aqueous solution that is also 0.050 M in fluoride ion, F-. Ksp = (x)(2x + 0.05)2. 2x = 4.210 4

Write a question you could ask the scientists who made Graph A (above) to learn more about how their evidence relates to global temperatures?

(Your question should show that you understand how changes in the amount of energy from the sun reaching Earth might affect global temperatures. Hint: use some information from the graph to make up your question.)

Answers

Answer:

The hypthesis of the stated thesis, states that the changes in solar irradiance effect surface tempeture of the glove. Why does the suns tempture effects the globes tempture?

Explanation:

The hypthesis of the stated thesis, states that the changes in solar irradiance effect surface tempeture of the glove. Why does the suns tempture effects the globes tempture?

How would the graph below change if a catalyst were added to the reaction?
2
Potential Energy
3
Reaction Progress
A. Part 1 would be higher, and part 2 would be lower.
B. Parts 1, 2, and 3 would be lower.
C. Part 2 would be lower, and parts 1 and 3 would be unchanged.
D. Parts 1 and 3 would be higher, and part 2 would be unchanged.

Answers

In an energy profile diagram, part 2 the initiation or activation energy is lowered and parts 1 and 3 would be unchanged; option C.

What is the effect of addition of a catalyst to reaction?

A catalyst is a substance which alters the rate of a chemical reaction but is not chemically altered in the reaction.

Addition of a catalyst to a reaction lowers the activation energy of that reaction.

Thus, in an energy profile diagram, part 2 the initiation or activation energy is lowered and parts 1 and 3 would be unchanged.

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In an energy profile diagram, in part 2 the initiation or activation energy is lowered and parts 1 and 3 would be unchanged. Hence, option C is correct.

What is the effect of the addition of a catalyst to the reaction?

The addition of a catalyst provides an alternate pathway/mechanism with a lower energy of activation, thus speeding up the reaction.

Catalysts typically speed up a reaction by reducing the activation energy or changing the reaction mechanism.

Thus, in an energy profile diagram, in part 2 the initiation or activation energy is lowered and parts 1 and 3 would be unchanged.

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What is the mass of oxygen in 25. 0 grams of potassium permanganate kmno4.

Answers

Answer: The mass of oxygen in 25.0 grams of potassium permanganate, KMnO4 is 10.13 grams. molar mass of KMnO₄ = 39 + 55 + 16(4).

Explanation:hope this helps ^^ have a good day xlXCherryColaXlx..(pls mark me brainliest)

To determine the mass of oxygen in 25.0 grams of potassium permanganate (KMnO4), we need to consider the molar mass and the ratio of oxygen atoms in the compound.

What is molar mass ?

Molar mass is a term used in chemistry to denote the mass of one mole of a substance. It is expressed in grams per mole (g/mol). Molar mass is calculated by summing up the atomic masses of all the atoms in a molecule, as indicated by its chemical formula.

The molar mass of potassium permanganate (KMnO4) can be calculated as follows:

Molar mass of K = 39.10 g/mol

Molar mass of Mn = 54.94 g/mol

Molar mass of O = 16.00 g/mol (since there are 4 oxygen atoms in KMnO4)

Molar mass of KMnO4 = (39.10 g/mol) + (54.94 g/mol) + (4 * 16.00 g/mol)

= 39.10 g/mol + 54.94 g/mol + 64.00 g/mol

= 158.04 g/mol

Now, we can calculate the mass of oxygen in 25.0 grams of KMnO4 using the molar mass and the molar ratio:

Mass of oxygen = (Molar mass of O / Molar mass of KMnO4) * Mass of KMnO4

= (4 * 16.00 g/mol / 158.04 g/mol) * 25.0 g

= (64.00 g / 158.04 g) * 25.0 g

= 0.4052 * 25.0 g

= 10.13 g (rounded to two decimal places)

Therefore, the mass of oxygen in 25.0 grams of potassium permanganate (KMnO4) is approximately 10.13 grams.

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A sample of CH3OH(g) is placed in the previously evacuated vessel with a pressure of P1 at 600 K. What is the final pressure in the vessel after the reaction is complete and the contents of the vessel are returned to 600 K

Answers

For a  sample of CH3OH(g) is placed in the previously evacuated vessel with a pressure of P1 at 600 K, the final pressure in the vessel is

Pt=3P1

What is the final pressure in the vessel after the reaction is complete and the contents of the vessel are returned to 600 K?

Generally, the Chemical reaction is given as

CH3OH----->CO +2H2

Therefore, The pressure P1 doubled at the product side of the reaction

In conclusion, the final pressure in the vessel at 600k

Pt=P1+P2

Pt=3P1

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Mercury-203 undergoes beta minus decay. the subscript in the nuclide notation, hg, is . 203 ? hg →? the element symbol produced is . it has a mass number and an atomic number . 203 80 hg → 203 81 ti ?

Answers

When Mercury-203 undergoes beta minus decay, the nucleus that is formed is 203/81Tl.

What is beta emission?

A parent nucleus is said to undergo beta emission when only when an electron is lost to form the daughter nucleus. This would make the atomic number of the daughter nucelus to increase by 1.

Hence, when Mercury-203 undergoes beta minus decay, the nucleus that is formed is 203/81Tl.

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Answer:

Mercury-203 undergoes beta minus decay. The subscript in the nuclide notation, Hg, is ____80______

The element symbol produced is __TI__ . It has a mass number __203__ and an atomic number ___81____

80

Explanation:

what is the molarity of a solution that contains 1.25 moles of K2SO4 dissolved into water to make 1.5 liters of solution?

Answers

Answer: 0.8 M

Explanation:

molarity = (moles of solute)/(liters of solution) = 1.25/1.5 = 0.8 M

Where would you find ocean water with the most solar radiation?
Near the Equator
Near the South Pole
Near the Arctic Circle​

Answers

Answer:

The answer is Near the Equator.

Explanation:

Its near africa and africa is near the equator.

Answer:

near the equator

Explanation:

took the quiz its right for me

How many moles of chlorine gas at 120.0 °C and 33.3 ATM would occupy a vessel of 25.5 L?​

Answers

solution:

Temperature (T) = 120°C

= (120+273) K

= 393 K

Pressure (P) = 33.3 atm

Volume (V) = 25.5 L

Gas Constant (R) = PV/T

= (1*22.4)/273

= 0.082 atm.L/K.mol

Law= PV = nRT

= (33.3*25.5)

= (n*0.082*393)

= 849.15

= 32.226n

= 26.349n

= 26.3 mol Cl₂

therefore, the number of moles are 26.3 mol Cl₂.

PV = nRT

P = 33.3 atm

V = 25.5 L

n = ? mol

R = 0.08206 L•atm/K•mol

T = 120.0 °C + 273.15 = 393.15 K

Solve for moles:

n = PV/RT

n = (33.3 atm × 25.5 L)/(0.08206 L•atm/K•mol × 393.15 K)

= 26.3 mol Cl₂

Strong nuclear forces inside the atomic nucleus tend to ____ .

a. cause nuclear decay
b. hold the nucleus together
c. make the nucleus unstable
d. push the nucleus apart

Answers

Answer: a. cause nuclear decay

Explanation:

Find the concentration of 0.75 mol.dm-³ AgNO3

Answers

The mass concentration of the 0.75 mol.dm-³ AgNO3 solution is 127.5 g/dm³.

What is concentration?

Concentration is the amount of a solute present ina a given volume of solution.

Concentration of solutions can either be expressed as:

molar concentration Mass concentration Percentage concentration

The concentration of 0.75 mol.dm-³ AgNO3 is a molar concentration.

The concentration can be converted to mass. concentration as follows:

Mass concentration = molar concentration × molar mass

molar mass of AgNO3 = 170 g/mol

Mass concentration = 0.75 × 170 = 127.5 g/dm³.

Therefore, the mass concentration of the AgNO3 solution is 127.5 g/dm³.

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What two layers in the atmosphere protect us?

Answers

Answer:

The Stratosphere and Troposphere

Answer:

trophosphere and stratosphere protect us from ozone rays

Explanation:

A 100-gram sample of material requires 1220 calories of heat energy to raise its temperature from 20 0C to 80 0C. What is the specific heat capacity of the material?

Answers

Taking into account the definition of calorimetry, sensible heat and latent heat, the specific heat capacity of the material is 0.203 [tex]\frac{calories}{gC}[/tex].

Calorimetry

Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.

Sensible heat is defined as the amount of heat that a body absorbs or releases without any changes in its physical state (phase change).

The amount of heat a body receives or transmits is determined by:

Q = c× m× ΔT

where Q is the heat exchanged by a body of mass m, made up of a specific heat substance c and where ΔT is the temperature variation.

Specific heat capacity of the material

In this case, you know:

Q= 1220 caloriesc= ?m= 100 gΔT=Tfinal - Tinitial= 80 C - 20 C= 60 C

Replacing in the definition of amount of heat:

1220 calories= c× 100 g× 60 C

Solving:

c= 1220 calories÷ (100 g× 60 C)

c= 0.203 [tex]\frac{calories}{gC}[/tex]

Finally, the specific heat capacity of the material is 0.203 [tex]\frac{calories}{gC}[/tex].

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Which group of compounds tastes bitter and are usually slippery when placed in water?.

Answers

Answer:

Bases

Explanation:

Soap is a common example of a base. They taste bitter (try tasting soap or shampoo) and are slippery (that is why a wet bar of soap flies out of your hands)

An electric motor in a bike has a voltage of 24 V and produces 240 W of power. How much current does it draw?]

Answers

Answer:

Electrical energy is the product of power multiplied by the length of time it was consumed. So if we know how much power, in Watts is being consumed and the time, in seconds for which it is used, we can find the total energy used in watt-seconds. In other words, Energy = power x time and Power = voltage x current.

The amount of current the electric motor having a power of 240 W Will draw from the 24 V supply is 10 A

What is power?

This is defined as the rate in which energy is consumed. Electrical power is expressed mathematically as:

Power (P) = voltage (V) × current (I)

P = IV

How to determine the current

From the question given above, the following data were obtained:

Voltage (V) = 24 V

Power (P) = 240 W

Current (I) = ?

P = IV

240 = I × 24

Divide both sides by 24

I = 240 / 24

I = 10 A

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Shaila is collecting data to calculate the density of a piece of wood. First, she
places the wood on a triple beam balance; its mass is 63.85 g. Then, she fills a
graduated cylinder with 50.0 mL of water. She places the wood in
graduated cylinder with the water and notes that the water level rises to 125.0
mL. Calculate the density of the wood given that D = m/V. i need some1 to explain this

Answers

Answer:

Explanation:

Remark

You have 2 facts that you got from the experiment. The first is that the mass of the wood is 63.85 grams and the volume can be calculated.

From there, the desity can be found.

Givens

m = 63.85 grams

vo = 50 mL

vf = 125 mL

Solution

Volume = vf - vo

Volume = 125 mL - 50 ml. This gives you the amount of water that has been moved aside (called displaced)

volume = 75 mL

D = 63.85 grams/ 75 mL

D = 0.851 grams / mL

Some woods actually do have a density less than 1 which is the density of water. These woods float.

_____2. To eliminate the spattering and aerosolization associated with flaming of loops, char the material before fully inserting the loop into the flame: i. E. , before flaming, hold the loop close to (but not into) the flame. Alternatively, use disposable loops or a micro-incinerator.

Answers

The description included refers to safety measurements when using microbiological transfer loops in the laboratory.

What are microbiological transfer loops?

These are simple tools used to pick up small samples of microorganisms, which is often used to transfer the microorganisms.

How to use trasnfer loops?

Transfer loops can easily contaminate; due to this, it is essential to flame loops. This should be done either by:

Using a micro-incinerator.Holding the loop very close to a flame without inserting it.

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________ can be made in small amounts by creating a chemical reaction through the mixing of pseudoephedrine with regular household items.

Answers

Synthetic cathinone can be made in small amounts by creating a chemical reaction through the mixing of pseudoephedrine with regular household items.

What is cathinone?

Cathinone is an alkaloid drug obtained from a shrub plant (Catha edulis) and is equivalent to Akovaz (ephedrine).

The cathinone can also be artificially designed by using a pseudoephedrine medical drug.

Synthetic cathinone can be artificially produced in order to obtain this substance for medical use.

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A sample of 10.5g of Nirtogen reacts with 20.2g of Hydrogen to produce ammonia.
3H2(g)+N2(g)=2NH3(g)
a. What is the theoretical yield of ammonia?
b. What is the limiting reactant?
c. What is the excess reactant?
d. How much is the excess reactant?
e. If 4.1 g of ammonia is actually produced, what is the precent yield?​

Answers

Answer:

Explanation:

a) The mass of the reactants is 10.5 + 20.2 = 30.7, so the theoretical yield of ammonia is also 30.7 grams (by the law of conservation of mass)

b) The gram-formula mass of diatomic nitrogen is about 28.014 g/mol, so 10.5 grams of nitrogen is 10.5/28.014 = 0.37 moles. In comparison, the gram-formula mass of diatomic hydrogen is about 2.016 g/mol, so 20.2 grams of hydrogen is about 20.2/2.016 = 10.0 moles. Dividing this by 3, we get 3.33 moles. So, nitrogen is the limiting reactant.

c) Hydrogen

d) 0.37 moles of nitrogen is consumed, so (0.37)(3) = 1.11 moles of hydrogen is consumed. This means that 3.33-1.11=2.22 moles of hydrogen are remaining, which has a mass of (2.22)(2.016)=4.47 grams.

e) (actual)/(theoretical) * 100 = (4.1)/(30.7) * 100 = 13%

Which is a characteristic of atoms?
O They come in ten major types.
© They are the smallest units of matter
0
They can be found in nonliving things only.
O They cannot combine together.

Answers

Answer:

They are the smallest units of matter

Explanation:

Atom are the basic units of a chemical element; the smallest unit of an element that retains the properties of an element

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