Which element contains four electrons in its third and outer main energy level? ​

Answer:

The exposed metal rusts is an example of a chemical change because rust is an example of a chemical change in objects for example bicycles, scooters, etc.

Answer:

Liquid paint.

Explanation:

Liquid paints are dissolved first in acetone. Most of the food dyes are not soluble in acetone.

Acetone is an organic compound comes under the category of ketones. It contains a carbonyl group and can dissolve most of the organic solvents.

The active ends in acetone easily forms hydrogen bonds with other solvents with polar or nonpolar groups.

Xylene, benzene, toluene, aromatic azo dyes etc. are common components in paint. Which are easily miscible with acetone.

Hence, liquid paints dissolve in acetone and food dyes are hard o dissolve in it.

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Answer:

10 N Left

Explanation:

Given parameters;

   Forces acting on the box

Left force  = 40N

Right force = 30N

Unknown:

Net force on the box and the direction = ?

Solution:

Force is a pull or push on a body;

                            ←   BODY →

                        40N                30N

The forces acting on the body are in the opposite directions, the greater force will determine the direction of pull.

  Net force  = Left force - Right force  = 40 - 30 = 10N

The force will be directed left with a net value of 10N

Answer:

Explanation:

The percentage error of a certain measurement can be found by using the formula

[tex]P(\%) = \frac{error}{actual \: \: number} \times 100\% \\ [/tex]

From the question

actual density = 2.49g/mL

error = 2.49 - 1.47 = 1.02

We have

[tex]p(\%) = \frac{1.02}{2.49} \times 100 \\ = 40.96385542...[/tex]

We have the final answer as

Hope this helps you

Answer:

Explanation:

The volume of a substance when given the density and mass can be found by using the formula

[tex]volume = \frac{mass}{density} \\ [/tex]

From the question we have

[tex]volume = \frac{244}{2.7} \\ = 90.370370...[/tex]

We have the final answer as

Hope this helps you

Answer:

2.528x10⁻³M

Explanation:

Molarity is an unit of concentration used in chemistry. Is defined as the moles of solute per liter of solution.

To find the molarity of the solution we need to determine the moles of ammonium sulfate present in the initial 49.16mL solution and, with total volume, we can find the molarity, thus:

Moles ammonium sulfate:

49.16mL = 0.04916L * (0.0270 moles / L) =

1.327x10⁻³moles ammonium sulfate

These moles are present in 525.0mL = 0.525L. Thus, molarity of the solution will be:

1.327x10⁻³moles ammonium sulfate / 0.525L =

Answer:

A. Cells are able to provide support

Answer:

wood

Explanation:

i can take the seds from the trees to row new trees and still use the wood without causing deforestation

Answer:

5 extractions to extract at least 99.5% of 50.0 g Compound A from 100 mL of water

Explanation:

If K=10...

Partition coefficient is defined as the ratio of concentrations of a compound A in two inmiscibles solvents:

K = 10 = Conc. Organic solvent / Conc. Water

Usually organic phase over aqueous phase.

In the first 20mL extraction, the organic solvent will extract:

10 = X / 20mL / (50.0g - X) / 100mL

10 = 100X / (1000-20X)

10000 - 200X = 100X

10000 = 300X

X = 33.3g of compound A are extracted in the first extraction

Remember you want to extract 99.5%, that is 50.0g*99.5% = 49.75g

In the aqueous phase remain: 50-33.3g = 16.7g:

Second extraction:

10 = X / 20mL / (16.7g - X) / 100mL

10 = 100X / (334-20X)

3340 - 200X = 100X

3340 = 300X

11.1g are extracted and will remain: 16.7g - 11.1g = 5.6g

Third extraction:

10 = X / 20mL / (5.6g - X) / 100mL

10 = 100X / (112-20X)

1120 - 200X = 100X

1120 = 300X

3.8g are extracted and will remain: 5.6g - 3.8g = 1.8g

Fourth extraction:

10 = X / 20mL / (1.8g - X) / 100mL

10 = 100X / (36-20X)

360 - 200X = 100X

360 = 300X

1.2g are extracted and will remain: 1.8g -1.2g =  0.6g

Fifth extraction:

10 = X / 20mL / (0.6g - X) / 100mL

10 = 100X / (12-20X)

120 - 200X = 100X

120 = 300X

0.4g are extracted. The total extractions gives:

33.3g + 11.1g + 3.8g + 1.2g + 0.4g = 49.8g

That means, you need to do:

Answer:

22 is P

23 is C

24 is P

25 is C

26 is P

27 is P

28 is P

29 is C because youre using thermal heat and you cannot return to raw batter

Answer:

Long term condition of the atmosphere

Explanation:

I think this is right.

I hope this helps! (✿◕‿◕✿)

Answer:

1) No

2) The solvent contaminated the analyte

3) The solvent should be evaporated properly before washing and drying the analyte

Explanation:

During separation of organic compounds, solvents are used. These solvents are able to contaminate the analyte and lead to a large difference in melting point of solids obtained.

However, the error can be minimized by evaporating the solvent before washing, drying and melting point determination of the solid.

Answer: Aluminum

Explanation:

Al3+ indicates an ion of aluminum having a charge of + 3. I.e., since an aluminum atom normally has 13 protons and 13 electrons, this ion has 10 electrons (-10 charge) and 13 protons (+ 13 charge) giving it a charge of + 3 (-10 + 13 = +3).

Answer:

Explanation:

Al3+ indicates an ion of aluminum having a charge of + 3. I.e., since an aluminum atom normally has 13 protons and 13 electrons, this ion has 10 electrons (-10 charge) and 13 protons (+ 13 charge) giving it a charge of + 3 (-10 + 13 = +3).

ccto.

Answer:

0.5 M NaOH solution

Explanation:

Initially, we have 0.25L or 250 mL of 8M NaOH solution

Which means that 1L of this solution would have 8 moles of NaOH

Moles present in 250 mL of solution:

Molarity * Volume( in L)

8 * 0.25 = 2 moles

There is 2 moles of NaOH in 0.25 L of the provided NaOH solution

More water is going to be added to this solution but the number of moles of NaOH will remain the same

now that the solution has a volume of 4L after adding the additional water, we have a 4L solution which contains 2 moles of NaOH

Molarity of the new solution:

Molarity = Number of moles in solution / Volume of solution

Molarity = 2 / 4

Molarity = 0.5 M

Answer:

molar mass of unknown gas = 1.987 g/mol

Explanation:

First, the number of moles of the unknown gas is found

Using the ideal gas equation: PV = nRT

P = 1.00 atm, V = 5.00 L, T = 298.15 K, R = 0.082 L.atm.mol⁻¹K⁻¹

n = PV/RT

n = (1.00 atm * 5.00 L)/(298.15 K *0.082 L.atm.mol⁻¹K⁻¹)

n = 0.2109 moles

Molar mass = mass/ number of moles

molar mass = 0.419 g/ 0.2109 mols

molar mass of unknown gas = 1.987 g/mol

The molar mass of unknown gas by using ideal gas equation = 1.987 g/mol.

This equation gives the relation between pressure, volume, temperature as given below:

[tex]PV = nRT[/tex]

P = 1.00 atm, V = 5.00 L, T = 298.15 K, R = 0.082 L.atm.mol⁻¹K⁻¹

Substitute the above values in the above equation as follows:

n = (1.00 atm * 5.00 L)/(298.15 K *0.082 L.atm.mol⁻¹K⁻¹)

n = 0.2109 moles

[tex]Molar mass = mass/ number of moles[/tex]

Calculate molar mass by using the above equation,

molar mass = 0.419 g/ 0.2109 moles

The molar mass of unknown gas = 1.987 g/mol

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And we can see that the potassium ion, K+, has the same electronic configuration as the chloride ion, Cl-, and the same electronic configuration as an atom of argon, Ar. Therefore, Ar, Cl-, and K+ are said to be isoelectronic species.

Answer:

The answer to this question is 33.8

Answer:

A. It occupies 22.4 L

Explanation:

STP (Standard Conditions for Temperature and Pressure) = 22.4 L per mole at 1 atm

Avogadro's Law states that 1 mol at 1 atm occupies 22.4 L.

Answer:

2H₂ + O₂       →     2H₂O

Explanation:

Chemical equation:

H₂ + O₂       →     H₂O

Balance chemical equation:

2H₂ + O₂       →     2H₂O

Step 1:

H₂ + O₂       →     H₂O

Left hand side                     Right hand side

H = 2                                    H = 2

O = 2                                    O = 1

Step 2:

H₂ + O₂       →     2H₂O

Left hand side                     Right hand side

H = 2                                    H = 4

O = 2                                    O = 2

Step 3:

2H₂ + O₂       →     2H₂O

Left hand side                     Right hand side

H = 4                                    H = 4

O = 2                                    O = 2

Answer:

The answer is D - Atom

The smallest unit of an element that can exist either alone or in combination with other such particles of the same or different elements is the atom.

An atom is defined as the smallest unit of matter which forms an element. Every form of matter whether solid,liquid , gas consists of atoms . Each atom has a nucleus which is composed of protons and neutrons and shells in which the electrons revolve.

The protons are positively charged and neutrons are neutral and hence the nucleus is positively charged. The electrons which revolve around the nucleus are negatively charged and hence the atom as a whole is neutral and stable due to presence of oppositely charged particles.

Atoms of the same element are similar as they have number of sub- atomic particles which on combination do not alter the chemical properties of the substances.

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Answer:

G is correct option:

# of Ba atoms = coefficient 4 × subscript 1= 4

Explanation:

Formula:

4Ba(OH)₂

G is correct option:

# of Ba atoms = coefficient 4 × subscript 1= 4

Because there are only 4 atoms of Ba in given formula.

Ba(OH)₂ contain one atom of Ba while in question there are 4 moles of Ba(OH)₂ present thus total 4×1 = 4 atoms of Ba present.

Other options are incorrect. Because,

F:

# of Ba atoms = coefficient 4 + subscript 1 = 5

This shows given formula contain 5 Ba atoms. So it is incorrect.

H:

# of Ba atoms = subscript 4 ×  coefficient 2 = 6

This shows that subscript is 4 which is incorrect because coefficient is 4 and subscript is 1.  

j:

# of Ba atoms = subscript 1  + coefficient 1 = 2

This option shows that subscript is one which is correct but coefficient is incorrect. The coefficient of Ba is 4 and coefficient is always multiply with subscript not added. So this option is also incorrect.

Answer:

t = 7.58 * 10¹⁹ seconds

Explanation:

First order rate constant is given as,

k =  (2.303 /t) log  [A₀] /[Aₙ]

where  [A₀]  is the initial concentraion of the reactant; [Aₙ] is the concentration of the reactant at time, t

[A₀]  = 615 calories;

[Aₙ] = 615 - 480 = 135 calories

k = 2.00 * 10⁻²⁰ sec⁻¹

substituting the values in the equation of the rate constant;

2.00 * 10⁻²⁰ sec⁻¹ = (2.303/t) log (615/135)

(2.00 * 10⁻²⁰ sec⁻¹) / log (615/135) = (2.303/t)

t = 2.303 / 3.037 * 10⁻²⁰

t = 7.58 * 10¹⁹ seconds

This question is incomplete, the complete question is;

Tonksite is a solid at 300.00K.  At 300.00 K its enthalpy of sublimation is 66.00 kJ/mol. The sublimation pressure at 300.00 K is 5.00 × 10⁻⁴ atm

Calculate the sublimation pressure of the solid at the melting point of 400.00 K assuming that the enthalpy of sublimation is not a function of temperature.

Answer: the sublimation pressure of the solid at the melting point is  0.3727 atm

Explanation:

Given that;

T1 = 300 K

T2 = 400 K

H_sub = 66 kJ/mol = 66000 J/mol

P1 = 5.00 × 10⁻⁴ atm

p2 = ?

now using the expression

log( p2 / 5.00 × 10⁻⁴ ) = (H_sub / R ×  2.303 ) (( T2 - T1) / T1T2)

now we substitute of given values into the expression

log(p2/p1) = (66000 / 8.314 ×  2.303 ) (( 400 - 300) / 300 × 400 )

p2 = 0.3727 atm

therefore the sublimation pressure of the solid at the melting point is  0.3727 atm

Answer:

the fish can't survive in that warm water

Explanation:

when the factory puts that warm water into the stream where the fish live they changed their environment. by adding unknown chemicals and changing the temp of the water the fish start to die.

The fish aren't used to living in that warm water, and if they can't adapt fast enough they will die, also the unknown chemicals that could be in the water will act as a poison for them making that stream unable to support any life.

Answer:

A landform is a feature on the Earth's surface that is part of the terrain. Mountains, hills, plateaus, and plains are the four major types of landforms. Minor landforms include buttes, canyons, valleys, and basins. Tectonic plate movement under the Earth can create landforms by pushing up mountains and hills.

Explanation:

"Waterways" are the other large features that cover the surface of the earth.

A canal would be any body of water throughout which boats may move. Waterways, on the other hand, comprise waterways that seem to be expansive as well as shallow enough already to allow freight-carrying watercraft just to travel through.

Some bodies of water are usually regularly dredged to maintain an appropriately deep course throughout all circumstances. Dams change the depth of other rivers in particular parts.

Thus the response above i.e., "Option B" is correct.

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Analysing the question:

To calculate the density of a material, we need its mass and volume

We are given:

Mass of sample = 21 grams

dimensions of the sample = 1 * 1 * 2 = 2 cm³

Calculating the density:

Density = Mass of sample / volume of sample

Replacing the variables

Density = 21 / 2

Density  = 10.5 g / cm³

Determining the Material:

From the table provided, we can see that the density of Silver is 10.5 g/cm³

Therefore, the material is Silver