Giselle is working with a chemical substance in a laboratory. She observes that when the chemical is heated, it gives off a gas. She assumes that the gas is oxygen but decides to test this assumption to verify it. Which type of scientific knowledge is Giselle’s assumption? A. fact B. hypothesis C. law D. observation E. theory

The element with the electron configuration, 1s2 3s2 3p6 3s2 3p6 3d6 4s2, will be iron.

In the electronic configuration of elements, the number of electrons possessed by the element is shared into the orbitals according to their energy levels.

The electrons are first shared in orbitals in the same energy level before pairing starts.

Also for neutral atoms, the number of electrons is equivalent to the number of protons. The number of protons in itself represents the atomic number of elements.

Thus, considering this electron configuration, 1s2 3s2 3p6 3s2 3p6 3d6 4s2; the total number of electrons in all the orbitals is 26. The element with the atomic number of 26 is iron.

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Answer:

D

Explanation:

Answer:

D Atoms are made up of smaller subatomic particles

Explanation:

I just took the quiz, I hope this helps!

Answer:

Explanation: Fractional distillation

Answer:

301.92 g of CaCl2.

Explanation:

The following data were obtained from the question:

Volume of CaCl2 solution = 3.20 L

Molarity of CaCl2 solution = 0.850 M

Mass of CaCl2 =?

Next, we shall determine the number of mole of CaCl2 in the solution. This can be obtained as illustrated below:

Volume of CaCl2 solution = 3.20 L

Molarity of CaCl2 solution = 0.850 M

Mole of CaCl2 =?

Molarity = mole /Volume

0.850 = mole of CaCl2 /3.20

Cross multiply

Mole of CaCl2 = 0.850 × 3.20

Mole of CaCl2 = 2.72 moles

Finally, we shall determine the mass of the CaCl2 needed to prepare the solution as follow:

Mole of CaCl2 = 2.72 moles

Molar mass of CaCl2 = 40 + (2×35.5)

=40 + 71

= 111 g/mol

Mass of CaCl2 =?

Mole = mass /Molar mass

2.72 = mass of CaCl2 /111

Cross multiply

Mass of CaCl2 = 2.72 × 111

Mass of CaCl2 = 301.92 g

Therefore, 301.92 g of CaCl2 is needed to prepare the solution.

Answer:

1. solute dissolved in solvent makes up a solution.

Explanation:

Elements in same row (i.e, from left to right) have the same number of electron shells.

Answer:

Chemistry deals with matter, and there is a tremendous variety of matter in the universe. The behavior of matter depends on the type of elements that are present and on the structure of those elements—how they are connected to make a molecule. In this exercise, you will evaluate some representative models to develop the rules used to classify a compound, to predict the formula of a compound, and to name the compound. This exercise is just the beginning of the work needed to be done to master the rules of writing formulas and nomenclature. Your textbook has tables of the names and formulas of common cations and anions, and discusses the rules of nomenclature in detail. You will need to spend some time with this material, as the formal rules of nomenclature may not be presented in lecture, although they will certainly be used in discussions of Lewis structures and reaction chemistry.

Explanation:

In a covalent compound, valence electrons are shared between the two atoms in the bond. These can be evenly shared (covalent bond) or unevenly shared (polar covalent bond). In an ionic bond, electrons are localized to one of the atoms (giving it an overall negative charge), while the other atom has an overall positive charge. The difference in electronegativity between the two atoms in the bond can help predict whether the bond is likely to be ionic, covalent, or polar covalent, as can the type of atoms involved (metals or non-metals). A bond with two identical atoms is always pure covalent, while a covalent bond with two different atoms is likely to be polar covalent.

Answer:

[tex]V=23.9mL[/tex]

Explanation:

Hello!

In this case for the solution you are given, we first use the mass to compute the moles of CuNO3:

[tex]n=2.49g*\frac{1mol}{125.55 g}=0.0198mol[/tex]

Next, knowing that the molarity has units of moles over liters, we can solve for volume as follows:

[tex]M=\frac{n}{V}\\\\V=\frac{n}{M}[/tex]

By plugging in the moles and molarity, we obtain:

[tex]V=\frac{0.0198mol}{0.830mol/L}=0.0239L[/tex]

Which in mL is:

[tex]V=0.0239L*\frac{1000mL}{1L}\\\\V=23.9mL[/tex]

Best regards!

Answer: Servsafe 9

Explanation:

Remove food from the surface

clean the surface

rinse the surface

sanitize the surface

allow the surface to air dry

Cups and glasses are taking too long to air dry. This could be caused by the ventilation system not working properly. The correct option is D.

A ventilation system is a mechanical device that is normally created and built to supply airflow into and out of a structure or other enclosed space. Because air is provided by a functioning ventilation system, moisture on surfaces like cups and glasses can dry more quickly.

It is possible to describe air-drying as a technique or process for removing moisture from surfaces using either heated, forceful, or dry air. Therefore, air drying aids in making the surface of goods like cups and glasses dry, or free of moisture.

Thus, the correct option is D. The ventilation system not working properly.

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The question is incomplete. Your most probably complete question is given below:

A. Incorrect timing of the wash cycle.

B. An improper use of chemical sanitizer.

C. The water temperature being too high.

D. The ventilation system not working properly.

Answer:

So the answer to this question would be C. 400 J

Explanation:

Now for this problem, what is given is a 40 Newtons which would represent the force to be applied to the object, and a distance of 10 meters after the application of the said force. When these two combine, work is done. The unit for work is Joules and this is what we are looking for. The formula to get Joules or for work would be the force applied to the object multiplied by the distance that it travelled after the application of the force. It looks like this

work = force x distance

Joules = Newtons x meter

so let us substitute the variables to their corresponding places

Joules = 40 N x 10 m

Joules = 400 J

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Answer:

I also have this question but see the 69 page of ur question book

Answer:

See Explanation

Explanation:

Positional Energy for electron as function of principle energy level (n)

=> Eₙ = -A/n²; A = 2.18x10⁻¹⁸J

Positional Energy for electron in n=2 => E₂ = -2.18x10⁻¹⁸/(2)² = -5.45x10⁻¹⁹J

Positional Energy for electron in n=3 => E₃ = -2.18x10⁻¹⁸/(3)² = -2.42x10⁻¹⁹J

ΔE(n=3→2) = -5.45x10⁻¹⁹J - (-2.42x10⁻¹⁹J) =   -3.03x10⁻¹⁹J

Answer:

86

Explanation:

The reaction that takes place is:

First we convert moles of ethanol to moles of water:

Then we convert moles of water to grams of water, using its molar mass:

So 84.6 grams of water will be produced.

The mass of water, H₂O produced when 1.6 moles of ethanol, C₂H₅OH are completely burned is 86.4 g

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

C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O

From the balanced equation above,

1 mole of C₂H₅OH reacted to produce 3 moles of H₂O.

From the balanced equation above,

1 mole of C₂H₅OH reacted to produce 3 moles of H₂O.

Therefore,

1.6 moles of C₂H₅OH will react to produce = 1.6 × 3 = 4.8 moles of H₂O.

Mole of H₂O = 4.8 moles

Molar mass of H₂O = (2×1) + 16 = 18 g/mol

Mass = mole × molar mass

Mass of H₂O = 4.8 × 18

Thus, the mass of water obtained from the reaction is 86.4 g

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Answer:

It's circulatory system

Hope it's help ^_^

Answer: circilutory

Explanation:

Answer:

2.

a.Sodium bromide

b. Magnesium dichloride

c. Lithium iodide

not sure about 3 or 4 sry

Answer:

I want to say 10 grams

Explanation:

80 grams is your start

and a half-life is half of that so...

half of 80 ( and or 80/2)

40 grams

then another half is...

half of 40 (and or 40/2)

20 grams

then another half-life is...

half of 20 (and or 20/2)

10 grams

That is 3 half-life of 80 grams

*becareful not to just divide 80 / 3 you will get 26.666 (repeating) that is  incorrect

you want a half of a half of a half

Answer:

3

Explanation:

Sodium is not a gas, it is a Alkali Metal. I recommend studying the sections of the periodic table to help remember what each element should be.

Hope this helps.

liquid 1 and 2 have the same color and mass so the answer would be liquid 1 and 2

Explanation:

hope this is helpful

The concentration in mol L-l (M) = 0.717

Given

12% solution of tetrahydrate magnesium chloride (MgCl₂)

Required

The concentration

Solution

Tetrahydrate magnesium chloride (MgCl₂)⇒MgCl₂.4H₂O

MW = Ar Mg+2. Ar Cl+8. Ar H + 4. Ar O

MW=24.31 + 2 x 35.45 + 8 x 1.01 + 4 x 16

MW=24.31+70.9+8.08+64

MW=167.29 g/mol

12% solution = 12 % m/v = 12 g in 100 ml solution

For 1 L solution :

[tex]\tt \dfrac{1}{0.1}\times 12~g=120~g[/tex]

The concentration in g/L = 120 g/L

Convert grams to moles :

[tex]\tt mol=\dfrac{120}{167.29}=0.717[/tex]

Answer:

0.02088M of EDTA

Explanation:

The Ca²⁺ is chelated in presence of EDTA in a relation 1:1, when there is no free Ca²⁺ the eriochorme black T change its colour showing endpoint.

Thus, we need to find final concentration of Ca²⁺ solution and, thus, we can find concentration of the EDTA solution:

Molarity Ca²⁺ solution:

0.2191g * (1mol / 40.08g) = 0.005467 moles of Ca²⁺ in 250mL = 0.250L:

0.005467 moles of Ca²⁺ / 0.250L = 0.02187M

Moles of Ca²⁺ added:

0.025L * (0.02187 mol / L) = 5.467x10⁻⁴ moles of Ca²⁺ = Moles of EDTA at endpoint.

Molarity EDTA:

5.467x10⁻⁴ moles EDTA / 0.02618L = 0.02088M of EDTA

Answer:

mercury

Explanation:

I hope it is helpful for ........

Answer:

Revolution of the earth around the sun in its own orbit. A complete revolution of the earth is a year equal to 365 days

Explanation:

Answer:

Sentences are where there is a beginning and an end of a section of a paragraph. Letters are individual parts of sentences.

The answer that would make the MOST sense would be SENTENCES

Answer:

B

Explanation:

The second one is not balanced correctly.

2 NaOH + 2HNO3 → 2NaNO3 + 2 H20

I didn't notice this before but it can be balanced without the twos.

 NaOH + HNO3 → NaNO3 +  H20

It was still wrong. It needed to have the twos removed, not 2 more added. Adding two more isn't wrong, but it should be balanced without 2s if at all possible.

Answer:

NaF, CaBr2, MgO

Explanation:

Hi! For this problem, you are going to want to look at the charges of the elements in order to write their formulas.

NaF: Na has a charge of +1 and F has a charge of -1. This means that they have a 1:1 ratio and the formula is written as such - NaF.

CaBr2: Ca has a charge of +2 and Br has a charge of -1. For this problem you want to make sure that their formal charge (the charge of the entire molecule) equals 0. This means that the negative charges need to equal the positive charges. Looking at this, you are going to need to Br ions with a charge of -1 to equal one Ca ion with a charge of +2 - CaBr2.

MgO: Mg has a charge of +2 and O has a charge of -2. This means that they have a 2:2 ratio which simplifies to a 1:1 ratio and the formula is written as such - MgO.

Hope this helps!

Answer:  B. [tex]125\ cm^3[/tex].

The volume of the given object = [tex]125\ cm^3[/tex]

Explanation:

Given : Dimensions of an object : 5 cm x 5 cm  x 5 cm [ it is a cube with all equal sides]

Formula to find the volume of a cube = [tex](side)^3[/tex]

[tex]=5^3\ cm^3=125\ cm^3[/tex]

Hence, the volume of the given object = [tex]125\ cm^3[/tex]

Therefore , the correct option is B. [tex]125\ cm^3[/tex].

Answer:

H:H

Explanation: