Hey can you please help me with this I really need y’all

This is known as modern periodic law

According to this repetition of properties occurs when elements are arranged in order of increasing atomic number.

This law was proposed by Mendleev.

Previously the periodic law was that the properties are repeated with atomic mass.

The periodic law, which emerged in the 20th century, suggests that properties of elements repeat periodically when arranged by their atomic numbers. This is depicted in the periodic table, where elements are ordered by their atomic numbers in rows and columns, grouping elements with similar properties. The periodic table thus facilitates the prediction of element behavior.

The repetition of properties in elements, when arranged in order of increasing atomic number, is best described by the periodic law. This law states that the properties of elements are periodic functions of their atomic numbers. The periodic table, where this law is visibly demonstrated, organizes elements in increasing order of their atomic numbers in horizontal rows (periods) and vertical columns (groups).

Atoms with similar properties within this table are grouped in the same column. Each atomic box typically contains the element's symbol, atomic number, average atomic mass, and possibly its name. The periodic mapping of elements through atomic numbers rather than atomic masses emerged in the twentieth century and its modern version is widely accepted across the world today.

Since the periodic table's organization is based on shared properties among elements, it provides an efficient system for predicting the behavior of an element. Therefore, it becomes simpler to understand why elements in the same group have similar characteristics, for instance, why the metallic character increases as we move down a group.

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Answer: Reducing the time of contact between the two objects will decrease the heat transfer between them.

Explanation:

the answer is d you guys and girls i just took it on the test

The answer is 32 electrons.

Answer:

32 electrons are the maximum electrons found in the N shell.

Explanation:

According to the periodic table, Maximum number of electrons in any energy level of known element is 32 which is found in N shell.

Each shell can contain fixed number of electrons. The first shell is the K shell that holds two electrons, the second shell that is L shell which holds eight electrons(2+6), The third shell is M shell which holds 18 electrons(2+6+10), and the fourth shell is N shell which holds the maximum number of electrons that is thirty two(2+6+10+14) electrons. The general formula is [tex]2n^{2}[/tex] electrons.

The outermost shell is called the valence shell and the electrons present in these shell are called valence electrons. Each shell consists of one or more subshells, and each subshell consists of one or more atomic orbitals.

Answer: 6.71 g

Explanation: [tex]6Li(s)+N_2(g)\rightarrow 2Li_3N[/tex]

[tex]{\text{no of moles}}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]

[tex]{\text {moles of lithium}}=\frac{4g}{6.914g/mol}=0.578moles[/tex]

[tex]\text{moles of nitrogen}=\frac{4g}{28g/mol}=0.143moles[/tex]

Limiting reagent is the reagent which limits the formation of product. Excess reagent is one which is in excess and thus remains unreacted.

Thus lithium is the limiting reagent and nitrogen is the excess reagent.

As can be seen from the balanced chemical equation,  6 moles of lithium reacts with 1 mole of nitrogen to give 2 moles of lithium nitride.

Thus 0.578 moles of lithium react with 0.096 moles of nitrogen.

6 moles of lithium give = 2 moles of lithium nitride

Thus 0.578 moles of lithium give=[tex]\frac{2}{6}\times {0.578}=0.19moles[/tex] of lithium nitride.

Mass of lithium nitride [tex]Li_3N={\text {no of moles}}\times {\text {Molecular mass}}[/tex]

Mass of lithium nitride[tex]Li_3N[/tex]=[tex]{0.192moles}\times {34.83g/mol}=6.71g[/tex]

Answer: 4.02

Explanation:

-- 4.00 g Li x   1 mol Li   x   2 mol LiN   x   20.948 g LiN   = 4.02 g LiN

                      --------------     ----------------       ---------------------

                      6.941 g Li        6 mol Li              1 mol LiN

-- 4.00 g N2 x   1 mol N2   x   2 mol LiN   x   20.948 g LiN   = 5.98 g LiN

                          --------------     ----------------       ---------------------

                       28.014 g N2      1 mol N2           1 mol LiN

I believe the correct answer would be the substances that are formed. Why?  Because during a chemical change, the substances (scientifically called reactants) which are changed into other substances are called products.  

Hope I could help! :)

A chemical reaction is a series of events that involves the reactants and the products. The product of the reaction is the substances that are formed. Thus, option A is correct.

Products are the substances that are formed when the chemical reactants undergo changes in the bond breaking and formation resulting in a new substance in the form of compounds, molecules, or elements. They are formed at the end of the reaction and are on the right side of the equation.

The reactants are the chemical substances that underwent reactional alterations that cause the change in the bonds and the chemical properties causing the formation of the products. They are present at the initial stage of the reaction and are on the left side of the equation.

Therefore, the products are formed at the end of the reaction.

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Your question is incomplete, but most probably your full question was, Which of the following describes the products of a chemical reaction?

A.The substances that are formed

B.The substances that are changed

C.The starting materials

D.The chemical ingredients

stand up eye wash station

Answer:

The answer is: When a foreign substance, usually irritating, penetrates the eyes, and for people with sensitive eyes.

Explanation:

An eyewash liquid, or eyewash liquid system is a liquid, usually a saline solution, used as an emergency or safety mechanism in laboratories and industrial plants as an aid to eye rinsing, s when a foreign substance, usually irritating, penetrates in them.

These eye drops can be beneficial for people with sensitive eyes and can provide relief from the side effects of painful sensation.

The answer is: When a foreign substance, usually irritating, penetrates the eyes, and for people with sensitive eyes.

Answer:

The answer will be (B) Kinetic energy to potential energy

Explanation:

When something is in movement, it has kinetic energy. When that object beings to slow down it gains more potential energy than kinetic.

The potential needed to do work is called energy. It can exist in several forms like kinetic, potential, thermal, nuclear etc.

The correct answer is:

option B. Kinetic to potential energy.

This can be explained by the following:

Therefore, when a roller coaster slowly climbs a steep hill then the kinetic energy gets transformed into potential energy.

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A positive calcium ion and a negative oxygen ion can form an ionic bond with each other, as they have opposite charges which attract. Such a pairing would result in the formation of the ionic compound calcium oxide (CaO). Options involving two negatively charged ions or two positively charged ions, as well as a neutral atom paired with a negative ion, do not produce ionic bonds because there is no attractively charged pairing.

An ionic bond is formed when one atom donates an electron to another atom, resulting in the formation of positively charged ions (cations) and negatively charged ions (anions). This type of chemical bond typically occurs between metals, which tend to lose electrons, and non-metals, which tend to gain electrons, leading to a compound with a net zero charge. For particle pairs to form an ionic bond, one must be a positive ion and the other a negative ion.

Looking at the options provided:

A. A negative oxygen ion (anion) and a negative chlorine ion (anion) would both have a negative charge and therefore could not form an ionic bond with each other due to like charges repelling.

B. A positive sodium ion (cation) and a positive magnesium ion (cation) both have positive charges and, like option A, would repel rather than form an ionic bond.

C. A positive calcium ion (Ca2+) and a negative oxygen ion (O2-) have opposite charges and would attract each other to form an ionic bond, resulting in the ionic compound calcium oxide (CaO).

D. A neutral fluorine atom and a negative sulfur ion (anion) also cannot form an ionic bond because the neutral fluorine atom does not have a charge to attract the negatively charged sulfur ion.

Therefore, the correct answer is C: a positive calcium ion and a negative oxygen ion can form an ionic bond with each other, illustrating the transfer of electrons and the electrostatic attraction that characterizes ionic bonding.

In the electromagnetic spectrum , among the following ultraviolet rays carry the most energy.

The electromagnetic spectrum consists of electromagnetic radiation which consists of waves made up of electromagnetic field which are capable of propogating through space and carry the radiant electromagnetic energy.

The radiation are composed of electromagnetic waves which are synchronized oscillations of electric and magnetic fields . They are created due to change which is periodic in electric as well as magnetic fields.

In vacuum ,all the electromagnetic waves travel at the same speed that is with the speed of air.The position of an electromagnetic wave in an electromagnetic spectrum is characterized by it's frequency or wavelength.They are emitted by electrically charged particles which undergo acceleration and subsequently interact with other charged particles.

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Final answer:

Ultraviolet waves carry the most energy out of the options provided, as they have a higher frequency than visible light, infrared waves, and microwaves.

Explanation:

The electromagnetic wave that carries the most energy among the options provided is ultraviolet waves (A). The energy of electromagnetic waves is related to their frequency. The higher the frequency, the more energy the waves carry. Ultraviolet waves have higher frequencies than visible light, infrared waves, and microwaves, which means they have more energy. It is important to note that waves like X-rays and gamma rays carry even more energy than ultraviolet waves. The general order from lowest to highest energy in electromagnetic waves is radio, microwave, infrared, visible, ultraviolet, X-ray, and gamma.

Answer:

The correct answer is

D. the temperature

Explanation:

According to the forces of attraction,the average kinetic energy of the particles in a gas is determined by the temperature.

Forces of attraction  is a force by which atoms in a molecule  combine. it is basically an attractive force in nature.  It can act between an ion  and an atom as well.It varies for different  states  of matter that is solids, liquids and gases.

The forces of attraction are maximum in solids as  the molecules present in solid are tightly held while it is minimum in gases  as the molecules are far apart . The forces of attraction in liquids is intermediate of solids and gases.

As the forces of attraction are least in gases they have maximum average kinetic energy which is further increased by an increase in temperature.

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A separate proteins from nucleus

Molecules or atoms. One of those. although atoms make up everything so i would go with atoms.

Answer:

Mixtures

Explanation:

The air,soil,and most foods and beverages are example of Mixtures. Mixtures are a combination of two or more substances into a single substance. Air is a mixture of gases, soil is mixture of elements, most foods are also mixtures.

The mixture can be both homogeneous or heterogeneous. A homogeneous mixture has a uniform appearance throughout and uniform composition as well. Whereas, a heterogeneous mixture neither has uniform composition nor it has uniform appearance.

When making toast in toast oven, the following energy transformation occur

a) electric energy is converted to heat energy which heat up the filaments of toaster, which helps in roasting of toast.

b)the heat energy is transferred to bread or toast

When making toast in a toaster oven, energy transformations occur from electrical energy to thermal energy, and from thermal energy to radiant energy.

When making toast in a toaster oven, two examples of energy transformation that occur are:

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Answer : The pressure of the gas is, 14.925 atm

Solution :

using ideal gas equation,

[tex]PV=nRT[/tex]

where,

n = number of moles of gas  = 0.3 mole

P = pressure of the gas = ?

T = temperature of the gas = [tex]30^oC=273+30=303K[/tex]

R = gas constant = 0.0821 Latm/moleK

V = volume of the gas = 0.5 L

Now put all the given values in the above equation, we get the pressure of the gas.

[tex]P\times (0.5L)=(0.3mole)\times (0.0821L.atm/mole.K)\times (303K)[/tex]

[tex]P=14.925atm[/tex]

Therefore, the pressure of the gas is, 14.925 atm

Atomic mass of an element is the weighted average.

It works because soap is made up of molecules with two very different ends.

Hope this Helps

Soap breaks up the oil (grease) into smaller drops, which can mix with the water. This is why we use soap to clean grease because it break it apart causing it to wash off object clean. Hope this help!!!:)

James Chadwick was assigned the task of tracking down evidence of Rutherford's tightly bound "proton-electron pair" or neutron. In 1930 it was discovered that Beryllium, when bombarded by alpha particles, emitted a very energetic stream of radiation. This stream was originally thought to be gamma radiation.

In most cases, carbon shares electrons with other atoms (usual valence of 4). This is because carbon typically bonds with elements which have a similar electronegativity. Examples of covalent bonds formed by carbon include carbon-carbon, carbon-hydrogen, and carbon-oxygen bonds

answer is covalent bond because carbon has 4 valence electron and shared them hence it is a covalent bond.

Answer : The correct options are, stir the water, crush the salt and heat the water.

Explanation :

As we know that the increase or decrease of the rate depends on many factors which are, temperature, surface area, etc.

Stir the water : By this action the rate increases because when we are stirring the water, the some amount of energy is released that means the temperature of the solution increases. Thus the salt dissolves easily in water by stirring.

Crush the salt : By this action the rate increases because the surface area of solute (salt) increased by the crushing. So, the salt will be dissolved easily in water.

Heat the water : By this action the rate increases because when we are heating the water the temperature of the water increases. As the temperature increases, some empty voids created in the water molecule. Thus, the more salt will be dissolved in water.

But by the use of less water and cool the salt action, the rate decreases.

Hence, the correct options are, stir the water, crush the salt and heat the water.

Answer: The answer is B: Crush The Salt.

Yes. B.p. tend to increase with the number of carbon atoms in the backbone.

Straight-chain alkanes have the general molecular formula C[tex]_n[/tex]H[tex]_{2n+2}[/tex]. Adding carbon atoms to the chain increases the number of electrons in each molecules.

Alkane molecules are not polar without any functional groups. The only possible force between them is London Dispersion Force (a.k.a. induced dipole). Electrons shift within molecules to create instantaneous dipole in this type of force.

Molecules with a large number of electrons experience the most significant shift. London Dispersion Force is strongest in those molecules. They shall have the highest boiling points.

Examples: (SynQuest)

The conclusion in (a) likely holds molecules in the same homologous series.

Molecules in the same homologous series have the same types and numbers of functional groups. However, they differ only in the number of repeating units (-CH₂ in this case) that they contains. The number of such units in each molecule is directly related to the length of its carbon backbone.

Functional groups introduce extra types of forces between the molecules. For instance:

Functional groups tend to have similar effects on the b.p. in the same homologous series. The extra interaction due to the functional groups stays generally the same. Trends in the strength of dispersion forces likely follow the reasoning in (a). There shall be a similar conclusion. Molecules with the longest backbone in the same homologous series would have the highest b.p.

Example: (FooDB)

Note, that it's only the number of repeating units in the carbon backbone that differs. Functional groups shall be on the similar positions on members of the series. For instance, 1,1-dichloroethane Cl₂-CH-CH₃ and 1,1-dichloropropane Cl₂-CH-CH₂-CH₃ are on the same series; whereas 1,3-dichloropropane Cl-CH₂-CH₂-CH₂-Cl is not.

A sodium cation is smaller than a sodium atom.

Hopefully this is right...

The percentage composition by mass of carbon in ethanoic acid is 40%

Answer:

40.00 %  

Step-by-step explanation:

Let's rewrite the formula of ethanoic acid as C₂H₄O₂.

The masses of each element are:

2C = 2 × 12.01  =  24.02   u

4H = 4 × 1.008 =    4.032 u

2O = 2 × 16.00 = 32.00   u

            TOTAL = 60.05   u

=====

% C = 24.02/60.05 × 100

% C = 0.400 × 100

% C = 40.00 %

If a bald eagle flies at 50 km/h, then it would take about 1.2 minutes to fly 1 kilometer. Therefore, the closest answer is B. 1 minute.

If an eagle flies at an average speed of 50 km/h, it means that in 1 hour, the eagle would cover 50 kilometers. To find out how long it would take the eagle to fly 1 kilometer, we have to divide the total time for its average (1 hour, or 60 minutes) by the total distance it can cover (50 kilometers).

So, 60 minutes divided by 50 kilometers equals 1.2 minutes. Thus, it would take the eagle approximately 1.2 minutes to fly 1 kilometer. Therefore, the answer is B. 1 minute (rounded off).

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Answer is: D. Heat is released when atomic nuclei split.

Nuclear fission is a nuclear reaction or a radioactive decay where nucleus of atom split into smaller ligher nuclei.

Nuclear fission is exothermic reaction which release large amounts of energy (electromagnetic radiation or as kinetic energy, which heat reactors where fission reaction take place).

Nuclear energy is the energy found in the nucleus of an atom.

Answer is: D. Heat is released when atomic nuclei split.

Nuclear fission is a nuclear reaction or a radioactive decay where nucleus of atom split into smaller ligher nuclei.

Nuclear fission is exothermic reaction which release large amounts of energy (electromagnetic radiation or as kinetic energy, which heat reactors where fission reaction take place).

Nuclear energy is the energy found in the nucleus of an atom.

Hi,

To solve the question, first of all we will find out the no. of moles of H2SO4 in  19 g of sulfuric acid.

As we know:

              No . of moles = Mass/ Molar mass

              No. of moles= 19 g/98.08 g

               No. of moles= 0.1937

Now we know the no of moles of H2SO4 that will react with 2LiOH. We also know the  molar equivalence of H2SO4 , and 2LiOH that will react.

So, the  water that will be produced will be 2H2O and 1 Li2SO4 when H2SO4 that will react with 2LiOH.

                          0.1937 x 2x 18.01

                                 =6.977

                                  =6.98

Therefore, approximately 6.98 grams of water will be produced from 19 g of sulfuric acid.

Hope it helps!