How many atoms are there in 65.89 g of lead?

When an electron goes from a higher shell to a lower shell then it loses energy.

A photon is a particle of light defined as a discrete bundle (or quantum) of electromagnetic (or light) energy.

When an electron goes from a higher shell to a lower shell then it loses energy.

So, when an electron moved from shell n = 2 to shell n = 1 then a photon of energy is released.

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The following types of bonds exists between the listed atoms;

A bond is polar covalent when the electronegativity difference between the bonding atoms is above that found in a nonpolar covalent bond.  Now we shall see the types of bonds between these atoms.

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Answer:

3666.33 gm

Explanation:

O3  mole mass = 47.997

Each mole has   6.022 x 10^23   molecules

4.6 x 10^25 / 6.022 x 10^23     x    47.997 gm/mole  = 3666.33 gm

Answer:

cannot remain at rest under the action of any shear force.

The Ksp of the solution is 1.97 * 10^-9.

The pH is defined as the hydrogen ion concentration of the solution. Now we have the pH of the solution as 10.9.

We know that;

pOH = 14 - pH

pOH = 14 - 10.9

pOH = 3.1

[OH^-] = Antilog [-3.1]

[OH^-] =7.9 * 10^-4 M

Now

Ksp = [M^2+] [2OH^-]^2

Ksp = s * (2s)^2

Ksp = 4s^3

Now s = 7.9 * 10^-4 M

Ksp = 4(7.9 * 10^-4)^3

Ksp = 1.97 * 10^-9

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3.08 is the pOH of a 0.175 M aqueous solution of [tex]NX_3[/tex].

0.215% is the per cent ionization of a 0.325 M aqueous solution of [tex]NX_3[/tex]

pH is a measure of how acidic/basic water is.

A)

[tex]NX_3 + H_2O[/tex] →[tex]NHX_3^+ + OH^-[/tex]

Kb = 4.5 x[tex]10^-6[/tex]

Kb = {concentration of (NH₄⁺) x concentration of (OH⁻)} ÷ concentration of (NH₃).

concentration of (NH₄⁺) = concentration of (OH⁻) = x.

x² = Kb x concentration of (NH₃)

x² = 4.5 × 10⁻⁶ × 0.175 = 7.0 × 10⁻⁷.

x = concentration of (OH⁻) = √(7.0 × 10⁻⁷)

= 8.367 × 10⁻⁴

pOH = -log(c(OH⁻))

=- log ( 8.367 × 10⁻⁴)

= 3.08

B)

Chemical reaction: NX₃ + H₂O ⇄ NX₃H⁺ + OH⁻.

Concentration of (NX₃) = 0.325 M.

Kb = 4.5 x 10⁻⁶.

[NX₃H⁺] = [OH⁻] = x.

[NX₃] = 0.325 M - x.

Kb = [NX₃H⁺] x [OH⁻] ÷  [NX₃].

4.5 x 10⁻⁶ = x² ÷ (0.325 M - x).

x = 0.0007 M.

Per cent of ionization:

α = 0. 0007 M ÷ 0. 325 M x 100%

= 0.215%.

Hence,

3.08 is the pOH of a 0.175 M aqueous solution of [tex]NX_3[/tex].

0.215% is the per cent ionization of a 0.325 M aqueous solution of [tex]NX_3[/tex]

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From the equation of the graph, the activation energy of the reaction is -2.2 * 10⁴ J/mol.

Activation energy is the minimum required energy that reactant molecules must possess for a reaction to proceed towards formation of products.

The activation energy is determined from the slope of ln k against 1/T(K).

Given the equation, y = -2.2 * 10⁴ x + 45.0.

Comparing with the equation of a straight line, y = mx + c

The gradient, m = -2.2 * 10⁴

Therefore, the activation energy of the reaction is -2.2 * 10⁴ J/mol.

In conclusion, reactant molecules must break the activation energy barrier in order to form products.

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Answer:

[tex]\huge\boxed{\sf 102.5\ cm}[/tex]

Explanation:

Given that,

Circumference = C = 41 inches

Also,

Multiply 41 to both sides

41 inches = 2.5 × 41 cm

41 inches = 102.5 cm

So, The tree has a circumference of 102.5 cm.

[tex]\rule[225]{225}{2}[/tex]

The experiment seeks to find out if the seeds take up oxygen as they germinate.

An experiment is carried out in order to  determine cause and effect relationships. The independent variable is the variable that is manipulated in the experiment.

a. The set up B is the control set up

b. The independent variable is the presence/ absence of the seeds while the dependent variable is the color of the solution in both containers.

c. The amount of oxygen in each container can be measured before and after.

d. The hypothesis is that the seeds take up oxygen as they germinate.

Hence, the experiment seeks to find out if the seeds take up oxygen as they germinate.

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The electromagnetic spectrum of an element is not limited only to the visible region of the spectrum.

An electromagnetic spectrum is a range of frequencies and wavelengths into which an electromagnetic wave is distributed into.

In Science, the electromagnetic spectrum consist of the following types of energy from highest to lowest frequency and shortest to longest wavelength:

In this context, we can infer and logically deduce that the electromagnetic spectrum of an element is not limited only to the visible region of the spectrum.

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Answer:

An electron in an excited energy level of an atom will always drop to lower energy levels, emitting very specific wavelengths of light in the process.

Answer:

AuW₃

Explanation:

Answer: The new pressure is 2.8 atm.

Explanation:

Since our given information only involves pressure and volume, we will use Boyle's Law: [tex]P_{1} V_{1} =P_{2} V_{2}[/tex]. Let's input the data into the formula.

[tex]1.4atm*500mL=P_{2} *250mL[/tex]

We have to rearrange our data a bit now because the volume is supposed to be in liters. To convert from milliliters(mL) to liters(L), you must divide the number by 1000. That is what we will do with both of our given volumes.

[tex]\frac{500mL}{1000} =0.5L[/tex]     [tex]\frac{250mL}{1000} =0.25L[/tex]

Now that our volumes are in liters, we can correctly plug in our data.

[tex]1.4atm*0.5L=P_{2} *0.25L[/tex]

Since we do not know the value [tex]P_{2}[/tex], we must rearrange the formula into a stoichiometric equation to find out the answer.

[tex]P_{2}=\frac{1.4atm*0.5L}{0.25L}[/tex]    [tex]P_{2}=2.8 atm[/tex]

Our final answer is 2.8 atmospheres.

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Answer:

carbon molecules share their 4 valence electrons through single, double, and triple bonds.

Explanation:

I think you meant ionic bonds not lonic bonds

Answer:

AgNO3 + KI → AgI + KNO3

Explanation:

Yes, it's produced potassium nitrate

Answer:

320

Explanation:

Because the question is asking for 2 significant figures, you want to try to get rid of all of the numbers to the right of the 1. That way, the only numbers that will be significant are the numbers in the position of the 3 and the 1.

Before you can make the rest of the numbers equal 0, you need to correctly round the number in the last significant position (the number 1).

If the number to the right of the 1 is from 0-4, the number stays the same. If the number is from 5-9, the 1 needs to be increased by a unit.

Since the number to the right is an 8, you need to change the 1 to a 2. Now, you can make all of the other numbers a 0. There should be no decimal place because it would mean that the zero to the left of it is significant.

The hydrogen bonding atoms in melatonin are phospholipids and cholesterol.

This is the type of interaction which involves a hydrogen atom being covalently bound to a more electronegative "donor".

Melatonin controls sleep-wake cycle and has phospholipids and cholesterol which have high affinity for hydrogen bonding.

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The correct rate law for the reaction is given as Rate = -0.208 hr-1 [sucrose].

A first order reaction is one in which a plot of the logarithm of the concentration against time gives a straight line graph. Now we know that this is a decomposition reaction thus the slope is negative.

Thus, in this case, the correct rate law for the reaction is given as Rate = -0.208 hr-1 [sucrose].

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21.1 grams of calcium chloride will be produced when 27.0 g of calcium carbonate is combined with 14.0 g of hydrochloric acid.

The reactant that is consumed first in a chemical reaction is the limiting reagent or limiting reactant because it stops any more reactions from taking place. The limiting reagent controls how much product is produced during the reaction.

CaCO3(s) + 2HCl(aq) ==> CaCl2(aq) + H2O(l) + CO2(g)  

[tex]mols CaCO3 =[/tex] [tex]27 *\frac{1 mol}{100g}[/tex] = 0.27 mol

[tex]mols HCl = 15 gx \frac{1 mol}{36.5 g}[/tex] = 0.38 mol

Limiting reactant = HCl ( it takes 2x the mols of HCl compared to mols CaCO3 as per balanced equation)

mass of CaCl2 = [tex]0.411 mols HCl x\frac{ 1 mol CaCl2}{ 2 mols HCl } x 111.0 g/mol[/tex]

mass of CaCl2 = 21.1 g

Hence, 21.1 g of calcium chloride will be produced when 27.0 g of calcium carbonate is combined with 14.0 g of hydrochloric acid.

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From the coefficients of the equation, we know that for every 2 moles of Al consumed, 6 moles of HCl are consumed.

This means 6(2/2)=6 moles of HCl are needed.

Since there are [tex]6.022 \times 10^{23}[/tex] molecules in 1 mole of a substance, there are :

[tex]6(6.022 \times 10^{23}}=\boxed{4 \times 10^{24} \text{ (to 1 sf)}}[/tex]

The answers include:

This involves the formation of a new products from substances. In this scenario, a rising bread contains alcohol which evaporates.

Photographs also fall under this category and is therefore an irreversible chemical change.

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Answer:

1470 kJ (to 3 sf)

Explanation:

(802)(1.83) = 1470 kJ (to 3 sf)

Answer:

The surface tension of water is high due to the dipole nature of water, meaning that the water molecules pull on each other by electrical charge. Soap and detergents interrupt this layer, reducing the surface tension.

A visual, though not scientifically accurate, would be a set of magnetic marbles that form a sheet. If you randomly stick in glass marbles the overall strength decreases since they are not all pulling together in order.

There are some substances, called super wetters, generally silicone surfactants that give a truly amazing drop in surface tension, where a small puddle of water can spread to many times it’s own size. These types of surfactants are used in laundry detergent and french fry oil to prevent foaming and in polymers to promote flow.

Hope it helps!

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Answer:

The surface tension of water is high due to the dipole nature of water, meaning that the water molecules pull on each other by electrical charge. Soap and detergents interrupt this layer, reducing the surface tension.

A visual, though not scientifically accurate, would be a set of magnetic marbles that form a sheet. If you randomly stick in glass marbles the overall strength decreases since they are not all pulling together in order.

There are some substances, called super wetters, generally silicone surfactants that give a truly amazing drop in surface tension, where a small puddle of water can spread to many times it’s own size. These types of surfactants are used in laundry detergent and french fry oil to prevent foaming and in polymers to promote flow.

Explanation:

Answer: 2.23

Explanation:

The dissociation of acetic acid is as follows:

HCOOH(aq) ⇋ HCOO− (aq) + H+(aq)

The ICE table for the concentrations of ions is given below. From the table, the concentration of HCOO- and H+ can be found out.

                                                     HCOOH → HCOO−  +   H+
Initial Concentration                     0.019 M         0             0
Equilibrium Concentration          (0.019−x) M    x              x

Where,

At equilibrium, dissociation constant can be calculated as follows.

[tex]K_{\mathrm{a}}=\frac{x^{2}}{(0.19-x) \mathrm{M}}[/tex]

At equilibrium, the concentration of x is negligible as compared to that of HCOOH.

Substitute the value of Ka in the above equation.

[tex]\begin{aligned}K_{\mathrm{a}} &=\frac{x^{2}}{0.19-x} \\x &=\sqrt{1.8 \times 10^{-4} \times 0.19} \\&=0.00584 \mathrm{M}\end{aligned}[/tex]

Here, the concentration of hydrogen ion is obtained. From the hydrogen ion concentration, the pH of the solution is found out as follows:

[tex]\begin{aligned}\mathrm{pH} &=-\log \left[\mathrm{H}^{+}\right] \\&=-\log (0.00584 \mathrm{M}) \\&=2.23\end{aligned}[/tex]

Therefore, the pH of 0.19M HCCOH is 2.23

Answer:

The rate constant of the reaction at 125˚ is [tex]0.3115 \ \text{sec}^{-1}[/tex].

Explanation:

The Arrhenius equation is a simple equation that describes the dependent relationship between temperature and the rate constant of a chemical reaction. The Arrhenius equation is written mathematically as

                                                  [tex]k \ = \ Ae^{\displaystyle\frac{-E_{a}}{RT}}[/tex]

                                               [tex]\ln k \ = \ \ln A \ - \ \displaystyle\frac{E_{a}}{RT}[/tex]

where [tex]k[/tex] is the rate constant, [tex]E_{a}[/tex] represents the activation energy of the chemical reaction, [tex]R[/tex] is the gas constant, [tex]T[/tex] is the temperature, and [tex]A[/tex] is the frequency factor.

The frequency factor, [tex]A[/tex], is a constant that is derived experimentally and numerically that describes the frequency of molecular collisions and their orientation which varies slightly with temperature but this can be assumed to be constant across a small range of temperatures.

Consider that the rate constant be [tex]k_{1}[/tex] at an initial temperature [tex]T_{1}[/tex] and the rate constant [tex]k_{2}[/tex] at a final temperature [tex]T_{2}[/tex], thus

                         [tex]\ln k_{2} \ - \ \ln k_{1} = \ \ln A \ - \ \displaystyle\frac{E_{a}}{RT_{2}} \ - \ \left(\ln A \ - \ \displaystyle\frac{E_{a}}{RT_{1}}\right) \\ \\ \\ \rule{0.62cm}{0cm} \ln \left(\displaystyle\frac{k_{2}}{k_{1}}\right) \ = \ \displaystyle\frac{E_{a}}{R}\left(\displaystyle\frac{1}{T_{1}} \ - \ \displaystyle\frac{1}{T_{2}} \right)[/tex]

                                         [tex]\rule{1.62cm}{0cm} \displaystyle\frac{k_{2}}{k_{1}} \ = \ e^{\displaystyle\frac{E_{a}}{R}\left(\displaystyle\frac{1}{T_{1}} \ - \ \displaystyle\frac{1}{T_{2}} \right)} \\ \\ \\ \rule{1.62cm}{0cm} k_{2} \ = \ k_{1}e^{\displaystyle\frac{E_{a}}{R}\left(\displaystyle\frac{1}{T_{1}} \ - \ \displaystyle\frac{1}{T_{2}} \right)}[/tex]

Given that [tex]E_{a} \ = \ 26.5 \ \ \text{kJ/mol}[/tex], [tex]R \ = \ 8.3145 \ \ \text{J mol}^{-1} \ \text{K}^{-1}[/tex], [tex]T_{1} \ = \ \left(40 \ + \ 273\right) \ K[/tex], [tex]T_{2} \ = \ \left(125 \ + \ 273\right) \ K[/tex], and [tex]k_{1} \ = \ 0.0354 \ \ \text{sec}^{-1}[/tex], therefore,

           [tex]k_{2} \ = \ \left(0.0354 \ \ \text{sec}^{-1}\right)e^{\displaystyle\frac{26500 \ \text{J mol}^{-1}}{8.3145 \ \text{J mol}^{-1} \ \text{K}^{-1}}\left(\displaystyle\frac{1}{313 \ \text{K}} \ - \ \displaystyle\frac{1}{398 \ \text{K}} \right)} \\ \\ \\ k_{2} \ = \ 0.3115 \ \ \text{sec}^{-1}[/tex]                      

The equilibrium expression for the reaction; C(s) + O₂(g) ------->CO₂(g) is [CO2]/[C] [O2] option C.

The equilibrium expression shows how much of the reactants are converted into products. If the equilibrium constant is large and positive, most of the reactants have been converted into products.

Thus, the equilibrium expression for the reaction; C(s) + O₂(g) ------->CO₂(g) is [CO2]/[C] [O2] option C.

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The mole ratio would be 4:3

Mole ratio is the ratio of the stoichiometric number of moles of components of reactions.

From the equation: [tex]4NH_3 + 3O_2 --- > 2N_2 + 6H_2O[/tex]

The mole ratio of [tex]NH_3[/tex] to that of [tex]N_2[/tex] is the ratio of their coefficients. The coefficients are 4 and 3 respectively

Thus, the ratio is 4:3.

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From the calculations, the change in energy is - 190 J.

From the first law of thermodynamics, the energy is neither created nor destroyed but is transformed from one form to another.

From the law;

U = q + w

U = internal energy

q = heat

w = work

Since work is done on the surroundings and the gas absorbs heat then;

U = 132 J - 322 J

U = - 190 J

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Answer:

1. H₂SO₄

Explanation:

A balanced equation tells us how each reactant and product is related to each other in terms of moles.

The equation given has already been balanced since the number of atoms of each element is the same on both sides of the arrow. From the equation, we can see that 1 mole of H₂SO₄ reacts with 2 moles of NaOH. Whichever reactant that we do not have enough of to make more products is known as the limiting reagent, since it limits the amount of products formed.

Mole ratio of H₂SO₄: NaOH= 1: 2

The amount of NaOH needed is twice the amount of H₂SO₄ in terms of moles.

Given that there are 0.40 moles of H₂SO₄, let's calculate the amount of NaOH needed.

Amount of NaOH needed

= 2(0.40)

= 0.80 moles

However, there are only 0.75 moles of H₂SO₄. Since 0.75 <0.80, H₂SO₄ is the limiting reactant.

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Answer:

See below

Explanation:

From the balanced equation you can see you need twice as many moles of NaOH as H2SO4....

   you have .4 moles of H2SO4   so you need .8 moles of NaOH

              but you only have .75 mole....so NaOH is the limiting factor (because you do not have enough)