(A) Calculate the wavelength (in nm) of light with energy 1.89 × 10–20 J per photon, (b) For light of wavelength 410 nm, calculate the number of photons per joule, (c) Determine the binding energy (in eV) of a metal if the kinetic energy possessed by an ejected electron [using one of the photons in part (b)] is 2.93 × 10–19 J.

Answers

Answer 1

Answer:

For A: The wavelength of the light is [tex]1.052\times 10^4nm[/tex]

For B: The number of photons per joule is [tex]2.063\times 10^{18}[/tex]

For C: The binding energy of a metal is 1.197 eV.

Explanation:

The equation used to calculate the energy of a photon follows:

[tex]E=\frac{hc}{\lambda}[/tex]            ......(1)

where,

E = energy of a photon

h = Planck's constant = [tex]6.626\times 10^{-34}J.s[/tex]

c = speed of light = [tex]3\times 10^{8}m/s[/tex]

[tex]\lambda[/tex] = wavelength

For A:

Given values:

E = [tex]1.89\times 10^{-20}J[/tex]

Putting values in equation 1, we get:

[tex]\lambda=\frac{(6.626\times 10^{-34}J.s)\times (3\times 10^8m/s)}{1.89\times 10^{-20}J}\\\\\lambda=1.052\times 10^{-5}m[/tex]

Converting the wavelength into nanometers, the conversion factor used is:

[tex]1m=10^9nm[/tex]

So, [tex]\lambda=1.052\times 10^{-5}m\times \frac{10^9nm}{1m}=1.052\times 10^4nm[/tex]

Hence, the wavelength of the light is [tex]1.052\times 10^4nm[/tex]

For B:

Given values:

[tex]\lambda=410nm=410\times 10^{-9}m[/tex]

Putting values in equation 1, we get:

[tex]E=\frac{(6.626\times 10^{-34}J.s)\times (3\times 10^8m/s)}{410\times 10^{-9}m}\\\\E=4.848\times 10^{-19}J[/tex]

To calculate the number of photons, we use the equation:

[tex]\text{Number of photons}=\frac{\text{Total energy}}{\text{Energy of a photon}}[/tex]

Total energy = 1 J

Energy of a photon = [tex]4.848\times 10^{-19}J[/tex]

Putting values in the above equation:

[tex]\text{Number of photons}=\frac{1J}{4.848\times 10^{-19}J}\\\\\text{Number of photons}=2.063\times 10^{18}[/tex]

Hence, the number of photons per joule is [tex]2.063\times 10^{18}[/tex]

For C:

To calculate the binding energy of a metal, we use the equation:

[tex]E=K+B[/tex]             .....(2)

E = Total energy

K = Kinetic energy of a photon

B = Binding energy of metal

Converting the energy from joules to eV, the conversion factor used is:

[tex]1eV=1.602\times 10^{-19}J[/tex]

Using the above conversion factor:

[tex]K=2.93\times 10^{-19}J=1.829eV\\\\E=4.848\times 10^{-19}J=3.026eV[/tex]

Putting values in equation 2:

[tex]B=(3.026-1.829)eV=1.197eV[/tex]

Hence, the binding energy of a metal is 1.197 eV.


Related Questions

please help! what is the correct answer to this picture

Answers

Answer:

i think its c [everything is so blury]

Explanation:

The reaction below was carried out in an acidic solution l-+10-3--->l2 Which statement is true about this equation? Although it is unbalanced, it can be balanced by using the half-reaction method It has been balanced by using the half-reaction method. It has been balanced by directly using spectator ions. O Although it is unbalanced, it can be balanced by directly using spectator ions.​

Answers

Answer:

answer is b. : It has been balanced by using the half-reaction method.

Explanation:

edge 2021

Answer:b

Explanation:cuz it is

Which event is an example of melting?
A. Wax drips down the side of a lit candle.
B. Perspiration dries on a person's skin.
C. Rain turns to ice pellets.
D. A mirror fogs up when someone takes a hot shower.
I’m just curious tbh

Answers

Answer:

A. Wax drips down the side of a lot candle.

Explanation:

The chemical change from solid to liquid. This is a combustion reaction, so carbon dioxide gas and water vapour is also produced but you can't see them

Answer:

A. Wax drips down the side of a lot candle.

Explanation:

The combustion of ethylene proceeds by the reaction



C2H4 (g) + 3O2 (g) → 2CO2 (g) + 2H2O (g)



When the rate of disappearance of C2H4 is 0.13 M s-1, the rate of appearance of CO2 is ________ M s-1.

Answers

The answers D man have fun

Identify the item that does not have kinetic energy.
A. A worm crawling
B. A falling leaf
C. An airplane flying
D. A butterfly sitting on a twig

Answers

Answer:

D

Explanation:

there is no other answer choice that does not move. This is a fool-proof question because all the other answer choices contain movement except the butterfly resting

Liquid nitrogen becomes a gas when it is poured out of its container. The nitrogen is

Answers

Answer:

aasjajiakjka

Explanation:

Answer: Boiling

It turns into a vapor

65. Which of the following heavy metal is not
toxic?
(1 Point)
Hg
Pb
O As
O Ni

Answers

I believe it is ni . Hope this helps

The product of an organic reaction is analyzed by column chromatography using silica as the stationary phase and toluene as the mobile phase.

a. True
b. False

Answers

Answer:

The product of an organic reaction is analyzed by column chromatography using silica as the stationary phase and toluene as the mobile phase.

Explanation:

The given statement is true.

In chromatography silica gel is used as the predominant stationary phase.

Since silica gel is a good adsorbent.

It is a polar adsorbent.

In order to remove polar components, silica gel is used as the stationary phase.

Answer is a.true.

PLZ HELP!!!! NO LINKS

Answers

Answer:

the answer would be 6.720

Simply subtract the combined mass by the mass of the beaker.

The answer has 3 decimal places because the least amount of decimal places in the equation is 3.

What is the source of coal?
A. Compressed ancient plants
B. Crystallized magma
O C. Compressed ancient sea life
D. Modern forests

Answers

Coal is a fossil fuel, formed from vegetation, which has been consolidated between other rock strata and altered by the combined effects of pressure and heat over millions of years to form coal seams. The energy we get from coal today comes from the energy that plants absorbed from the sun millions of years ago.

Coal and Energy obtained from coal are formed as a result of decomposed life matter such as plants

A. Compressed ancient plants

Fossil Fuels

It should be noted that coal is also a type of fossil fuel formed by prolong compaction of fossil material e.g dead plants over millions of years, forest lives etc. and as a result of high pressure and heat acting on these fossil matter they are transformed to fuel.

In summary, fossil fuels are formed as a result of age long compressed matter.

Learn more about fossil matter here:

https://brainly.com/question/11829803

The bond order denotes:_____.1. the order of filling of bonding vs. antibonding orbitals. 2. the pattern in which Lewis dot structures of atoms combine to form bonds. 3. the order that orbitals are filled in electron configurations. 4. an estimate of the polarity or dipole moment of a bond. 5. an estimate of the strength of a bond.

Answers

Answer:

an estimate of the strength of a bond.

Explanation:

The bond order is given as;

1/2(number of bonding electrons - number of anti bonding electrons)

The bond order tells us about the strength of bond. As the bond order increases, so does the strength of the bond because atoms involved in bonding come closer to each other as the bond length decreases.

Hence, bond order is an index of bond strength. Triple bonds are stronger than double bonds which are stronger than single bonds.

Steel is an alloy consisting of Fe with a small amount of C. Elemental Cr can be added to steel to make the steel less likely to rust

a. True
b. False

Answers

The statement is true

To make the steel less likely to rust, element like chromium is added to it. Therefore, the given statement is correct.

What is steel?

Steel can be described as an alloy composed of iron with a few tenths of a percent of carbon to enhance its strength and fracture resistance. In steel, alloying elements inclusions within the iron act as hardening agents as they stop the movement of dislocations.

Stainless steels are corrosion- and oxidation-resistant but they need an additional 11% chromium. This type of steel is used in buildings, infrastructure, ships, trains, machines, electrical appliances, weapons, and rockets because of its high tensile strength and low cost.

It can take two crystalline forms body-centered cubic and face-centered cubic depending on the temperature. The interaction of the allotropes of iron with elements such as carbon gives the steel its range of unique properties.

Therefore, the given statement is true that chromium is used in steel formation.

Learn more about steel, here:

https://brainly.com/question/13292254

#SPJ5

A sample of drinking water was tested for Pb2 and was found to have a Pb2 concentration of 17.50 ppb. A 9.00 mL sample of the drinking water was spiked with 1.00 mL of a 2.29 ppb Pb2 standard. Analysis of the spiked sample gave a concentration of 15.93 ppb Pb2 . Find the percent recovery of the spike.

Answers

Answer:

[tex]X=75\%[/tex]

Explanation:

From the question we are told that:

Concentration [tex]C_1=17.50ppb[/tex]

Volume [tex]v=9mL[/tex]

Spike Volume [tex]V_s=1.00mL[/tex]

spike Conc [tex]C_2=2.29 ppb[/tex]

Analysis Conc [tex]C_s=15.93 ppb[/tex]

Generally the equation for  percent recovery is mathematically given by

 [tex]X=\frac{C_s'-C_1'}{C_2'}[/tex]

Where

Concentration of spiked sample C_s'

 [tex]C_s'=C_s*(v+v_s)[/tex]

 [tex]C_s'=15.92*(9+1)[/tex]

 [tex]C_2=159.2[/tex]

Concentration of unspiked sample C_1'

 [tex]C_1'=17.50*9mL[/tex]

 [tex]C_1'=157.5[/tex]

Concentration of spike sample C_2'

 [tex]C_2=2.29*1[/tex]

 [tex]C_2=2.29[/tex]

Therefore

 [tex]X=\frac{159.2-157.5}{2.29}[/tex]

 [tex]X=75\%[/tex]

Chromosomes contain the genetic material found in cells. true or false?

1. true
2. false

Answers

Answer:

1) True

Explanation:

An atom that ______ electrons is called a positive ion. A. has 0 B. has 8 C. loses D. gains

Answers

Answer:

Gains

Explanation:

It gets more electrons

Loses because then it will have a positive charge

please answer all if you can!

Answers

Answer:1.b 2.A (i think it might be c) 3 (i have no clue) 4.(no clue) Sorry i only got 1 and 2 witch i think are right its been a while sense i have done this....

Explanation:

Classify each amino acid by the chemical properties of its side chain (R group) at pH 7 . Select the amino acid that fits best in each category. Each amino acid will be selected only once. Which amino acid has a positively charged R group

Answers

Answer: The amino acid that has a positively charged R group are LYSINE and ARGININE.

Explanation:

AMINO ACIDS are the basic structural units of proteins. Each amino acid contains an amino group ( -NH2) and a carboxyl group (-COOH) in its molecule. The carbon atom of amino acid to which the functional groups are attached is know as the alpha-carbon. In neutral solution, amino acids are mainly in the form of dipolar ions. Amino acids can be prepared through hydrolysis of protein by boiling with dilute hydrochloric acid.

Amino acids can be classified according to the chemical properties of its side chain (R group) at pH 7, these include:

--> Amino acids with POSITIVELY CHARGED R group

--> Amino acids with negatively charged R group

--> Amino acids with neutral polar R group

--> Amino acids with nonpolar aliphatic R group.

Amino acids with POSITIVELY CHARGED R group are those amino acids that has side chains which contain nitrogen and resemble ammonia, which is a base. Their pKa's are high enough that they tend to bind protons, gaining a positive charge in the process. Example include LYSINE and ARGININE.

What is the quantity of
heat required to raise the
temperature of 500 g of
iron by 2°C?
The specific heat capacity
of iron is 500 J/(kg °C)

Answers

Answer:

The quantity of  heat required to raise the  temperature of 500 g of  iron by 2°C is 500 J.

Explanation:

Calorimetry is responsible for measuring the amount of heat generated or lost in certain physical or chemical processes.

The sensible heat of a body is the amount of heat received or transferred by a body when undergoing a temperature variation (Δt) without there being a change in physical state (solid, liquid or gaseous).

Its mathematical expression is the fundamental equation of calorimetry. This is:

Q = c * m * ΔT

where Q is the heat exchanged by a body of mass m, made up of a specific heat substance c and where ΔT is the temperature variation.

In this  case:

Q= ?c= 500 [tex]\frac{J}{kg*C}[/tex]m= 500 g= 0.500 kgΔT= 2 C

Replacing:

Q= 500 [tex]\frac{J}{kg*C}[/tex] *0.500 kg*2 C

Solving:

Q= 500 J

The quantity of  heat required to raise the  temperature of 500 g of  iron by 2°C is 500 J.

Calculate the mass of water produced when 9.57 g of butane reacts with excess oxygen.
Express your answer to three significant figures and include the appropriate units.

Answers

Answer:

14.9 g

Explanation:

Step 1: Write the balanced equation

C₄H₁₀ + 6.5 O₂ ⇒ 4 CO₂ + 5 H₂O

Step 2: Calculate the moles corresponding to 9.57 g of C₄H₁₀

The molar mass of C₄H₁₀ is 58.12 g/mol.

9.57 g × 1 mol/58.12 g = 0.165 mol

Step 3: Calculate the moles of H₂O produced from 0.165 moles of C₄H₁₀

0.165 mol C₄H₁₀ × 5 mol H₂O/1 mol C₄H₁₀ = 0.825 mol H₂O

Step 4: Calculate the mass corresponding to 0.825 mol of H₂O

The molar mass of H₂O is 18.02 g/mol.

0.825 mol × 18.02 g/mol = 14.9 g

If you keep adding sugar to water and there comes a point that you cannot dissolve any more sugar into it then this is called?
A) solvent solution
B) solute solution
C) saturated solution
D) Dilute solution

Answers

Answer:

the answer is letter D, Dilute solution

2.The rate constant of a first order reaction is 66 s-1. What is the rate constant in units of minutes

Answers

Answer:

66s^-1 will be 1/66

then to convert to minute you multiply by 69

1/66 x 60 = 3960 mins

Which of the following colors has the highest energy? O A. Red O B. Green O C. Blue O D. Yellow​

Answers

Answer:

C. Blue

Explanation:

This is because, Blue color highest frequency of energy after Violet and Indigo.

Help me please , I got 0.003 for a I need help with b and c

Answers

Answer:

(a) The moles of CuSO₄ is 3.125 × 10⁻³ moles.

(b) The moles of Cu is 3.125 × 10⁻³ moles.

(c) The mass of Cu is 0.2 g.

Explanation:

Given:

Mass of CuSO₄ = 0.5 g

Molar mass of CuSO₄ = 160 g/mol

The given balanced chemical equation is:

[tex]2Al+3CuSO_4\rightarrow 3Cu+Al_2(SO_4)_3[/tex]

Part (a):

Calculating the moles of CuSO₄.

[tex]\text{Moles of } CuSO_4=\frac{\text{Mass of }CuSO_4}{\text{Molar mass of }CuSO_4}\\\\\text{Moles of } CuSO_4=\frac{0.5g}{160g/mol}\\\\\text{Moles of } CuSO_4=3.125\times 10^{-3}mol[/tex]

Thus, the moles of CuSO₄ is 3.125 × 10⁻³ moles.

Part (b):

Calculating the moles of Cu.

From the balanced chemical equation, we conclude that:

As, 3 moles of CuSO₄ reacts to give 3 moles of Cu

So, 3.125 × 10⁻³ moles of CuSO₄ reacts to give 3.125 × 10⁻³ moles of Cu

Thus, the moles of Cu is 3.125 × 10⁻³ moles.

Part (c):

Calculating the mass of Cu.

Mass of Cu = Moles of Cu × Molar mass of Cu

Molar mass of Cu = 64 g/mol

Mass of Cu = (3.125 × 10⁻³ mole) × (64 g/mol)

Mass of Cu = 0.2 g

Thus, the mass of Cu is 0.2 g.

HELLP I NEEED HELP NOWW NO GUESSING FRFR



What will happen when a piece of magnesium metal is dropped into a beaker
containing a 1 M solution of copper(II) chloride?
Mg2+ + 2e → Mg(s) ° =- 2.37 V
Cu2+ + 2e → Cu(s) £° = + 0.34 V

Answers

It’s b . The magnesium will dissolve and the copper will be deposited

Write a balanced equation for the complete combustion of 2,3,3-trimethylpentane. Use the molecular formula for the alkane (C before H) and the smallest possible integer coefficients.

Answers

Answer:

C8H18 + 25/2O2 ----> 8CO2 + 9H2O

Explanation:

2,3,3-trimethylpentane has the molecular formula C8H18.

The general formula for the combustion of an alkane is;

CnH2n+2 + 3n+1/2O2 ----->nCO2 + (n+1)H2O

In writing a balanced chemical reaction equation, the number of atoms of each element on the left hand side of the reaction equation must be the same as the number of atoms of the same element on the right hand side of the reaction equation.

For C8H18, the balanced chemical reaction equation for combustion is;

C8H18 + 25/2O2 ----> 8CO2 + 9H2O

Suppose an element has two naturally occurring isotopes

42
X
20

44
X
20
with atomic masses 42.00 amu and 45.00 amu, respectively. Determine the percent abundance of the
45
X
20
isotope given an average atomic mass of 43.22 amu.

Answers

Answer:

Chlorine

Chlorine has two naturally occurring isotopes. In a sample of chlorine, 75.77% of the atoms are Cl-35, with a mass of 34.97amu.

Explanation:

hope it helps thanks❤

Chlorine has two naturally occurring isotopes. In a sample of chlorine, 75.77% of the atoms are Cl-35, with a mass of 34.97amu.

How do you calculate the atomic mass in percentage by isotopes?

List the known and unknown values ​​and edit the problem. Convert each percentage value into a decimal by dividing it by 100. Multiply this number by the atomic mass of that spot. Mix together each isotope to find the median atomic mass.

How do you get the maximum amount of two isotopes?

To calculate the maximum percentage of each isotope in a sample of something, chemists usually divide the atomic number of a particular isotope by the total number of atoms of all that isotope and multiply the result by 100.

Learn more about isotopes here: brainly.com/question/6258301

#SPJ2

What are the two types of addition compounds

Answers

Answer:

electrophilic addition and

nucleophilic addition.

Answer:

the two types of addition compoundsare:

1.electrophilic addition

2. nucleophilic addition.

How many milliliters of a 6.00 M NaCl solution are needed to make 250.0 milliliters of a 0.500 M NaCl solution?​

Answers

Answer:

20,8ml  NaCl 6M

Explanation:

C1V1 = C2V2

Calculate the number of molecules of carbon (IV) oxide
produced when 10g of CaCO3 is treated with 100cm of
0.2mol dm HCl. The equation of the reaction is
CaCO3(s) + 2HCl(aq) → CaCl2(aq) + H2O(1) + CO2(g)
ICa=40 (=12 O=161

Answers

Answer: The mass of [tex]CO_2[/tex] produced is 0.44 g

Explanation:

For calcium carbonate:

The number of moles is defined as the ratio of the mass of a substance to its molar mass.  The equation used is:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)

Given mass of calcium carbonate = 10 g

Molar mass of calcium carbonate = 100 g/mol

Plugging values in equation 1:

[tex]\text{Moles of calcium carbonate}=\frac{10g}{100g/mol}=0.1 mol[/tex]

For HCl:

The formula used to calculate molarity:

[tex]\text{Molarity of solution}=\frac{\text{Moles of solute}\times 1000}{\text{Volume of solution (mL)}}[/tex] .....(2)

Molarity of HCl = [tex]0.2mol/dm^3=0.2mol/L[/tex]     (Conversion factor: [tex]1L=1dm^3[/tex]

Volume of solution = [tex]100cm^3=100mL[/tex]          (Conversion factor: [tex]1mL=1cm^3[/tex]

Putting values in equation 2, we get:

[tex]0.2=\frac{\text{Moles of HCl}\times 1000}{100}\\\\\text{Moles of HCl}=\frac{0.2\times 100}{1000}=0.02mol[/tex]

For the given chemical reaction:

[tex]CaCO_3(s)+2HCl(aq)\rightarrow CaCl_2(aq)+H_2O(l)+CO_2(g)[/tex]

By stoichiometry of the reaction:

If 2 moles of HCl reacts with 1 mole of calcium carbonate

So, 0.02 moles of HCl will react with = [tex]\frac{1}{2}\times 0.02=0.01mol[/tex] of calcium carbonate

As the given amount of calcium carbonate is more than the required amount. Thus, it is present in excess and is considered as an excess reagent.

Thus, HCl is considered a limiting reagent because it limits the formation of the product.

By the stoichiometry of the reaction:

If 2 moles of [tex]HCl[/tex] produces 1 mole of [tex]CO_2[/tex]

So, 0.02 moles of [tex]HCl[/tex] will produce = [tex]\frac{1}{2}\times 0.02=0.01mol[/tex] of [tex]CO_2[/tex]

We know, molar mass of [tex]CO_2[/tex] = 44 g/mol

Putting values in equation 1, we get:

[tex]\text{Mass of }CO_2=(0.01mol\times 44g/mol)=0.44g[/tex]

Hence, the mass of [tex]CO_2[/tex] produced is 0.44 g

.What shape does each galaxy have?

Answers

Answer:

as in shapes

Explanation:

4 different shapes, spiral, elliptical, lenticular, and irregular. Spiral galaxies are one of the most familiar galaxy shapes.
Other Questions
10x-3(x-6)=x+30 please help me Josie is purchasing a $75 appliance for her kitchen. She has three coupons to the store that she can choose from. Which is a true statement about Josies options? BocODA metal has a specific heat capacity of 360J/(kgC).An object made of this metal has a mass of 2.0kg.What is the thermal capacity (heat capacity) of the object? Help with number 16 please Pls dont have much time Bari Jay, a gown manufacturer, received an order for prom dresses from China. Her cost is $32 a gown. If her markup based on selling price is 76%, what is the selling price of each gown? (Round your answer to the nearest cent.) The radius of a cylinder of volume 2970cm is 30mm. Find the volume of a similar cylinder of radius 40mm. Assume that you manage a risky portfolio with an expected rate of return of 14% and a standard deviation of 30%. The T-bill rate is 6%. Your risky portfolio includes the following investments in the given proportions: Stock A 24 % Stock B 32 Stock C 44 Your client decides to invest in your risky portfolio a proportion (y) of his total investment budget with the remainder in a T-bill money market fund so that his overall portfolio will have an expected rate of return of 13%. a. What is the proportion y? (Round your answer to 1 decimal places.) b. What are your client's investment proportions in your three stocks and in T-bills? (Round your intermediate calculations and final answers to 2 decimal places.) c. What is the standard deviation of the rate of return on your client's portfolio? What is the value of 2 + (-2/3) ^2 1/3 ?163 -20. The average daily volume of a computer stock in 2011 was =35.1 million shares, according to a reliable source. A stock analyst believes that the stock volume in 2018 is different from the 2011 level. Based on a random sample of 40 trading days in 2018, he finds the sample mean to be 31.8 million shares, with a standard deviation of s=14.6 million shares. Test the hypotheses by constructing a 95% confidence interval.(a) State the hypotheses for the test.(b) Determine if the researcher will reject the null hypothesis. 1 - Replace the letter with the appropriate tense of the verbs in parentheses to complete the sentences about the history of the radio.James Clerk Maxwell A ________________ (not/create) the first radio.He B________________ (develop) the first radio-wave mathematical formula.In 1888, Heinrich Hertz C________________ (test) Maxwells assumption.The radio D ________________ (be) a subdivision of telecommunication.When E ________________Oliver Lodge F ________________ (name) the coherer? In 1894.In 1888, Temistocle Calzecchi-Onesti G ________________ (demonstrate) that a tube with iron filings conducted an electrical current.Radio communication H ________________ (involve) the transmission of electromagnetic waves.Before the 19th century, many scientists I ________________ (try) to invent something like the radio.Marconi J ________________ (notice) that electromagnetic waves K ________________ (travel) between two points separated by an obstacle. Write a single Python regular expression for each of the following. Note: For each problem, you must use only ONE regular expression. Matches a string that has both the substring dog and cat in the string in either order. For instance, both of the following strings match: 'The dog chased the cat' and 'xxcatxxdogxx'. Select the correct text in the passage.Which word or group of words best helps to clarify the meaning of block printing in the last paragraph?from "The Printing Press"in Great Inventions and Discoveries by Willis Duff Piercy1 "Except a living man," says Charles Kingsley, "there is nothing more wonderful than a booka message to us from the deadfrom human souls whom we never saw, who lived perhaps thousands of miles away; and yet these, on those little sheets of paper, speak to us, amuse us, vivify us, teach us, comfort us, open their hearts to us as brothers. We ought to reverence books, to look at them as useful and mighty things." Milton calls a good book "the precious life blood of a master spirit, embalmed and treasured up on purpose to a life beyond life." Cicero likens a room without books to a body without a soul. Ruskin says, "Bread of flour is good; but there is bread, sweet as honey, if we would eat it, in a good book." And Thomas Carlyle exclaims: "Wondrous, indeed, is the virtue of a true book! O thou who art able to write a book, which once in two centuries or oftener there is a man gifted to do, envy not him whom they name city-builder, and inexpressibly pity him whom they name conqueror or city-burner!"2 For centuries the traditions, stories, and songs of men were handed down orally from father to son and were preserved only in the memory. The poems of Homer, the great Greek bard, were recited by readers to large audiences, some of them numbering probably twenty thousand. By and by men felt the need of perpetuating their thoughts in some more permanent way than by memory, and there grew up a rude system of writing.3 The early Greeks and Romans used for their books tablets of ivory or metal or, more commonly, tablets of wood taken from the beech or fir tree which was then followed by a material called parchment. This was made from the skins of animals, particularly sheep or lambs. About the end of the ninth century or the beginning of the tenth, after Christ, parchment and vellum as material for books gave way to paper. Initially paper produced, was made of cotton, but during the twelfth century it was produced from linen. It is not known who invented linen paper, but its introduction was the first great catalyst to book making. About the beginning of the fifteenth century after Christ, there came over the world an enormous wave of intellectual awakening.4 The human intellect began to awake, to stretch itself, to go forth and conquer, which hence brought about the invention of printing. Before this time, ever since man began to record his thoughts, whether on plank, stone, or papyrus, on bark of tree, skin of animal, or tablet of wax or paper, every letter was made by hand. The process was necessarily slow, books were rare and costly, and only the few could have them. But with the advent of a process that would multiply books andmake them cheap, learning wasmade accessibleto the legion. Before theinventionof printing with movable, metal types, a kind of block printing was used. The words or letters were carved on a block of wood; the block was applied to paper, silk, cloth, or vellum, and thusimpressionswere made. Factor each trinomial completely. A. 2x^2 + 17x + 21B. 3x^2 - 17x + 10 What previous legislation did Jim Crow laws closely resemble?Select the best answer from the choices provided.A. the Civil Rights Act of 1875B. the grandfather clauseC. the Northwest OrdinanceD. the Black Codes Earth's seasons are caused by itsO A. precessionO B. rotationO C. revolutionO D. ecliptic Please help Ill give brainliest Define the word phytoplankton! What is the value of U if a loaf of bread coast 1.52 how much change will you get from 10 if you buy 4loaves