Help me please
Answer & exp.

the answer is the third one

Explanation:

it just is I think

Answer: 10 minutes

Explanation:

ln(No/N) = kt

No = 80 mg

N = 10 mg

t = 30 min

solve for k, then

k = 0.693/t1/2

Substitute k from above and solve for t1/2

10 min is correct.

Answer: The new pressure is 831 mm Hg

Explanation:

The combined gas equation is,

[tex]\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}[/tex]

where,

[tex]P_1[/tex] = initial pressure of gas = 740 mm Hg

[tex]P_2[/tex] = final pressure of gas = ?

[tex]V_1[/tex] = initial volume of gas = 2.2 L

[tex]V_2[/tex] = final volume of gas = 2.0 L

[tex]T_1[/tex] = initial temperature of gas = 290 K

[tex]T_2[/tex] = final temperature of gas = 296 K

Now put all the given values in the above equation, we get:

[tex]\frac{740\times 2.2}{290}=\frac{P_2\times 2.0}{296}[/tex]

[tex]P_2=831mmHg[/tex]

The new pressure is 831 mm Hg

Explanation:

is used for making ropes, used for climbing rocks and for making parachutes. Their usage shows that nylon fibres have high tensile strength

Answer:

it's either B. or C.. hope this helps!

Explanation:

Answer:

D. A bus moves on a straight road and then  makes a right turn.

Explanation:

Acceleration is a change in direction or speed. All of the other examples involve straight lines or constant speed.

Answer:

1 M

Explanation:

Molarity is moles per liter (mol/L).

You have 3 moles of HCl in 3 L of water.  Divide the two values.

(3 mol)/(3 L)

= 1 mol/L

= 1 M

Answer:

21.2 grams CH2Cl2

Explanation:

Number of moles: .25

Molar mass of CH2Cl2: 84.93 g/mol

Mass in grams: 84.93(0.250) = 21.2325

Considering the definition of molar mass, the mass of 0.250 moles of CH₂Cl₂ is 21.225 grams.

The molar mass of substance is a property defined as its mass per unit quantity of substance, in other words, molar mass is the amount of mass that a substance contains in one mole.

The molar mass of a compound (also called Mass or Molecular Weight) is the sum of the molar mass of the elements that form it (whose value is found in the periodic table) multiplied by the number of times they appear in the compound.

In this case, you know the molar mass of the elements is:

So, the molar mass of the compound CH₂Cl₂ is calculated as:

CH₂Cl₂= 12 g/mole + 2× 1 g/mole + 2× 35.45 g/mole

Solving:

CH₂Cl₂= 84.9 g/mole

Next, you can apply the following rule of three: If by definition of molar mass 1 mole of the compound contains 84.9 grams, 0.250 moles of the compound contains how much mass?

[tex]mass=\frac{0.250 molesx84.9 grams}{1 mole}[/tex]

mass= 21.225 grams

The mass of 0.250 moles of CH₂Cl₂ is 21.225 grams.

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Answer:

question 1 i believe is c i will put the other answeres in comments

when i finish the test

Explanation:

The carbon cycle plays an important in maintaining carbon balance on the earth.

The carbon cycle is the cycle by which carbon is recycled between the atmosphere and the geosphere.

In the carbon cycle, the process of recycling carbon do not include deep burial, compaction, and cementation.

Volcanic eruptions are one natural way that carbon can move OUT of the geosphere.

Fossil fuels, atmosphere, land biomass and rocks are all carbon reservoirs, but fossil fuels contains the MOST carbon.

The atmosphere is the carbon reservoir that changes the quickest and has the biggest direct effect on climate.

Ocean acidification occurs because the ocean absorbs more human-produced CO2, causing the acidity to increase.

A potential impact of ocean acidification is that ocean ecosystems may suffer, making it harder for humans to get food from the ocean.

Therefore, the carbon cycle is important in maintaining carbon balance on the earth.

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The second thesis statement is perfect. It supports the claim and presents main idea.

The atmosphere of the earth is layered and each layer of the atmosphere has its own properties. The atmosphere of the earth is divided into four layers. The thermosphere typically breaks up meteors before they hit Earth is not correct. The correct option is C.

The four important layers of atmosphere are troposphere, stratosphere, thermosphere and mesosphere. The layer of the atmosphere which is found above the stratosphere is defined as the mesosphere. It is the coldest layer of the atmosphere.

A meteor is known as a celestial object which is made up of rocks and minerals which enters the atmosphere of the earth and burns out completely before reaching the surface of the earth. It is known as the shooting star or falling star.

The temperature of mesosphere drops with altitude. By 80 km it reaches 100 degree celsius. The meteors burn up in this layer not in thermosphere.

Thus the correct option is C.

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Answer: If we work it out with direct proportions, the vapor pressure of propanone is 56 degrees Celsius. The atmospheric pressure is about 101.

Explanation: hope this helps.

The vapor pressure of propanone at 50°C is :

- 78° vapor pressure

When the vapor pressure is specifically work through the extents to a temperature rate it response is intensely subordinate on their possess a mass nature.

The vapor weight of propanone is calculated and shape in degree Celsius in rate.

The rate of vapor when it is calculated by 50°C with propanone its at long last gives us a 78° vapor pressure.

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Answer:

1.25 moles NaNO

Explanation:

Molarity = moles/Volume (L)

moles = Molarity (M) x Volume (L)

M = 2.5 M

V = 500 mL = 0.5L

moles = M x V = 2.5 x 0.5 = 1.25 moles

The largest mass percentage of nitrogen in NO. Therefore, option (A) is correct.

The percentage by mass of an element in a chemical compound can be described as the number of parts by mass of the element contained in 100 parts by mass of a chemical compound.

The mass percentage of an element can be determined in two steps:

First, calculate the molar mass of the compound and then the percentage of each element by dividing the total mass of the element present in the compound by the molecular mass of the compound multiplied by 100.

Given, the molecular formula of the compound is NO.

The molecular mass of the NO = 30 g/mol

The mass percentage of the Nitrogen = (14/30) × 100 = 46.67 %

the molecular formula of the compound is NO₂.

The molecular mass of the NO = 46 g/mol

The mass percentage of the Nitrogen = (14/46) × 100 = 30.4 %

the molecular formula of the compound is N₂O.

The molecular mass of the NO = 44 g/mol

The mass percentage of the Nitrogen = (14/44) × 100 = 31.81 %

the molecular formula of the compound is N₂O₃.

The molecular mass of the NO = 76 g/mol

The mass percentage of the Nitrogen = (28/76) × 100 = 36.84 %

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The type of bond formed depends on the valence electrons (no: of electrons in the outermost shell)

When two atoms share one electron pair between each other, then they are said to be bonded by single covalent bond

When two atoms share two electron pairs between each other, they are said to be bonded by double covalent bond

When two atoms share three electron pairs between each other, they are said to be bonded by triple covalent bond.

Hope u understand

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Answer:

0.99997661 moles

Explanation:

Answer:

ysys7sbssiej hsbed hdbd hdbd

Answer:

If the organ systems do not work together, then homeostasis is not maintained. If homeostasis is not maintained, the cells of the body will not work properly. As a result, the body will not work properly.Feb 4, 2017

Explanation:

Answer:

If the organ systems do not work together, then homeostasis is not maintained. If homeostasis is not maintained, the cells of the body will not work properly. As a result, the body will not work properly.

Explanation: Edge 2020 :)

Answer:

Yes, it is a good conductor of electricity.

Explanation:

They allow electric particles to pass through them (the bases).

(Hope this made sense)

Answer:b

Explanation:

bc

In the given chemical equation, H₃PO₄ is an acid while it's conjugate base is OH⁻.

Chemical equation is a symbolic representation of a chemical reaction which is written in the form of symbols and chemical formulas.The reactants are present on the left hand side while the products are present on the right hand side.

A plus sign is present between reactants and products if they are more than one in any case and an arrow is present pointing towards the product side which indicates the direction of the reaction .There are coefficients present next to the chemical symbols and formulas .

The first chemical equation was put forth by Jean Beguin in 1615.By making use of chemical equations the direction of reaction ,state of reactants and products can be stated. In the chemical equations even the temperature to be maintained and catalyst can be mentioned.

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Answer:

It means beside or alongside.

Answer:

The word Paralympics means “parallel with the Olympics”, with the para prefix coming from the Greek word for alongside. The name was chosen to embody the spirit of the two movements existing side-by-side.

Explanation:

Answer:

the answer is D the dominant over powers the resecive traits

Answer:

yez so the answer is mg 1.0

Explanation:

The excess reactant is present in an amount that is greater than required. The amount of MgO that is produced in the reaction is 0.74 moles.

An excess reactant is that reantant thatis present in an amount that is more than required.

Now we are told that the magnessium is the reactant in excess so we have to use the amount of oxygen.

The reaction is: 2Mg + O2 ---->2MgO

1 mole of O2 produces 2 mole of MgO

0.37 moles of O2 produces 0.37 moles  * 2 moles/1 mole

= 0.74 moles

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Answer:

a) both their average kinetic energy and temperature will be the same

Explanation:

Temperature is the measure of the average kinetic energy of a system. As temperature increases, so will kinetic energy. As kinetic energy increases, speed increases. As one decreases, so does the other. When two objects are in contact with each other, their molecules will exchange energy and cause an eventual equilibrium of temperature and kinetic energy.

Answer:

true

Explanation:

we need gravity to stay on ground

Answer:

True.

Explanation:

Weight in a physics or scientific sense is defined mathematically as "mass times gravity." It is literally a measure of the force of gravity pulling mass downward towards Earth (or whatever object you're considering).

I think true..

Explanation:

im not sure.

Explanation:

H2O, what is the maximum amount of H2O which could be formed from 10.9 g of H2 and 16.03 g ofO2? Answer in units of g. ... 0.500 mol O2 x 2 mol H2O / 1 mol O2 x 18 g H2O/mol H2O = answer in ..

Answer: The volume of the gas is 0.84 Liters

Explanation:

According to ideal gas equation:

[tex]PV=nRT[/tex]

P = pressure of gas = 1530 mm Hg = 2.01 atm     (760mmHg=1atm)

V = Volume of gas = ?

n = number of moles = 0.275

R = gas constant =[tex]0.0821Latm/Kmol[/tex]

T =temperature =[tex]75K[/tex]

[tex]V=\frac{nRT}{P}[/tex]

[tex]V=\frac{0.275atm\times 0.0820 Latm/K mol\times 75K}{2.01atm}=0.84L[/tex]

Thus the volume of the gas is 0.84 Liters