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Answer:

its C

Explanation:

Answer:

1 mole H2O has 6.02 × 10^23 molecules

Explanation:

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:

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

Explanation:

the digestive system

Answer:

chắc là câu B í

Explanation:

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 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.

The answer is 32 grams!

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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

Explanation:

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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:

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:

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.

[tex]\\ \rm\longmapsto Distance=Speed(Time)[/tex]

[tex]\\ \rm\longmapsto Distance=25(2700)[/tex]

[tex]\\ \rm\longmapsto Distance=67500m[/tex]

The object travelling at 25 m/s, will travel a distance of 67500 m in 45 mins.

1 min = 60 s

Therefore,

45 mins = 45 × 60

Time = 2700

Speed = 25 m/s

Distance = speed × time

Distance = 25 × 2700

Therefore, the object will cover a distance of 67500 m in 2700 s (i.e 45 mins)

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Answer:

1s2, 2s1

Explanation:

Lithium is the first element in the 2nd row of elements meaning its 1s orbital is completely filled and 1 electron is in the 2s orbital.

Answer:

the answer is C

Explanation:

The question requires a good knowledge of the meaning of Tyndall effect or scattering of light by false solutions in chemistry

The student observed a beam of visible light through mixture A because A exhibits Tyndall effect

Tincture of Iodine does not show Tyndall effect because its solution consists of particles less than 1 nanometer in solution.

A solution may be classified as a true solution or a false solution. A true solution consists of particles which are less than 1 nanometer in solution. A true solution does not scatter visible light.

A false solution, on the other hand consists of particles larger than 1 nanometer and does scatter visible light.

Starch in water is an example of a false solution or colloid hence it exhibits Tyndall effect. The scattering of visible light by a solution is known as Tyndall effect.

Tincture of iodine and sodium chloride in water are all true solutions hence they do not scatter visible light.

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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:

filtration is the process of using a filter to remove solids from liquids or gasses.

Example:

an example of this is tea.

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.

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

Explanation:

People also ask

What is the importance of nitrogen for plants?

Nitrogen is an essential macronutrient for plant function and is a key component of amino acids, which form the building blocks of plant proteins and enzymes. Proteins make up the structural materials of all living matters and enzymes facilitate the vast array of biochemical reactions within a plant.

Answer:

Nitrogen is vital because it is a major component of chlorophyll, the compound by which plants use sunlight energy to produce sugars from water and carbon dioxide(i.e.,photosynthesis). It is also a major component of amino acids, the building blocks of proteins. Without proteins, plants wither and die.

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Answer:

I think no b

Explanation:

because in chemistry I have nothing listen

CHF3

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:

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

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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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:

The polar nature of water splits the acid molecules into its cations and anions. Cations and anions are charged particles and are free to move inside the aqueous medium. As a result when a potential difference has applied the solution to conduct electricity.

Explanation:

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