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1.What is the most common isotope for element X

2.Calculate the average atomic mass or element X

Answer:

its C

Explanation:

Answer:

Ethene

Explanation:

High-density polyethylene (HDPE) was introduced as a bearing surface in orthopedics in 1962 by Sir John Charnley from Manchester, England. Polyethylene is created through polymerization of ethene. It can be produced through radical polymerization, anionic polymerization, and cationic polymerization

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:

one atom of oxygen is not equal to oxygen

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:

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:

1 mole H2O has 6.02 × 10^23 molecules

Explanation:

the answer is highly possible to be C

Prefixes are used to indicate the number of atoms in both

covalent and ionic compounds.

Covalent or molecular compounds form when elements share electrons in a covalent bond to form molecules. Molecular compounds are electrically neutral.

Ionic compounds are (usually) formed when a metal reacts with a nonmetal (or a polyatomic ion). Covalent compounds are formed when two nonmetals react with each other. Since hydrogen is a nonmetal, binary compounds containing hydrogen are also usually covalent compounds.

Learn more about covalent and ionic compounds.

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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 and Explanation:

There are 7 base units, m is one of them. Any unit made up of a combination of them is a derived unit. Also, any unit that is defined to be equivalent to a combination of base units is a derived unit.

Answer:

Explanation:

meters has to go on the bottom of the bracket used for conversion

50m [ 1000 mm / 1 m]= 50000 mm The meters cancel

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.

Answer:

chắc là câu B í

Explanation:

Answer:

Xenon

Explanation:

The core electrons of an element are the electrons that do not take part in the chemical reactions of the element

The electronic configuration of barium Ba is presented as follows;

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s²

2+2+6+2+6+2+10+6+2+10+6

The valence electrons of boron are the 6s² electrons

The core electrons of boron are the; 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶

The electronic configuration of xenon, Xe, which is the previous noble element before barium, is presented as follows;

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ which is the same as the core electrons of barium

Therefore, the total number of electrons in xenon is equal to the number of core electrons in barium

Answer:

An orbit is a fixed path on which electrons revolve around the nucleus. An orbital is the probable area of finding the maximum density of electrons in an atom. An orbit is a planar representation, i.e., a two dimensional representation.

Answer:

they have weak intermolecular forces

Answer:

They will be considered ions of the same element.

Explanation:

Ions form from elements when they gain or loss an electron, causing the number of protons (positively charged) to be unequal to the number of electrons (negatively charged), resulting in a net charge.

If there are more electrons than protons (from an element gaining 1 or more electrons), the ion is negatively charged and is called an anion.

If there are more protons than electrons (via the loss of electrons), the ion is positively charged and is called a cation.

Answer:

I think no b

Explanation:

because in chemistry I have nothing listen

CHF3

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:

you have to use the avogadro's constant of 6.023×10^23 to calculate the number of molecules of carbon dioxide.and you also have to use the molecular mass which is 44.

35.5/44×6.023×10^23

=4.85×10^23

I hope this helps and sorry if it's wrong

Answer:

You have provided wrong option.

Their interparticle forces of attraction are in the order D>A>C>B

So, option (d) D should be there.

Answer:

High levels of turbidity can affect aquatic life in several ways.

Explanation:

Turbidity is the measure of relative clarity of a liquid. The higher the intensity of scattered light, the higher the turbidity. Material that causes water to be turbid include clay, silt, very tiny inorganic and organic matter, algae, dissolved colored organic compounds, and plankton and other microscopic organisms

Answer:

it is made up of atoms that are held together by covalent bond

Answer:

A) NaOH

got it right on the test.

Explanation:

Answer:

NaOH  

Explanation:

Explanation:

hope it will help you Mark me as a brilliant

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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:

Atomic size gradually decreases from left to right across the periodic table because within a period of elements, all electrons are added to the same shell. However, at the same time, protons are being added to the nucleus, making it more positively charged. The effect of increasing proton number is greater than that of the increasing electron number. Therefore, there is a stronger nuclear attraction. This means that the nucleus attracts the electrons more strongly, pulling the atom's electron shells closer to the nucleus. As a result, the atomic diameter of the atom decreases.

Answer:

Hi! hopefully this helps you

Explanation:

You can make a buffer solution for a specific pH (potential of hydrogen) by mixing together a weak acid like acetic acid HC2H3O2 with a salt that contains the conjugate base like sodium acetate NaC2H3O2. A neutralization reaction would occur as you are mixing a weak acid and a strong base.

When you add the base to an acidic solution, the solution becomes less acidic and moves toward the middle of the pH scale. Aka neutralization

Hope this helps! best of luck <3