classify the reaction type 2LiBr+Pb(NO3)

Answer:

6.44 moles

Explanation:

At STP, 1 mole = 22.4 L

145 L × (1 mole ÷22.4 L) = 6.44 moles

Answer:

39698

Explanation:

Mass= 4.6kg

latent heat= 863

ML= 4.6*863= 39698

approximately = 397 In three significant figures

Answer : The specific latent heat of fusion of ice is, 187.608 J/g

Explanation :

Formula used :

[tex]Q=m\times L_f[/tex]

where,

Q = heat supply = 863 KJ = 863000 J

conversion used : (1 KJ = 1000 J)

m = mass of the substance = 4.6 Kg = 4600 g

conversion used : (1 Kg = 1000 g)

[tex]L_f[/tex] = specific latent heat of fusion = ?

Now put all the given values in the above formula, we get the specific latent heat of fusion of ice.

[tex]863000J=4600g\times L_f[/tex]

[tex]L_f=187.608J/g[/tex]

Therefore, the specific latent heat of fusion of ice is, 187.608 J/g

Explanation:

perhaps is NO3

this question is somehow not correct

Answer:

NO₃⁻ is reduced; I₂ is oxidized

Explanation:

I think your equation is supposed to be

NO₃⁻ + I₂ ⟶ IO₃⁻ + NO₂

If you break the equation into two half-reactions, you get

NO₃⁻ + 2H⁺ + e⁻ ⟶ NO₂ + H₂O

I₂ + 3H₂O ⟶ IO₃⁻ + 6H⁺ + 5e⁻

We see that NO₃⁻ gains an electron, so it is reduced.

I₂ loses five electrons, so it is oxidized.

The combustion of carbon is a spontaneous process where carbon reacts with oxygen to form carbon dioxide. During this process, the enthalpy of the system decreases and the entropy increases.

The combustion of carbon, a chemical reaction involving carbon and oxygen, primarily results in the formation of carbon dioxide. This process is spontaneous under standard conditions, which means that it occurs naturally without needing any additional input. However, the statement that carbon is produced from oxygen and carbon dioxide is incorrect; rather, carbon and oxygen react to form carbon dioxide in a combustion reaction.

From the thermodynamic perspective, the enthalpy of the system decreases as heat is released during the combustion, so it's not true that enthalpy remains constant. This is an exothermic reaction, which involved a negative change in enthalpy. The entropy, or the degree of randomness or disorder, increases due to the production of gas molecules from a single carbon atom and oxygen molecule, contrary to the claim that the entropy decreases.

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Answer:

Here's what I get.

Explanation:

Your argument makes sense. For example, the density of C₅H₁₂ is about 0.63 g/mL, and it increases gradually to a limit of about 0.83 g/mL.  

With the lower alkyl halides, the halogen atom is the major contributor to the mass of the molecule. The density of chloromethane is 2.2 g/mL.

As you increase the number of C atoms, the Cl atom becomes a smaller part of the molecule. The alkyl halide becomes more like an alkane.

By the time you have reached four C atoms, the density has reached a limiting value of about 0.89 g/mL.

Answer:

Stirring the salt and water

Crushing the salt so the grains are smaller

Explanation:

Another way that is not in the choices that would increase the rate of dissolving of a solute in the solvent is heating the solvent.  This increases the kinetic energy of the particles hence increasing collision rates. This helps increase the dissolution of the solute.

Stirring helps break down the solute to smaller particles. Smaller particles have a larger surface area to volume ration on which collision with solvent molecule can occur hence faster dissolution.  

Answer :  The correct option is, Only Student B

Explanation :

Lewis-dot structure : It shows the bonding between the atoms of a molecule and it also shows the unpaired electrons present in the molecule.

In the Lewis-dot structure the valance electrons are shown by 'dot'.

The given molecule is, [tex]NH_3[/tex]

As we know that nitrogen has '5' valence electrons and hydrogen has '1' valence electron.

Therefore, the total number of valence electrons in [tex]NH_3[/tex] = 5 + 3(1) = 8

According to Lewis-dot structure, there are 6 number of bonding electrons and 2 number of non-bonding electrons.

The Lewis dot structure of student A is wrong because there is a coordinate bond present between the nitrogen and hydrogen is not covalent.

The correct Lewis-dot structure of [tex]NH_3[/tex] is shown by the student B.

Answer:

niether of them

Explanation:

the rest are bs

Answer:

15.4 mol CO₂

Explanation:

5.12 mol C₃H₈ × (3 mol CO₂ / mol C₃H₈) ≈ 15.4 mol CO₂

Answer:

15.36 moles of carbon dioxide are produced when 5.12 mol of propane gas is burned in excess oxygen

Explanation:

The Balanced Chemical equation is :

[tex]C_3 H_8 (g) + 5O_2 (g) > 3CO_2 (g) + 4H_2 O(l)[/tex]

Mole ratio of [tex]C_3 H_8:CO_2[/tex] is 1 : 3

That is, 1 mole of propane gas produces 3 moles of carbon dioxide gas.

Using mole ratio we can solve this  

[tex]5.12mol C_3 H_8  \times \frac {(3mol CO_2)}{(1mol C_3 H_8 )}[/tex]

[tex]=15.36 mol CO_2[/tex] is produced.

(Answer)

Please note  :

To convert moles to mass, we multiply by molar mass  

To convert mass to moles, we divide by molar mass

Molar mass is the mass of 1 mole of the substance

For example molar mass of [tex]CO_2[/tex] is

[tex](12.0+2\times16)=44 g/mol[/tex]

(we just add the atomic mass of the atoms to get the molar mass of the substance)

Answer:

0.7M

Explanation:

Volume of NaOH = 35mL = 0.035L

Concentration of NaOH = 0.5M

Volume of HCl = 25mL = 0.025L

Concentration of HCl = ?

Solution;

The balanced equation of the reaction is shown below:

              NaOH + HCl  → NaCl + H₂O

To solve this problem, we solve from the known to the unknow. The known here is the parameters of NaOH. From here, we can find the number of moles;

Number of moles of NaOH = concentration x volume= 0.035 x 0.5

                                             = 0.0175mole

From the balanced reaction equation, we can state that:

       1 mole of NaOH reacted with 1 mole of HCl

         0.0175mole of NaOH will reacted with 0.0175mole of HCl

Now that we know the number of moles of the acid used, we can calculate the concentration of the acid used using the expression below:

  Concentration of acid = [tex]\frac{number of moles of acid}{volume of acid}[/tex]

 Concentration of acid= [tex]\frac{0.0175}{0.025}[/tex] = 0.7M

Answer:

whether their componets are made of elements or compounds

Explanation:

remeber homo means same and hetero mean different.

knowing this you also know that elements would be homogeneous and compounds would be heterogeneous since compunds are made of two or more things

Answer: Option (a) is the correct answer.

Explanation:

A mixture is defined as the substance that contains two or more different number of substances that are physically mixed together.

For example, a mixture of iron nails, sand and water.

A mixture in which solute particles are unevenly distributed into the solvent then it is known as a heterogeneous mixture.

For example, sand in water is a heterogeneous mixture.

A homogeneous mixture is defined as the mixture in which solute particles are evenly distributed in a solvent.

A homogeneous mixture is a clear solution.

For example, salt dissolved in water is a homogeneous mixture.

Thus, we can conclude that mixtures are classified as homogeneous and heterogeneous according to the distribution of their components.

Answer:

Explanation:

You can deduce the ratio of PV to nRT from the ideal gas equation.

        ⇒ PV / nRT = 1.

Thus the ratio PV to nRT is constant and equal to 1, at all pressures, such as the statement B describes.

Hence, if P increases or decreases, the other variables, V, n, or T must change to keep the ration constant and equal to 1. R is the universal constant.

Answer:

The correct answer option is A. the ratio increases as the pressure increases.

Explanation:

We are to determine whether which of the given answer options explains how does a change in pressure affect the ration of PV to nRT.

We know that, for real gases:

[tex]PV = nRT[/tex]

where,

[tex] P [/tex] is the pressure of the gas ,

[tex] V [/tex] is the volume of gas ,

[tex] n [/tex] is the number of moles ,

[tex] R [/tex] is the gas constant; and

[tex] T [/tex]  is the temperature of the gas.

Gay-Lussac’s law states that for a constant volume, the pressure of that gas is directly proportional to the temperature on the Kelvin scale.

Therefore, the ratio increases as the pressure increases.

Answer:

11 atoms

Explanation:

The formula for lead(II) bicarbonate is: Pb(HCO3)2.

Atoms in Pb(HCO3)2:

Pb=1, H=1×2, C=1×2, O=3×2

1+1×2+1×2+3×2

=1+2+2+6

=11 atoms

A molecule of Lead (II) bicarbonate, which is a binary compound, consists of 11 atoms in total: 1 lead atom, 2 hydrogen atoms, 2 carbon atoms, and 6 oxygen atoms.

The formula for lead (II) bicarbonate is Pb(HCO₃)₂. This indicates there is 1 atom of lead (Pb), 2 atoms of hydrogen (H), 2 atoms of carbon (C), and 6 atoms of oxygen (O). So, in total, there are 11 atoms in a molecule of lead (II) bicarbonate. This is a binary compound, an example of the broader category known as binary compounds, which are compounds composed of two elements.

In terms of the bicarbonate anion, it consists of 1 carbon atom, 1 hydrogen atom, and 3 oxygen atoms. It is a polyatomic ion that frequently combines with metal ions, forming a variety of essential compounds.

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Answer:

[tex]\boxed{\text{6.02 $\math{\times 10^{21}}$ molecules}}[/tex]

Explanation:

A pressure of 1 atm and a temperature of 0 °C is the old definition of STP. Under these conditions, 1 mol of a gas occupies 22.4 L.

1. Calculate the moles of hydrogen.

[tex]n = \text{0.224 L} \times \dfrac{\text{1 mol}}{\text{22.4 L}} = \text{0.0100 mol}[/tex]

2. Calculate the number of molecules

[tex]\text{No. of molecules} = \text{0.0100 mol} \times \dfrac{\text{6.022 $\times 10^{23}$ molecules}}{\text{1 mol}}\\\\= \textbf{6.02 $\mathbf{\times 10^{21}}$ molecules}\\\\\text{The sample contains }\boxed{\textbf{6.02 $\mathbf{\times 10^{21}}$ molecules}}[/tex]

Answer:  6.02 × [tex]10^{21}[/tex] molecules of hydrogen are in the container. The Ideal Gas Law equation gives the relationship among the pressure, volume, temperature, and moles of gas.  Once the moles of gas is determined, we use Avogadro's number, 6.022 × [tex]10^{23}[/tex] to get he number of molecules.

Further Explanation:

The Ideal Gas Equation is:  

[tex]PV = nRT[/tex]  

where:  

P - pressure (in atm)  

V - volume (in L)  

n - amount of gas (in moles)  

R - universal gas constant [tex]0.08206 \frac{L-atm}{mol-K}[/tex]  

T - temperature (in K)  

In the problem, we are given the values:  

P = 1 atm  

V = 224 mL  = 0.224 L (3 significant figures)

n = ?

T = 0 degrees Celsius

We need to convert the temperature to Kelvin before we can use the Ideal Gas Equation. The formula to convert from degree Celsius to Kelvin is:  

[tex]Temperature \ in \ Kelvin = Temperature\ in \ Celsius \ + \ 273.15[/tex]  

Therefore, for this problem,  

[tex]Temperature\ in \ K = 0 +273.15\\Temperature\ in \ K = 273.15[/tex]  

Solving for n using the Ideal Gas Equation:  

[tex]n \ = \frac{PV}{RT}\\n \ = \frac{(1 \ atm) \ (0.224 \ L)}{(0.08206 \ \frac{L-atm}{mol-K})( 273.15 \ K)} \\ n \ = 9.99\ X \ 10^{-3} mol[/tex]

Now that we know the number of moles of hydrogen gas, we can determine how many molecules there are:

[tex]no.\ of \ molecules \ = moles \ of \ hydrogen \ (\frac{6.022 \ X \ 10^{23} molecules}{1 \ mole\ of \ hydrogen} )\\no.\ of \ molecules \ = 9.99 \ X \ 10^{-3} \ moles \ (\frac{6.022 \ X \ 10^{23} molecules}{1 \ mole\ of \ hydrogen} )\\ no. \ of \ molecules \ = 6.02 \ X 10^{21} \ molecules \ of \ hydrogen[/tex]

Learn More  

1. Learn more about Boyle's Law https://brainly.com/question/1437490  

2. Learn more about Charles' Law https://brainly.com/question/1421697  

3. Learn more about Gay-Lussac's Law https://brainly.com/question/6534668  

Keywords: Ideal Gas Law, Volume, Pressure  

Answer:

Frogs and toads lose their tails as they develop into adults, but salamanders keep their tails

Explanation:

The salamanders, frogs, and toads are part of the amphibian family. They all live in both water and land. The water is still crucial for their live, despite them being relatively well developed for terrestrial live, with the biggest importance being that their offspring needs it in order to develop. The salamander offspring has only front limbs and tail, thus it can not live on land until it is fully developed, while the frog and toad offspring doesn't have any limbs at the start, only tail, thus not being able to even come out of the water. As they mature, the salamander offspring develops hind limbs as well, while retaining the tail. The frog and toad offspring develops front and back limbs, but its loses its tail.

Answer:

A) Frogs and toads lose their tails as they develop into adults, but salamanders keep their tails

Explanation:

Answer:

an increase in pressure will result in a decrease in volume

Explanation:

boy's law

Answer:

B. The reaction rate decreases

Explanation:

Increasing the pressure on a reaction involving reacting gases increases the rate of reaction.  

Changing the pressure on a reaction that involves only solids or liquids has no effect on the rate.

If you increase the pressure of a gas, you squeeze it into a smaller volume

Greater density of molecules increases the number of collisions. When you decrease the pressure, molecules don't hit each other as often and the rate of reaction decreases.  

Answer:

The main difference between the two models was about the location of the electron in an atom.

Explanation:

Rutherford described that:

Bohr improved the Rutherford model:

Exact Answer:

In the Rutherford model, electrons can exist in any location outside the nucleus.

In the Bohr model, electrons can exist only in certain energy levels surrounding the atom.

The exothermic reaction among the choices is B. iron rusting. An exothermic reaction is a reaction that releases heat. Rust is formed from the reaction of iron with oxygen. This reaction releases heat, hence, an exothermic reaction.

Further Explanation:

A. melting ice is an endothermic process. An endothermic process requires the absorption of energy from the surroundings. Heat is needed to change ice to liquid water. That is why, when ice is removed from the freezer and left on a warmer place it melts. The heat from the surroundings is absorbed by the ice causing it to change to liquid phase.

B. iron rusting is exothermic. Heat is released when oxygen and iron react to form rust.

C. dissolving sugar in water is an endothermic process. Heat is needed to break up the intermolecular forces of attraction holding the sugar molecules together. Also, adding heat makes the process of dissolution faster

D. dissolving ammonium nitrate in water is an endothermic process. A characteristic of endothermic reactions is that it turns the container of a substance colder. As the substance absorbs heat from the surroundings, the temperature of the surroundings, including the container, decreases. In exothermic reactions, heat is released to the surroundings making the container feel hotter during and after the reaction.

Learn More

Keywords: exothermic reaction, endothermic reaction

Answer:

That's called a first-order reaction.

Explanation:

In kinematics, the order of a chemical reaction is the sum of the power of concentrations in is rate law.

For example, consider a reaction with the following rate law:

[tex]\text{Rate} = k\cdot [\mathrm{A}]^{a}\cdot [\mathrm{B}]^{b}[/tex],

where [tex][\mathrm{A}][/tex] and [tex][\mathrm{B}][/tex] are the concentrations of the two reactants, [tex]\mathrm{A}[/tex] and [tex]\mathrm{B}[/tex].

The order of this reaction will be equal to the sum of the powers of the concentrations in the rate law. For this sample reaction, the order is equal to [tex]a + b[/tex].

For the reaction in this question, the rate law will resemble the following:

[tex]\text{Rate} = k\cdot [\mathrm{A}][/tex].

Note that the power "[tex]1[/tex]" next to the concentration of [tex]\mathrm{A}[/tex] is omitted. The order of this reaction will be numerically equal to one.

However, by convention, the order of the reaction is named in ordinals. (That is: first, second, third, etc.) The reaction here is known as a first-order reaction.

(Reference: "The Rate Law", Physical & Theoretical Chemistry, Chemistry Libretexts; "Cardinal and Ordinal Numbers Chart", Math Is Fun)

Answer:

Here is the complete statement: The overall change in enthalpy of a reaction depend ONLY ON REACTANTS AND THE PRODUCTS.

Explanation:

Change in enthalpy of a chemical reaction refers to the heat change that is associated with a chemical change when the pressure is held constant. Generally, chemical reaction involves the breaking of chemical bonds in the reactants and the formation of new chemical bonds in the products. The breaking and forming of bonds involve heat change; the amount of heat that is given off and absorb in each chemical reaction depend on the type of reactants and products that are involved in the chemical reaction.

Answer:

A

Explanation:

Answer:

In this theory, an acid is a substance that can release a proton (like in the Arrhenius theory) and a base is a substance that can accept a proton. A basic salt, such as Na+F-, generates OH- ions in water by taking protons from water itself (to make HF)

Answer:

1 is B

Explanation:

Ice is crystalline so when water drops below freezing it forms crystals, I don't know the rest.

Answer:

1. D

2. C

3. Ice is less dense than water because the orientation of hydrogen bonds causes molecules to push farther apart, which lowers the density. More organized in the solid forms verse the liquid form.

Explanation:

1. When temperatures drop below freezing crystals are formed, and crystals = ice. Ice = solid and there are more bonds in ice than there are in water.

2. When ice forms the hydrogen atoms in a water molecule bond with the oxygen atoms in other water molecules.

Final answer:

Dark matter and dark energy are termed 'dark' because they do not emit, absorb, or reflect light, which makes them invisible to traditional detection methods such as telescopes; they are detectable only through their gravitational effects.

Explanation:

Dark matter and dark energy are described as "dark" not because they emit blackbody radiation, absorb light, or are merely found in shadows, but because they are difficult to detect by conventional means. The correct answer is D. Because we cannot easily detect them. Dark matter does not emit, absorb, or reflect any light, making it invisible to traditional telescopes that detect electromagnetic radiation. Astronomers infer its existence through the gravitational effects it has on visible objects, such as the rotation curves of galaxies and the gravitational lensing of light from distant objects.

The term "dark" in dark matter and dark energy refers to the fact that these components do not interact with electromagnetic radiation in a way that allows us to detect them directly. Dark matter makes up approximately 80% of the matter in the Universe, and its presence is known primarily through its gravitational influence. Similarly, dark energy is hypothesized to be responsible for the observed acceleration of the expansion of the Universe. However, its nature remains a profound mystery in physics.

The correct answer is D. 1.13 x 10^22 atoms are present in 0.378 g of neon. Avogadro's number (6.022 x 10^23) gives the ratio of representative particles per mole of substance. For every mole of substance, there are 6.022 x 10^23 representative particles present. Since 0.378 g of neon is less than one mole of neon, the answer should be less than Avogadro's number, which makes option D a logical answer.

Further Explanation:

To get the number of atoms present in 0.378 g of neon the following steps must be done:

STEP 1: Convert 0.378 g of Neon to moles of Neon

[tex]moles \ of \ neon \ = 0.378 \ g \ Ne (\frac{1 \ mol \ Ne}{20.1797 \ g \ Ne})\\\\\boxed {moles \ of \ Ne \ = 0.018732 \ mol}[/tex]

STEP 2: Use Avogadro's number to calculate the number of atoms of Ne

[tex]no. \ of \ atoms \ Ne \ = 0.018732 \ mol \ Ne \ (\frac{6.022 \ x \ 10^{23} \ Ne \ atoms}{1 \ mol \ Ne})\\\\ no. \ of \ atoms \ Ne \ = 1.128 \ x \ 10^{22} \ atoms[/tex]

Since the given, 0.378 g has 3 significant figures, the final answer must also have 3 significant figures. Therefore,

[tex]\boxed {no. \ of \ atoms \ Ne \ = 1.13 \ x \ 10^{22} \ atoms}[/tex]

A. 6.02 x 10^23 atoms is FALSE because the given amount of neon is less than one mole. Hence, the number of atoms cannot be equal to Avogadro's number.

B. 1.187 x 10^-2 atoms is FALSE because atoms are very very small particles. It will require a large number of atoms to make up something that is measurable like a 0.378 g sample of neon. Having less than 1 atom to make up this much sample is not logical.

C. 2.28 x 10^23 atoms is FALSE because this much atoms make up 0.3781 mol of Neon but the given is 0.378 grams not moles of Ne.

D. 1.13 x 10^22 atoms is TRUE because the value is less than 6.022 x 10^23 which is logical since the sample is less than 1 mole.

Learn More

Keywords: Avogadro's Number, Mole Conversion, Atoms

Final answer:

To find the number of atoms of neon in 0.378g, we divide the mass by the atomic mass of neon to find the number of moles, then multiply by Avogadro's number. The result is approximately 1.13 × 10²² atoms. So the correct answer is option d.

Explanation:

To determine how many atoms of neon are in 0.378g of neon, first, we need to use Avogadro's number, which is 6.022 × 10²³ atoms per mole. This number helps us to convert between the number of atoms and the number of moles. Neon has an atomic mass of approximately 20.18 g/mol. Therefore, we can calculate the number of moles of neon in 0.378g by using the formula:

moles of Neon = mass (g) / atomic mass (g/mol)

moles of Neon = 0.378g / 20.18g/mol

moles of Neon = 0.0187286 mol

Now, we convert this number into atoms using Avogadro's number:

number of atoms = moles of Neon × Avogadro's number

number of atoms = 0.0187286 mol × 6.022 × 10²³ atoms/mol

number of atoms ≈ 1.13 × 10²² atoms

So the answer is (d) 1.13 × 10²² atoms of neon in 0.378g of neon.

Answer:

¹³₆C

Explanation:

The given nuclear reaction is:

          ¹⁰₅B + ₂⁴He → ᵃₙX + ₁¹H

In balancing nuclear reaction equation, the mass number which are the superscript and atomic number, the subscript on both sides of the equation must be the same.

For the mass number:

                  10 + 4 = a + 1

                  14 = a + 1

                    a = 13

For the atomic number:

             5 + 2 = n + 1

                7 = n + 1

                  n = 6

Note: n is the same as z from the equation

        therefore our atom is ¹³₆X which is an isotope of carbon, ¹³₆C

Answer:

All atoms of isotopes of a particular element have the same number of protons, but different numbers of neutrons in their nuclei.- True

Answer: True

Explanation:

All isotopes have equal number of protons but differ by number of neutrons in the nucleus. The number of neutrons changes the weight of the elements, but not the atomic number since that is a function of protons. Most isotopes are radioactive and are not stable. Eg C has two isotopes ¹²C and ¹³C, they only varies by number of neutrons and still have the same type of chemical reactivity. But ¹²C is found in nature while ¹³C is radioactive and used in carbon dating.

Answer:

[tex]\boxed{\text{6.022 $\times 10^{23}$ kg; 2.5 $\times 10^{-4}$\ mol}}[/tex]

Explanation:

1. Mass of 1 mol of bricks

[tex]m = 6.022 \times 10^{23}\text{ bricks} \times \dfrac{\text{4.0 kg}}{\text{ 1 brick}} = 2.4 \times 10^{24}\text{ kg}\\\\\text{The mass of 1 mol of bricks is }\boxed{\textbf{2.4 $\times\mathbf{10^{24}}$ kg}}[/tex]

2. Number of moles

(a) Convert grams to kilograms

[tex]6.0 \times 10^{24}\text{ g} = 6.0 \times 10^{21}\text{ kg}[/tex]

(b) Convert kilograms to moles

[tex]n = 6.0 \times 10^{21}\text{ kg} \times \dfrac{\text{1 mol bricks }}{2.4 \times 10^{24}\text{ kg}} = \text{0.0025 mol bricks}\\\\\text{The mass of the Earth equals the mass of }\boxed{\textbf{0.0025 mol of bricks}}[/tex]

Answer: The mass of 1 mole of brick is [tex]24.088\times 10^{26}g[/tex] and the moles of brick having same mass as earth is 2.49 moles.

Explanation:

We are given:

Mass of a brick = 4.00 kg = 4000 g  (Conversion factor:  1 kg = 1000 g)

According to mole concept:

[tex]6.022\time 10^{23}[/tex] number of atoms are contained in 1 mole of an atom.

As, mass of 1 brick is 4000 g

So, mass of [tex]6.022\times 10^{23}[/tex] number of bricks will have = [tex]\frac{4000}{1}\times 6.022\times 10^{23}=24.088\times 10^{26}g[/tex]

Now, calculating the moles of brick having the mass equal to the mass of Earth.

Mass of Earth = [tex]6\times 10^{27}g[/tex]

To calculate the moles of bricks, we apply unitary method, we get:

[tex]24.088\times 10^{26}g[/tex] of mass is occupied by 1 mole of brick

So, [tex]6.0\times 10^{27}g[/tex] of mass will be occupied by [tex]\frac{1}{24.088\times 10^{26}}\times 6.0\times 10^{27}=2.49moles[/tex]

Hence, the mass of 1 mole of brick is [tex]24.088\times 10^{26}g[/tex] and the moles of brick having same mass as earth is 2.49 moles.

The average mass of an atom is calculated with the formula:

average mass = abundance of isotope (1) × mass of isotope (1) + abundance of isotope (2) × mass of isotope (2) + ...  an so on

For the boron we have two isotopes, so the formula will become:

average mass of boron = abundance of isotope (1) × mass of isotope (1) + abundance of isotope (2) × mass of isotope (2)

We plug in the values:

10.81 = 0.1980 × 10.012938  + 0.8020 × mass of isotope (2)

10.81 = 1.98 + 0.8020 × mass of isotope (2)

10.81 - 1.98 = 0.8020 × mass of isotope (2)

8.83 = 0.8020 × mass of isotope (2)

mass of isotope (2) = 8.83 / 0.8020

mass of isotope (2) = 11.009975

mass of isotope (1) = 10.012938 (given by the question)

Answer:

B: Physical Science

Explanation:

The answer is physical science because you need to know the laws of physics and chemistry to know how a car works. Physical sciences = the sciences concerned with the study of inanimate natural objects, including physics, chemistry, astronomy, and related subjects.

Answer:

C its atomic number

Explanation:

Every element has a unique atomic number. The atomic number is always the same for a given element and does not change.

The number of protons in an atom is the atomic number. Protons are located in the nucleus. Being nuclei particles, they do not have a variable number. Their number is fixed and we can easily identify an atom with the number of protons, which is the atomic number.