The element that doesn't occur in elemental state in nature is​

Answers

Answer 1

Answer:

technetium, atomic number 43; promethium, number 61; astatine, number 85; francium, number 87; neptunium, number 93; and plutonium, number 94.

Explanation:


Related Questions

An ion has a charge of +3 and has 51 electrons. How many protons does it have?

Answers

Answer:

54 protons

Explanation:

51 electrons 'balance' the charge of 51 protons....but there is three more PLUS charges ......means three more protons

51 + 3 = 54

According to the kinetic molecular theory, the molecules of an ideal gas is

Answers

Answer:

exert no attractive forces on each other, or on the walls of the container

Explanation:

I need help with this one.

Answers

Magnesium and Calcium Oxide

Trick : Reactants are always on left

Answer:

magnesium and calcium oxide

What is an ionic solid?
A. A crystalline solid held together by a shared electron pool
B. A crystalline solid held together by dipole-dipole forces
C. A crystalline olid held together by covalent bonds
D. A crystalline solid held together by charge attractions

Answers

Answer:

D

Explanation:

An ionic solid is a crystalline solid held together by charge attractionsAn example is a salt crystal (Na⁺ + Cl⁻ → NaCl)

An ionic solid is a crystalline solid held together by charge attractions or an ionic bond.

What is an ionic bond?

Ionic bond or electrovalent bond is a type of bond which is formed between two elements when there is an exchange of electrons which takes place between  the atoms resulting in the formation of ions.

When the atom looses an electron it develops a positive charge and forms an ion called the cation while the other atom gains the electron and develops a negative charge  and forms an ion called the anion.

As the two atoms are oppositely charged they attract each other which results in the formation of a bond called the ionic bond.They are good conductors of heat and electricity. They have high melting points. These compounds are brittle.

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Carbon 14 decays to Carbon 12 and has a half-life of 5730 years. If a fossil is analysed and it has 5 grams of Carbon 14 and 15 grams of Carbon 12, how old is the fossil?

Answers

Answer:

im sorry but this question doesnt make sense

Explanation:

calculate the oxidation state of the underlined elements of K2 Cr2 O7
----- ​

Answers

Answer:

+4

Explanation:

In PbO2, oxygen exhibits an oxidation number of -2 (since it's not a peroxide or superoxide):

Let the oxidation number of Pb be x. Then, for the compound to be neutral, the oxidation numbers of all atoms should add up to zero.

⇒ x + (−2) + (−2) = 0

x = +4

So the oxidation no. of Pb is +4.

I hope this helps.

Can someone please help me? :(

Answers

Answer:

A. Each type of cell carries out a specific function for the organism.

Explanation:

[tex]hope[/tex] [tex]this[/tex] [tex]helps![/tex] [tex]:)[/tex]

NEED HELP ASAP!!! WILL MARK BRAINLIEST!!! A scuba tank can hold 18 L of air 6 atm of pressure. If the gas were to be released all underwater at 4 atm, it would take up how much volume assuming that the temperature remained constant?

Answers

[tex]\qquad\qquad\huge\underline{{\sf Answer}}♨[/tex]

If temperature remains constant, then we can apply the formula :

[tex]\qquad \tt \dashrightarrow \:p_1v_1 = p_2v_2[/tex]

[tex]\qquad \tt \dashrightarrow \:4 \times v_1 = 6 \times 18[/tex]

[tex]\qquad \tt \dashrightarrow \: v_1 = 108 \div 4[/tex]

[tex]\qquad \tt \dashrightarrow \:v_1 = 27[/tex]

So, the required volume is 27 litres

Consider the following reaction: 2 Bi(s) + 3 Cl2(g) → 2 BiCl3(s)
How many grams of chlorine gas are required to produce 3.32 grams of bismuth chloride is
produced? Use correct significant digits and units, for example 1.234 g.

Answers

Taking into account the reaction stoichiometry, 1.119 grams of chlorine gas are required to produce 3.32 grams of bismuth chloride is produced.

Reaction stoichiometry

In first place, the balanced reaction is:

2 Bi + 3 Cl₂ → 2 BiCl₃

By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:

Bi: 2 molesCl₂: 3 moles BiCl₃: 2 moles

The molar mass of the compounds is:

Bi: 209 g/moleCl₂: 70.90 g/moleBiCl₃: 315.45 g/mole

Then, by reaction stoichiometry, the following mass quantities of each compound participate in the reaction:

Bi: 2 moles ×209 g/mole=418  g

Cl₂: 3 moles ×70.90 g/mole= 212.7 g

BiCl₃: 2 moles ×315.45 g/mole= 630.9 g

Mass of Cl₂ required

The following rule of three can be applied: If by reaction stoichiometry 630.9 grams of BiCl₃ are formed by 212.7 grams of Cl₂, 3.32 grams of BiCl₃ are formed by how much mass of Cl₂?

[tex]mass of Cl_{2} =\frac{3.32 grams of BiCl_{3}x212.7 grams of Cl_{2} }{630.9 grams of BiCl_{3}}[/tex]

mass of Cl₂= 1.119 grams

Finally, 1.119 grams of chlorine gas are required to produce 3.32 grams of bismuth chloride is produced.

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What is the pressure in atm of a 5. 00 l tank with 2. 50 moles of oxygen


at 39. 3 °c?


1


4


7

Answers

Answer:

1

Explanation:

The volume of a gas at 5.0 atm is 3.5 L. What is the volume of the gas at 7.0 atm at the same temperature?
025L
O5.0 L
O10. L
O 12L

Answers

Answer:

10 L

Explanation:

Boyle's Law

states that the pressure exerted by a gas (of a given mass, kept at a constant temperature) is inversely proportional to the volume occupied by itP ∝ [tex]\frac{1}{V}[/tex]P₁V₁ = P₂V₂

Our values

P₁ = 5 atmV₁ = 3.5 LP₂ = 7 atm

Using the equation

5 x 3.5 = 7 x V₂V₂ = [tex]\frac{35}{3.5}[/tex]V₂ = 10 L

Answer:

0.25L

Explanation:

Please help

AB+C<— A+CB
—>

Question 1: Imagine that the reaction starts with 100 molecules of reactants and zero molecules of products. Explain why the amount of reactants will never reach zero.

Question 2: imagine that the reaction starts with 0 molecules of reactants and 100 molecules of products. Will the amount of products increase or decrease as the reaction proceeds? Explain.

Answers

The rate of forward reaction equal to the rate of reverse reaction hence  the amount of reactants will never reach zero.

Chemical reaction

A chemical reaction involves the combnation of two or more species to yiled products. We must know that a point is always reached in a reaction when the rate of forward reaction equal to the rate of reverse reaction hence  the amount of reactants will never reach zero.

Also, if the reaction starts with 0 molecules of reactants and 100 molecules of products, the amount of products will decrease overtime.

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How many joules are required to eat 5.25 g of titanium from 85.5 celsius to 132.5 celsius

Answers

The amount of energy required to eat 5.25 g of Titanium from 85.5 celsius to 132.5 celsius is 129 joules.

How do we calculate required heat?

Absorbed or released amount of heat will be calculated by using the below formula as:

Q = mcΔT, where

m = mass of titanium = 5.25g

c = specific heat of titanium = 0.523 J/gram degree celsius

ΔT = change in temperature = 132.5 - 85.5 = 47 degree celsius

On putting these values on the above equation we get,

Q = (5.25)(0.523)(47) = 129 joules

Hence required heat is 129 joules.

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Vascular plants have an internal transport system to move water and nutrients throughout the plant. Which of these is used to transport water from the roots to the leaves?

Answers

ANSWER : The two primary vascular tissues are xylem, which transports water and dissolved minerals from the roots to the leaves, and phloem, which conducts food from the leaves to all parts of the plant.

what is the result of cell division that includes mitosis?
A. new cells with different chromosomes
B. four cells with new chromosomes
C. two identical new cells
D. one genetically different cell

Answers

Answer:

I think C is the answer

Explanation:

because Mitosis results in two identical daughter cells......

How many moles of sulfur are in 53.7 grams of sulfur?

Answers

NO.OF.MOLES= MASS/ATOMIC MASS
THE ATOMICITY OF SULPHUR IS 8 AND ITS MASS NUMBER IS 32.
SO, THE ATOMIC MASS IS 256
NO.OF.MOLES= 53.7/256
= 537/2560
= 0.2097

Answer:

1.67 moles (find this by dividing 53.7 by the gram formula mass of sulfur, which is about 32.1)

Why is it possible to compress a gas

Answers

Answer:

Gas can be compress easily than liquid or solid because, molecules are more spread in gas than solin or liquid.

Brainliest if this helps you. please

Explain how DNA can provide some evidence for evolution.

Answers

The shared ancestry of life is reflected in DNA and genetic code. DNA comparisons can reveal how closely two species are related. Biogeography. Evolution and geological change are reflected in the global distribution of life and the particular characteristics of island species.

please answer thank tou

Answers

Answer:

ion

Explanation:

more protons than electrons

Draw a structural formula for the more stable carbocation intermediate formed in the reaction shown.

Answers

A carbocation is a carbon atom that bears a positive charge. The most stable carbocation here must be a secondary carbocation .

What is a carbocation?

A carbocation is a carbon atom that bears a positive charge. These species pften pccur as intermediates in a chemical reaction and can be detercted spectroscopically.

The most stable carbocation here must be a secondary carbocation hence, the structural formula for the more stable carbocation intermediate formed in the reaction is shown in the image attached.

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What is the molar mass of a 3.228 g sample of a gas if it occupies 3.21 L at 298 K and 1.25 atm?

Answers

Taking into account the ideal gas law and the definition of molar mass, the molar mass of a 3.228 g sample of a gas if it occupies 3.21 L at 298 K and 1.25 atm is 19.66 [tex]\frac{g}{moles}[/tex].

What is ideal gas law

An ideal gas is a theoretical gas that is considered to be composed of randomly moving point particles that do not interact with each other. Gases in general are ideal when they are at high temperatures and low pressures.

The pressure, P, the temperature, T, and the volume, V, of an ideal gas, are related by a simple formula called the ideal gas law:

P×V = n×R×T

where P is the gas pressure, V is the volume that occupies, T is its temperature, R is the ideal gas constant, and n is the number of moles of the gas. The universal constant of ideal gases R has the same value for all gaseous substances.

Definition of molar mass

The molar mass of substance is a property defined as its mass per unit quantity of substance, in other words, molar mass is the amount of mass that a substance contains in one mole.

Number of moles in this case

In this case, you know:

P= 1.25 atmV= 3.21 Ln= ?R= 0.082 [tex]\frac{atmL}{mol K}[/tex]T= 298 K

Replacing in the ideal gas law:

1.25 atm× 3.21 L = n× 0.082 [tex]\frac{atmL}{mol K}[/tex]× 298 K

Solving:

n= (1.25 atm× 3.21 L)÷ (0.082 [tex]\frac{atmL}{mol K}[/tex]× 298 K)

n= 0.1642 moles

So, the number of moles in this case are 0.1642 moles.

Molar mass of the sample

In this case, you know:

mass= 3.228 gnumber of moles= 0.1642 moles

Then, considering the definition of molar mass, it is calculated as:

[tex]molar mass=\frac{3.228 g}{0.1642 moles}[/tex]

Solving:

molar mass= 19.66[tex]\frac{g}{moles}[/tex]

Finally, the molar mass of a 3.228 g sample of a gas if it occupies 3.21 L at 298 K and 1.25 atm is 19.66 [tex]\frac{g}{moles}[/tex].

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name the follwing compound, KBr​

Answers

Answer:

Potassium bromide

Explanation:

According to the first law of thermodynamics, what quantity is conserved?.

Answers

Answer:

energy

Explanation:

The First Law of Thermodynamics (Conservation) states that energy is conserved, it cannot be created nor destroyed.

During the degradation of many amino acids, the first step involves transfer of the amino group to which citric acid cycle intermediate?.

Answers

Ketoglutarate
if you looking for more answers involving this assignment you can search up on quizlet biochem practice questions unit 2

How many nitrate ions are in 2 mol of iron (II) nitrate

Answers

Answer:

Two

Explanation:

Nitrate has a charge of negative 1 and the Iron (II) tells us the iron in that formula has a charge of +2, so in order for the iron to have to equal positive two, there has to be two negative. Since on nitrate ion is -1, you need two to make -2.

PLEASE HELP!!!! WILL MARK BRAINLIEST!!!! A rigid steel container with a volume of 30 L is filled with oxygen to a pressure of 9.00 atm at 28.0 °C. What is the pressure in the container if the temperature is raised to 129.0 °C?

Answers

Answer:

12 atm

Explanation:

First, let us convert Celcius into Kelvin: 28.0 °C = 301.15 K and 129.0 °C = 402.15 K

For this question we must employ the Combined Gas Law: [tex]\frac{P_1V_1}{P_2V_2}=\frac{n_1RT_1}{n_2RT_2}[/tex], where [tex]P_1[/tex] is the initial pressure and [tex]P_2[/tex] is the new pressure.

We know that intitially, P=9 atm, V=30 L, and T=301.15K. From our problem, only temperature and pressure changes, while the number of moles, volume and the gas constant, R, stay the same, so they are irrelevant.

Thus, the filled out Combined Gas Law would be:

[tex]\frac{9 atm}{P_2}[/tex]=[tex]\frac{301.15K}{402.15K}[/tex], where the volume, moles of gas, and R are cancelled out.

We can manipulate this equation to derive the new pressure. We find that

9atm≈0.74885[tex]P_2[/tex].  

This means that

[tex]P_2[/tex]≈9/0.74885≈12 atm

How many hybrid orbitals form when three atomic orbitals of a central atom mix?.

Answers

Answer:

three _ _E _ _ _

Explanation:

What are the 10 most important chemical reactions?
Choose ALL correct answers
A.) Combustion of methane (hydrocarbons)
B.) Photosynthesis.
C.) Synthesis of sulfuric acid.
D.) Equilibrium of carbonic acid and carbon dioxide gas.
E.) Biological formation of calcium carbonate.
F.) Rusting of iron.
G.) Production of hydrogen from the action of acid on metal.
H.) Oxidation of alcohol.
I.) Decomposition.
J.) Redox.

Answers

Answer:

Combustion of methane (hydrocarbons)

Photosynthesis.

Synthesis of sulfuric acid.

Equilibrium of carbonic acid and carbon dioxide gas.

Biological formation of calcium carbonate.

Rusting of iron.

Production of hydrogen from the action of acid on metal.

Oxidation of alcohol.

Explanation:

how this helps if do mark brainllest pls!!! :)

In the chemical formula h2o, which description explains what the 2 represents?.

Answers

H_2O is the chemical formula of compound water.

Here

2 denotes to no of hydrogen atoms as it's after H

In water

There are

2Hydrogen atoms1 Oxygen atoms A lone pair is present over Oxygen atom

Calculate the molarity of a solution prepared by diluting 7.0 mL of 4.0 M solution to a volume of 30 mL.

Answers

Considering the definition of dilution, the molarity of a solution prepared by diluting 7.0 mL of 4.0 M solution to a volume of 30 mL is 0.93 mL.

What is diluion

First of all, you have to know that when it is desired to prepare a less concentrated solution from a more concentrated one, it is called dilution.

Dilution is the process of reducing the concentration of solute in solution, which is accomplished by simply adding more solvent to the solution at the same amount of solute.

In a dilution the amount of solute does not change, but as more solvent is added, the concentration of the solute decreases, as the volume (and weight) of the solution increases.

A dilution is mathematically expressed as:

Ci×Vi = Cf×Vf

where

Ci: initial concentrationVi: initial volumeCf: final concentrationVf: final volume

Molarity of the solution in this case

In this case, you know:

Ci= 4 M Vi= 7 mLCf= ?Vf= 30 mL

Replacing in the definition of dilution:

4 M× 7 mL= Cf× 30 mL

Solving:

(4 M× 7 mL)÷ 30 mL= Cf

Cf= 0.93 mL

In summary, the molarity of a solution prepared by diluting 7.0 mL of 4.0 M solution to a volume of 30 mL is 0.93 mL.

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