what is the scientific name for the chemical formula know as P2Os

Answers

Answer 1

Explanation:

I know only P2O5 = Phosphorus pentoxide


Related Questions

In which of the following compounds is the octet expanded to include 12 electrons?
PC13
H2S
SF6
PCIE

Answers

Answer: SF6

Sulfur hexafluoride or sulphur hexafluoride, is an inorganic, colorless, odorless, non-flammable, non-toxic but extremely potent greenhouse gas, and an excellent electrical insulator. SF₆ has an octahedral geometry, consisting of six fluorine atoms attached to a central sulfur atom.

what is the chemistery​

Answers

Answer:

Explanation:

Chemistry is the science that studies the composition, structure and properties of matter and the changes it undergoes during chemical reactions and their relationship with energy

Explanation:

Chemistry is the branch of science concerned with the substances of which matter is composed, the investigation of their properties and reactions, and the use of such reactions to form new substances.

Q- 30. The number of grams of solute
30:dissolved in 100 grams of solution
is called:30.09
سولیوٹ کی گرامز :
مقدار جو سلوشن کے 100 گرامز د حل
ہو، یہ پرسینٹیج کہلاتا ہے
ماس /ماس Mass
/
Mass
ماس / واليم Mass
/
Volume
والیم /ماس Volume
/
Mass
والیم و البم Volume
/
Volumne​

Answers

Answer:

Mass by mass

Explanation:

Because it's telling only about mass in grams



Things that you learn through your senses during an experiment are
A. hypotheses
B. controls
C. observations
D. conclusion

Answers

Answer:

c- observations

hope this helps

Explanation:

graduated cylinder is filled with water to a volume of 6.2 ML. an irregular shaped plastic object weighing 1.2 g is placed in the water and the volume 7.59 mL. what is the density of the object? Does it float or sink? (density of water is 1.00 g/ml)

Answers

Answer:

A. Density of object = 0.86 g/mL

B. The object will float in the water.

Explanation:

The following data were obtained from the question:

Volume of water = 6.2 mL

Mass (m) of object = 1.2 g

Volume of water + Object = 7.59 mL

Density of object =?

Density of water = 1 g/mL

Next, we shall determine the volume of the object. This can be obtained as follow:

Volume of water = 6.2 mL

Volume of water + Object = 7.59 mL

Volume of object =?

Volume of object = (Volume of water + Object) – (Volume of water)

Volume of object = 7.59 – 6.2

Volume of object = 1.39 mL

Therefore, the volume of the object is 1.39 mL

A. Determination of the density of the object.

Mass (m) of object = 1.2 g

Volume (V) of object = 1.39 mL

Density (D) of object =?

Density = mass /volume

Density = 1.2/1.39

Density of object = 0.86 g/mL

B. Determination of whether the object will float or sink.

Density of object = 0.86 g/mL

Density of water = 1 g/mL

From the above, we can see that the density of water is greater than that of the object. This implies that the object is lighter than water. Therefore, the object will float in the water.

How would you prepare 1.00 L of a 0.50 M solution of each of the following?
HCI from "concentrated" (12 M) reagent.

Answers

Answer:

Take approx 41.7 mL of 12-M HCl in a 1.00-L flask and fill the rest of the volume with distilled water.

Explanation:

Hello,

In this case, for the dilution process from concentrated  12-M hydrochloric acid to 1.00 L of the diluted 0.50M hydrochloric acid, the volume of concentrated HCl you must take is computed by considering that the moles remain constant for all dilution processes as shown below:

[tex]n_1=n_2[/tex]

Which can also be written in terms of concentrations and volumes:

[tex]M_1V_1=M_2V_2[/tex]

Thus, solving for the initial volume or aliquot that must be taken from the 12-M HCl, we obtain:

[tex]V_1=\frac{M_2V_2}{M_1} \\\\V_1=\frac{1.00L*0.5M}{12M}\\ \\V_1=0.0417L=41.7mL[/tex]

It means that you must take approx 41.7 mL of 12-M HCl in a 1.00-L flask and fill the rest of the volume with distilled water for such preparation.

Best regards.

Match the scientist with their scientific idea. Question 2 options: Substances combine or break apart to create new, different substances. Gases are formed from tiny particles so small you can’t see them. The particles are spread out into a certain area and move when people walk through them. Matter was made of different kinds of things. 1. Democritus 2. Bernoulli 3. Priestley

Answers

Answer:

1. Democritus - Matter was made of different kinds of things.

2. Bernoulli- Gases are formed from tiny particles so small you can’t see them. The particles are spread out into a certain area and move when people walk through them.

3. Priestley- Substances combine or break apart to create new, different substances.

Explanation:

1. Democritus was a philosopher who because of his immense contribution to atomic theory was regarded as the "FATHER OF SCIENCE". His idea was that matter was made of different kinds of things called which he called ATOMOS meaning ATOM.

2. Daniel Bernoulli was another outstanding mathematician and scientist who played a major part in the kinetic molecular theory of gases via his "HYDRODYNAMICA". His idea, which states that "gases are formed from tiny particles so small you can’t see them. The particles are spread out into a certain area and move when people walk through them"

was based on fluid dynamics.

3. Joseph Priestley is remarkably known for his 1774 discovery of oxygen. His findings that air is a mixture of gases and not just a substance made of one element paved the way for his idea that " Substances combine or break apart to create new, different substances".

How many moles of HCl are present in 75.0 mL of a 0.200 M
solution?

Answers

Answer:

0.015 mol HCL

Explanation:

Molarity = moles solute/liters solution

Step 1: Define variables

M = 0.200

L = 75.0 mL

m = unknown, x

Step 2: Convert mL to L

1000 mL = 1 L

75.0 mL/1000 mL = 0.075 L

Step 3: Substitute

0.200 M = x mol/0.075 L

Step 4: Find x

x = 0.015 mol HCL

1. What is the relationship between science and society?

Answers

Societies have changed over time, and consequently, so has science. For example, during the first half of the 20th century, when the world was enmeshed in war, governments made funds available for scientists to pursue research with wartime applications — and so science progressed in that direction, unlocking the mysteries of nuclear energy. At other times, market forces have led to scientific advances. For example, modern corporations looking for income through medical treatment, drug production, and agriculture, have increasingly devoted resources to biotechnology research, yielding breakthroughs in genomic sequencing and genetic engineering. And on the flipside, modern foundations funded by the financial success of individuals may invest their money in ventures that they deem to be socially responsible, encouraging research on topics like renewable energy technologies. Science is not static; it changes over time, reflecting shifts in the larger societies in which it is embedded

Please answer this it’s 8th grade science and we are only 1 month into the year!

Answers

Answer:

Earth's gravitational pull

Explanation:

Astronauts in the space shuttle float because they are in “free fall” around Earth, just like a satellite or the Moon. Again, it is gravity that provides the centripetal force that keeps them in circular motion.

Match the scientist with their scientific idea.
Substances combine or
break apart to create new,
different substances.
1. Democritus
2. Bernoulli
Gases are formed from tiny
particles so small you can't
see them. The particles are
spread out into a certain
area and move when
people walk through them.
3. Priestley
Matter was made of
different kinds of things.

Answers

Answer:

1. Democritus- Matter was made of

different kinds of things.

2. Bernoulli- Gases are formed from tiny particles so small you can't see them. The particles are spread out into a certain area and move when people walk through them.

3. Priestley- Substances combine or

break apart to create new different substances.

Explanation:

1. Democritus was a Greek philosopher regarded to be the "Father of Science". He discovered that all matter were composed of indestructible things he called ATOMOS. Hence, his idea was that Matter was made of different kinds of things (atoms).

2. David Bernoulli, a mathematician, was born in 1700. He contributed immensely to the kinetic molecular theory of gases. In his postulated theory, he gave the idea that gases are formed from tiny particles so small you can't see them. The particles are spread out into a certain area and move when people walk through them.

3. Priestley- Joseph Priestley, born in 1733, is widely known for his discovery of oxygen gas among other gases. His idea was that substances combine or

break apart to create new different substances.

Group one elements, such as lithium, sodium, and
potassium, are known as
OA) alkali metals.
B)
halogens.
C) alkaline earth metals.
D) noble gasses.

Answers

Answer:

Alkali Metals

Explanation:

Because they are in group one, but Hydrogen is not an alkali metal.

A sample of copper is heated to 122.0 C and then placed in a container of 500 g of water at 25.3 °C. The final temperature of the water and copper is 29.7 °C. What is the mass of the copper assuming that all the heat lost by the copper is gained by the water? The specific heat capacity of copper is 0.20 J/°C g.

Answers

Answer:

Mass of copper is 500.542 g.

Explanation:

Initial temperature of copper = [tex]122^{0}[/tex]C

specific heat capacity of copper = 0.20 J/°C g

Mass of water = 500 g

Initial temperature of water = [tex]25.3^{0}[/tex]C

Specific heat capacity of water = 4.2 J/°C g

Final temperature of water and copper = [tex]29.7^{0}[/tex] C

Heat loss by copper = Heat gained by water

[tex]m_{c}[/tex][tex]c_{c}[/tex]Δ[tex]T_{c}[/tex] = [tex]m_{w}[/tex][tex]c_{w}[/tex]Δ[tex]T_{w}[/tex]

[tex]m_{c}[/tex] x 0.2 x (122 - 29.7) = 500 x 4.2 x (29.7 - 25.3)

[tex]m_{c}[/tex] x 0.2 x 92.3 = 500 x 4.2 x 4.4

[tex]m_{c}[/tex] x 18.46 = 9240

[tex]m_{c}[/tex] = [tex]\frac{9240}{18.46}[/tex]

     = 500.5417

mass of copper is 500.542 g.

Answer:

500.542

Explanation:

edge

2) 183 cg =
kg
5
.00183 kg
0.0183 kg
.183 kg
3) 0.25 kg =
g

Answers

Answer:

183 cg = 0.00183 kg

0.25 kg = 250 g

Explanation:

Use conversion factors. 1kg is equal to 1 x 10^5 cg (100000) and 1 kg is equal to 1 x 10^3 grams (1000 grams).

forces can make things move faster or_______them down.​

Answers

Answer:

Slower

Explanation:

Different forces, such as gravity, can affect an object in many ways.

Scenario 1: A car is climbing a hill and then starts to coast.

Here, when the car starts to not accelerate anymore, gravity could pull it to slow down and eventually stop.

Scenario 2: A car is speeding downwards.

Here, when the car isn't on the gas pedal, gravity could act upon the car and make it go faster.

forces can make things move faster or slower them down.

please helpp neep asap ik its late at night but i just need this one page and i can rest ​

Answers

Answer:

15. Velocity = 3 X 10^8

     Distance = 1580 m

time = distance / velocity

t = 1580 / 3 * 10^8

t =  1580 * 10^-8 / 3

t = 158 * 10^-7/3

t = 5.26 * 10^-8 seconds  

16. Converting the distance to 'm'

Given distance (in miles), multiplying by 1.609 to convert to  km and also multiplying by 1000 to convert to 'm'

s= 4.8 * 1.609 * 10^7 * 1000

v = 3 * 10^8

t =  4.8 * 1609  * 10^7 / 3 * 10^8

t = 1.6 * 1609 * 10^-1

t = 2574.4 * 10^ -1

t = 2.5744 * 10^-4 s

17. Mass in 1 tsp of medicine = 5 mL at a density of 25 mg/mL

Mass in 1 tsp of medicine = 5 * 25 = 125 mg

Mass prescribed by the doctor  = 375 mg

Number of table spoons required = Mass prescribed / Mass in 1 tsp

N = 375/125 = 3 table spoons of the medicine

18. Density of medicine = 400g/ 5mL = 80g / mL

Medicine required = 1500 g

Volume of medicine required = Medicine Required / Density of medicine

Volume = 1500 / 80 = 18.75 mL of medicine is required

Hence, the volume of the suspension should be at least 18.75 mL

19. Volume of 10 drops = 1 mL

Volume of 5 drops = 1/2 mL

The faucet is leaking 5 drops or 1/2 mL water per minute

Number of minutes in a day = 60 * 24  = 1440 minutes in a day

Water leaked in 1440 minutes = 1440 * 1/2 = 720

0.720 L (720 mL) Water leaked from the faucet in a day

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1. The strength with which an organic compound binds to an adsorbent depends on the strength of the following types of interactions: ion-dipole, dipole-dipole, hydrogen bonding, dipole induced dipole, and van der Waals forces. With silica gel, the dominant interactive forces between the adsorbent and the materials to be separated are_________________.

Answers

Answer:

Dipole-dipole interactions

Explanation:

Dipole-dipole interactions occur between two molecules with two polar end- a partially positive end and a partially negative end. The dipoles exists in these molecules due to the difference in the electronegativities of the atoms if the molecule. The positive end of a dipolar molecule will be attracted to the partially negative end of the neighboring molecule.

In the separation of molecules using silica gel as the adsorbent surface, the dominant interactive forces between the adsorbent and the materials to be separated are dipole-dipole interactions. The silica gel have polar SiOH groups on its surface which attracts polar molecules in the material to be separated. These polar molecules are strongly adsorbed to the silica gel surface whereas nonpolar or less polar molecules in the material to be separated are less strongly adsorbed, and thus, are eluted faster than the polar molecules.

The standard curve was made by spectrophotographic analysis of equilibrated iron(III) thiocyanate solutions of known concentration. You are asked to analyze a Fe(SCN)2+ solution with an unknown concentration and an absorbance value of 0.410 . The slope-intercept form of the equation of the line is y=4541.6x+0.0461 . The unknown was analyzed on the same instrument as the standard curve solutions at the same temperature. What is the Fe3+ concentration of the unknown solution?

Answers

Answer:

Molar concentration of the Fe³⁺ in the unknown solution is 8.01x10⁻⁵M.

Explanation:

When you make a calibration curve in a spectrophotographic analysis you are applying the Lambert-Beer law that states the concentration of a compound is directely proportional to its absorbance:

A = E*l*C

Where A is absorbance, E is molar absorption coefficient, l is optical path length and C is molar concentration

Using the equation of the line you obtain:

y = 4541.6X + 0.0461

Where Y is absorbance and X is concentration -We will assume concentration is given in molarity-

As absorbance of the unknown is 0.410:

0.410 = 4541.6X + 0.0461

X = 8.01x10⁻⁵M

Molar concentration of the Fe³⁺ in the unknown solution is 8.01x10⁻⁵M.

Give the number of significant figures in the following measurement 1278.50​

Answers

Answer:

5 significant figures all figures are significant except for 0

A laser with a wavelength of 225 nm is shown on an isolated gas-phase sodium atom. Calculate the velocity of the ejected electron from the ionized atom. The first ionisation energy of sodium is 496 kJ/mol and the mass of an electron is 9.109 x 10^-31 kg.

Answers

Answer:

The velocity of the ejected electron from the ionized atom is 3.6 × 10⁵ m/s

Explanation:

Using the conservation of energy, we can write that

Photon energy (E) = Ionisation energy (I.E) + Kinetic energy (K.E)

Photon  energy, E = [tex]hf[/tex]

Where [tex]h[/tex] is Planck's constant ( [tex]h[/tex] = 6.626 × 10⁻³⁴ kgm²/s)

and [tex]f[/tex] is the frequency

Also,

Kinetic energy, K.E = [tex]\frac{1}{2} mv^{2}[/tex]

Where [tex]m[/tex] is mass

and [tex]v[/tex] is velocity

Hence, we can write that

[tex]hf = I.E + \frac{1}{2}mv^{2}[/tex]

But, [tex]c = f\lambda[/tex]

where [tex]c[/tex] is the speed of light ( [tex]c[/tex] = 3.0 × 10⁸ m/s)

and λ is the wavelength

∴ [tex]f = \frac{c}{\lambda}[/tex]

Then,

[tex]\frac{hc}{\lambda} = I.E + \frac{1}{2}mv^{2}[/tex]

From the question, the first ionisation energy of sodium is 496 kJ/mol

This is the ionisation energy for 1 mole of sodium,

For 1 atom of sodium, we will divide by Avogadro's constant

∴ The ionisation energy becomes

(496 KJ/mol) / (6.02 × 10²³ molecules)

= 8.239 × 10⁻¹⁹ J

This is the ionisation energy for one atom of sodium

Now, to determine the velocity of the ejected electron from the ionized atom,

From,

[tex]\frac{hc}{\lambda} = I.E + \frac{1}{2}mv^{2}[/tex]

Then,

[tex]\frac{6.626\times 10^{-34} \times 3.0 \times 10^{8} }{225 \times 10^{-9} } = 8.239 \times 10^{-19} + \frac{1}{2}(9.109\times10^{-31} )v^{2}[/tex]

[tex]8.835 \times 10^{-19} = 8.239 \times 10^{-19} + 4.5545 \times 10^{-31}v^{2}[/tex][tex]8.835 \times 10^{-19} - 8.239 \times 10^{-19} = 4.5545 \times 10^{-31}v^{2}[/tex]

[tex]5.96 \times 10^{-20} = 4.5545 \times 10^{-31}v^{2}[/tex]

[tex]v^{2} = \frac{5.96 \times 10^{-20}}{4.5545 \times 10^{-31}}[/tex]

[tex]v^{2} = 1.3086 \times 10^{11}[/tex]

[tex]v = \sqrt{1.3086 \times 10^{11} }[/tex]

[tex]v = 361745.77 m/s[/tex]

[tex]v = 3.6 \times 10^{5} m/s[/tex]

Hence, the velocity of the ejected electron from the ionized atom is 3.6 × 10⁵ m/s

Which two parts of the atom are found in nucleus?

Answers

Answer:

protons and neutrons are found in nucleus

What mass of nitrogen is needed to fill an 855 L tank at STP?

Answers

Answer:

1068.8 g of N₂ are required.

We can also say, 1.07 kg of N₂

Explanation:

Let's apply the Ideal Gas Law equation to solve the problem:

Formula is  P . V = n . R . T

At STP we know, that P is 1 atm and T is 273.15 K. So let's replace the formula:

1 atm . 855 L = n . 0.082 L.atm /mol.K . 273.15 K

(1atm . 855L) / (0.082 L.atm /mol.K . 273.15 K) = n

38.17 moles = n

Let's convert the moles to mass, nitrogen is a dyatomic gas → N₂

Molar mass N₂ = 28 g/mol

38.17 mol . 28 g/mol = 1068.8 g of N₂ are required.

AT STP the 1 moles of gas is equal to the 22.4 L of gas. The mass of the nitrogen gas in the 855 L tank at STP is 1068 g.

The mass of the Nitrogen gas can be calculate using the formula,

[tex]\bold {w = n \times m}\\[/tex]

Where,

w -mass = ?

n - number of moles = [tex]\bold {=\dfrac {855}{22.4} = 38.169\ moles }[/tex] at STP.

m - molar mass  [tex]\bold {N_2}[/tex] =  

Put the values in the formula,

[tex]\bold {w = 38.169 \times 28 = 1068.73\ g}[/tex]

Therefore, the mass of the nitrogen gas in the 855 L tank at STP is 1068 g.

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Would phosphoric acid or succinic acid be a better buffer at ph5?

Answers

Answer:

Explanation:

For the pH value of a buffer solution , the Henderson formula given is as follows

pH = pKa + log [ A⁻] / [AH ]

Now let us discuss about the phosphoric and succinic acid . The phosphoric acid has a pKa value of 2.3 and for succinic acid , the pKa value is 4.2 . The pKa value of succinic acid is more close to 5 . So to achieve pH value of 5 , succinic acid is a better alternative . The value of  [ A⁻] / [AH ]  is kept almost equal to 1 to increase the buffer capacity .

5) Read each Eco fact. Propose a solution to prevent the environmental problems of the

seaport of troy described in the eco fact.

Answers

Answer:

The creation of regulations that limit timber activities and the exploitation of wood can prevent soil erosion in Troy.

Explanation:

The exploitation of the wood was an intense activity and that did not have any regulation that would limit its damages, caused by its exploratory activities.

As the timber market was totally undisciplined, the exploitation of the wood caused a strong deforestation, leaving the soil totally unprotected and susceptible to strong erosion.

Soil erosion has a very negative impact on the environment, requiring regulations to be made to prevent this from happening.

Based on this, we can say that one way to prevent environmental problems in the seaport of troy is by establishing laws and regulations that limit logging activities.

Which of the following alkyl halides has the smallest molecular dipole moment?
A) CH3F
B) CH3Cl
C) CH2I2
D) CH2Cl2
E) CF4

Answers

Answer:

Explanation:

B

At 50 degree C pK_w = 13.26. What is the pH of pure water at this temperature?
a. 6.63
b. 7.00
c. 7.37
d. 13.26

Answers

Answer:

6.63

Explanation:

From the relationship;

pH = pKw/2

Pkw = 13.26

Then it follows that;

pH = 6.63

Hence if. pKw = 13.26, the pH = 6.63

An element can be broken down into simpler means. True or false?​

Answers

Answer:

They can only be broken down to the Atom like neutron proton and electrons. I hope that help

Calculate the KE of an object that has a mass of 25kg that is moving at 5m/s2.

Answers

Answer:

312.5J

Explanation:

K.E=1/2*mv°2

=1/2*25*25

=312.5

What volume (mL) of 0.135 M NaOH is required to neutralize 13.7 mL of 0.129 M HCl? a: 0.24 b: 13.1 c: 0.076 d: 6.55 e: 14.3

Answers

Answer:

The volume (mL) of 0.135 M NaOH that is required to neutralize 13.7 mL of 0.129 M HCl is 13.1 mL (option b).

Explanation:

The reaction between an acid and a base is called neutralization, forming a salt and water.

Salt is an ionic compound made up of an anion (positively charged ion) from the base and a cation (negatively charged ion) from the acid.

When an acid is neutralized, the amount of base added must equal the amount of acid initially present. This base quantity is said to be the equivalent quantity. In other words, at the equivalence point the stoichiometry of the reaction is exactly fulfilled (there are no limiting or excess reagents), therefore the numbers of moles of both will be in stoichiometric relationship. So:

V acid *M acid = V base *M base

where V represents the volume of solution and M the molar concentration of said solution.

In this case:

V acid= 13.7 mL= 0.0137 L (being 1,000 mL= 1 L)M acid= 0.129 MV base= ?M base= 0.135 M

Replacing:

0.0137 L* 0.129 M= V base* 0.135 M

Solving:

[tex]V base=\frac{0.0137 L*0.129 M}{0.135 M}[/tex]

V base=0.0131 L = 13.1 mL

The volume (mL) of 0.135 M NaOH that is required to neutralize 13.7 mL of 0.129 M HCl is 13.1 mL (option b).

Write a conclusion statement that addresses the following questions: • Do your data support or fail to support your hypothesis (include examples)? • Describe the pattern observed in volume measurements as different masses or volumes of the unknown solid or liquid were selected. Explain why this pattern exists. • How do you think the investigation can be explored further?

Answers

Answer: My data strongly supported my hypothesis. I was right when guessed the solids density would be higher than the liquids and also that the mass affected the volume of the objects. The experiment proves that hypothesis is correct. To test further I could use different types of liquid and rocks with material.

Write a conclusion statement that addresses the following questions: Do your data support or fail to support your hypothesis (include examples)?My findings backed up my notion.When I predicted that solids would have a higher density than liquids and that mass would affect the volume of the objects, I was correct. The experiment confirms the validity of the theory. Describe the pattern observed in volume measurements as different masses or volumes of the unknown solid or liquid were selected. Explain why this pattern exists.

When I predicted that solids would have a higher density than liquids and that mass would affect the volume of the objects.

How do you think the investigation can be explored further?

I may use different sorts of fluids and rocks with stuff to test further.

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What is one important way the Hebrew and Phoenician cultures differed from other early civilizations? help with domain and range. Rewrite the sentence , using colloquial speech. Would you like to go to the dance with me 1,006 in scientific notation Help me please I only have a few minutes to get this doneplease and thank q What is the range of the function on the graph?O all real numbersO all real numbers greater than or equal to 0O all real numbers greater than or equal to 1O all real numbers greater than or equal to 2 Siena downloaded a file at a rate of 800 kilobytes per second for about 110 seconds. What calculation will give us the estimated size of the file Siena downloaded, in megabytes? The interactive activities in this courseA. will be tested in lesson quizzes but not the final examB. will be tested in the final exam but not the lesson quizzesC. will be scored by your instructorD. will not be score These type of photographers main goal was to make money/sell for profit:1. Amateur Photographer2. Official Photographers3. Commercial Photographers4. Artistic Photographers Question 510 ptsA grocery store sells 2 boxes of cereal for $4.95. Which method can be used tofind the total cost c of purchasing n boxes of cereal?O Multiply n by the cost of one box.O Multiply n by c.O Divide n by the cost of one box.Divide n by c. STORIES OF USEFUL INVENTIONS, excerpt By S. E. Forman 1911 THE MATCH There never was a time when the world was without fire, but there was a time when men did not know how to kindle fire; and after they learned how to kindle one, it was a long, long time before they learned how to kindle one easily. In these days we can kindle a fire without any trouble, because we can easily get a match; but we must remember that the match is one of the most wonderful things in the world, and that it took men thousands of years to learn how to make one. Let us learn the history of this familiar little object, the match. Fire was first given to man by nature itself. When a forest is set on fire by cinders from a neighboring volcano, or when a tree is set ablaze by a thunderbolt, we may say that nature strikes a match. In the early history of the world, nature had to kindle all the fires, for man by his own effort was unable to produce a spark. The first method, then, of getting fire for use was to light sticks of wood at a flame kindled by natureby a volcano, perhaps, or by a stroke of lightning. These firebrands were carried to the home and used in kindling the fires there. The fire secured in this way was carefully guarded and was kept burning as long as possible. But the flame, however faithfully watched, would sometimes be extinguished. A sudden gust of wind or a sudden shower would put it out. Then a new firebrand would have to be secured, and this often meant a long journey and a deal of trouble. In 1827, John Walker, a druggist in a small English town, tipped a splint with sulphur, chlorate of potash, and sulphid of antimony, and rubbed it on sandpaper, and it burst into flame. The druggist had discovered the first friction-chemical match, the kind we use to-day. It is called friction-chemical because it is made by mixing certain chemicals together and rubbing them. Although Walker's match did not require the bottle of acid, nevertheless it was not a good one. It could be lighted only by hard rubbing, and it sputtered and threw fire in all directions. In a few years, however, phosphorus was substituted on the tip for antimony, and the change worked wonders. The match could now be lighted with very little rubbing, and it was no longer necessary to have sandpaper upon which to rub it. It would ignite when rubbed on any dry surface, and there was no longer any sputtering. This was the phosphorus match, the match with which we are so familiar. How does the author develop the idea that humanity's early fire-starting tools may have been dangerous? Please respond in three to five complete sentences, using evidence from the text to support your answer. (5 points) Pythagorean theorem Determine if the two triangles shown are similar. If so, write the similarity statement. Find the value of x and the value of y.A. y=9, x = 40B. y= 12,4 = 12C. y= 10,2 = 16D. not enough information to determine Solve: m + 2/3 = 1/2 Given the function h (x) = 2x + 4, for which value of x does h (x) = 18? What causes phobias? Cite evidence from the text that explains where phobias come from. 1. How many two-digit numbers can beformed using the digits 3. 4. 5 and 6?1213141516 Where are semilunar valves to be found in a mammalian heart? Which website navigation method consists of a single web page containing a list of hyperlinks representing all the pages in the website? main menu site search site map fly-out menu A.historian B.navigational analyze C.notary public D.Cartographer