On the periodic table, the elements known as noble gases are all found in

Answer:

[tex]\rm C_4 H_8[/tex].

Explanation:

Look up the relative atomic mass of [tex]\rm C[/tex], [tex]\rm H[/tex], and [tex]\rm O[/tex] on a modern periodic table:

Calculate the molecular mass of [tex]\rm CO_2[/tex] and [tex]\rm H_2O[/tex]:

[tex]M(\mathrm{CO_2}) = 12.011 + 2 \times 15.999 = 44.009\; \rm g \cdot mol^{-1}[/tex];

[tex]M(\mathrm{H_2O}) = 2 \times 1.008 + 15.999 = 18.015\; \rm g \cdot mol^{-1}[/tex].

Given the mass [tex]m[/tex] of [tex]\rm CO_2[/tex] and [tex]\rm H_2O[/tex] produced, calculate the number of moles of molecules that were produced:

[tex]\displaystyle n(\mathrm{CO_2}) = \frac{m(\mathrm{CO_2})}{M(\mathrm{CO_2})} \approx 0.80\; \rm mol[/tex];

[tex]\displaystyle n(\mathrm{H_2O}) = \frac{m(\mathrm{H_2O})}{M(\mathrm{H_2O})} \approx 0.80\; \rm mol[/tex].

Calculate the number of moles of [tex]\rm C[/tex] atoms and [tex]\rm H[/tex] atoms in these [tex]\rm CO_2[/tex] and [tex]\rm H_2O[/tex] molecules.

The combustion reaction here include two reactants: the hydrocarbon and [tex]\rm O_2[/tex].

As the name suggests, hydrocarbons contain only [tex]\rm C[/tex] atoms and [tex]\rm H[/tex] atoms. On the other hand, [tex]\rm O_2[/tex] contains only [tex]\rm O[/tex] atoms.

Therefore, all the [tex]\rm C[/tex] and [tex]\rm H[/tex] atoms in those [tex]\rm CO_2[/tex] and [tex]\rm H_2O[/tex] molecules are from the unknown hydrocarbon. (With a similar logic, all the [tex]\rm O[/tex] atoms in those combustion products are from [tex]\rm O_2[/tex].)

In other words, that [tex]0.20\; \rm mol[/tex] of this unknown hydrocarbon molecules contains:

Hence, each of these hydrocarbon molecules would contain [tex](0.80\; \rm mol) / (0.20\; \rm mol) = 4[/tex] carbon atoms and [tex](1.60\; \rm mol) / (0.20\; \rm mol) = 8[/tex] hydrogen atoms.

The molecular formula of this hydrocarbon would be [tex]\rm C_{4} H_{8}[/tex].

Answer:

Explanation:

N₂ (g ) + 4H⁺( aq ) + 4e⁻ = N₂H₄ ( aq )

H⁺ ion comes from acidic medium . 4 positive charge on proton is balanced by 4 electron to make left hand side neutral because right hand side is neutral .

Answer:

4P + 5O₂ —> P₄O₁₀

Explanation:

From the question given above, we obtained:

P + O₂ —> P₄O₁₀

The above equation can be balance as illustrated below:

P + O₂ —> P₄O₁₀

There are 4 atoms of P on the right side and 1 atom on the left side. It can be balance by 4 in front of P as shown below:

4P + O₂ —> P₄O₁₀

There are 10 atoms of O on the right side and 2 atoms on the left side. It can be balance by putting 5 in front of O₂ as shown below:

4P + 5O₂ —> P₄O₁₀

Now the equation is balanced.

How does the environment play an important role in creating petrified fossils?

The right conditions need to be present in order for fossilization to occur.

Drier environments, such as land, are more susceptible to the effects of erosion and so it is more difficult to preserve the organism before it decays.

Answer:

8 electrons

Explanation:

Number of atoms = 128

Half life = 15 s

After each half life, the number of atoms reduces by half. So we need to determine how many half lives are in 60s.

Number of half lives = 60s / 15s = 4

After the first life;

Number of electrons left = 128 / 2 = 64

After the second life;

Number of electrons left = 64 / 2 = 32

After the third half life;

Number of electrons left = 32 / 2 = 16

After the fourth half life;

Number of electrons left = 16 / 2 = 8

Answer:

C. 8

Explanation:

correct on gizmo; After one half-life (15 seconds), about 64 radioactive atoms will remain, half of the original 128. After a second half-life passes (30 seconds total), about 32 radioactive atoms will remain, half of 64. After a third half-life passes (45 seconds), about 16 radioactive atoms will remain. A time of 60 seconds represents four half-lives, so about 8 radioactive atoms will remain.

Answer:

False

Explanation:

In every substance, there is a valence band and there is a conduction band. The gap between the valence band and the conduction band determines Whether a substance is a conductor or an insulator.

Conductors have a narrow gap between the valence band and the conduction band while insulators have a large gap between conduction band and insulation band. However, elements with a large number of electrons in the valence band are non conductors.

Answer:

the answer is : 28.6

1: 8+6+4+3 =21

2: there are 6 brown M&Ms = 6

3: %= 100

6×100÷21 = 28.57

round 1 Dec place = 28.6

Answer:

that they all dissolved went on watef

Particles in a metal are held together by Covalent attractions. These are the strongest attraction or types of bonding

The bonds that hold atoms together to form molecules are called covalent bonds. They are pretty tough and not easily made or broken apart. It takes energy to make the bonds and energy is released when the bonds are broken.

For example, there is a covalent bonding between a Chlorine molecule. the two chlorine atoms are held strongly via covalent bonds.

Find more information about Covalent bonding here:

brainly.com/question/11674395

Answer:

1. Mn = +7

2. S = +4

3. C = +4

4. P = +4

5. O = -1

Explanation:

The oxidation number of each element in a compound is as follows:

1. Mn in KMnO4

KMnO4 = 0

Where; K = +1, O = -2, Mn = x

+1 + x -2(4) = 0

1 + x - 8 = 0

x - 7 = 0

x = +7

2. S in SO2

SO2 = 0

Where; S = x, O = -2

x + -2(2) = 0

x - 4 = 0

x = +4

3. C in COCl2

COCl2 = 0

Where; C = x, O = -2, Cl = -1

x + -2 + -1(2) = 0

x + -2 + -2 = 0

x -2 - 2 = 0

x - 4 = 0

x = +4

4. P in PF4

PF4 = 0

Where; P = x, F = -1

x + -1 (4) = 0

x - 4 = 0

x = +4

5. O in K2O2

K2O2 = 0

Where; K = +1, O = x

+1(2) + x(2) = 0

2 + 2x = 0

-2x = 2

x = -1

Answer:

b. Heat flows from the surroundings to the system and the temperature of the water decreases.

Explanation:

The laws of thermodynamics lets us know that energy is neither created nor destroyed but can be converted from one form to another. Also, energy transfer does accompany chemical reactions in the form of heat.

For an endothermic reaction, heat is absorbed by the system from the surroundings. This leads to a drop in the temperature of the surroundings as energy is removed.

This implies that the water temperature decreases.

Answer:

A dam: 3

solar cells: 2

food: 1

a rocket: 1

Answer:

1: yes

Explanation:

Answer:

V = 296.6 liters of oxygen.

Explanation:

The reaction of combustion of sulfur is:

O₂(g) + S(s) → SO₂(g)        (1)

To find the volume of the oxygen we need to use the Ideal Gas Law:

[tex] V = \frac{n_{O}RT}{P} [/tex]   (2)

Where:

V: is the volume

[tex]n_{O}[/tex]: is the number of moles of oxygen

R: is the gas constant = 0.082 L*atm/(K*mol)

T: is the temperature = 273 K (at STP)

P: is the pressure = 1 atm (at STP)

So we need to find the number of moles of oxygen that reacts with sulfur:

[tex]n_{S} = \frac{m}{M}[/tex]

Where:

[tex]n_{S}[/tex]: is the number of moles of sulfur

m: is the mass of sulfur = 425 g

M: is the molar mass of sulfur = 32.065 g/mol                                                                            

[tex]n_{S}=\frac{m}{M} =\frac{425 g}{32.065 g/mol} = 13.25 moles[/tex]

From reaction (1) we have that 1 mol of O₂ reacts with 1 mol of S, hence the number of moles of oxygen is:

[tex] n_{S} = n_{O} = 13.25 moles [/tex]  

Finally, the volume of oxygen is (equation (2)):

[tex]V = \frac{13.25 moles*0.082 L*atm/(K*mol)*273 K}{1 atm} = 296.6 L[/tex]

Therefore, are necessary 296.6 liters of oxygen for the combustion of sulfur.

I hope it helps you!

Answer:

0.39 moles

Explanation:

Given mass of calcium nitrate =64gram

Molar mass of calcium nitrate = 164 gram

No of moles = given mass/ molar mass

No of moles = 64/164

= 0.39 moles

Answer:

d

Explanation:

i think its d but im not sure.

Answer:

C. average transnational kinetic energy of the particles in an object.

Explanation:

Answer:

yes

Explanation:

Answer:

im pretty sure! good job :))

Explanation:

im sorry if it isnt in advance, hope this helped a little!

Answer:

He or She used the wrong table of bond energies

Explanation:

We know that we obtain the energy of a reaction also known as the enthalpy of reaction from the formula; ΔHo(reaction) = sum of the bond energies of bonds being broken - sum of the bond energies of the bonds being formed.

Combustion is an exothermic reaction for which the value of ΔH is expected to the negative. If ΔH is not negative, then the calculation was not properly done and the wrong values of bond energy were probably used.

Answer:

He or she may have subtracted the bond energies for the reactants from the products.

Explanation:

Answer:

it is the one below that. NO, because it debt net the octet rule

Answer:

Female

Explanation:

Answer: A. Female.

Explanation: The word 'heroine' means a female or a woman that is admired and looked upon for her courage, bravery, and noble qualities.

Answer:

0.052636002587839 moles

Explanation:

im not sure so sorry if u get it wrong...

Answer:

Remain the same.

Explanation:

The reaction of the temperature of the content of the container will remain the same because no heat energy is transfer from the container to the external environment due to insulating material of the container. Insulators are poor conductor of heat and electricity so the container is unable to absorb the heat energy produced during a chemical reaction and all energy of the product remain the same.

Answer:

D

Explanation:

Human activities that contribute to desertification include the expansion and intensive use of agricultural lands, poor irrigation practices, deforestation, and overgrazing. ... Some meteorologists and soil scientists measure the impacts and length of a drought to determine if it is an example of desertification.

Answer:

A - Liquid molecules forming a gas and gas molecules forming a

liquid are equal in number.

Explanation:

A P E X

This question is incomplete, the complete question is;

Describe how to use a transfer pipet to deliver 10.00 mL of liquid by placing the following steps in the correct order;

- Replace the bulb with your index finger and wipe excess liquid off the outside of the pipette.

- Place the tip of the pipette against the side of the beaker and drain the liquid from the pipette until the bottom of the meniscus reaches the calibration mark.

- Transfer the pipette to the receiving vessel.

- Drain the pipette by gravity while holding the tip against the side of the receiving vessel.

- Use a rubber bulb to suck liquid up past the 10.00 ml calibration mark.

- Suck up a third volume of liquid past the 10.00 ml calibration mark.

- Discard the first two pipette volumes of the liquid to rinse the pipette.

Answer:

- Use a rubber bulb to suck liquid up past the 10.00 ml calibration mark.

- Discard the first two pipette volumes of the liquid to rinse the pipette.

- Suck up a third volume of liquid past the 10.00 ml calibration mark.

- Replace the bulb with your index finger and wipe excess liquid off the outside of the pipette.

- Place the tip of the pipette against the side of the beaker and drain the liquid from the pipette until the bottom of the meniscus reaches the calibration mark.

- Transfer the pipette to the receiving vessel.

- Drain the pipette by gravity while holding the tip against the side of the receiving vessel.  

Explanation:  

First of all, We use a suction device to suck up liquid into pipet. Then we will fill the pipet up to the 10 mL marks and will discard the initial two volumes of liquid and will take a final third volume. We will replace the bulb with index finger and will drain it by placing the tip of pipet at the wall of beaker and drain the liquid.

Arranged in the following steps correctly;

- Use a rubber bulb to suck liquid up past the 10.00 ml calibration mark.

- Discard the first two pipette volumes of the liquid to rinse the pipette.

- Suck up a third volume of liquid past the 10.00 ml calibration mark.

- Replace the bulb with your index finger and wipe excess liquid off the outside of the pipette.

- Place the tip of the pipette against the side of the beaker and drain the liquid from the pipette until the bottom of the meniscus reaches the calibration mark.

- Transfer the pipette to the receiving vessel.

- Drain the pipette by gravity while holding the tip against the side of the receiving vessel.