question 8 chemistry help

Answer: B

Explanation:

Answer:

The Correct Answer Is B.

The Answer is A)4 atoms of NA are present in 92 a.m.u

Answer:

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Answer:

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Explanation:

Answer:

hope it helps you see the attachment for further information

Explanation:

21. The given molecule for cracking is tetradecane.

On cracking it forms one mole of decane (C10H22) and two moles of ethene gas.

The chemical equation is shown below:

[tex]C_1_4H_3_0->C_1_0H_2_2+2C_2H_4[/tex]

22. The essential condition for the formation of an ester is the reaction of alcohol and acid in presence of concentrated sulfuric acid.

Thus among the given options, the first option is the correct one.

23. Isomers of butanol are shown below:

It is 2-butanol.

The position of -OH group changes to the second carbon.

Answer:

Is this chemistry or ELA!

Answer:

1. 3-methylpentane

2. 2-bromo-3-chloropentane

3. 2,2,4-trimethylpentane

Explanation:

1. CH3CH2CH(CH3)CH2CH3.

Methyl group is in the third carbon atom in the long chain. The organic compound has five(5) carbon atoms thus it is named as pentane.

Therefore the name of the compound is

3-methylpentane

2. CH3CH(Br)CH(Cl)CH2CH3

The compound has Chlorine and Bromine in the carbon chain. Chlorine is given as chloro-, Bromine is given as bromo, depending on the position in the carbon chain. Bromine is located in 2 carbon atom and chlorine is in third(3) carbon atom in the long chain. The long chain has five carbon atoms thus pentane.

Naming of the compound we begin with the on lowest in the alphabet. The name of the organic compound is therefore;

2-bromo-3-chloropentane

3. CH3CH(CH3)3CH(CH3)CH2CH3

In this long chained organic compound, methyl-group is found in 2,2 and 4th positions. Since this is still pentane, naming the organic compounds, we start with the one with the lowest carbon. Therefore this becomes;

2,2,4-trimethylpentane

I hope this helps you to know how to name the organic compounds.

Answer:

milk and starch solution are the colloids, hence these will show the tyndall effect

Answer:

milk and starch solution

Explanation:

Tyndall effect is shown by colloidal solutions. It is not shown by true solutions or suspensions.

Milk and starch solution are colloidal solutions. They show tyndall effect. On the other hand, common salt and copper sulphate solution are true solutions. They do not show tyndall effect.

If I could change something in my previous science classes, it would have been the fact that I struggled in the question concerning exponents. It was simple one, but I don't know how I didn't understood that. For example, if there is a question with a calculation "xy²", then I would first multiply x and y, and then calculate the exponent. I did 3 of the questions wrong because of this, it was when I was in 7th grade. I wish I had not done this kind of silly mistake. I an in 10th grade and understand it well now, though.

Answer:

one atom of oxygen is not equal to oxygen

Answer:

B.electrostatic repulsion by gold nuclei

Explanation:

According to Rutherford's experiment, a thin gold foil was bombarded with alpha particles. Some of the particles passed through the foil undeviated, some were scattered through large angles while some bounced backwards.

It follows that the particles that bounced backwards must have encountered a massive particle of like charge.

The atom is composed of a nucleus which contains positively charged particles. Some of the alpha particles which are positively charged particles bounced back when they encountered the positively charged particles in the nucleus.

Answer: The correct option is B (electrostatic repulsion by gold nuclei).

Explanation:

In the Rutherford's experiment, he used positively charged particles called alpha particles to bombard an atom in order to find out what is inside the atom. Together with two other scientists, Geiger and Marsden, they used a narrow beam of alpha particles emitted from a radioactive source to bombard a thin gold foil. The scattering of the particles from the gold foil was detected by a movable zinc sulphide screen which could be rotated to various positions around the foil.

Each time an alpha particle hit the screen, a visible flash of light or scintillation was produced. This was observed by a microscope attached to the screen. It was then observed that some of the particles followed a straight path through the gold foil while a few where scattered in a backward direction. This was as a result of electrostatic repulsion by gold nuclei which occurs due to the greater part of the mass of the atom was concentrated in a minute nucleus with positive charge.

Answer:

337.5kPa ~ 338kPa

Explanation:

Using the ideal gas law PV=nRT we have the following definitions from the problem:

V(initial) = 20cm³

P(initial) = ?kPa

V(final) = 75cm³

P(final) = 90kPa

Since we know that the number of moles of the sample did not change, nor did the temperature, nor does the ideal gas constant (R) we can rewrite this equation to state:

P(initial)V(initial) = nRT =P(final)V(final) ~  P(initial)V(initial) = P(final)V(final)

Rearranging this equation as we are solving for the initial pressure we find that:

P(initial) = (P(final)V(final))/V(initial)

P(initial) = ((90kPa)(75cm³))/20cm³

P(initial) = 337.5kPa ~ 338kPA

i) Be has a fully filled 2s level.

ii) This is because chlorine is larger than fluorine.

iii) Fluorine needs only one electron to attain the octet configuration.

Electron affinity is the ability of an electron to accept  gaseous electrons to yield gaseous ions with a negative charge.  

Electron affinity depends on the size of an atom. Larger atoms have a higher electron affinity because they are better able to accept electrons.

The drop between Li and Be is because the 2s orbital in Be is already fully filled while Li has incompletely filled 2s level. electrons do not easily go into the higher energy 2p level.

The higher peak of chlorine is because chlorine is larger than fluorine hence the electron affinity of fluorine is less than that of chlorine. The smaller the ion the lesser the electron affinity.

Fluorine has the highest electron affinity in period 2 because it needs only one electron to attain the octet structure.

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Answer:

2,400,000 torr (3 s.f.)

Explanation:

Convert the pressure from Pascal to atm first:

[tex]\boxed{1 \: atm = 101325 \:Pa }[/tex]

3.20 ×10⁸ Pa

= [(3.20 ×10⁸) ÷101325] atm

= 3158.2 atm (5 s.f.)

Convert atm to torr:

[tex]\boxed{1 \: atm = 760 \: torr}[/tex]

3158.2 atm

= (3158.2 ×760) torr

= 2400000 torr (3 s.f.)

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The pressure in atm exerted by 1.8 g of H₂ gas exert in a 4.3 L balloon at 27ºC is 5.12 atm

The ideal gas law (PV = nRT) relates the macroscopic properties of ideal gases. An ideal gas is a gas in which the particles (a) do not attract or repel one another and (b) take up no space (have no volume).

Let's convert grams to moles (via molar mass).

Molar Mass (H₂) :  2 (1.008 g/mol)

Molar Mass (H₂) :  2.016 g/mol

1.8 grams H₂               1 mole

----------------------  x  ----------------------  =  0.893 moles H₂

                                2.016 grams

The Ideal Gas Law equation looks like this:

PV = nRT

In this equation,

After converting Celsius to Kelvin, you can put the given values into the equation and simplify to find the pressure.

P = ? atm                                R = 0.0821 L*atm/mol*K

V = 4.3 L                               T = 27 °C + 273.15 = 300.15 K

n = 0.893 moles

PV = nRT

P (4.3 L) = (0.893 moles) (0.0821 L*atm/mol*K)( 300.15 K)

P (4.3 L) =  22.0021

P = 5.12 atm

Therefore, The pressure in atm exerted by 1.8 g of H₂ gas exert in a 4.3 L balloon at 27ºC is 5.12 atm

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Answer:

The amount of acid rain caused by the burning of fossil fuels can be reduced by creating nitrogen oxides in the process of burning coal and other fossil fuels, some power plants are changing the way they burn coal. A great way to reduce acid rain is to produce energy without using fossil fuels. Instead, people can use renewable energy sources, such as solar and wind power.

Explanation:in testing for oxygen a glowing splint is used.

the glowing splint is brought in the presence of the test tube containing the gas

the glowing splint rekindles or lights up showing that oxygen is present.

this is a positive test because oxygen supports burning or combustion

Answer:

all of this

Explanation:

Answer:

im a just achild

Explanation:

Answer:

c

Explanation:

0.5dm³

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Answer:

Explanation:

           The world is made up of ​living beings .    

Answer:

Explained below

Explanation:

In simple average, we just add all the given data variables and divide it by the number of data given.

However, when it comes to weighted average, what we do is that we multiply each given variable by their weights and then divide the sum of that by the sum of the weights.

Thus, if the variables are denoted by x and their weights are denoted by y, then we have;

Weighted average = Σ(xy)/Σy

The mass percent of a sodium fluoride solution prepared by dissolving 0.64 moles of sodium fluoride into 63.5 grams of water is 29.7%.

Mass percent is a means to describe a component in a specific combination or to convey a concentration. The mass percentage used to describe the solution composition indicates the mass of solute contained in a given mass of solution.

To determine the mass percent of an element in a compound, we divide the mass of the element in one mole of the compound by the compound's molar mass and multiply the result by 100.

Given:

Number of moles = 0.64 moles

Moles of sodium fluoride = Given mass/molar mass

0.64 moles = Mass / 42

Mass = 26.88gram

Mass % = Mass of solute/ mass of solution × 100

= 26.88/90.48 × 100

= 29.7 %

Thus, 29.7 % is the mass percent of a sodium fluoride solution prepared by dissolving 0.64 moles of sodium fluoride into 63.5 grams of water

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Answer:

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a) Solution 1: Solute is ethyl alcohol, solvent is water. Solution 2 and 3: Solute is salt, solvent is water.

b) Concentration by weight of solution 3: Approximately 3.85%.

c) Solution 3 has a higher concentration than solution 2.

a) Solutions and their solutes and solvents:

Solution 1: The solute is ethyl alcohol, and the solvent is water. This is because ethyl alcohol is the substance that dissolves in water to form the solution.

Solution 2: The solute is salt, and the solvent is water. Salt is the substance that dissolves in water to form the solution.

Solution 3: The solute is salt, and the solvent is water. Similar to solution 2, salt is the substance that dissolves in water to form the solution.

b) Weight concentration of solution number 3:

The weight concentration is calculated by dividing the mass of the solute (80 g of salt) by the total mass of the solution (80 g of salt + 2000 g of water):

Weight concentration = (80 g / 2080 g) * 100% ≈ 3.85%

c) Comparison of concentrations between solution 2 and 3:

Solution number 3 has a higher concentration than solution 2, as the weight concentration of solution 3 is approximately 3.85%, while the exact amount of water is not provided for solution 2 to calculate its concentration. However, solution 2 contains only 20 g of salt dissolved in 500 ml of water, which implies that the concentration will be lower than solution 3. Therefore, solution number 3 has a higher concentration compared to solution 2.

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The purpose of a catalyst in the production of hydrogen is to increase the rate at which water molecules decompose.

What is a catalyst-A catalyst is a substance that increases the rate of a chemical reaction without itself being consumed or produced during the reaction. As a result, catalysts assist in speeding up chemical reactions while also decreasing the amount of energy needed for the reaction to occur. In hydrogen production, catalysts are used to speed up the decomposition of water into hydrogen and oxygen. The use of catalysts lowers the activation energy required for the reaction to occur, resulting in a faster reaction rate and lower operating temperatures.What is the process of hydrogen production?Hydrogen production has various methods, and one of the most commonly used methods is water electrolysis. In this method, water molecules are split into hydrogen and oxygen using an electric current passed through an electrode. Water is broken down into hydrogen and oxygen during the process, with the assistance of a catalyst. During this process, a catalyst like platinum or nickel is employed to speed up the chemical reaction of water decomposition.

When an electric current is applied to the catalyst, water molecules are broken apart, releasing hydrogen and oxygen atoms.Catalysts lower the activation energy of the reaction, allowing it to occur faster than it would otherwise. In hydrogen production, catalysts are crucial since they enable the reaction to occur at a lower temperature, reducing energy consumption and minimizing operating costs. As a result, the use of catalysts is essential to the production of hydrogen.

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Answer:

chắc là câu B í

Explanation:

Answer:

A body becomes weightless in a zero-gravity scenario and when a force is applied to a body that is equal and opposite to the force of gravity. If the body is falling only under the influence of gravity.

Answer:

A body becomes weightless in a zero-gravity scenario and when a force is applied to a body that is equal and opposite to the force of gravity.If the body is falling only under the influence of gravity.

Answer:

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Explanation:

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