Which of the following two periods contain the same number of element?
A. 2 & 3
B.3 & 4
c. 4 & 6
D. 2 & 4​

Answers

Answer 1

Answer:

4 and 6

Explanation:

Period 4 has 18 elements and so does period 6.


Related Questions

How many moles of Al2O3 can be formed from 10.0 g of Al?
Select an answer and submit. For keyboard navigation, use the up/down arrow keys to
select an answer.

Answers

Answer:

n Al=  10/27( mol)- >n Al2O 3 =5/27(mol)

Explanation:

Give me an atom with the following characteristics:
Lanthanide series
Boron
Chalogen
Alkaline Earth metal

Answers

Explanation:

Lanthanide series= E4

Boron=Si

Chalogen=O

Alkaline Earth metal =M9

State the different radiations emitted by radioactive elements.

Answers

The emissions of the most common forms of spontaneous radioactive decay are the alpha (α) particle, the beta (β) particle, the gamma (γ) ray, and the neutrino.

Answer: Alpha, beta, and gamma after the first three letters of the Greek alphabet. Alpha and beta particles consist of matter, and gamma rays are bursts of energy. The type of radiation emitted depends on the radioactive substance; cesium-137, for example, produces beta and gamma radiation but not alpha particles.

Considering a fish breeder decided to breed small fishes which needs a pH between 6,0 to 7,0 to stay alive. He needs to adjust the water's pH that is 5,0 to a value of 6.5, having available only calcium carbonate. The mass in mg added to 5L of water is about:



A)2,5

B)5,5

C)6,5

D)7,5

E)9,5

Answers

6.5< x < 8.5 hope this helps

5. Calcule las concentraciones cuando se alcanza el equilibrio si partimos de unas concentraciones iniciales [A]=[B]=1M ; [C]=[D]=0M y una constante de equilibrio de 5.

Answers

Las concentraciones en el equilibrio para la reacción química presentada son:

[tex][A] = [B] = 1-x = 1-0.69 = 0.31 M\\[C] = [D] = x = 0.69 M[/tex]

Consideremos la siguiente reacción química genérica:

A + B ⇄ C + D

Para calcular las concentraciones en el equilibrio, debemos construir una Tabla ICE. Cada fila representa una instancia (Inicial, Cambio, Equilibrio) y la completamos con la concentración o cambio de concentración ("x" para concentraciones desconocidas). Como inicialmente no hay productos, la reacción se desplazará hacia la derecha para alcanzar el equilibrio.

          A + B ⇄ C + D

I          1      1      0    0

C       -x    -x     +x    +x

E      1-x    1-x    x     x

La constante de equilibrio, Kc, es:

[tex]Kc = 5 = \frac{[C][D]}{[A][B]} = \frac{x^{2} }{(1-x)^{2} } \\\sqrt{5} = x/1-x\\x = 0.69[/tex]

Las concentraciones en el equilibrio son:

[tex][A] = [B] = 1-x = 1-0.69 = 0.31 M\\[C] = [D] = x = 0.69 M[/tex]

Puedes aprender más sobre equilibrio químico aquí: https://brainly.com/question/21632386

Consider the balanced chemical equation below.

3 A ⟶ C + 4 D

How many moles of D would be produced if 9 moles of A were used?

Answers

hope the picture above helps :)

what is the difference between 25ml and 25.00ml​

Answers

Answer:

There is no difference between the two.

Explanation:

They both show the same volume. But, adding decimal places shows the least count of the instrument used and is more acceptable when recording values in scientific experiments

What type of bonding is occuring in the compound below?

A. Covalent polar
B. Metallic
C. Ionic
D. Covalent nonpolar

Answers

Answer:

(B). it's metallic bonding

how many moles of oxygen are present in 16 g of oxygen gas​

Answers

Hope this helps

Answer- 1 mole

Answer:

Mole = molecular weight / molecular mass

Mole = 16/16

Mole= 1

What is the sum of the coefficients of the balanced equation for the following reaction: FeCl2(aq) K2Cr2O7(aq) HCl(aq) ---> CrCl3(aq) FeCl3(aq) KCl(aq) H2O(l)

Answers

Answer:

The unbalanced chemical equation is

K

2

Cr

2

O

7

+HCl→KCl+CrCl

3

+H

2

O+Cl

2

Balance all atoms except H and O.

K

2

Cr

2

O

7

+10HCl→2KCl+2CrCl

3

+H

2

O+Cl

2

Assign oxidation numbers.

K

2

+6

Cr

2

O

7

+10H

−1

Cl

→2KCl+2

+3

Cr

Cl

3

+H

2

O+

0

Cl

2

The oxidation number of Cr decreases from +6 to +3. Total decrease in the oxidation number of two Cr atoms is 6. The oxidation number of Cl increases from -1 to 0. Total increase in the oxidation number of 2 Cl atoms is 2.

Balance increase in oxidation number with decrease in oxidation number by using appropriate coefficients.

K

2

Cr

2

O

7

+14HCl→2KCl+2CrCl

3

+H

2

O+3Cl

2

Balance O atoms by adding six water molecules on products side.

K

2

Cr

2

O

7

+14HCl→2KCl+2CrCl

3

+7H

2

O+3Cl

2

H atoms are balanced.

K

2

Cr

2

O

7

+14HCl→2KCl+2CrCl

3

+7H

2

O+3Cl

2

This is balanced chemical equation.

The sum of the coefficients of the products is 2+2+7+3=14

Give the formula of each coordination compound. Include square brackets around the coordination complex. Do not include the oxidation state on the metal. Use parentheses only around polyatomic ligands.
a) potassium tetracyanonickelate(II)
b) sodium diamminedicarbonatoruthenate(III)
c) diamminedichloroplatinum(II)

Answers

Answer:

a) K2[Ni(CN)4]

b) Na3[Ru(NH3)2(CO3)2]

c) Pt(NH3)2Cl2

Explanation:

Coordination compounds are named in accordance with IUPAC nomenclature.

According to this nomenclature, negative ligands end with the suffix ''ato'' while neutral ligands have no special ending.

The ions written outside the coordination sphere are counter ions. Given the names of the coordination compounds as written in the question, their formulas are provided above.

A reaction rate increases by a factor of 500. in the presence of a catalyst at 37oC. The activation energy of the original pathway is 106 kJ/mol. What is the activation energy of the new pathway, all other factor being equal

Answers

Answer:

[tex]E_2=999984KJ/mole[/tex]

Explanation:

From the question we are told that:

Factor [tex]dK=500[/tex]

Temperature [tex]T=37 C=310k[/tex]

Activation energy [tex]E=10^6kJ/mol[/tex]

Generally the Arhenius equation is mathematically given by

[tex]ln \frac{K_2}{K_1}=\frac{ E_1-E_2}{RT}[/tex]

Where

[tex]\frac{K_2}{K_1}=500[/tex]

[tex]ln 500=\frac{ 10^6-10^3-E_2}{8.314*310}[/tex]

[tex]E_2=999984KJ/mole[/tex]

The activation energy of the new reaction is 105.99 kJ/mol.

Using the Arrhenius equation;

ln(k2/k1) = -Ea2/RT2 +  Ea1/RT1

Now, from the information in the question;

k2/k1 = 500

Ea = ?

R = 8.314 JKmol-1

T2 = 37oC + 273 = 310 K

T1 = 37oC + 273 = 310 K

Substituting values;

ln (500) =- Ea2 + Ea1

6.2 = -Ea2 + 106 × 10^3 J

Ea = 106 × 10^3 J - 6.2

Ea = 105.99 × 10^3 J  or 105.99 kJ/mol

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6. Who stated that matter is not composed of particles​

Answers

After careful consideration your answer is...

Leucippus and Democritus

*Hope I helped*

~Alanna~

Answer:

The first theories of matter were put forward by Empedocles in 450 BC, he proposed that all matter was composed of four elements - Earth, air, fire and water. Later, Leucippus and Democritus suggested matter was made up of tiny indestructible particles continuously moving in empty space.

Explanation:

Select the choice that best completes the following sentence: When cooled slowly, transformations near the melting temperature tend to yield ______ grains due to the formation of ______ nucleation sites followed by ______ grain growth.

Answers

Question Completion with Options:

O coarse...few...rapid

O fine...few...slow

O fine...multiple...rapid

O coarse...few...slow

O fine...multiple...slow

Answer:

The choice that best completes the sentence is:

O coarse...few...slow

Explanation:

Transformations near the melting temperature develop coarse grains because few nucleation sites are formed and the rate of the grain growth is usually slow.  This is because of the process that starts with  recrystallization, recovery, and nucleation before growth can occur.  While recrystallization enables the grain to increase in size at high temperature, nucleation gives the grain the energy to irreversibly grow into larger-sized nucleus.

Consider the following reaction:
Cr(NO3)3 (aq) + 2NaF (aq) --> 3NaNO3 (aq) + CrF3 (s)
If 21.0 grams of NaF are needed to precipitate all of the Cr+3 ions present in 0.125L of a solution of Cr(NO3)3, what is the molarity of the Cr(NO3)3 solution?

Your answer should be to 2 decimal places.

Answers

Answer:

2.01

Explanation:

First, let's convert grams to moles

(Na) 22.99 + (F) 18.998 = 41.988

Every mole of NaF is  41.988 grams

21/41.988 = 0.500143 moles of NaF

For every Cr+3, we will need 2 NaF, so Cr+3 will be half of NaF

0.500143/2 = 0.250071

molarity = moles/liters

0.250071/0.125 = 2.0057 M

PLEASE HELP ME
a)
b)
c)
or d)?

Answers

Answer:

D / 15.0 g

Explanation:

3 % volume thus shows that there are 3 g of an solute in every 100mL of solutions

.. there will be 3 × 5000÷ 100 of H2O2 in a 500 mL bottle

What is the molarity of a solution that contains 0.75 mol Naci in 3.0 L of solution? Select one: O a. 4.0 M O b. 2.3 M O d. 3.8 M O d. 0.25 M Clear my choice​

Answers

Answer:

[tex]\boxed {\boxed {\sf D. \ 0.25 \ M}}[/tex]

Explanation:

Molarity is a measure of concentration in moles per liter.

[tex]molarity= \frac{moles \ of \ solute}{ liters \ of \ solution}[/tex]

The solution contains 0.75 moles of sodium chloride and has a volume of 3.0 liters.

moles of solute = 0.75 mol NaCl liters of solution = 3.0 L

Substitute these values into the formula.

[tex]molarity= \frac{ 0.75 \ mol \ NaCl}{3.0 \ L}[/tex]

[tex]molarity= 0.25 \ mol \ NaCl/L[/tex]

Molarity has the molar (M) as its unit. 1 molar is equal to 1 mole per liter.

[tex]molarity= 0.25 \ M \[/tex]

The molarity of the solution is 0.25 Molar and Choice D is correct.

If the starting material has no stereogenic centers, when carbonyl compounds are reduced with a reagent such as LiAlH4 or NaBH4 and a new stereogenic center is formed, what will the composition of the product mixture be?
A) Forms a racemic mixture of the two possible enantiomers.
B) Forms more of one enantiomer than another because of steric reasons around the carbonyl.
C) Forms more of one enantiomer than another depending on the temperature of the reaction.
D) Forms different products depending on the solvent used.

Answers

Answer:

A) Forms a racemic mixture of the two possible enantiomers

When carbonyl compounds are reduced with a reagent such as LiAlH₄ or NaBH₄ and  new stereogenic center is formed chemical change will lead to products that form a racemic mixture of the two possible enantiomers.

What is a chemical change?

Chemical changes are defined as changes which occur when a substance combines with another substance to form a new substance.Alternatively, when a substance breaks down or decomposes to give new substances it is also considered to be a chemical change.

There are several characteristics of chemical changes like change in color, change in state , change in odor and change in composition . During chemical change there is also formation of precipitate an insoluble mass of substance or even evolution of gases.

There are three types of chemical changes:

1) inorganic changes

2)organic changes

3) biochemical changes

During chemical changes atoms are rearranged and changes are accompanied by an energy change as new substances are formed.

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if an element has an atomic number of 9 what is the electronic structure of the same element​

Answers

 9 is the element Florine

Florine has 9 electrons as well as the 9 protons that determine its atomic number.

The ground state configuration is the lowest energy configuration.

If you ran the reaction for this experiment and began with 65.0 mmol of isopentyl alcohol, how many grams of isopentyl acetate could you theoretically produce assuming only a 77.0% attainable yield

Answers

Answer:

6.52g = Actual yield (g)

Explanation:

The yield of a reaction is:

Percent yield = Actual yield (g) / Theoretical Yield (g) * 100

As 1 mol of isopentyl alcohol produce 1 mol of isopentyl acetate (Theoretical Yield), the theroretical yield of isopentyl acetate is 65.0mmol = 0.0650mol. To solve this question we need to convert the moles of isopentyl acetate to mass using its molar mass (130.19g/mol).

With the equation of percent yield we can find the mass obtained as follows:

Theoretical yield:

0.0650mol * (130.19g/mol) = 8.46g of isopentyl alcohol

Mass produced:

77 = Actual yield (g) / 8.462g * 100

6.52g = Actual yield (g)

The mass of isopentyl acetate that can be produced is 6.52 g

Balanced equation

See attached photo

From the balanced equation,

1 mole of isopentyl alcohol reacted to produce 1 mole of isopentyl acetate.

Therefore,

65 mmole (i.e 0.065 mole) of isopentyl alcohol will also react to produce 0.065 mole of isopentyl acetate.

How to determine the actual yield (in mole) Percentage yield = 77%Theoretical yield = 0.065 mole Actual yield =?

Actual yield = percent × theoretical

Actual yield = 77% × 0.065

Actual yield = 0.05005 mole

How to determine the mass Mole of isopentyl acetate = 0.05005 mole Molar mass of isopentyl acetate = 130.19 g/molMass of isopentyl acetate =?

Mass = mole × molar mass

Mass of isopentyl acetate = 0.05005 × 130.19

Mass of isopentyl acetate = 6.52 g

Learn more about stoichiometry:

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Calculate the percent error in the atomic weight if the mass of a Cu electrode increased by 0.4391 g and 6.238x10-3 moles of Cu was produced. Select the response with the correct Significant figures. You may assume the molar mass of elemental copper is 63.546 g/mol. Refer to Appendix D as a guide for this calculation.

Answers

Answer:

10.77%

Explanation:

Molar mass of Cu = mass deposited/number of moles of Cu

Molar mass of Cu = 0.4391 g/6.238x10^-3 moles

Molar mass of Cu = 70.391 g/mol

%error = 70.391 g/mol - 63.546 g/mol/63.546 g/mol × 100

%error = 10.77%

Consider the chemical reaction: N2 3H2 yields 2NH3. If the concentration of the reactant H2 was increased from 1.0 x 10-2 M to 2.5 x 10-1 M, calculate the reaction quotient (Q) and determine which way the chemical system would shift by comparing the value of Q to K.

Answers

In this equilibrium, the chemical system will shift to the right in order to produce more NH₃.

The equilibrium constant of a reaction is defined as:

"The ratio between equilibrium concentrations of products powered to their reaction quotient and  equilibrium concentration of reactants powered to thier reaction quotient".

The reaction quotient, Q, has the same algebraic expressions but use the actual concentrations of reactants.

To solve this question we need this additional information:

For this reaction, K = 6.0x10⁻² and the initial concentrations of the reactants are:

[N₂] = 4.0M; [NH₃] = 1.0x10⁻⁴M and [H₂] = 1.0x10⁻²M

Thus, for the reaction:

N₂ + 3H₂ ⇄ 2NH₃

The equilibrium constant, K, of this reaction, is defined as:

[tex]K = \frac{[NH_3]^2}{[H_2]^3[N_2]}[/tex]

Where [] are concentrations in equilibrium.

And Q, is:

[tex]Q = \frac{[NH_3]^2}{[H_2]^3[N_2]}[/tex]

Where actual concentrations are:

[NH₃] = 1.0x10⁻⁴M

[N₂] = 4.0M

[H₂] = 2.5x10⁻¹M

Replacing:

Q = 1.6x10⁻⁷

As Q < K,

The chemical system will shift to the right in order to produce more NH₃

Learn more about chemical equililbrium in:

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1. What happens to global temperature averages that start an ice age?

Answers

Answer:

Around 46° F (7.8° C)

Explanation:

"Scientists have predicted that the global average temperature during the ice age was around 46 degrees Farenheit (7.8 degrees Celsius.) However, the polar regions were far colder, around 25 degrees Fahrenheit (14 degrees Celsius) colder than the global average."

Source: http://www.weforum.org

what are the properety of covalent bond​

Answers

Explanation:

1. boiling and melting point

2. electrical conductivity

3. Bond strength

4. bond length

A covalent bond consists of negative electrons that are shared in between atoms. Because of this bond, they possess and manifest physical abilities, including electrical pressure/conductivity and lower melting points compared to ionic compounds.

20. An oxide of osmium (symbol Os) is a pale yellow solid. If 2.89 g of the compound contains 2.16 g of osmium, what is its empirical formula?​

Answers

The empirical formula is OsO₄ :

Explanation:

Osmium oxide contains osmium and oxygen only.

Thus, we shall determine the mass of oxygen in osmium oxide. This can be obtained as follow:

Mass of compound = 2.89 g

Mass of Os = 2.16 g

Mass of O =?

Mass of O = (Mass of compound) – (Mass of Os)

Mass of O = 2.89 – 2.16

Mass of O = 0.73 g

Finally, we shall determine the empirical formula of the compound. This can be obtained as follow:

Mass of Os = 2.16 g

Mass of O = 0.73 g

Empirical formula =..?

Os = 2.16 g

O = 0.73 g

Divide by their molar mass of

Os = 2.16 / 190 = 0.011

O = 0.73 / 16 = 0.046

Divide by the smallest

Os = 0.011 / 0.011 = 1

O = 0.046 / 0.011 = 4

Empirical formula = OsO₄

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Tartaric acid is the white, powdery substance that coats sour candies such as Sour Patch Kids. Combustion analysis of a 12.01-gg sample of tartaric acid, which contains only carbon, hydrogen, and oxygen, produced 14.08 gg CO2CO2 and 4.32 gg H2OH2O. Part A Find the empirical formula for tartaric acid. Express your answer as a chemical formula. Enter the elements in the order C, H, and

Answers

Answer:

C2H3O3

Explanation:

Empirical formula is the simplest whole number ratio of moles of atoms that you can find in a molecule.

In combustion analysis all Carbon reacts producing CO2 and all hydrogen reacts producing H2O. With the differences in masses we can find the mass of oxygen and their moles:

Moles CO2 = Moles C:

14.08g * (1mol/44.01g) = 0.3199 moles C * (12.01g/mol) = 3.8423g C

Moles H2O:

4.32g H2O * (1mol/18.01g) = 0.2399 moles H2O * (2mol H / 1molH2O) = 0.4797moles H = 0.4797g H

Mass O:

12.01g = Mass O + 3.8423g C + 0.4797g H

Mass O = 7.688g O

Moles O:

7.688g O * (1mol/16g) = 0.48 moles O

The ratio of atoms (Dividing in the moles of C that are the lower number of moles):

O: 0.48moles O / 0.3199 moles C = 1.50

C: 0.3199 moles C / 0.3199 moles C = 1

H: 0.4797 moles H / 0.3199 moles C = 1.50

As empirical formula requires whole numbers:

O: 1.50* 2 = 3

C: 1*2 = 2

H: 1.50*2 = 3

The empirical formula is:

C2H3O3

name a factor tht affects the value of electron affinity​

Answers

Answer:

Atomic sizeNuclear chargesymmetry of the electronic configuration
Various factors that affect electron affinity are atomic size, nuclear charge and the symmetry of the electronic configuration. Atomic size: With increase in the atomic size, the distance between the nucleus and the incoming electron also increases.

A sample of Br2(g) takes 12.0 min to effuse through a membrane. How long would it take the same number of moles of Ar(g) to effuse through the same membrane

Answers

Answer:

6 mins

Explanation:

The time taken for Ar to effuse can be obtained as follow:

Time for Br₂ (t₁) = 12 mins

Molar mass of Br₂ (M₁) = 2 × 80 = 160 g/mol

Molar mass of Ar (M₂) = 40 g/mol

Time for Ar (t₂) =?

t₂/t₁= √(M₂/M₁)

t₂ / 12 = √(40/160)

Cross multiply

t₂ = 12 × √(40/160)

t₂ = 12 × 0.5

t₂ = 6 mins

Therefore, it will take 6 mins for the same amount of Ar to effused out.

For an atoms electrons, how many energy sublevels are present in the principal energy level n = 4?
A. 4
B. 9
C. 10
D. 16
E. 32

Answers

Answer:

by the own's formula energy sublevels are 2 the power of n or principal quantum number this means 2 the power of 4 equal to 32

What is the energy of a photon emitted with a wavelength of 654 nm?
O A. 3.04 x 10^-19 J
O B. 1.01 * 10^-27 J
O C. 1.30 x 10^-22 J
O D. 4.33 * 10^-22 J ​

Answers

Answer:

A. 3.04×10^-19J

Explanation:

Hope this will help you.

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