How were the elements in the first periodic table arranged? O A. In order of atomic number B. Alphabetically by element name C. In order of date of discovery O D. In order of atomic mass​

Answers

Answer 1

Answer:

in order of their atomic mass

Answer 2

The first periodic table created by Mendeleev was based on the atomic masses of elements. Later Mosely modified it based on the atomic number.

What is periodic table ?

Periodic table is the classification of all the known  elements based on their atomic number. There are 118 elements in periodic table now. They are classified into different groups and periods.

Mendeleev was first to create periodic table for the easy classification of elements. He classified elements based on their atomic masses. At that time there were only 60-65 elements discovered.

Later Mosley modified it to modern periodic table based on the increasing order of atomic number of elements. Therefore, the first arrangement was based on atomic masses.

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Related Questions

Please can someone answer quickly this do tomorrow morning

Which of the five signs should not be used by themselves?

Precipitate
Temperature change
Color change
Odor
Bubbles

Answers

Answer

Temperature change

Pls corret my answer if its wrong ●~●#CarryOnLearning

The mass of a neutron is

Answers

A milimter is the answebti this

What is the balance equation for

_ Ba + _ HNO3 —> _ H2 + _ Ba(NP3)2


_ H3PO4 + _ NaOH —> _ H2O + _ Na3PO4

Answers

1st one

2_2_2

2nd one

3_1_1_3

i looked it up

What is good conductor of electricity???​

Answers

Answer:

Metals , silver and copper which allows to pass the electricity through it is called good conductor of electricity .

hope it is helpful to you ☺️

Hi, in some texts number of water molecules released during polymerization is 2n but in others 2n-1 , why?

Answers

Answer:

Explanation:

Because you only have one repeat unit, n=1. 2n-1 becomes 2(1)-1 which is equal to one, meaning one molecule of H2O is produced, as is shown by the top condensation polymerisation reaction.

If you had two repeat units, n=2 so 2n-1=3. Three H2O molecules are produced because you would need two molecules of each reactant so three condesation reactions would occur and three molecules of H2O would be released.

If 250 grams of water is to be heated from 24.0°C to 100.0°C to make a cup of tea, how much
heat must be added? The specific heat of water is 4.18 J/g∙C

Answers

Answer:

[tex]\boxed {\boxed {\sf 79,420 \ J}}[/tex]

Explanation:

We are given the mass, a change in temperature, and the specific heat of water. We should use the following formula to solve this problem.

[tex]q=mc\Delta T[/tex]

In this formula, m is the mass, c is the specific heat, and ΔT is the change in temperature.

We know there are 250 grams of water and the specific heat of water is 4.18 J/g · °C.

We are given two temperature, so have to find the change in temperature. This is the difference between the initial temperature and final temperature. The water is heated from 24 °C to 100 °C. Therefore, the initial is 24 and the final is 100.

[tex]\bullet \ \Delta T= T_{final} - T_{initial} \\\bullet \ \Delta T=100 \textdegree C - 24 \textdegree C\\\bullet \Delta T= 76 \textdegree C[/tex]

Now we know all three of the variables and we can substitute them into the formula.

[tex]\bullet \ m= 250 \ g\\ \bullet \ c=4.18 \ J/g \textdegree C \\ \bullet \ \Delta T= 76 \textdegree C[/tex]

[tex]q= (250 \ g)( 4.18 \ J/g * \textdegree C)( 76 \textdegree C)[/tex]

Multiply the first two numbers together. The units of grams will cancel.

[tex]q= (1045 \ J/\textdegree C)(76 \textdegree C)[/tex]

Multiply again. This time, the units of degrees Celsius cancel.

[tex]q= 79420 \ J[/tex]

79, 420 Joules of heat must be added.

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…..

Answers

Answer:

Inference

Explanation:

I mean, it's not difficult.

A theory is an unproven explanation.

An inference is a guess/educated guess where you don't have all the facts.

For example, if "Bob" is caught in the kitchen with a ketchup stain on his shirt, you are inferencing that he used the ketchup.

However, if you see a ketchup bottle nearby or saw it earlier, then it is not, because you already have the facts that ketchup was used.

Inference

You made an educated guess based on the events that happened after the fact.

Hope this helps!


How are carbon-based molecules suited for sustaining life?

Answers

[tex]\huge\fcolorbox{red}{pink}{Answer ♥}[/tex]

Life on Earth is based on carbon, likely because each carbon atom can form bonds with up to four other atoms simultaneously. This quality makes carbon well-suited to form the long chains of molecules that serve as the basis for life as we know it, such as proteins and DNA.

Hope it helps uh ✌️✌️✌️

HELP HELP HELP PLSSS

Answers

Answer:

the answer is c kept in blue and with light

plant growth is chemical change or physical change




Answers

Answer:

its a chemical change.

hope it helps.

stay safe healthy and happy...

Answer: it is a chemical change because it involves chemical process

Explanation:

The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction _____.

Answers

Is the reductant and is being oxidised

How many moles of atoms does H2O

Answers

3 atoms, so there are approximately 1.8 x 1024 atoms in a mole of water.

What is the name of the process manufacturers use to make unsaturated fatty acids more solid at room temperature and prevent oxidation.

Answers

Answer:

Hydrogenation

Explanation:

Look up the definition to confirm

40 POINTS! WILL MARK BRAINLIEST!! Determine the mass in grams of 4.83 × 10²¹ atoms of arsenic. (The mass of one mole of arsenic is 74.92 g.)

Answers

Answer:

[tex]\boxed {\boxed {\sf 0.601 \ g \ As}}[/tex]

Explanation:

We want to convert atoms of arsenic to mass in grams. We have to complete 3 steps.

1. Convert Atoms to Moles

The first step is converting atoms to moles. We use Avogadro's Number for this. This number is 6.022*10²³ and it is the number of representative units (molecules, atoms, etc.) in 1 mole of a substance. In this problem, the particles are atoms of arsenic. So, 1 mole of arsenic contains  6.022*10²³ atoms of arsenic. Use this information to make a ratio.

[tex]\frac{1 \ mol \ As}{{6.022*10^{23} \ atoms \ As} }[/tex]

Multiply by the number of atoms provided in the problem: 4.83 × 10²¹

[tex]4.83 *10^{21} \ atoms \ As *\frac{1 \ mol \ As}{{6.022*10^{23} \ atoms \ As} }[/tex]

The units of atoms of arsenic (atoms As) cancel.

[tex]4.83 *10^{21} *\frac{1 \ mol \ As}{{6.022*10^{23}} }[/tex]

Condense into 1 fraction.

[tex]\frac{4.83 *10^{21} }{{6.022*10^{23}} } \ mol \ As[/tex]

[tex]0.008020591166 \ mol \ As[/tex]

2. Convert Moles to Grams

The next step is converting moles to grams. We use the molar mass for this, which is provided. There are 74.92 grams of arsenic in 1 mole of arsenic, so we can make another ratio.

[tex]\frac {74.92 \ g\ As}{ 1 \ mol \ As}[/tex]

Multiply by the number of moles we calculated.

[tex]0.008020591166 \ mol \ As*\frac {74.92 \ g\ As}{ 1 \ mol \ As}[/tex]

The units of moles of arsenic (mol As) cancel.

[tex]0.008020591166 *\frac {74.92 \ g\ As}{ 1}[/tex]

[tex]0.6009026901 \ g \ As[/tex]

3. Round

The original measurement of atoms (4.83 × 10²¹ ) has 3 significant figures, so our answer must have the same.

For the number we calculated, that is the thousandth place. The 9 in the ten-thousandth place (0.6009026901) tells us to round the 0 to a 1.

[tex]0.601 \ g \ As[/tex]

There are approximately 0.601 grams of arsenic.

Someone plz help me here are the photos, I need the last one

Answers

Answer:

(6 mol)·(-393.5 kJ/mol) + (6 mol)·(-285.83 kJ/mol) - (1 mol)·(-1,273.02 kJ/mol) + (6 mol)·(0 kJ/mol)

Explanation:

Question; From the given options, the chemical reaction in the question is presented as follows;

C₆H₁₂O₆(s) + 6O₂(g) → 6CO₂(g) + 6H₂O(l), given that we have;

[tex]\Delta \text H _f^{\circ}[/tex] for C₆H₁₂O₆ = -1,273.02 kJ/mol

[tex]\Delta \text H _f^{\circ}[/tex] for O₂(g) = 0 kJ/mol

[tex]\Delta \text H _f^{\circ}[/tex] for CO₂(g) = -393.5 kJ/mol

[tex]\Delta \text H _f^{\circ}[/tex] for H₂O(l) = -285.83 kJ/mol

The heat or enthalpy of a reaction,  is given as follows;

[tex]\Delta\text H_{rxn}^{\circ} = \sum \text n \cdot \Delta \text H _f^{\circ}(\text {products}) - \sum \text m \cdot \Delta \text H _f^{\circ}(\text {reactants} \text)[/tex]

Therefore, the equation which should be used to calculate [tex]\Delta\text H_{rxn}^{\circ}[/tex], is given as follows;

[tex]\sum \text n \cdot \Delta \text H _f^{\circ}(\text {products})[/tex] = (6 mol)·(-393.5 kJ/mol) + (6 mol)·(-285.83 kJ/mol)

[tex]\sum \text m \cdot \Delta \text H _f^{\circ}(\text {reactants} \text)[/tex] = (1 mol)·(-1,273.02 kJ/mol) + (6 mol)·(0 kJ/mol)

Therefore;

[tex]\Delta\text H_{rxn}^{\circ}[/tex] = (6 mol)·(-393.5 kJ/mol) + (6 mol)·(-285.83 kJ/mol) - (1 mol)·(-1,273.02 kJ/mol) + (6 mol)·(0 kJ/mol)

Why is the average atomic mass used when calculating grams of a
substance?
A. The exact weights of the isotopes are not known.
B. The elements in the substance are mixtures of their isotopes.
ОО
C. The average atomic mass is known to more significant figures.
D. The number of isotopes in the sample is constantly changing.

Answers

Answer:

The average atomic mass includes all of the isotopes of that atom which exist in nature. Almost all elements have at least two isotopes which naturally occur. Recall that isotopes are atoms with the same atomic number (protons), but a different number of neutrons.

What is the difference between an orbit in the Bohr model of the hydrogen atom and an orbital in the quantum mechanical model

Answers

Answer:

See explanation

Explanation:

In Bohr's theory, electrons are found in specific regions in space called orbits. These orbits are also called energy levels. An electron may move from one energy level to another by absorbing or emitting energy.

In the wave mechanical model, electrons are not found in a particular region in space according to Heisenberg's uncertainty principle.

We rather define a certain region in space where there is a high probability of locating the electron. This region in space where there is a high probability of locating the electron is called an orbital.

Hence, in the Bohr's model of the atom,electrons can surely be found in orbits while in the wave mechanical model, the orbital is a probability function that describes a region in space where an electron may be found.

what is the application of chemistry​

Answers

Answer:

Chemistry plays an important and useful role towards the development and growth of a number of industries. This includes industries like glass, cement, paper, textile, leather, dye etc. We also see huge applications of chemistry in industries like paints, pigments, petroleum, sugar, plastics, Pharmaceuticals.

alculating Displacement under Constant Acceleration
Use the information from the graph to answer the
question
What is the total displacement of the object?
m
Velocity vs. Time
40
30
Velocity (m/s)
20
10
0
0
5
10
15
20
25
Time (s)
Intro
Done
ODO
ODDO
tivity

Answers

Answer:

[tex]10 {7}^{2} = [/tex]

How could the experiment be changed to allow for a result to be shown for the insoluble food
colouring?

Answers

Answer:

no lo se yo hablo en español no en ingles

A 4.369 g sample of metal is placed in a flask. Water is added to the flask and the total volume in the flask is read to be 126.4 ml. The mass of the water, flask, and metal is 268.5 g. If the mass of the flask is 139.3 g and the density of water is 1.000 g/mL, the density of the solid is ________ g/cm3.

Answers

Answer:

Density of the solid=[tex]2.78 g/cm^3[/tex]

Explanation:

We are given that

Mass of sample of metal=4.369 g

Volume in the flask, V=126.4 ml

Mass of water, flask, and metal=268.5 g

Mass of flask=139.3 g

Density of water=1.000 g/mL

We have to find the density of the solid.

Mass of water=268.5-4.369-139.3=124.831 g

Volume of water=[tex]\frac{Mass\;of\;water}{density\;of\;water}[/tex]

Volume of water=[tex]\frac{124.831}{1}=124.831 mL[/tex]

Volume of solid=126.4 ml-124.831 mL

=1.569mL

Now,

Density of the solid=[tex]\frac{mass\;of\;solid}{volume\;of\;solid}[/tex]

=[tex]\frac{4.369}{1.569}[/tex]

[tex]=2.78g/mL[/tex]

1mL=1 cubic cm

Therefore,

Density of the solid=[tex]2.78 g/cm^3[/tex]

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Answers

Answer: Solve problems

Explain specifically how an electron gives off light in an atom.

Answers

Answer:

Then, at some point, these higher energy electrons give up their "extra" energy in the form of a photon of light, and fall back down to their original energy level.

Explanation:

When properly stimulated, electrons in these materials move from a lower level of energy up to a higher level of energy and occupy a different orbital.

What mss of sulfamic acid is required to make 250cm3 of a 0.150mol/dm3 solution? please help

Answers

Answer:

sorry i dint understand can u ask it in a simpler way

Explanation:

alguien que me pase una pagina para mirar nopor

Answers

Answer:

no pues nadie te pasa la pagina

1. How do metals and non-metals react with acids? Write and explain the chemical equation for the reaction of magnesium with sulphuric acid and aluminium with hydrochloric acid.​

Answers

Answer:

1. How do metals and non-metals react with acids?

Ans : Non metals does not react with acids while metals react with acids and produce hydrogen gas that burns with a 'pop'sound.

2. Write and explain the chemical equation for the reaction of magnesium with sulphuric acid and aluminium with hydrochloric acid.

Magnesium + sulphuric acid = Hydrogen + salt

Mg(s) + H2SO4 (aq) MgSO 4(aq) +H2 (g)

Aluminium + Hydrochloric acid = Hydrogen + Aluminium chloride

2Al(s)+6HCl(aq)→2AlCl3(aq)+3H2(g)

Answer:

Metals react with acid but non metals donot react with acid because

when a substance, reacts with acids it provides electrons to the H+ ions produced by the acids. Non-metals are acceptors of electrons and hence, they cannot donate electrons.

Explanation: H2SO4 + Mg(OH)2 = H2O + MgSO4. 2Al+6HCl→2AlCl3+3H2 2 A l + 6 H C l → 2 A l C l 3 + 3 H 2

Which has more mass, 2 kg of steel or 5 kg of feather.

Answers

Answer:

5 kg of feather

Explanation:

Among the given solutions of potassium permanganate (KMnO4), which one has the highest concentration of water in it?

Answers

Answer: Solution D has the highest concentration of all.

Explanation:

The formula used to calculate molarity:

[tex]\text{Molarity of solution}=\frac{\text{Moles of solute}\times 1000}{\text{Volume of solution (mL)}}[/tex]  .....(1)

For A:

Molarity of permanganate solution = 0.1 M

Volume of solution = [tex]100 cm^3=100mL[/tex]        (Conversion factor: [tex]1mL=1cm^3[/tex])

Putting values in equation 1, we get:

[tex]0.1=\frac{\text{Moles of permanganate solution}\times 1000}{100}\\\\\text{Moles of permanganate solution}=\frac{100\times 0.1}{1000}=0.01mol[/tex]

For B:

Molarity of permanganate solution = 0.01 M

Volume of solution = [tex]100 cm^3=100mL[/tex]

Putting values in equation 1, we get:

[tex]0.01=\frac{\text{Moles of permanganate solution}\times 1000}{100}\\\\\text{Moles of permanganate solution}=\frac{100\times 0.01}{1000}=0.001mol[/tex]

For C:

Molarity of permanganate solution = 2 M

Volume of solution = [tex]100 cm^3=100mL[/tex]

Putting values in equation 1, we get:

[tex]2=\frac{\text{Moles of permanganate solution}\times 1000}{100}\\\\\text{Moles of permanganate solution}=\frac{100\times 2}{1000}=0.2mol[/tex]

For D:

Molarity of permanganate solution = 2.5 M

Volume of solution = [tex]100 cm^3=100mL[/tex]

Putting values in equation 1, we get:

[tex]2.5=\frac{\text{Moles of permanganate solution}\times 1000}{100}\\\\\text{Moles of permanganate solution}=\frac{100\times 2.5}{1000}=0.25mol[/tex]

The solution having the highest number of moles will have the highest concentration for the same volume.

Thus, solution D has the highest concentration of all.

Aluminum hydroxide, with heat, creates__
Which of the following
Combination,decomposition,
Single replacement,
Double replacement,
Combustion

Answers

Answer: Decomposition is the answer

Explanation: why because aluminium hydroxide would decomposes in the presence of heat and would form an oxide which is aluminium oxide and would also form water as a product.

HOPE THIS HELPS!!

The normal boiling point of ethanol is 78.4 oC. Its enthalpy of vaporization is 38.6 kJ/mol. Estimate the vapor pressure of ethanol at 26.3 oC.

Answers

Answer: The vapor pressure of ethanol at [tex]26.3^{o}C[/tex] is 238.3 torr.

Explanation:

Given: [tex]\Delta H_{vap}[/tex] = 38.6 kJ/mol

[tex]T_{1} = 26.3^{o}C = (26.3 + 273) K = 299.3 K[/tex]

[tex]T_{2} = 78.4^{o}C = (78.4 + 273) K = 351.4 K[/tex]

Formula used to calculate the vapor pressure of ethanol is as follows.

[tex]ln\frac{P_{2}}{P_{1}} = \frac{\Delta H_{vap}}{R} [\frac{1}{T_{1}} - \frac{1}{T_{2}}]\\[/tex]

Substitute the values into above formula as follows.

[tex]ln\frac{P_{2}}{P_{1}} = \frac{\Delta H_{vap}}{R} [\frac{1}{T_{1}} - \frac{1}{T_{2}}]\\ \\ln \frac{760 torr}{P_{1}} = \frac{38600 J}{8.314 J/mol K}[\frac{1}{299.3} - \frac{1}{351.4}]\\\frac{760}{P_{1}} = 3.18\\P_{1} = 238.3 torr[/tex]

Thus, we can conclude that the vapor pressure of ethanol at [tex]26.3^{o}C[/tex] is 238.3 torr.

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