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What is the SI system? What are its benefits?

Answer:

c2h4 (etthane........

bexcuse it has 6 bond of hydrogen

C₂H₄ molecules contains six bonding electrons. Therefore, option A is correct.

Chemical bonding is the process through which two or more atoms, molecules, or ions establish a chemical link to create a chemical compound. The atoms in the resultant molecule are held together by these chemical bonds.

Chemical bonds have three basic characteristics that must be taken into account: their strength, length, and polarity. The distribution of electrical charge among the atoms connected by a bond determines its polarity.

C₂H₄ molecules has six bonding electrons. This molecule is called as Ethylene. When bonding is done between two atoms, each atom shares a pair of electrons with each other.

Hence, for every one bond, two electrons are shared between two atoms

Thus, option A is correct.

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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:

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.)

KMnO4 + H2O = MnO2 + O2 + KOH

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Answer:

ty po hehe

Explanation:

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Answer:

one atom of oxygen is not equal to oxygen

Answer:

im a just achild

Explanation:

Answer:

c

Explanation:

0.5dm³

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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.

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:

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:

Is this chemistry or ELA!

Answer:

hope it helps you see the attachment for further information

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

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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:

Acetone is captured and cooled.

Explanation:

The boiling point of acetone is lower than that of water, so it will vaporise before water. Then acetone will be captured and cooled to separate it from its mixture with water.

The statement which is correct about distilling a mixture of acetone and water is as follows:

Thus, the correct option is C.

Distillation may be defined as a procedure that generally involves the conversion of a liquid into a vapor that is eventually condensed back to liquid form. With the help of this process, the separation of components or substances from a liquid mixture by using selective boiling and condensation occurs.

Acetone has the lowest boiling point as compared to water. So, it boils faster than that water and vaporizes before water. After the termination of this process, the acetone will be predominantly captured and cooled to separate it from its mixture with water.

Therefore, the correct option for this question is C.

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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.

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:

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

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.

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.

cubic unit cell is the smallest repeated unit which have all angles equal to 90 and all have edge lengths equal

It is the type of the Unit cell which is having all angles equal to 90 and all sides equal to each other

it's is a unit cell with cubic structure

Answer: B

Explanation:

Answer:

The Correct Answer Is B.

Answer:

chắc là câu B í

Explanation:

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:

Explanation:

           The world is made up of ​living beings .    

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.