Pleas e help I will mark brainy

Answer:

A pure solid is heated and turns into a pure liquid.

Explanation:

No colour change recorded, only change of state, hence this is a physical change - physical changes I.e. change of state and temperature are not chemical reactions.

Answer: 12

Explanation:

Answer:

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

[tex]n = \frac{N}{L} \\[/tex]

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

From the question we have

[tex]n = \frac{8.02 \times {10}^{25} }{6.02 \times {10}^{23} } \\ \\ = 1.33 \times {10}^{2} \: \: \: moles[/tex]

Hope this helps you

Compared to ionic compounds, molecular compounds generally have a low boiling point and the correct option is option D.

Molecular compounds are held together by covalent bonds. They are also called covalent compounds.

Covalent bonds are responsible for many of the properties of covalent compounds. Covalent compounds have relatively low boiling points, cannot conduct electricity, and may not dissolve in water.

Unlike ionic compounds, covalent compounds do not have freely moving electrons, so they cannot conduct electricity.

The individual molecules of covalent compounds are more easily separated than the ions in a crystal, so most covalent compounds have relatively low boiling points.

Therefore, compared to ionic compounds, molecular compounds generally have a low boiling point and the correct option is option D.

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Answer:

4. A subscript is a sentence below a line. You cannot change subscripts in a chemical formula to balance a chemical equation

5. where's/whats the equation??

6. ^^^

Explanation:

Answer:

Iron(II) oxide

Explanation:

Iron(II) oxide or ferrous oxide is the inorganic compound with the formula FeO. Its mineral form is known as wüstite.

Answer:

A

Explanation:

exam review :)

Answer:

tell your teacher when he/she get back report him/she

Answer:

A.) Linear

Explanation:

The geometry of the molecular oxygen (O₂) is linear. Thus, option (A) is correct.

Valence shell electron-pair repulsion theory (VSEPR theory) is used to predict the molecular structure, and bond angles around a central atom of a molecule by using the number of bonds and lone electron pairs in Lewis structure.

The VSEPR model considers that electron pairs present in the valence shell of a central atom have an arrangement so that repulsions between these electron pairs will be minimized by maximizing the distance between them.

The valence electrons of a central atom form either bonding pairs or lone pairs. The electrostatic repulsion of these electrons is minimized when several regions of high electron density maximum possible distance.

The oxygen molecule has linear geometry with a bond angle of 180°. Each oxygen in oxygen molecule has two lone pairs of electrons on it.

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Answer:

1. Reactants collect in chloroplasts

2. A chemical reaction occurs

3. Products result as food and water

Double replacement is the reaction that typically occurs when different atoms in two different compounds trade places (Option C).

Double-replacement is a class of chemical reaction where two atoms can exchange their places to generate new combinations.

In conclusion, double replacement is the reaction that typically occurs when different atoms in two different compounds trade places (Option C).

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Answer:

True

Explanation:

The percent of SO₂ in H₂SO₄ : 65.3%

Proust states the Comparative Law that compounds are formed from elements with the same Mass Comparison so that compounds have a fixed composition of elements

%Mass A in AxBy =  

[tex]\tt \dfrac{x.Ar~A}{MW~A_xB_y}\times 100\%[/tex]  

For SO₂ in H₂SO₄ :

MW SO₂ = 32 + 2.16=64 g/mol

MW H₂SO₄ =2.1+32+4.16=98 g/mol

The percent of SO₂ :

[tex]\tt \dfrac{64}{98}\times 100\%=65.3\%[/tex]

Answer:

It is b

Explanation: I did it on the test and got it right

The moles of water are produced when 5 moles of hydrogen gas react with 2 moles of oxygen gas - b. 4 moles of water

The stoichiometric coefficients can be considered in a balanced equation as moles of reactants needed or moles of products formed in the reaction.  

2H2 + O2 → 2H2O  

Thus, the moles of water are produced when 5 moles of hydrogen gas react with 2 moles of oxygen gas - b. 4 moles of water

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Answer:

I think its D

Explanation:

Answer:

D

Explanation:

It's B because homeostasis is the ability to maintain a relatively stable internal state that persists despite changes.

Hope this helps!!! If this is incorrect, I'm so sorry! Have a lovely day.

Answer:

The ratio is  [tex]0.67 : 1[/tex]

Explanation:

From the question we are told that

 The activation energy separating the equatorial and the axial form is [tex]\Delta E = 0.24\ kcal/mol[/tex]

 Generally according to the Boltzmann distribution , the relationship between  concentration(in terms of number of molecule) of the equatorial form and  the concentration of the axial form is mathematically represented as

       [tex]N = N_o e^{-\frac{\Delta E }{RT} }[/tex]

Here [tex]N_o[/tex] is the number of molecule in equatorial form and  N is the number of the molecules in the axial form.

   R is the gas constant with value  [tex]R = 1.987 *10^{-3} \ kcal\cdot mol^{-1} \cdot k^{-1}[/tex]

     T is the temperature of the room with value  [tex]T = 25^oC = 298 \ K[/tex]

So

    [tex]\frac{N}{N_o} = e^{-\frac{0.24 }{1.987*10^{-3} * 298} }[/tex]

=> [tex]\frac{N}{N_o} = 0.67[/tex]

So the ratio of the concentration of equatorial form to the axial form is

      [tex]0.67 : 1[/tex]

Answer:

Explanation:

[tex]--------------------------------------------[/tex]

Microgram = 0.000001 Grams = Smallest Unit of Weight

1 ) Milligram = 0.001 Grams =

2 ) Centigram = 0.01 Grams

Decigram = 0.1 Grams

3 ) Gram = 1 Gram

Dekagram = 10 Grams

Hectogram = 100 Grams

4 ) Kilogram = 1000 Grams = Largest Unit of Weight = Answer

[tex]--------------------------------------------[/tex]

Hope this helps! <3

[tex]--------------------------------------------[/tex]

Kilograms are the largest unit among the options listed.

The metric system is a decimal-based system of measurement widely used around the world. It provides a standardized and convenient way to express measurements by utilizing prefixes that represent powers of 10.

In the metric system, the base unit for measuring mass is the gram (g). The gram is a relatively small unit, and to express larger or smaller masses, prefixes are added to the base unit. Here are some commonly used metric prefixes for mass.

The largest measurement among the options provided is kilograms (kg). Kilograms are larger units of measurement compared to grams (g), milligrams (mg), and centigrams (cg). The metric system follows a decimal-based system, where each unit is 10 times larger or smaller than the adjacent unit.

1 kilogram (kg) is equal to 1,000 grams (g), 1,000,000 milligrams (mg), and 10,000 centigrams (cg). Therefore, kilograms are the largest unit among the options listed.

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Answer:

3.329 g

Explanation:

First you need to determine the molar mass of H2S which is 34.1 g/mol.

With that we know that to find the moles of H2S we just divide the mass of sample with the molar mass.

3.54 g / 34.1 g/mol = 0.103812317  mol of H2S

This means that there is also 0.103812317  mol of sulfur since there is 1 mole of sulfur per 1 mole of H2S.

The molar mass of sulfur is 32.065 g/mol and to find the mass of sulfur you need to multiply the molar mass with the moles of the compound.  

0.103812317  mol * 32.065 g/mol = 3.329 g of sulfur

Let me know if you get something else or if something is unclear in the comments so that we can figure it out.

Answer:

10.76 grams

Explanation:

Given that the amount of [tex]KMnO_4[/tex] is 25.0 grams.

Mass of 1 mole of [tex]KMnO_4[/tex] = 158 grams

The number of atoms in 1 mole of [tex]KMnO_4[/tex] is 4.

Mass of oxygen in 1 mole of [tex]KMnO_4[/tex] = 16\times 4 = 68 grams.

Here, 158 grams of [tex]KMnO_4[/tex] has 68 grams of oxygen

So, the amount of oxygen in 1 gram of [tex]KMnO_4[/tex] = 68/158 grams

Therefore,  the amount of oxygen in 1 gram of [tex]KMnO_4[/tex] = [tex]\frac {68}{158}\times 25[/tex] grams

=10.76 grams

Hence, 25 grams of [tex]KMnO_4[/tex] has 10.76 grams of oxygen.

The mass of oxygen in 25.0 grams of potassium permanganate , KMnO4 is 10.13 grams.

molar mass of KMnO₄ = 39 + 55 + 16(4)

molar mass of KMnO₄ = 39 + 55 + 64

molar mass of KMnO₄ = 158 grams

molar mass of oxygen in the compound  = 64 g

Therefore,

158g of potassium permanganate has 64 g of oxygen

25 g of potassium permanganate will contain ? of oxygen

cross multiply

mass of oxygen = 25 × 64 / 158

mass of oxygen = 1600 / 158

mass of oxygen = 10.1265822785

mass of oxygen ≈ 10.13 grams

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Answer:

CaKr Na2S BaCl3 MgF. CaKr-Kr is a noble gas Na2S-not balanced BaCl3-not balanced MgF-not balanced.

Explanation:

The CaKr is  compound which is likely to form because its charge will be balanced.

A chemical compound is referred to as a substance made up of several similar molecules linked together with chemical bonds and containing atoms from multiple elements. A molecule made up of only one element's atoms is hence not a compound.

It gains charge when electrons are transferred between each other. When the count of protons is higher than the count of electrons, the charge is positive.

Ca has 1 charge and Kr has also 1 charge. hence, CaKr will form as a compound. The charge of  [tex]Na_{2}S, BaCl_{3}[/tex] and MgF is not balanced that's why they can not form compound.

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Fe produced : 27.53 g

Reaction

Fe₃O₄ + 4H₂ = 3Fe + 4H₂O

mol Fe₃O₄ (MW=233.55 g/mol) :

[tex]\tt \dfrac{49}{233.55 g/mol}=0.21[/tex]

mol ratio Fe₃O₄ : Fe = 1 : 3, so mol Fe :

[tex]\tt 3\times 0.21=0.63~g/mol[/tex]

mass Fe(Ar=55,845 g/mol)

[tex]\tt 0.63\times 55,845=35.18~g[/tex]

grams produced :

[tex]\tt \%yield=\dfrac{actual}{theoretical}\times 100\%\\\\actual=\%yield\times theoretical\\\\actual=78.25\%\times 35.18\\\\actual=27.53~g[/tex]

Answer:

I think b) C12H22O11.

Hope this answer is helpful for u.

Answer:

Chemistry, the science that deals with the properties, composition, and structure of substances (defined as elements and compounds), the transformations they undergo, and the energy that is released or absorbed during these processes

Answer:

hope it helps you a little

Answer:

Explanation:

In Pre-AP Chemistry, the development of models to explain their macroscopic observations is a primary means through which students develop an understanding of the molecular world.

You will be forced to think and apply concepts to new situations, and even derive your own theories from application. This is excellent preparation for the higher levels of thinking required in college.

Chemistry, the science that deals with the properties, composition, and structure of substances (defined as elements and compounds), the transformations they undergo, and the energy that is released or absorbed during these processes.