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Rusting is a chemical change where iron reacts with oxygen and water to form iron oxide, a new substance with distinct chemical properties. This process signifies a release of energy and is a part of corrosion, differentiating it from mere physical changes.

Rusting is considered a chemical change because it results in the formation of a new substance with different properties compared to the starting materials. When iron is exposed to oxygen and water, a reaction occurs that produces iron oxide, commonly known as rust. This process, known as corrosion, involves not just a change in the appearance of the iron, but also the formation of a new chemical compound with its own distinct properties.

A chemical property of iron is its tendency to combine with oxygen, an observation that can be made when iron begins to rust. The rusting process not only changes the color and texture of the iron but also signifies that energy stored in the reactants has been released during the formation of the rust. Unlike physical changes that do not affect the substance's chemical identity, chemical changes like rusting create a fundamentally different kind of matter.

Answer:

The mass of copper piece is 44.8 grams

Explanation:

Density is defined as amount of mass present in the unit volume of the substance.

Mathematically written as:

[tex]\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}[/tex]

We are given:

Density of copper, d =[tex]8.96 g/cm^3[/tex]

Mass of copper piece = M

Volume of the copper piece = V = [tex] 5.0 cm^3[/tex]

Putting values in above equation, we get:

[tex]8.96 g/cm^3=\frac{M}{ 5.0 cm^3}[/tex]

[tex]M=8.96 g/cm^3\times 5.0cm^3=44.8 g[/tex]

Hence, the mass of copper piece is 44.8 grams

More protons in the nucleus need more neutrons to bind the nucleus together. The graph below is a plot of the number of neutrons versus the number of protons in various stable isotopes. The stable nuclei are in the pink band known as the belt of stability. They have a neutron/proton ratio between 1:1 and 1.5.

The ratio of neutrons to protons in Radon-222 has been found to be 1.58.

The radon has been the radioactive element.  The atomic number of the element has been 222. The element has been consisted of 86 protons.

The number of neutrons and protons has been the mass of the nucleus and has been consisted of the atomic mass of the element. In an isotope, the element has 222 as the atomic number.

Since. Atomic number = Neutrons + Protons

222 = Neutrons + 86

Neutrons = 136

The ratio of neutrons to protons can be given as:

[tex]\rm \dfrac{Neutrons}{Protons}[/tex] = [tex]\rm \dfrac{136}{86}[/tex]

[tex]\rm \dfrac{Neutrons}{Protons}[/tex] = 1.58

The ratio of neutrons to protons in Radon-222 has been found to be 1.58.

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Answer:

D.

all of these

1) We don't actually need to solve this, because we can tell by eye-balling this; however, let's solve it anyway to go over the steps.

At STP, or standard temperature and pressure, a mole of gas always has a volume of 22.4 L.

We have 48.6 g [tex]CO_2[/tex]. Using the molar mass of carbon dioxide, we find the number of moles

[tex]48.6 \ g \ CO_2 \ * \dfrac{1 \ mol \ CO_2}{44.01 \ g \ CO_2} = 1.10 \ CO_2[/tex].

To get the volume, we write

[tex]1.10 \ mol \ CO_2 * \dfrac{22.4 \ L}{mol} = 24.7 \ L \ CO_2[/tex].

2) We have 0.179 g of this gas taking up 1 L.

That means we have [tex] \frac{1}{22.4} \ mol[/tex] of this gas, because one mole of a gas at STP takes up 22.4 L.

If [tex]\frac{1}{22.4} \ mol=0.179 g[/tex], we can solve to find its molar mass and then its identity.

[tex](22.4)(0.179) \ \dfrac{g}{mol} = 4.00 \ \dfrac{g}{mol} [/tex]

He has this molar mass, so we know the identity of the gas is He.

3) 

1. This is a decomposition reaction of the form AX ⇒ A + X.

2. ΔH refers to the change in enthalpy in a reaction. For a positive value, the reaction is endothermic; for a negative value, it is exothermic. An endothermic reaction requires energy added to run the reaction, so when this is the case, we write that KE is a reactant. 

To find the value for enthalpy, we use known values to calculate 572 kJ, meaning the reaction is endothermic. We write KE as a reactant. (You can also find enthalpy relatively, which is useful when you don’t have the known values for your calculation).

3. The Law of Conservation of Mass states that in a closed system like a chemical reaction, matter (and thus mass) can neither be created nor destroyed. The Law of Conservation of Energy states that energy can never be created or destroyed. Thus, all reactants and products, including energy, must be balanced in a thermochemical equation.

4) We need to write a balanced equation for this reaction.

[tex]2H_2O = 2H_2+O_2[/tex]

Next, we go from grams to moles.

[tex]1 \ mol \ H_2O = 18.016 \ g \ H_2O[/tex]

[tex]38.0 \ g \ H_2O * \dfrac{1 \ mol \ H_2O}{18.016 \ g \ H_2O} = 2.11 \ mol \ H_2O[/tex].

We use the same process to determine there are [tex]1.98 \ mol \ H_2[/tex].

That means that for 2.11 moles of water, we get 1.98 moles of diatomic hydrogen. There are two moles of diatomic hydrogen per mole of diatomic oxygen here in the balanced equation, so we write 

[tex]1.98 \ mol \ H_2 * \dfrac{1 \ mol \ O_2}{2 \ mol H_2} = 0.99 \ mol \ O_2[/tex]

[tex]0.99 \ mol \ O_2 * \dfrac{32.00 \ g \ O_2}{mol \ O_2 } = 32.00 \ g \ O_2[/tex]

5) [tex]1 \ g \ H_2 = 2.016 \ g \ H_2[/tex]

[tex]12.0 \ g \ H_2 * \dfrac{1 \ mol \ H_2}{2.016 \ g } =5.95 \ mol \ H_2[/tex]

One mole of a gas at STP has a volume of 22.4 L.

5.95 mol * 22.4 L/mol = 133 L

6) [tex]1 \ g \ H_2 = 2.016 \ g \ H_2[/tex]

[tex]2 \ mol \ H_2 * \dfrac{2.016 \ g \ H_2}{1 \ mol \ H_2}=4 \ mol \ H_2[/tex]

7) [tex]1 \ mol \ H_2O = 18.016 \ g \ H_2O[/tex]

[tex]150.0 \ g \ H_2O * \dfrac{1 \ mol \ H_2O}{18.016 \ g \ H_2O} = 8.326 \ mol \ H_2O[/tex]

8) We first balance this to get [tex]2H_2O = 2H_2 + O_2[/tex]. There are two moles of water per mole of diatomic oxygen.

9) To produce 8.0 mol diatomic hydrogen, we use the balanced equation from above.

We have a one-to-one ratio of water to diatomic hydrogen, so we need 8.0 mol water.

10) Again, using our balanced equation, we first find the number of moles of water.

[tex]1 \ mol \ H_2O = 18.016 \ g \ H_2O[/tex]

[tex]50.0 \ g \ H_2O * \dfrac{1 \ mol \ H_2O}{18.016 \ g \ H_2O} = 2.78 \ mol \ H_2O[/tex]

We have that there are two moles of water for every one mole of diatomic oxygen, so we have 1.39 mol diatomic oxygen.

This is [tex]1.39 \ mol * \dfrac{32.00 \ g \ O_2}{1 \ mol \ O_2} = 44.5 \ g \ O_2[/tex]

The three main factors that help in determining the composition of ocean water are temperature, salinity, and density.  

The temperature helps in determining the rate of evaporation of the sea. Next factor is salinity, it helps in knowing the salty nature of the ocean, and helps in identifying the other essential factor of ocean water, that is, density. The density is one of the most essential factors, as ocean having more salt composition are less dense in comparison to those having less salt.  

Answer : The magnitude of the current is, 3 ampere

Solution :

In a series circuit, the total resistance will be,

[tex]R=R_1+R_2[/tex]

[tex]R=10\Omega +4\Omega =14\Omega[/tex]

Using coulomb's law,

[tex]V=I\times R\\\\I=\frac{V}{R}[/tex]

where,

V = voltage = 42 V

I = electric current

R = resistance = 14 ohms

Now put all the given values in the above formula, we get

[tex]I=\frac{42V}{14\Omega}=3ampere[/tex]

Therefore, the magnitude of the current is, 3 ampere

To convert mass of a product to mass of a reactant, determine the molar mass of both substances, convert the product's mass to moles, apply the mole ratio, and convert the reactant's moles back to mass.

To convert the mass of a product to the mass of a reactant in a chemical reaction, you need to follow several steps:

First, determine the molar mass of the product.

Use this molar mass to convert the product's mass to moles.

Next, apply the mole ratio from the balanced chemical equation to find out the number of moles of the reactant.

Finally, use the molar mass of the reactant to convert these moles back to mass.

This process involves a sequence of conversions from mass to moles, mole ratio application, and finally, from moles back to mass.

Answer: The balanced chemical equation is given by,

[tex]2C_2H_6+7O_2\rightarrow 4CO_2+6H_2O[/tex]

Explanation:

[tex]C_2H_6+O_2\rightarrow CO_2+H_2O[/tex]

Law of conservation of mass states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form.  

This also means that total mass on the reactant side must be equal to the total mass on the product side.

So, the balanced chemical equation is given by, will writing stoichiometric coefficient 2 in front of ethane , 7 in front of oxygen , 4 in front of carbon dioxide gas and 6 in front of water.

[tex]2C_2H_6+7O_2\rightarrow 4CO_2+6H_2O[/tex]

According to reaction, 2 moles of ethane reacts with 7 moles of oxygen to give 4 moles f carbon dioxide gas and 6 moles of water.

Icing sugar dissolves in water faster than granular sugar because it has a larger surface area, which enhances interactions with solvent molecules, thus speeding up dissolution. Stirring and temperature also affect the rate of dissolution but icing sugar's fine particles inherently dissolve quicker.

Using the particle theory of matter, we can explain why icing sugar dissolves more rapidly than granular sugar. The rate at which a solute dissolves is influenced by the surface area exposed to the solvent. Icing sugar, being finely ground, has a much larger surface area compared to granuler sugar, allowing for more interactions between the sugar particles and the water molecules, leading to a faster rate of dissolution.

Agitation of the solution can also increase the rate at which sugar dissolves. Stirring introduces fresh solvent molecules to the solute, enhancing dissolution by preventing saturation at the interface. This principle applies to both icing and granular sugars but is more pronounced with larger particles like those found in granular sugar.

The dissolving process, or rate of dissolution, is enhanced not only by increasing surface area and agitation but also by temperature. Hot water will dissolve sugar faster than cold water due to the increased energy, which in turn increases the frequency and energy of collisions between solvent and solute particles.

A globe is a spherical model that precisely represents the Earth's geography with a true-scale size and shape of continents and oceans, but it has limitations such as being less portable and not showing all sides simultaneously.

To describe the physical properties of a globe placed on a desk, one would note several characteristics. A globe is a spherical representation of the Earth, including details such as continents, countries, and geographical features like mountains and oceans. It is equipped with a geographic coordinate system and a scale which helps to maintain accurate distances and proportions between locations. Due to its shape, a globe provides a distortion-free representation of Earth's geography, preserving both the size and shape of landmasses and bodies of water. However, a globe has limitations as it is not as portable as flat maps, cannot be viewed entirely at once, and cannot be easily stored in compact spaces. Moreover, while globes provide a true-to-scale representation of the Earth, they cannot be easily enlarged to show detailed views of specific areas.

Answer:

The salinity of the sea decreases due to an increase in fresh water in the ocean from the melting of the polar ice caps.

Explanation:

Ocean water can become saltier or fresher depending on environmental factors.

 Melted ice, fresh water, will decrease the salinity of the oceans. That is, the process of oceanic desalination or decrease in salinity, known as freshening, is generated by the discharge of fresh water from the ice of glaciers into the salty water of the seas that surround it.

The two changes of state of the refrigerant are necessary to operate a refrigerator because liquid refrigerant must evaporate and cool.

A refrigerator is a heat engine in which work is done on a refrigerant substance in order to collect energy from a cold region and exhaust it in a higher temperature region, thereby further cooling the cold region.

The liquid refrigerant is used for heat transfer in a refrigeration system, which absorbs heat at a low temperature and low pressure and rejects heat at a higher temperature and a higher pressure.

The liquid refrigerant must evaporate (change from a liquid to a gas) and cool. This process releases heat. The cool gas is pumped through tubes so that it can absorb heat from the interior of the refrigerator, keeping it away from the food. Then the gas must condense into a liquid so that it can release the absorbed heat to the outside and begin the cycle again.

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Table salt (sodium chloride) and water are two fundamental examples of chemical compounds with distinct properties and essential roles in our daily lives. While table salt is ionic and dissolves easily in water, water itself is a covalent compound with unique properties that are vital for sustaining life and various industrial applications.

Table salt (sodium chloride, NaCl) and water (H2O) are examples of chemical compounds, which are formed when two or more elements combine in fixed proportions through chemical bonding. Here's an explanation of each:

Table Salt (Sodium Chloride, NaCl):

Table salt is a common chemical compound that consists of two elements, sodium (Na) and chlorine (Cl). Sodium is a highly reactive metal, and chlorine is a toxic, greenish-yellow gas. However, when these elements chemically react, they combine to form the stable compound sodium chloride (NaCl). Sodium donates one electron to chlorine, forming a positively charged sodium ion (Na+) and a negatively charged chloride ion (Cl-).

These oppositely charged ions are held together by ionic bonds due to electrostatic attraction. Table salt is a crystalline solid with a distinct salty taste and is commonly used to season food and preserve it. It is highly soluble in water, and when dissolved, it dissociates into its constituent ions, making it an electrolyte that conducts electricity in solution.

Water (H2O):

Water is a vital chemical compound consisting of two hydrogen (H) atoms covalently bonded to one oxygen (O) atom. Covalent bonds involve the sharing of electrons, resulting in a molecule with a bent, V-shaped geometry. Water is unique due to its high polarity, meaning it has a partial positive charge near the hydrogen atoms and a partial negative charge near the oxygen atom.

This polarity results in several of water's essential properties, such as its ability to form hydrogen bonds, which give water a high heat capacity, surface tension, and excellent solvent properties. Water is essential for life, serving as the universal solvent in which many biochemical reactions occur. It's also crucial for regulating temperature and maintaining life processes in living organisms.

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Answer:

Certainly! Here's an example that demonstrates how gravity affects objects through gases, liquids, and solids:

Explanation:

Consider a balloon filled with helium gas. When the balloon is released, it rises upwards due to the force of gravity acting on it. Gravity pulls the balloon downwards, but the buoyant force exerted by the surrounding air (a gas) is greater than the weight of the balloon, causing it to float or rise in the air.

Now, imagine a similar scenario but with a beach ball floating in water (a liquid). When the beach ball is placed in water, it experiences the force of gravity pulling it downwards. However, the buoyant force exerted by the water is greater than the weight of the beach ball, causing it to float or rise to the surface of the water.

Lastly, let's consider a solid object like a book placed on a table. The force of gravity pulls the book downwards, creating a normal force between the book and the table. This normal force counteracts the force of gravity, preventing the book from falling through the table and keeping it in place.

In all these examples, gravity acts on the objects, whether they are in the form of gases, liquids, or solids. The specific interactions between gravity and the objects depend on the density, buoyancy, and other physical properties of the substances involved.

Gravity's effects can be seen when a helium balloon (gas) rises in the air, an apple (solid) falls and sinks in water (liquid), and a book (solid) is held stationary on a table due to the force of gravity counteracted by the table's support.

Gravity affects all objects regardless of whether they're in gas, liquid, or solid states. An example that illustrates gravity's influence through gases, liquids, and solids could involve observing a helium balloon in the air (gas), an apple falling into water (liquid), and a book resting on a table (solid).