Scientific explanations are based on objective and systematic observations carried out under carefully controlled conditions

The crystalline allotropes of sulfur are very strong and have a high melting and boiling point while the amorphous allotropes of sulfur are brittle and breaks easily.

A crystalline substance is one that has a definite arrangement of the atoms in the substance. An amorphous substance lacks this definite arrangement. We can see this arrangement when we conduct an X-ray crystallography of the sulfur.

Also, the crystalline allotropes of sulfur are very strong and have a high melting and boiling point while the amorphous allotropes of sulfur are brittle and breaks easily.

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The three isotopes of Neon, Ne-20, Ne-21, and Ne-22 are said to have an atomic number. Neon - 20 with a mass of 19.99 amu predominate all other isotopes.

Isotopes as been defined as atoms of the same element with different atomic masses but the same atomic number as the number of neutrons differs in the atoms. The neon element has three isotopes, Ne-20, Ne-21, and Ne-22.

Ne - 20 is the most predominant isotope of the Neon element as it most abundant and stable isotope with an abundance of 90.48% followed by Ne-22 (9.25%), and Ne-21 (0.27%).

Therefore, Ne-20 is a predominant isotope of Neon.

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Ions form the proton number of an atom is changed. The correct option is A.

Thus, An atom will be neutrally charged if its protons and electrons are equal in number. An ion is created when an atom's protons and electrons are different numbers.

It is technically possible to make an ion if the number of protons varies but the number of electrons stays the same. The identity of the atom is determined by the amount of protons, not by the atom itself, which will change.

An isotope would be produced if the neutron count varied. An ion will also form if the number of electrons changes because this will cause a change in charge.

Thus, Ions form the proton number of an atom is changed. The correct option is A.

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An unknown element has three naturally occurring isotopes total average atomic mass 20.18 amu and element from the periodic table is neon

Isotopes are the members of a family of an element that all have the same number of protons but different numbers of neutrons

There are three neon isotopes and the more abundant ²⁰Ne and ²¹Ne are both essentially all primordial, as there is no significant global production of these isotopes and also ²²N

Neon 20 is made up of ten proton and ten neutron the atomic mass unit of the gas is 19.992 and the abundance of the gas is 90.48% and neon 21 is made up of ten proton and eleven neutron and the atomic mass unit of the gas is 20.994 and the abundance is 0.27% and neon 22 is made up of ten proton and twelve neutron and the atomic mass unit of the gas is 21.991 and the abundance of gas is 9.25%

Unknown element from the periodic table is neon

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A. Hot Plate - Materials are heated using hot plates. A stove may readily take the place of this equipment.

B. Test Tube Holder - Kitchen tongs, which come in various sizes, can be utilized in the absence of test tube holders.

C. Beakers and flasks are used for both measuring liquids and combining various ingredients. At home, measuring cups and measuring spoons can take their place because they are wide or tall enough to be used for mixing and still have the ability to be used to measure the ingredients.

D. Stirring Rod - A stirring rod can be replaced by a variety of items. Chopsticks are an example because of their similar shape, as are spoons, ladles, and forks if the container allows them.

E. Funnel - Typically, the material used to make a kitchen funnel and a laboratory funnel is the sole distinction. Kitchen funnels are often made of plastic, whereas laboratory funnels are made of heat-resistant glass. Nevertheless, as long as it is not exposed to extremely high temperatures, it can still perform the duties of a standard laboratory funnel.

1. Before conducting any type of experiment, you should always be familiar with your lab's equipment because, without it, you won't know how to use your materials or how to fix a mistake you might make with it.

2. You may aid in preventing or eliminating hazards by being familiar with the laboratory you're working in and by constantly adhering to the correct safety protocols. Additionally, you'll be aware of what to do in the unfortunate case that something goes wrong.

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The percentage of the first cation that remained in the solution when the second cation starts to precipitate is 12.86%.

[tex]Ca ^{ + } in \: the \: solution \: = 0.0440[/tex]

[tex]Ag ^{ + } \: in \: the \: solution = 0.0940[/tex]

The balanced reaction for the equation is,

[tex]Ag_{3} PO _{4} →3Ag ^{3 + } + \: PO ^{3 - } _{4}[/tex]

[tex]Solubility \: product \: constant \: of[/tex]

[tex]Ag_{3} PO _{4} = 8.89 \times 10 ^{ - 17} [/tex]

[tex]k _{s} =[Ag ^{ + } ]^{3} \: [PO _{4} ^{3 - } ] [/tex]

[tex]8.89 \times 10 ^{ - 7} = (0.940) ^{3} \: [PO _{4} ^{3 - } ] [/tex]

[tex] \frac{8.89 \times 10 ^{ - 7}} { (0.940) ^{3}} = \: [PO _{4} ^{3 - } ] [/tex]

[tex] [PO _{4} ^{3 - } ] = 1.07 \times 10 ^{ - 13} [/tex]

The balanced equation for the reaction is,

[tex]Ca_{3} (PO _{4}) _{2}→3Ca ^{2 + } + 2PO _{4} ^{3 - } [/tex]

[tex]The \: solubility \: product \: constant \: of [/tex]

[tex]Ca_{3} (PO _{4}) _{2} = 2.07 \times 10 ^{ -32} [/tex]

[tex]k _{s} = [Ca ^{ 2 + } ] ^{ 3} \: (PO _{4}) _{2}[/tex]

[tex]2.07 \times 10 ^{ - 33} = (0.0440)^{3} \: (PO _{4} ^{3 - } )^{2} [/tex]

[tex] [PO _{4} ^{3 - } ] = \frac{2.07 \times 10 ^{ - 33} }{(0.0440)^{3} }[/tex]

[tex](PO _{4} ^{3 - }) = 4.93 \times 10 ^{ - 15} [/tex]

[tex]Ca_{3} (PO _{4}) _{2} \: will \: precipitate \: first.[/tex]

[tex]Concentration \: of \: Ca ^{ + 2} \: when \:[/tex]

the second cation starts to precipitate.

[tex]k _{s} = [Ca ^{ + 2} ] ^{ 3} \: (PO _{4} ^{3 - } ) ^{2} [/tex]

[tex]2.07 \times 10 ^{ - 33} = [Ca ^{ + 2}] ^{3} \: \times 10 ^{ - 33} [1.07 \times 10 ^{ - 13} ] ^{2} [/tex]

[tex] [Ca ^{ + 2}] = 0.00566[/tex]

The percentage of the first cation that remained in the solution when the second cation starts to precipitate is,

[tex]percentage \: \: of \: remaining \: Ca ^{ + 2} = \frac{concentration \: remaining}{initial \: concentration } [/tex]

[tex] = \frac{0.00566}{0.044} \times 100[/tex]

= 12.86 %

Therefore, the percentage of the first cation that remained in the solution when the second cation starts to precipitate is 12.86%.

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Answer:

0.0159 Liters

Explanation:

15.9 ÷ 1E3 aka 1000 = 0.0159 liters

milli means 1000 of something

The mass of copper piece use is 13.9 J/K

We are given:

• Initial temperature of copper, [tex]T_{Cu, i}[/tex] = 100°C

• Mass of water, [tex]m_{water}[/tex] = 50 g

• Initial temperature of water,[tex]T_w, i[/tex] = 20°C

• Final temperature, [tex]T_f[/tex] = 25°C

• Specific heat capacity of water, [tex]c_{water}[/tex]= 4.18 J/gK

From the given information, we need to determine the heat capacity of the copper ( [tex]C_{Cu}[/tex]).

The heat released by the copper can be calculated as:

[tex]Q_{Cu}=C_{Cu}(T_{f } - T_{Cu, i})[/tex]

While the heat absorbed by the water can be calculated as:

[tex]Q_{water}=m_{water}c_{water}(T_{f } - T_{w, i})[/tex]

we can assume that the heat released by the copper is just fully absorbed by the water. The sum of the two heats is zero.

[tex]Q_{Cu} + Q_{water } = 0[/tex]

[tex]C_{Cu}(T_f - T_{Cu, i}) + m_{water}c_{water}(T_f - T_{w,i} ) = 0[/tex]

Since we want to calculate the heat capacity of copper, we can rearrange the equation to obtain an equation for [tex]C_{Cu}[/tex].

[tex]C_{Cu}= \frac{ m_{water}c_{water}(T_f - T_{w,i} )} {(T_f - T_{Cu, i})}[/tex]

Since we are given the necessary information to solve the problem, we can just substitute the given values in the equation. Please note that the difference in temperatures in Kelvin is the same as the difference in temperatures in °C. So in this case, we can simply plug in the temperature values without changing them to Kelvin first.

[tex]C_{Cu}= \frac{ m_{water}c_{water}(T_f - T_{w,i} )} {(T_f - T_{Cu, i})} = \frac{(50g)(4.18J/gK)(25\textdegree C - 20\textdegree C)}{25\textdegree C-100\textdegree C}[/tex]

[tex]C_{Cu} = 13.9 J/K[/tex]

Heat capacity or thermal capacity is a physical property of matter, defined as the amount of heat to be supplied to an object to produce a unit change in its temperature.

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Sunlight energy can be converted by photosynthesis into chemical energy in the form of carbohydrates, which can then be used by the body for cellular respiration. Humans employ oxygen and carbohydrates, the byproducts of photosynthesis, to create energy, water, and carbon dioxide. Human breath carbon dioxide is used by the plant to complete photosynthesis.

Green plants and certain other organisms convert light energy into chemical energy through a process called photosynthesis. Light energy is gathered and utilized during photosynthesis in green plants to change the water, carbon dioxide, and minerals into oxygen- and energy-rich organic molecules.

It is impossible to overstate the role that photosynthesis plays in sustaining life on Earth. There would soon be little food or other organic materials on Earth if photosynthesis stopped. The majority of life would vanish, and eventually, the atmosphere of Earth would contain almost no gaseous oxygen. Only chemosynthetic bacteria, which can use the chemical energy of specific inorganic substances and are not reliant on the conversion of light energy, would be able to survive in such an environment.

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Using Pasteur Pipettes (or pipets) are the most commonly used tool for transferring small volumes of liquids (< 5mL) from one container to another.

A pipette, also called pipett, is a lab instrument frequently used in the fields of chemistry, biology, and medicine to transfer a predetermined volume of liquid, frequently as a media dispenser. Pipettes are available in a variety of styles with varying degrees of accuracy and precision, ranging from simple single-piece glass pipettes to more intricate adjustable or electronic pipettes. In order to draw liquid up and out of a pipette, a partial vacuum is often created above the liquid-holding chamber and then selectively released. Depending on the instrument, measurement accuracy varies substantially.

Although each form of pipette has particular descriptive titles, in practice any sort of pipette will only be referred to as a "pipette," and the required device will be clear from the context. Occasionally, pipettes that dispense.

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When keto-enol equilibrium has been reached, the compound with the largest percentage of enol is 1,2 cyclo hexanedione.

The chemical compound 1,2-cyclohexanedione has the formula (CH2)4(CO)2. It is one of three cyclohexanediones that are isomeric.

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the synthesis study of triaryl-1,3,5-triazinane-2,4,6-triones is functionalized by d6-transition metal acetylides complexes at their periphery .

triaryl-1,3,5-triazinane-2,4,6-triones (isocyanurates) peripherally functionalized by donor groups: The linear optical (LO) and nonlinear optical (NLO) properties of a series of isocyanurates functionalized by donor's arms at the periphery. These octupolar derivatives were obtained from commercial isocyanate derivatives several of these derivatives exhibit remarkable transparency or activity/ tradeoffs. In third‐order activity, the stronger donor groups (X=NH2, NMe2, or NPh2) with the longer derivatives possess effective two‐photon absorption cross sections displayed for the extended arylamino cyclotrimers. to rationalize their non linear properties and unravel their electronic structures DFT computations were also performed.

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Answer:

endothermic

Explanation:

It is endothermic since it absorbs heat.  If the reaction RELEASED heat (exothermic) the "+ heat" would be on the right side of the equation.

D

Explination: During condensation, a substance is changed from the gaseous to the liquid state of matter. Vaporization, which is more often referred to as "boiling," is the complementary process in which a chemical is converted from the liquid state of matter to a gaseous physical form.

Answer:

there are four protons in the nucleus

a) The substances in A and B mix and the result is depicted in C is chemical change.

b) The substances in A and B mix and the result is depicted in D is chemical change.

c) Under a third set of conditions, the sample depicted in C changes to that in D is a kind of physical change.

d) When the change in part (c) occurs both the sample formed have same chemical properties.

In first case,

When the substances A and B mix and the result is depicted in C this implies that A and B react to give another substance C. Since C contain atoms of both A and B therefore, it have different property than A and B. So, it is a kind of chemical change.

In second case,

When the substances A and B mix and the result is depicted in D this implies that A and B react to give another substance D in different set of condition. Since D also contain atoms of both A and B therefore, it also have different property than A and B. So, it is a kind of chemical change.

In third case,

As we know that C and D both formed by the reaction between A and B in different set of conditions. So, we can say that C and D basically differ from each other in terms of state. So, C can be converted into D by either cooling or boiling. So, it is a kind of physical change.

In fourth case,

Since, we found that both C and D are differ in state of matter but they have same Chemical properties as both are formed of A and B. So, we can say that, C and D have same chemical properties but have different Physical properties.

Thus, we concluded that when A and B react to form C and in other case form D it is Chemical change. When C converted into D, it is physical change while both have same chemical properties.

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Answer:

aaaaaaaaaaaaa

Explanation:

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Explanation:

The Periodic Law states that the physical and chemical properties of the elements recur in a systematic and predictable way when the elements are arranged in order of increasing atomic number. Many of the properties recur at intervals. When the elements are arranged correctly, the trends in element properties become apparent and can be used to make predictions about unknown or unfamiliar elements, simply based on their placement on the table.

Answer:

The periodic law states that, "properties of the elements very periodically with their Relative Atomic Mass

Explanation:

Then the modern periodic law states that, "The chemical and physical properties of element are a periodic function of the atomic number"

Hope it helps

To produce 807 kJ of heat, 33.85g of methanol ([tex]CH_3OH[/tex]) must be burned.

When -764.0 kJ of heat is involved, 1 mol of methanol, [tex]CH_3OH[/tex] is reacting

Therefore, mol of [tex]CH_3OH[/tex] for -8.07 x [tex]10^2[/tex] kJ:

= -8.07 x [tex]10^2[/tex] x 1/-764.0 kJ

= 1.056 mol

Molar mass of methanol ([tex]CH_3OH[/tex]),

MM = 1 x MM(C) + 4 x MM(H) + 1 x MM(O)

= 1 x 12.01 + 4 x 1.008 + 1 x 16.0

= 32.042 g/mol

mass of methanol ([tex]CH_3OH[/tex]) used:

Mass, m = number of mol x molar mass

= 1.056 mol x 32.04 g/mol

= 33.85 g

Hence, 33.85g of methanol ([tex]CH_3OH[/tex]) must be burned to produce 807kJ of heat.

The complete question is:

When methanol, [tex]CH_3OH[/tex], is burned in the presence of oxygen gas, [tex]O_2[/tex], a large amount of heat energy is released. For this reason, it is often used as a fuel in high performance racing cars. The combustion of methanol has the balanced, thermochemical equation

[tex]CH_3OH (g) + 32O_2 (g) \rightarrow CO_2 (g) + 2H_2O (l)[/tex]  Δ= −764 kJ

How much methanol, in grams, must be burned to produce 807 kJ of heat?

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Answer:

I'm guessing you are asking for the word that will make the hypothesis correct. In that case, it would be:
"If the mass of a sample of water is increased, then the rate at which it's temperature changes will be decreased."

Explanation:

Mass and temperature have an inverse relationship, so when one of the values increase, the other decreases. On Study.com there is more on this subject. I will put a link for you :)

https://homework.study.com/explanation/how-does-the-amount-of-a-substance-affect-the-rate-at-which-temperature-changes.html#:~:text=For%20a%20given%20amount%20of,a%20smaller%20increase%20in%20temperature.

I hope this helps!

Answer:

C

Explanation:

this is because the rest talk about the findings of protons,neutrons and electrons.

Answer:

Andrew made landfall at 5 a.m. as a Category 5 — at the time only the third Category 5 to land on U.S. soil — just south of Miami with top winds at 165 mph and a 16.9-foot storm surge

Explanation:

Natural gas contains methane (CH[tex]4[/tex]), which is used to produce hydrogen by thermal processes like stem-methane reformation and partial oxidation.

In steam-methane reforming, which is the most common method to produce hydrogen, high temperature steam (700°C - 1000°C). The pressure required is 3-25 bar pressure, in the presence of a catalyst. Steam reforming is an endothermic process. Carbon monoxide and steam are reacted using catalyst to produce carbon dioxide and hydrogen.

Partial oxidation is an exothermic process. It is much faster than steam reforming. This method initially produces less hydrogen.

These processes are more preferred because the use of petroleum is low and the emissions is also low. Total greenhouse gases emission is cut.

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In simple summary form, the calvin cycle requires an input of 3 CO₂ for every product that is formed and the output product is a three-carbon molecule, which is used for glucose synthesis.

Calvin cycle is light-independent (dark) reactions or carbon reactions.

In photosynthesis (convert light energy into chemical energy), the carbon in carbon(IV) oxide is being reduced to form glucose.

The pigment chlorophyll absorbs one photon and loses one electron (it passed throw an electron transport chain) in the light-dependent reactions.

The enzyme RuBisCO takes carbon(IV) oxide in the light-independent reactions.

During Calvin cycle, three molecules of carbon dioxide (CO₂) are combined with hydrogen ions to form three carbon-molecules (see the picture).

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Answer:

Electron gain enthalpy is defined as the amount of energy released when an electron is added to an isolated gaseous atom. 

Option 4- no, no, no, no. (for physical change.)

Chemical Change -A chemical change is the conversion of one substance into another, the development of new chemicals with unique features, or any combination of these.

There are five (simple) methods for identifying a reaction:

1. change of color

2. Gas formation

3. pH change

4. Temperature change

5. Precipitate formation

Physical change - A physical change happens when a substance's physical characteristics change without undergoing chemical composition. Common physical changes include melting, adjustments to size, volume, color, density, and crystal structure.

Therefore, according to the question physical changes are-

1. Reacts with another substance- no

2. Temperature change - no

3. Gas, sound, or light produced - no

4. New substance formed - no

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The true statement about the model is that the model shows how the various atoms are connected in the molecule.

A molecular model is a representation of a molecule. We know that the molecular model shows the extent to which the atoms are bonded in the compound. The model gives us an idea of the intricate atom to atom arrangement that exists in the molecule that is under study.

Now we know that the atoms that are in the models must be shown by the use of different colors. This enables us to be able to effectively and properly distinguish between the atoms of the compound as shown in the model.

The true statement about the model is that the model shows how the various atoms are connected in the molecule.

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There is 44 % of CaCO3 in the mixture

Step 1: Data given

Mass of mixture = 2.500 grams

Mass after heating = 2.016 grams

Step 2: The balanced equation

CaCO3 → CO2 + CaO

Step 3: Calculate mass CO2 lost

Mass CO2 lost = Mass before heating - mass after heating

Mass CO2 = 2.500 - 2.016 = 0.484 grams

Step 4: Calculate the mole's CO2

Moles CO2 = Mass CO2 / molar mass CO2

Moles CO2 = 0.484 grams / 44.01 g/mol

Moles CO2 = 0.0109 moles

Step 5: Calculate moles CaCO3

For 1 mol CaO we need 1 mol CO2 for 1 mol CaCO3

For 0.0109 mol CO2, we have 0.0109 mol CaCO3

Step 6: Calculate the mass of CaCO3

Mass CaCO3 = moles CaCO3 * molar mass CaCO3

Mass CaCO3 = 0.0109 moles * 100.08 g/mol

Mass CaCO3= 1.10 grams

Step 7: Calculate the mass per cent of CaCO3

Mass % CaCO3 = (

There is 53.8 % of CaCO3 in the mixture 1.10 grams / 2.750 grams )*100 %

Mass % CaCO3 = 44 %

The mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilograms of carbon 12.

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