Which two chemical formulas represent molecules?

Answer:

polar bonds are caused by different kind of atoms, because almost every atoms have different powers to attract electrons.

the answer will be the two same atoms, F2

Answer:

Explanation:

The new volume can be found by using the formula for Boyle's law which is

[tex]P_1V_1 = P_2V_2[/tex]

where

P1 is the initial pressure

P2 is the final pressure

V1 is the initial volume

V2 is the final volume

Since we are finding the new volume

[tex]V_2 = \frac{P_1V_1}{P_2} \\[/tex]

We have

[tex]V_2 = \frac{300 \times 2}{7} = \frac{600}{7} \\ = 85.714285...[/tex]

We have the final answer as

Hope this helps you

Answer:

I think it's A and D

Explanation:

I'm not sure if it's right

Answer:

The answer is B and D

Explanation:

trust fr

Explanation:

The degree of unsaturation is given as;

Degree of unsaturation = (2C + 2 + N - H - X) / 2

(a) C5H6

Using the formular above;

Degree of unsaturation = [ 2(5) + 2 - 6] / 2

Degree of unsaturation = [ 12 - 6 ] / 2 = 3

(b) C10H6Cl2

Using the formular above;

Degree of unsaturation = [ 2(10) + 2 - 6 -2 ] / 2

Degree of unsaturation = [ 22 - 8 ] / 2 = 7

(c) C4H3NO

Using the formular above;

Degree of unsaturation = [ 2(4) + 2 - 3 -1 ] / 2

Degree of unsaturation = [ 10 - 4 ] / 2 = 3

Note: Oxygen is ignored because its presence has no effect on the degree of unsaturation.

Answer:

The solvent

Explanation:

After the solid is recoverd by decanting the liquid, some solvent particles may still adhere to the solid.

In order to remove the solvent that may have adhered to the solid completely , the solid is washed before it is now dried.

In order to remove the remaining liquid present the solid material.

We are washing the solid in order to remove the liquid particles that is attached to the solid material with the help of water. Water is a universal solvent that dissolve large number of solutes in it.

Water removes the liquid from the solid by attaching with that liquid or dissolving in it so that's why we use water for washing a solid in order to remove the impurities from the solid material in which it is placed.

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Answer:

K₂ = 1.12s⁻¹

Explanation:

Based on Arrhenius equation:

ln K₂/K₁ = -Ea/R (1/T₂ - 1/T₁)

Where K is rate constant,

R is gas constant (8.314J/molK),

T is absolute temperature (In K) Of 1, initial state and 2, final state.

ln K₂/K₁ = -Ea/R (1/T₂ - 1/T₁)

ln K₂/2.10x10⁻²s⁻¹ = -82000J/mol/8.314J/molK (1/(273.15 + 58) - 1/(273.15 + 19))

ln K₂ / 2.10x10⁻²s⁻¹ = 3.976

K₂ / 2.10x10⁻²s⁻¹ = 53.3

Complete Question

You are given a solution containing a pair of enantiomers (A and B). Careful measurements show that the solution contains 98% A and 2% B. What is the enantiomeric excess?

Answer:

The value is  [tex]k  = 96 %[/tex]

Explanation:

From the question we are told that

   The  percentage of  enantiomer A is  A =  98%

    The  percentage of  enantiomer B is  B =  2%

Generally the enantiomeric excess is mathematically represented as

      [tex]k  =  \frac{A -B}{A+B}  *  100[/tex]

=>   [tex]k  =  \frac{98 -2}{98+2}  *  100[/tex]

=>   [tex]k  = 96 %[/tex]

Answer:

2.35 x 10²⁰ atoms Ga

Explanation:

After converting from mg to g, use the molar mass as the unit converter to convert to moles. Then using Avogadro's number, 6.022 x 10²³ convert from moles to atoms of Ga.

[tex]27.2mgGa*\frac{1g}{1000mg} *\frac{1 mol Ga}{69.72gGa} *\frac{6.022*10^2^3 atoms Ga}{1 molGa} = 2.349 * 10^2^0 atoms Ga[/tex]

Then round to 3 significant figures = 2.35 x 10²⁰ atoms Ga.

The number of atoms in 27.2 mg sample of Ga is 2.35 × 10²⁰ atoms

From the question, we are to calculate the number of atoms in a 27.2 mg sample of Ga.

First, we will determine the number of moles of Ga present

Using the formula,

[tex]Number\ of\ moles = \frac{Mass}{Molar\ mass} [/tex]

Mass = 27.2 mg = 0.0272 g

Molar mass = 69.72 g/mol

Then,

[tex]Number\ of\ moles \ of\ Ga = \frac{0.0272}{69.72} [/tex]

[tex]Number\ of\ moles \ of\ Ga = [/tex] 0.000390132 moles

Now, for the number of atoms present

From the formula

Number of atoms = Number of moles × Avogadro's constant

Then,

Number of Ga atoms = 0.000390132 × 6.022×10²³

Number of Ga atoms = 2.35 × 10²⁰ atoms

Hence, the number of atoms in 27.2 mg sample of Ga is 2.35 × 10²⁰ atoms

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Answer:

Hypothesis: IF a penny is dropped from a building, THEN it would kill a pedestrian below

Controls: Same building, Same distance

Independent variable: Penny

Dependent variable: Pedestrian's death

Conclusion: The hypothesis is rejected

Explanation:

- The hypothesis is a testable explanation to an observed problem or asked question. Based on the cientific question in this question, a possible hypothesis will be: IF a penny is dropped from a building, THEN it would kill a pedestrian below

- Independent variable is the variable that is changed or manipulated in an experiment. In this case, the PENNY is the independent variable

- Dependent variable is the variable that responds to the change made to the independent variable. It is the measured variable. In this case, the dependent variable is the DEATH OF PEDESTRIANS.

- Controls are those variables that is kept constant or unchanged throughout the experiment. The controls in this experiment are: Same building, Same distance of throw etc.

- The conclusion is whether the hypothesis is accepted or not depending on the result of the experiment conducted. In this case, the hypothesis will be rejected if the penny doesn't kill a pedestrian

Answer:

i wish i could help but t know either so i wish you luck for an answer once again truly sorry don'

Explanation:

i am sorry but i do not know :(

Answer:

Potassium chloride, KCl , is an ionic compound formed by the electrostatic force of attraction that holds the potassium cations and the chlorine anions together

Explanation:

Answer:

Exothermic

Explanation:

Nuclear fission means splitting, so there is a lot of energy being released.

Answer: The molar mass of the unknown gas  is 9 g/mol

Explanation:

From Graham's law of effusion rates, the rate of effusion of a gas is inversely proportional to the square root of its molar mass.

[tex]\frac{rate_1}{rate_2}=\sqrt{\frac{M_2}{M_1}} [/tex]

[tex]rate=\frac{volume}{time} [/tex]

Rate is volume effused per unit time. Since, the volumes are same, the formula could be written as:

[tex]\frac{t_B}{t_A}=\sqrt{\frac{M_B}{M_A}}[/tex]

Putting the values in the formula:

[tex]\frac{2.42min}{11.1min}=\sqrt{\frac{M_{H_2}}{M_A}} [/tex]

[tex]\frac{2.42min}{11.1min}=\sqrt{\frac{2}{M_A}} [/tex]

Squaring both sides:

[tex]\frac{2}{M_A}=0.218[/tex]

[tex]M_A=9g/mol[/tex]

The molar mass of the unknown gas  is 9 g/mol

Calcium (Ca) is in group 2 and period 4 on the periodic table be because Calcium has 2 valence electrons and 4 electron shell. Thus, calcium is a metal like all other group 2 element.

The correct answer to the question is Option C. Calcium, like all group 2 elements, is reactive and a solid at room temperature.

Calcium is a group 2 element majorly because it has 2 valence electrons. It is also in period 4 because it has 4 electron shells.

Being a group 2 element, calcium is a solid at room temperature and also reactive. All elements in the group 2 are metals.

There are other elements in period 4 which are not solid. For example krypton is an element in period 4 and it is a gas and not reactive.

From the above information, we can conclude that the correct answer to the question is:

Option C. Calcium, like all group 2 elements, is reactive and a solid at room temperature.

See attached image

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Answer:

Several extractions is more effective than a single extraction.

Explanation:

When extraction is carried out multiple times, for instance, in this case, the extraction was carried out with three portions of the solvent rather than with just a single portion of the solvent, the amount of material left in the residue will be lower, because the extraction is more complete.

Several extractions with smaller volumes of solvent are more effective than a single extraction with a large volume of solvent.

Answer:

c,a,b,d

Explanation:

Answer:

1. 14 moles of NH3 were produced.

2. 7 moles of CO2 were produced.

3. 7 moles of H2O were produced.

Explanation:

We'll begin by writing a balanced equation for the decomposition of ammonium carbonate, (NH4)2CO3.

This is illustrated below:

(NH4)2CO3(s) —> NH3(g) + CO2(g) + H2O(g)

There are 2 atoms of N on the left side and 1 atom on the right side. It can be balance by putting 2 in front of NH3 as shown below:

(NH4)2CO3(s) —> 2NH3(g) + CO2(g) + H2O(g)

Now the equation is balanced.

From the balanced equation above,

1 mole of (NH4)2CO3 decompose to produce 2 moles of NH3, 1 mole of CO2 and 1 mole of H2O.

1. Determination of the number of mole of NH3 produced.

From the balanced equation above,

1 mole of (NH4)2CO3 decompose to produce 2 moles of NH3.

Therefore, 7 moles of (NH4)2CO3 will decompose to produce = 7 × 2 = 14 moles of NH3.

Therefore, 14 moles of NH3 were produced.

2. Determination of the number of mole CO2 produced.

From the balanced equation above,

1 mole of (NH4)2CO3 decompose to produce 1 mole of CO2.

Therefore, 7 moles of (NH4)2CO3 will also decompose to produce 7 moles of CO2.

Therefore, 7 moles of CO2 were produced.

3. Determination of the number of mole of H2O produced.

From the balanced equation above,

1 mole of (NH4)2CO3 decompose to produce 1 mole of H2O.

Therefore, 7 moles of (NH4)2CO3 will also decompose to produce 7 moles of H2O.

Therefore, 7 moles of H2O were produced.

Answer:

C

Explanation:

Answer:

92.75%

Explanation:

The overall chemical equation for the reaction in the preparation of alum from the aluminium can be expressed as:

[tex]\mathtt{2Al + 2KOH + 4H_2SO_4 +2H_2O \to 2KAl(SO_4)_2 2H_2O +3H_2}[/tex]

From above; we will see that 2 moles of Aluminium react with sulphuric acid and water to produce 2 moles o aluminium alum.

Therefore, the theoretical yield can be determined as:

[tex]=0.4395 \ g Al \times \dfrac{1 \ mol \ Al}{27 \ g Al }\times \dfrac{2 \ mol \ KAl(SO_4)_2}{2 \ mol \ Al}\times \dfrac{294.23 \ KAl(SO_4)_2}{1 \ mol \ KAl(SO_4)_2}[/tex]

= 4.789g of [tex]KAl(SO_4)_2[/tex]

To find the percent yield, we need to divide the actual yield by the theoretical yield and then multiply it with 100.

∴

percent yield = ( mass of alum(g)/theoretical yield(g) ) × 100

percent yield = ( 4.789g / 5.1629g ) × 100%

percent yield = 0.9275 × 100%

percent yield = 92.75%

Thus, the percent yield of the experiment 92.75%

Ideal gas law is valid only for ideal gas not for vanderwaal gas. Therefore, value of the gas constant R is 0.0821LatmK⁻¹ when volume is 0.0413 L.

Ideal gas equation is the mathematical expression that relates pressure volume and temperature.

Mathematically the relation between Pressure, volume and temperature can be given as

PV=nRT

where,

P = pressure of nitrogen gas = 0.991 atm

V= volume of nitrogen gas =0.0413 L

n =number of moles of nitrogen gas = given mass ÷Molar mass

                                                          =0.0451 g ÷28

                                                          =0.0016mol

T =temperature of nitrogen gas =298 K

R = Gas constant =?

0.991 atm×0.0413 L=0.0016×R×298 K

R=0.0821LatmK⁻¹

Therefore, value of the gas constant R is 0.0821LatmK⁻¹.

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Answer:

PH = 4.0

Explanation:

We are given;

Ka1 = 8.9 × 10^(-8)

Ka2 = 1.0 × 10^(-19)

From the 2 values of K given above, we can see that Ka2 is far smaller than Ka1.

Thus, Positive hydrogen ion (H+) will be majorly formed from first dissociation which is Ka1.

Now, the breakdown of the H2S solution is;

H2S⇌[H+] + [HS−]

Thus;

Ka1 = [[H+] × [HS2^(-)]]/(H2S)

HS2^(-) also has a positive hydrogen ion.

Thus, we can rewrite as;

Ka1 = [[H+] × [H+]]/(H2S)

Ka1 = (H+)²/(H2S)

Concentration of H2S is given as 0.1M. Thus;

8.9 × 10^(-8) = (H+)²/0.1

(H+)² = 0.1 × 8.9 × 10^(-8)

(H+) = √(0.1 × 8.9 × 10^(-8))

(H+) = 0.00009433981

Now, PH is gotten from;

PH = -log (H+)

Thus;

PH = -log 0.00009433981

PH ≈ 4.0

Answer:

Cave Crystal

Explanation:

I believe it's cave crystal because sand dunes, river deltas, and valleys are all examples of deposition.

Answer:

XH₂ = 0.4885

XN₂ = 0.4290

XAr = 0.0825

Explanation:

Step 1: Given data

Step 2: Calculate the total pressure (P)

The total pressure is equal to the sum of the partial pressures of all the gases.

P = pH₂ + pN₂ + pAr = 441.0 Torr + 387.3 Torr + 74.5 Torr = 902.8 Torr

Step 3: Calculate the mole fraction (X) of each gas

We will use the following expression.

Xi = pi / P

where,

Xi: mole fraction of the gas i

pi: partial pressure of the gas i

P: total pressure

XH₂ = pH₂ / P = 441.0 Torr / 902.8 Torr = 0.4885

XN₂ = pN₂ / P = 387.3 Torr / 902.8 Torr = 0.4290

XAr = pAr / P = 74.5 Torr / 902.8 Torr = 0.0825

Grams of BW

i think thats irtu9rgirg

Independent variable in an investigation is the variable is does not depends on any other variable and on which we can have the control. Hence, the grams of BW is the independent variable here.

In an experiment the parameters which changes by control or depending on other changes are called variables. There are two kinds variables namely dependant and independent variables.

The dependant variables are those variable which depends upon other variables and whose changes are studying with respect to certain parameters.

Independent variables does not depends on other variable and can be controlled by the researcher. Here, we are studying the % of developing cold with respect to the amounts of BW. The changing variable is BW amount on which the percentage of cold depends.

Therefore, the independent variable is grams of BW and dependant variable is % development of cold.

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Answer:

Mass = 23.232 g

Explanation:

Given data:

Mass of C₈H₁₈ = 7.58 g

Mass of CO₂ produced = ?

Solution:

Chemical equation:

2C₈H₁₈ + 25O₂      →     16CO₂ + 18H₂O

Number of moles of octane:

Number of  moles =  mass/molar mass

Number of moles = 7.58 g/ 114.23 g/mol

Number of moles = 0.066 mol

Now we will compare the moles of CO₂ with octane from balance chemical equation.

                  C₈H₁₈            :           CO₂

                       2              :              16

                 0.066             :           16/2×0.066 = 0.528

Mass of CO₂ produced:

Mass = number of moles × molar mass

Mass = 0.528 mol × 44 g/mol

Mass = 23.232 g

Answer:

s = 22.352 m/s

Explanation:

Given data:

Time taken = 0.5 hours

Distance cover = 25 miles

Car speed = ?

Solution:

First of all we will convert the units.

1 hour = 3600 sec

0.5 hr ×3600 sec / 1hr = 1800 sec

miles to meter:

25 mi × 1609 m/ 1 mi = 40233.6 m

Formula:

s =  d/t

s = speed

d = distance

t = time

Now we will put the values in formula.

s = 40233.6 m / 1800 sec

s = 22.352 m/s

Answer:

The frequency is  [tex]f =  2,01 * 10^{15} \  Hz  [/tex]

Explanation:

From the question we are told that

   The energy required to ionize boron is [tex]E_b  =  801 KJ/mol[/tex]

Generally the ionization energy of boron pre atom is mathematically represented as

     [tex]E_a  =  \frac{E_b}{N_A}[/tex]

Here  [tex]N_A[/tex] is the Avogadro's constant with value [tex]N_A  =  6.022*10^{23}[/tex]

So

      [tex]E_a  =  \frac{801}{6.022*10^{23}}[/tex]

=>     [tex]E_a  =  1.330 *10^{-18} \  J/atom [/tex]

Generally the energy required to liberate one electron from an atom is equivalent to the ionization energy per atom and this mathematically represented as

       [tex]E =  hf  =  E_a[/tex]

=>     [tex]  hf  =  E_a[/tex]

Here h is the Planks constant with value [tex]h = 6.626 *10^{-34}[/tex]

So

       [tex]f =  \frac{1.330 *10^{-18}}{ 6.626 *10^{-34}}[/tex]

=>      [tex]f =  2,01 * 10^{15} \  Hz  [/tex]

Answer:

0.0611M of HNO3

Explanation:

The concentration of the NaOH solution must be 0.1198M

The reaction of NaOH with HNO3 is:

NaOH + HNO3 → NaNO3 + H2O

1 mole of NaOH reacts per mole of HNO3.

That means the moles of NaOH used in the titration are equal to moles of HNO3.

Moles HNO3:

12.75mL = 0.01275L * (0.1198mol / L) = 0.0015274 moles NaOH = Moles HNO3.

In 25.00mL = 0.025L -The volume of the aliquot-:

0.00153 moles HNO3 / 0.025L =

Answer:

5

Explanation:

The image attached shows the different monochlorination products obtained when chlorine gas is heated with methylcyclobutane.

We must keep in mind that the reaction occurs by free radical mechanism as shown in the image attached. The proportion in which the products are formed depends on the stability of the free radical intermediate leading to that particular product.

Image credit: askiitians