Calculate the number of moles of MgF2 that dissolved.

The 12 stands for the number of electrons that fill the f orbital

In an atom there are levels of energy in the shell and sub shell  

This energy level is expressed in the form of electron configurations.  

Writing electron configurations starts from the lowest to the highest sub-shell energy level. There are 4 sub-shells in the shell of an atom, namely s, p, d and f. The maximum number of electrons for each sub shell is  

• s: 2 electrons  

• p: 6 electrons  

• d: 10 electrons and  

• f: 14 electrons  

4f¹² :

4 : number of shell

12 : the number of electrons that fill the f orbital

Answer:

The wavelength of the energy that needs to be absorbed  = 52.36 nm

Explanation:

For this study;

Let consider the Rydgberg equation from Bohr's theory of atomic model:

i.e.

[tex]\dfrac{1}{\lambda} = R_H (Z^*)^2( \dfrac{1}{n_1^2}-\dfrac{1}{n_2^2})[/tex]

where

Z* = effective nuclear charge of atom = Z - σ = 6

n₁ = lower orbit = 3

n₂ = higher orbit = 4

[tex]R_H[/tex] = Rydyberg constant = 1.09 × 10⁷ m⁻¹

λ = wave length of the light absorbed

∴

[tex]\dfrac{1}{\lambda} = 1.09 \times 10^7}(6)^2( \dfrac{1}{3^2}-\dfrac{1}{4^2})[/tex]

[tex]\dfrac{1}{\lambda} = 1.09 \times 10^7}(36)( \dfrac{1}{9}-\dfrac{1}{16})[/tex]

[tex]\dfrac{1}{\lambda} = 392400000\times0.0486111111[/tex]

[tex]\dfrac{1}{\lambda} =19075000[/tex]

[tex]\lambda = \dfrac{1}{19075000}[/tex]

[tex]\lambda = \dfrac{1}{1.91\times 10^7 \ m^{-1}}[/tex]

[tex]\lambda = 5.236 \times 10^{-8} m[/tex]

[tex]\lambda = 52.36 \times 10^{-9} m[/tex]

[tex]\lambda = 52.36\ n m[/tex]

Therefore, the wavelength of the energy that needs to be absorbed  = 52.36 nm

Answer:

Microscope

Explanation:

Answer:

its a telescope you see stars or plants

Explanation:

J.J. Thomson's plum pudding model of the atom followed the discovery of negatively charged particles with a very small mass. Thus, the correct option for this question is A.

J.J. Thomson was a British physicist who discovered sub-atomic particles known as electrons within an atom. He also announced that atoms are made up of smaller components.

The plum pudding model is defined by Thomson in order to demonstrate that negatively charged sub-atomic particles known as electrons are surrounded by a volume of positively charged particles known as protons. It is one of the historical scientific model of the atom that governs all sorts of properties of sub-atomic particles.

Therefore, "negatively charged particles with a very small mass" is the discovery that follows J.J. Thomson's plum pudding model of the atom. Thus, the correct option for this question is A.

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Answer:  oxidation reactions are so fast the substance catches fire

Explanation:

Answer:

When oxidation reactions are so fast the substance catches fire

Explanation:

because i am big bwain

Answer:

Zamir walked

27

meters and Talia walked

19

meters.

Explanation:

27 and 19

Answer:

zamir:27  Talia:19

Explanation:

i got it right on my test :)

Answer:

I ordered the tiles from left to right and top to bottom as the numbers kept increasing. The tiles were also organized based on the color and shape that they were. The tiles with the same color and shape were arranged in the same column.

Explanation:

In the modern periodic table, the elements are listed in order of increasing atomic number and elements having similar chemical properties naturally line up in the same column (group).

Answer:

Mass is conserverd

Explanation:

Any chemical reaction must follow the law of conservation of mass. Meaning that mass cannot be created nor destroyed. Since all chemical reactions must follow this law, no matter what reaction happens, mass is conserved.

Answer:

please brainlist answer

Explanation:

The addition of K 3 Fe(CN) 6 to a solution causes the formation of a deep blue precipitate which indicates that iron(II) ions are present.

The conclusive test for iron(II) ions is the test by the use of potassium hexacyanoferrate III solution.

In qualitative analysis certain reagents are used to test for the presence of certain cations or anions. Those reagents react in a certain way with those reagents. Usually, a positive test may involve a color change, formation of a precipitate or evolution of a gas.

In the case of iron(II) ions, potassium hexacyanoferrate III solution is used in the conclusive qualitative test for the ion. A positive test involves the appearance of a deep blue precipitate.

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Answer:

C

Explanation:

Answer:

I think is A

Explanation:

Hope it helps

Answer:

a. Approximately [tex]1.3\; \rm mL[/tex].

b. Approximately [tex]7.2\; \rm mL[/tex].

Explanation:

The unit of concentration "[tex]\rm M[/tex]" is equivalent to "[tex]\rm mol \cdot L^{-1}[/tex]", which means "moles per liter."

However, the volume of both solutions were given in mililiters [tex]\rm mL[/tex]. Convert these volumes to liters:

[tex]\displaystyle 45\; \rm mL = 45\; \rm mL \times \frac{1\; \rm L}{1000\; \rm mL} = 0.045\; \rm L[/tex].

[tex]\displaystyle 330\; \rm mL = 330\; \rm mL \times \frac{1\; \rm L}{1000\; \rm mL} = 0.330\; \rm L[/tex].

In a solution of volume [tex]V[/tex] where the concentration of a solute is [tex]c[/tex], there would be [tex]c \cdot V[/tex] (moles of) formula units of this solute.

Calculate the number of moles of [tex]\rm NaCl[/tex] formula units in each of the two solutions:

Solution in a.:

[tex]n = c \cdot V = 0.045\; \rm L \times 0.10\; \rm mol \cdot L^{-1} = 0.0045\; \rm mol[/tex].

Solution in b.:

[tex]n = c \cdot V = 0.330\; \rm L \times 0.074\; \rm mol \cdot L^{-1} = 0.02442\; \rm mol[/tex].

What volume of that [tex]3.4\; \rm M[/tex] (same as [tex]3.4 \; \rm mol \cdot L^{-1}[/tex]) [tex]\rm NaCl[/tex] solution would contain that many

For the solution in a.:

[tex]\displaystyle V = \frac{n}{c} = \frac{0.0045\; \rm mol}{3.4\; \rm mol \cdot L^{-1}} \approx 0.0013\; \rm L[/tex].

Convert the unit of that volume to milliliters:

[tex]\displaystyle 0.0013\; \rm L = 0.0013\; \rm L \times \frac{1000\; \rm mL}{1\; \rm L} = 1.3\; \rm mL[/tex].

Similarly, for the solution in b.:

[tex]\displaystyle V = \frac{n}{c} = \frac{0.02442\; \rm mol}{3.4\; \rm mol \cdot L^{-1}} \approx 0.0072\; \rm L[/tex].

Convert the unit of that volume to milliliters:

[tex]\displaystyle 0.0072\; \rm L = 0.0072\; \rm L \times \frac{1000\; \rm mL}{1\; \rm L} = 7.2\; \rm mL[/tex].

The empirical formula : C₁₂H₁₇N₂O₄P

The empirical formula is the smallest comparison of atoms of compound =mole ratio of the components

The principle of determining empirical formula

[tex]\tt \dfrac{50.7}{12}=4.225[/tex]

[tex]\tt \dfrac{6.03}{1}=6.03[/tex]

[tex]\tt \dfrac{9.86}{14}=0.704[/tex]

[tex]\tt \dfrac{22.51}{16}=1.407[/tex]

[tex]\tt \dfrac{10.9}{31}=0.352[/tex]

Divide by the smallest mole ratio(0.352)

C : H : N : O : P

[tex]\tt C\rightarrow \dfrac{4.225}{0.352}=12[/tex]

[tex]\tt H\rightarrow \dfrac{6.03}{0.352}=17[/tex]

[tex]\tt N\rightarrow \dfrac{0.704}{0.352}=2[/tex]

[tex]\tt O\rightarrow \dfrac{1.407}{0.352}=4[/tex]

[tex]\tt P\rightarrow \dfrac{0.352}{0.352}=1[/tex]

Answer:

A

Explanation:

Answer:

its hydroxy and alkoxy

Explanation:

ester is mainly formed by substitution reaction of carboxylic acid and alcohol

The esters are generally produced as a result of the reaction called esterification. They are generally derived from carboxylic acids. The functional group present in ester is OR. The correct option is E.

The chemical compounds which are derived from an acid either organic or inorganic in which at least -OH ( hydroxyl group ) is replaced by an -O- alkyl group ( alkoxy ) group are called esters. Generally an ester can be represented as R - C = O - OR.

The chemical compounds that are formed by the reaction of an acid and alcohol by losing water molecule can be defined as the esters.

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Answer:

I think its b

Explanation:

well because thermal energy its connected to kidnetic energy

Answer:

Pb²⁺ (aq) + 2I⁻ (aq) → PbI₂ (s)

General Formulas and Concepts:

Explanation:

Step 1: RxN

Pb(NO₃)₂ (aq) + KI (aq) → PbI₂ (s) + KNO₃ (aq)

Step 2: Balance RxN

Pb(NO₃)₂ (aq) + 2KI (aq) → PbI₂ (s) + 2KNO₃ (aq)

Step 3: Ionic Equations

Total Ionic Equation:

Pb²⁺ (aq) + 2NO₃⁻ (aq) + 2K⁺ (aq) + 2I⁻ (aq) → PbI₂ (s) + 2K⁺ (aq) + 2NO₃⁻ (aq)

Cancel out spectator ions.

Net Ionic Equation:

Pb²⁺ (aq) + 2I⁻ (aq) → PbI₂ (s)

Answer:

Gneiss forms by regional metamorphism from both high temperature and pressure. Quartzite and marble are the most commonly used metamorphic rocks.

Answer:

[tex]\% Fe=11.4\%[/tex]

Explanation:

Hello!

In this case, for the described chemical reaction, we find it is:

[tex]8H^+(aq)+5Fe^{2+}(aq)+MnO_4^-(aq)\rightarrow 5Fe^{3+}(aq)+Mn^{2+}(aq)+4H_2O(l)[/tex]

Because it says that the iron is dissolved in a strong acid which provides addition hydrogen ions to the reaction media. Thus, for the questions attached on the figure we find:

- This a REDOX reaction because we see iron is being oxidized from 2+ to 3+ and manganese reduced from +7 to +2.

- Since it is a redox reaction and the oxidized species is that undergoing an oxidation number increase, we evidence iron goes from +2 to +3, which means iron is the oxidized species.

- In this case, for the used 59.2 mL (0.0592 L) of the 0.2000 M solution of potassium permanganate, we can compute the consumed grams of iron via stoichiometry including the 5:1 mole ratio between them in the chemical reaction:

[tex]m_{Fe^{2+}}=0.0592L*0.2000\frac{molMnO_4^-}{L}*\frac{5molFe^{2+}}{1molMnO_4^-} *\frac{55.85gFe^{2+}}{1molFe^{2+}} \\\\m_{Fe^{2+}}=3.31gFe^{2+}[/tex]

It means that the percent of iron in that sample is:

[tex]\% Fe=\frac{3.31g}{29.00g} *100\%\\\\\% Fe=11.4\%[/tex]

Best regards.

Answer:

It is A.

Explanation:

I took the test.

The Lewis structure shows the arrangement of valence electrons in H3PO4.

The Lewis structure gives us a picture of the number of valence electrons in a molecule. This is because, in a Lewis structure, the electrons in the molecule are shown as dots. A single line may be used to show shared electrons in a covalent bond.

The correct Lewis structure of H3PO4 is an upper P is single bonded above to an O, and to the left, right, and below to an O single bonded to an H. The O above the P has three pairs of dots to the left, above, and below; the O's to the sides have pairs of dots above and below, and the O below the P has pairs of dots right and left.

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Answer:

The correct option is the last option (Some dissolved solids may be nonelectrolytes)

Explanation:

Total dissolved solids (TDS) cannot be calculated by conductivity alone because conductivity involves ionic charges and there are solids that dissolve in water but do not carry ionic charges (and thus form non-electrolytes). Examples include sucrose (common sugar) and glucose. These two solids will dissolve in water but would not form ions that will carry ionic charges which are responsible for conductivity. Thus, if TDS only depends solely on conductivity, then a solution that contains dissolved sucrose will be wrongly accounted for as the sucrose will be omitted from the dissolved substances.

A valid reason why total dissolved solids (TDS) cannot be accurately

calculated by conductivity alone because some dissolved solids may be

non-electrolytes.

Conductivity means the ability of electric current to pass through a

substance and an electrolyte has a high conductivity when dissolved in

water.

Dissolved solids can't be measured by conductivity because not all

dissolved solids are electrolytes.

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Answer: pH = 10

Explanation: First solve for pOH using the equation pOH=-log[OH-] = 4

Then plug the pOH in the equation, pH + pOH =14

then solve for pH. pH =14 - 4 = 10

Answer:

pH= 10

Explanation:

The pH really depends on what your solution is.

For example, if we are assuming that the concentration of 1.0M is of a strong monoprotic acid e.g. HCl, it would be safe to assume that almost all of the 1.0M acid has dissociated into its H+ ion, and its conjugate base. Thus, the pH can be determined by taking the negative log(to base 10), of the concentration.

Inversely, if the solution is of a strong base, the pOH value would be found, assuming the steps above. This pOH value can be used to infer a pH from the formula - pH + pOH = 14 then 14 - 4 = 10

Finally, come the weak acids/bases, which follow the rules above, except as they only partially dissociate, one needs its equilibrium constant to determine its extent of ionisation, to substitute into the negative log. This also is the case for the second, and higher order dissociation of polyprotic acids e.g. H2SO4.the answer is 10

Hope it helps

Answer:

Can you give me your snap, so I can send you the foto

if you just look up the answer it comes up btw!!

have a great day

Answer:

True

Explanation:

Mixtures are substances with indefinite composition. They consist of two or more elements  and or compounds in any proportion by mass.

From these properties we can clearly identify that to separate mixtures, we use the differences in the chemical properties of the constituents of the mixtures.

Answer:

None. Electrons are not in the nucleus.

Explanation:

We know that an atom consist of electrons, protons and neutrons. Neutrons and protons are present inside the nucleus while electrons are present out side the nucleus. Electron has a negative charge and is written as e⁻. The mass of electron is 9.10938356×10⁻³¹ Kg . While mass of proton and neutron is 1.672623×10⁻²⁷Kg and 1.674929×10⁻²⁷ Kg respectively.

Symbol of proton= P⁺  

Symbol of neutron= n⁰  

The number of electron or number of protons are called atomic number while mass number of an atom is sum of protons and neutrons. The umber of protons and electrons are always equal to make the atom electrically neutral .

The atom having atomic number 16 have 16 electrons and these electrons are present out side the nucleus.