Mendeleev's periodic table of elements was created in 1901.
O A. True
O B. False

Answers

Answer 1
B. False
It was created in 1869
Answer 2
Answer:B. False

Explanation:APΕX


Related Questions

Identify the following as an example of a physical or chemical. Olive oil, vinegar, salt, and pepper are shaken together together to make salad dressing

Answers

Answer:

Chemical Change

Explanation:

Mixing these elements together creates a chemical change

Making of a salad dressing is a physical change  as there is no change in the chemical composition.

What is a physical change?

Physical changes are defined as changes which affect only the form of a substance but not it's chemical composition. They are used to separate mixtures in to chemical components but cannot be used to separate compounds to simpler compounds.

Physical changes are always reversible using physical means and involve a change in the physical properties.Examples of physical changes include melting,boiling , change in texture, size,color,volume and density.Magnetism, crystallization, formation of alloys are all reversible and hence physical changes.

They involve only rearrangement of atoms and are often characterized to be changes which are reversible.

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In general, atmospheric pressure is greatest near Earth's surface and ____ as you move upward away from sea level.
(decreaes
(doubles
(stays the same
(increaes

Answers

Decreases, when you move upward and increases moving in due to various forces like gravity

what mass of methanol is produced when 280.2 g of carbon monoxide reacts with 50.5 g of hydrogen? CO(g)+2H2(g)—> CH3OH(l)

Answers

Answer:

320.23g of CH3OH.

Explanation:

We'll begin by writing the balanced equation for the reaction. This is given below:

CO(g) + 2H2(g)—> CH3OH(l)

Next, we shall determine the masses of CO and H2 that reacted and the mass of CH3OH produced from the balanced equation. This is illustrated below below:

Molar mass of CO = 12 + 16 = 28g/mol

Mass of CO from the balanced equation = 1 x 28 = 28g

Molar mass of H2 = 2x1 = 2g/mol

Mass of H2 from the balanced equation = 2 x 2= 4g

Molar mass of CH3OH = 12 + (3x1) + 16 + 1 = 32g/mol

Mass of CH3OH from the balanced equation = 1 x 32 = 32g

From the balanced equation above,

28g of CO reacted with 4g of H2 to produce 32g of CH3OH.

Next, we shall determine the the limiting reactant. This is illustrated below:

From the balanced equation above,

28g of CO reacted with 4g of H2.

280.2g of CO will react with =

(280.2 x 4)/28 = 40.03g of H2.

From the calculations made above, we can see that only 40.03g out of 50.5g of H2 is required to react completely with 280.2g of CO.

Therefore, CO is the limiting reactant and H2 is the excess reactant.

Finally, we shall determine the mass of methanol, CH3OH produced from the reaction.

In this case, the limiting reactant will be used because it will give the maximum yield of the reaction since all of it is used up in the reaction. The limiting reactant is CO and the mass of methanol, CH3OH produced can be obtained as follow:

From the balanced equation above,

28g of CO reacted to produce 32g of CH3OH.

Therefore, 280.2g of CO will react to produce = (280.2 x 32)/28 = 320.23g of CH3OH.

Therefore, 320.23g of CH3OH were produced from the reaction.

Consider the word equation.
calcium hydroxide + hydrochloric acid → calcium chloride + water
Which is the corresponding formula equation?
A: CaCl2(1)→ Ca(s) + Cl2(g)

B: O CaO(s)+ H2O(1)>Ca(OH)2(aq)

C: NaOH(aq) + 2HCl(aq) → NaCl(aq) + 2H2O(1)

D: Ca(OH)2(S) + 2HCI(I) → CaCl2(aq) + 2H20(1)

Answers

D:) ca(oh)2(s) + 2hci(I)

The chemical equation for the given word equation is Ca(OH)[tex]_2[/tex](S) + 2HCI(I) → CaCl[tex]_2[/tex](aq) + 2H[tex]_2[/tex]0(1).   Therefore, the correct option is option D.

Chemical equations are symbols or chemical formulas that depict a chemical reaction symbolically. With a plus sign separating the entities in the reactants and products, the reactant objects are listed on the left as well as the result entities are listed on the right.

An arrow indicating the reaction's direction points in the path of the products. The chemical formulas could be mixed, symbolic, or structural. The critical values of a stoichiometric figures are shown as coefficients beside the symbols as well as formulas of the various entities. The chemical equation for the given word equation is Ca(OH)[tex]_2[/tex](S) + 2HCI(I) → CaCl[tex]_2[/tex](aq) + 2H[tex]_2[/tex]0(1).  

Therefore, the correct option is option D.

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the lowest layer of Earths atmosphere is the__

Answers

Answer:

Troposphere

Explanation:

The troposphere is the lowest layer in the atmosphere, and where all the weather occurs. After the troposphere, there's the stratosphere, mesosphere, thermosphere, and exosphere.

I hope this helps!

Answer:

Troposphere is the lowest layer of the earths atmosphere.

Explanation:

What is the concentration of iodine molecules, I 2 in a solution containing 2.54g of iodine in 250 cm 3 of solution?

Answers

Answer:

) Molar concentration =1000*2.54/(127*250) ;since molarity=1000*W/M*V

=0.08 M here W=amount of solute in gm

M= molecular weight of solute

v=volume of solution in ml or cm3

2)% concentration (w/v) =(2.54/250)*100=1.016%

Explanation:

Which answer best describes what is happening in the following redox reaction?
4Fe + 302.
2Fe2O3

Answers

Answer:

Iron is oxidized to form rust.

Explanation:

Consider the reaction; 4Fe + 302------>2Fe2O3, we can see that iron is being oxidized to iron III oxide. Rust is the common name of iron III oxide.

Rusting is an electrochemical process, iron rusts when it comes into contact with air and water because electrochemical cells are set up at the surface of contact.

Iron usually functions as the anode in the electrochemical process. This process leads to the formation of iron III oxide. Rust is soft and breaks off easily thereby exposing the metal below the surface to further rusting.

Answer:

Iron is oxidized to form rust.

Explanation:

edge

The elements least likely to form bonds are found in which group?

Answers

Answer:

Noble gases are a unique set of elements in the periodic table because they don't naturally bond with other elements.

Explanation:

HAVE A GOOD DAY!

Answer:

The answer is Noble Gases!!

Explanation:

Hope i helped yall! Have a super fantastic day!! Play Among Us! (Of course when your done with school) lol, jk, but u can!! Byes yall!

Complete the following ionic equation: [tex]Zn + 2Ag^{+} ---\ \textgreater \ ......... + ..........[/tex]

Answers

Answer: [tex]Zn+2Ag^+\rightarrow Zn^{2+}+2Ag[/tex]

Explanation:

Oxidation-reduction reaction or redox reaction is defined as the reaction in which oxidation and reduction reactions occur simultaneously and the number of electrons lost is equal to the number of electrons gained.

Oxidation reaction is defined as the reaction in which a substance looses its electrons. The oxidation state of the substance increases.

Anode : [tex]Zn\rightarrow Zn^{2+}+2e^-[/tex]

Reduction reaction is defined as the reaction in which a substance gains electrons. The oxidation state of the substance gets reduced.

Cathode : [tex]2Ag^++2e^-\rightarrow 2Ag[/tex]

Thus the complete ionic equation will be :

[tex]Zn+2Ag^+\rightarrow Zn^{2+}+2Ag[/tex]

Which refers to a measure of how acidic or basic a solution is? pH solubility reactiveness hardness

Answers

Answer:

it is Ph of solution that tells you the acdic and basic nature of solution

if PH is lower than 7 the soution is acidic and if PH is larger than 7  the solution is basic

Explanation:

Answer:

A. Ph

Explanation:

Consider the unbalanced chemical equation HBr + B = BBr3 + H2. When
coefficients are added to balance the equation, which two substances will
have a coefficient of 2?
D A. H2
B. HBr
C. BBrg
D D B

Answers

Answer:

B and BBr3

Explanation:

1) 3HBr + B = BBr3 + H2 (double all equation because H2)

2) 6HBr + 2B = 2BBr3 + 3H2

Question 28 (2 points)
Which of the following is part of the Kinetic Molecular Theory?
1) gases consist of tiny particles that are close together
2) gas molecules are in constant random motion
3) Il of the above are part of the Kinetic Molecular Theory
4) the average kinetic motion of gas molecules decreases with an increase in
temperature
Marook nie

Answers

Answer:

Il of the above are part of the Kinetic Molecular Theory

Explanation:

Answer: Which of the following are part of kinetic-molecular theory?

Choices:

1. The particles in a solid do not move.

2. The particles in a liquid are moving past one another constantly.

3. The particles in gas move freely in all directions.

4. The particles in a solid vibrate in a fixed position.

5. The particles in a solid are far apart.

6. The particles in a gas have few attractions between them.

7. The particles in all states of matter are always moving.

Explanation: Which of the following are part of kinetic-molecular theory...

Answers:

2. The particles in a liquid are moving past one another constantly.

3. The particles in gas move freely in all directions.

4. The particles in a solid vibrate in a fixed position.

6. The particles in a gas have few attractions between them.

7. The particles in all states of matter are always moving.

an element p has atomic number 13 while q has the atomic 16..write down electric configuration of p and q​

Answers

Answer:

P = 2,8,3

q = 2,8,6

Explanation:

Because the first shell contain 2 electron and the 2nd contain 8 electron and the last shell contain the electron which is left

Explanation:

p=1s^2,2s^2,2p^6,3s^2,3p^1

q=1s^2,2s^2,2p^6,3s^2,3p^4

the quantum numbers are used in my answer.

there are 4 quantum numbers.

1.principal quantum numbers

2.angular momentum quantum numbers

3.magnetic quantum numbers

4.spin quantum numbers

In this case,the angular momentum quantum numbers is being used.it describes the unique quantum state of an electron and is designated by the letter L.this behaviour manifests itself as the shape of the orbital.electron shells have distinct shapes denoted by letters,s,p,d,f.

l can be numbers like,0,1,2,3

the maximum electrons in each letter is,

s=2

p=6

d=10

f=14

the shapes of the sub_shells

s sub_shell is spherical

p sub_shell is two dumb_bells

d sub_shell is four dumb_bells

f sub_shell is eight dumb_bells

Zinc will displace copper from a solution of copper sulfate, and magnesium will displace zinc from a solution of zinc sulfate. Why can these displacement reactions be regarded as redox reactions? Write down a series of reactivity for these three metals, putting them in order of increasing reactivity.

Answers

Answer:

The displacement reactions are regarded as redox reactions because they involve the formal transfer of electrons from one chemical specie to the other

2) The series of reactivity of the metals in the order of increasing reactivity are;

Copper

           ↓

Zinc

           ↓

Magnesium

Explanation:

1) Redox (oxidation-reduction) reaction is a chemical reaction involving the loss and gain of electrons from one chemical species to another, where the chemical species that undergoes oxidation, loses electrons and is termed the reducing agent, while the other chemical species that undergoes reduction, gains electrons, and is termed the oxidizing agent

2) The redox reaction can being based on the affinity for electrons depends on the positions of the reactants in the electrochemical series as well as the chemical reactivity of the metals with zinc being a stronger reducing agent and more chemically reactive than copper and magnesium being a stronger reducing agent and more chemically reactive than zinc

Least  reactive (Cu)  <     (Zn)        < Mg Most reactive

Copper                     <      Zinc       < Magnesium.

Predict the arrangement of the following substances in decreasing order of pH value Orange juice || Bitter gourd juice || Hydrochloric acid || Mineral water​

Answers

Answer:

Mineral water> Bitter gourd juice> Orange juice> Hydrochloric acid

Explanation:

pH is referred to as the degree of acidity or alkalinity of a substance. The pH scale is arranged from 0-14. Substance with a pH of 0-6.9 are acid, a pH of 7 indicates neutrality while a pH of 8-14 indicates alkalinity.

Mineral water is usually slightly acidic with a pH between 5-6. The pH of bitter gourd juice is between 4.24-4.45. The pH of orange juice ranges between 3.3 to 4.2 lastly, the pH of hydrochloric acid is about 3.01.

The pH values itemized above informed the arrangement of decreasing pH values shown in the answer box.

Mention 6 products from coal tar as a result of destructive distillation of coal

Answers

Answer:

Coke, coal gas, gas carbon, ammonia liquor, and coal oil 

Ethene is a useful substance that can form polymers. It has a melting point of 169°C and a boiling point of 104°C. At which temperature would ethene be a liquid?

Answers

Answer:

-169°C to -104°C

Explanation:

Ethene, also known as ethylene exists in solid, liquid and gaseous states. Ethene is an aliens with condensed structural formula C2H4. Athens is a colourless gas. It is flammable and is also a sweet smelling gas in its pure form. It is the monomer in the production of polyethylene which is of great importance in the plastic industry. In agriculture, it is used to induce the ripening of fruits. It can be hydrated in order to produce ethanol.

The liquid range of ethene refers to the temperatures at which ethene is found in the liquid state of matter. It is actually the difference between the melting point and the boiling points of ethene. Hence the liquid range of ethene is -169°C to -104°C

A chemistry student in lab needs to fill a temperature-control tank with water. The tank measures 24.0 cm long by 21.0 cm wide by 13.0 cm deep.

In addition, as shown in the sketch below, the student needs to allow 2.0 cm between the top of the tank and the top of the water, and a round-bottom flask

with a diameter of 10.5 cm will be just barely submerged in the water.

Calculate the volume of water in liters which the student needs. Round your answer to the nearest 0.1 L. ol.2 cm

M

flask

OL

6

water

Answers

Answer:

The required volume of water the student needs is 4.9 litres of water

Explanation:

From the diagram related to the question, we have;

The dimensions of the tank are;

Length of tank = 24.0 cm = 0.24 m

Width of tank = 21.0 cm = 0.21 m

Depth of tank = 13.0 cm. = 0.13 m

Allowance provided between the top of the tank and the top of the water = 2.0 cm

Diameter of the round bottom flask, D = 10.5 cm = 0.105 m

Therefore, the radius of the round bottom flask, r = 0.105/2 = 0.0525 m

Therefore we have;

Depth of water in the tank = Depth of tank - Allowance provided between the top of the tank and the top of the water

∴ Depth of water in the tank = 13.0 - 2.0 = 11.0 cm = 0.11 m

Given that the flask is immersed in the water contained in the tank to raise the tank water level, we have;

Volume of water + Volume of flask in the tank = Length of tank × Width of tank × Depth of water in the tank

Volume of water + Volume of flask in the tank =  0.24 × 0.21 × 0.11 = 0.005544 m³ = 0.005544 m³× 1000 l/m³ = 5.544 l

The volume of the spherical flask = 4/3·π·r³ = 4/3·π·0.0525³ = 6.06×10⁻⁴ m³ = 6.06×10⁻⁴ m³ × 1000 l/m³ = 0.606 l

The required volume of water the student needs , V = Volume of water + Volume of flask in the tank - The volume of the spherical flask = 5.544 l - 0.606 l = 4.9 l.

Consider the intermediate chemical reactions. 2 equations. First: upper C a (s) plus upper C upper O subscript 2 (g) plus one half upper O subscript 2 (g) right arrow upper C a upper C upper O subscript 3 (s). Delta H 1 equals negative 812.8 kilojoules. Second: 2 upper C a (s) plus upper O subscript 2 (g) right arrow 2 upper C a upper O (s). Delta H 2 equals negative 1, 269 kilojoules. The final overall chemical equation is Upper Ca upper O (s) plus upper C upper O subscript 2 (g) right arrow upper C a upper C upper O subscript 3 (s).. When the enthalpy of this overall chemical equation is calculated, the enthalpy of the second intermediate equation is halved and has its sign changed. is halved. has its sign changed. is unchanged.

Answers

Answer: When the enthalpy of this overall chemical equation is calculated, the enthalpy of the second intermediate equation is halved and has its sign changed.

Explanation:

Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.

According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.

The overall chemical reaction follows:

[tex]CaO(s)+CO_2\rightarrow CaCO_3(s)[/tex]     [tex]\Delta H^o_{rxn}=?[/tex]

The intermediate balanced chemical reaction are:

(1) [tex]Ca(s)+CO_2(g)+\frac{1}{2}O_2(g)\rightarrow CaCO_3(s)[/tex]    [tex]\Delta H_1=-812.8kJ[/tex]  

(2) [tex]2Ca(s)+O_2(g)\rightarrow 2CaO(s)[/tex]     [tex]\Delta H_2=-1269kJ[/tex]

The expression for enthalpy of the reaction follows:

[tex]\Delta H^o_{rxn}=[1\times (\Delta H_1)]+[\frac{1}{2}\times (-\Delta H_2)][/tex]

Hence, when the enthalpy of this overall chemical equation is calculated, the enthalpy of the second intermediate equation is halved and has its sign changed.

Answer:

A. is halved and has its sign changed.

Explanation:

just took the test on edge

Ammonia (NH3) reacts with oxygen to form nitrogen monoxide and water. All the materials involved in this reaction are gasses. 0.100 moles of each of the reactants are initially introduced to a 5.0-liter reaction vessel. a. What would be the quantity of each gas in the container upon completion of the reaction? b.What would be the partial pressure of each gas on the reaction vessel upon reaction completion if the temperature of the system is 105 degrees C? c. What is the total pressure of all the gases on the reaction vessel at 105 degrees C?

Answers

Answer:

a. 0.02 moles  of NH₃, 0 moles of O₂, 0.08 moles of NO, 0.12 moles of H₂O

b. [tex]P_{NH_3}[/tex] = 12,576.5 Pa, [tex]P_{NO}[/tex] = 50,306.05 Pa, [tex]P_{H_2O}[/tex] =  74,459.1 Pa

c. The total pressure is 138,341.64 Pa

Explanation:

a. NH₃ + O₂  → NO + H₂O

The balanced chemical equation is first found to be

4NH₃ + 5O₂  → 4NO + 6H₂O

Therefore, we have;

4 moles of NH₃ reacts with 5 moles of O₂ to form 4 moles of NO and 6 moles H₂O

Dividing by the reactant with the highest number of moles which is 5 moles of oxygen gives;

4/5 moles  of NH₃ reacts with 5/5 moles of O₂ to form 4/5 moles of NO and 6/5 moles H₂O

Which is the same as 4/5 moles  of NH₃ reacts with 1 mole of O₂ to form 4/5 moles of NO and 6/5 moles H₂O

Multiplying by 0.100 gives;

0.1×4/5 moles  of NH₃ reacts with 0.1 mole of O₂ to form 0.1×4/5 moles of NO and 0.1×6/5 moles H₂O

The quantity of each gas in the container upon completion of the reaction is therefore;

(0.1 - 0.1×4/5) = 0.02 moles  of NH₃

0 moles of O₂

0.08 moles of NO

0.12 moles H₂O

b. Given that the temperature = 105°C, we have;

PV = nRT

P = nRT/V

Where:

n = Total number of moles = 0.02 + 0.08 + 0.12 = 0.22 moles

R = Universal gas constant = 8.3145 J/(mol·K)

T = Temperature = 105°C = 378.15 K

V = Volume = 5 litre = 0.005 m³

P = 0.22×8.3145×378.15/0.005 = 138,341.64 Pa

From Dalton's law of partial pressure, we have;

Partial pressure Pₓ = Xₓ × P

Where:

Xₓ = Mole fraction

Which gives for ammonia NH₃ with 0.02 moles;

Mole fraction = 0.02/0.22 = 1/11

[tex]P_{NH_3}[/tex] = 1/11 × 138,341.64  = 12,576.5 Pa

For the 0.08 moles of NO, we have

Mole fraction = 0.08/0.22 = 4/11

[tex]P_{NO}[/tex] = 4/11 × 138,341.64  = 50,306.05 Pa

For the 0.12 moles H₂O

P = 0.12×8.3145×378.15/0.005 = 74,459.1 Pa

Mole fraction = 0.12/0.22 = 6/11

[tex]P_{H_2O}[/tex] = 6/11 × 138,341.64  = 74,459.1 Pa

c. The total pressure = 12,576.5 Pa + 50,306.05 Pa + 74,459.1 Pa = 138,341.64 Pa.

Wildflowers bloom earlier than large trees. This helps wildflowers compete for _____. water, light, food, or air

Answers

Answer: Light

Explanation:

The environment abiotic factors like sunlight, water, air, and soil are important for the growth of the plants. A wildflowers is a plant that grows in wild. It was not intentionally seeded or planted.

The light is one of the important environmental factor. As the wildflowers are blooming earlier than the large trees. Thus the wildflowers are receiving the light earlier than large trees.

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