GULLIVER'S TRAVELS CLASS 9 SUMMARY

Jonathan Swift
(30 November 1667 – 19 October 1745),

born in Dublin, is one of the most well known satirist, essayist, and political pamphleteer of the eighteenth century England. He studied at Kilkenny College and graduated from the Trinity College, Dublin.He began his career by working as a diplomat and writer to William Temple at Moor Park. From 1696 to 1699, Swift came up with his two major works, A Tale of a Tub and The Battle of the Books. He also wrote several essays, poetry and pamphlets.Published in 1726, Gulliver’s Travels is a satire.

In this book, Swift satirises politics and human nature of the people in the English society in the eighteenth century. His work is a classic and still remains the most widely discussed work of his times.At its first reading, Gulliver’s Travels may seem to be a simple travelogue amalgamated with fantastical events, but itis an acute satire on the lust of power of the English to acquire unknown lands. Set in the 1700s, it attacks the politics, religion, morality and human nature of the English.

It presents a parody of travel tales and satirises human nature and colonialism with its witty use of slapstick and humour.In the novel, Gulliver is a learned surgeon who gives an account of his travelling experiences in the course of his four voyages. In Lilliput, he meets miniature beings who are politically active; in Brobdingnag, he meets the boorish giants in front of whom he himself feels a Lilliputian; then,
he visits Laputians who are too deeply engrossed in science and mathematics; and finally, he meets the Houyhnhnms who seem to be the most virtuous race of rational beings on the earth. Swift uses these imaginary places and their inhabitants to highlight the shortcomings of his own country.

Reading this book is like enjoying a roller coaster ride that not only excites the youngsters with its adventures but also interests the adults with its camouflaged insight into the defects of the eighteenth century England.Lemuel Gulliver, a learned surgeon, decides to go for sea voyages to the remote islands of the world, as he is keen to explore the world.During his first voyage,
Gulliver is shipwrecked because of a storm but manages to swim safely to Lilliput.

While sleeping, Gulliver is held captive by about six inches tall inhabitants of the island. Dueto his large size, Gulliver is initially perceived to be a threat. Later on, he is considered to be a harmless creature but agreat expense on the kingdom.

After getting a brief summary of their historical events, Gulliver decides to assist them in their battle against their rival state, Blefuscu. He stops the battle by bringing the enemy fleets to the kingdom. For this, he is honoured with the title of a ‘Nardac’ by the king. Flimnap and Skyresh Bolgolam,officials of the court, envy his success and conspire against him. They bring out four articles of impeachment against him.

iTheseare extinguishing the fire at the queen’s palace in a disgraceful manner, refusing to obey the king’s order to enslave the Blefuscudians, maintaining good behaviourwith the delegates of the enemy and planning a visit to Blefuscu, their enemy. Therefore, an order is passed to blind him before starving him to death. Fortunately, Gulliver is warned against the charges beforehand and he escapes to Blefuscu. The emperor of Blefuscu welcomes him warmly. In Blefuscu, he finds a broken boat, which he repairs, and sails back to England.Within two months of his return, Gulliver departs for another voyage. During the voyage, their ship gets drifted by a storm. Some of the crew members get down at the shore of a deserted island to find drinking water. Unfortunately, Gulliver is left alone on this island of giants. In Brobdingnag, he is taken to a farmer homeand is left in the care of his nine years old daughter, Glumdalclitch. The farmer earns a good fortune by making him perform at various places. Consequently, Gulliver’s health starts deteriorating and the farmer sells him to the queen. Though the king andthe queen treat him with respect and fondness, Gulliver faces several misfortunes threatening his life. One day, his box apartment, in which he was carried by Glumdalclitch, is picked by an eagle and dropped into the sea. Finally, he is rescued by an English ship.Again, his thirst of seeing the world takes Gulliver on a new voyage.  In this voyage, his sloop is attacked by the pirates. Gulliveris punished by being left in the sea in a small boat with scanty provisions. He reaches a group of islands. On fifth day, he reaches an island where he finds a land mass floating in the air. He is pulled up to the island by chains. He finds the inhabitants busy in their own thoughts and interested in only mathematics and music. Hence, he decides to visit Balnibarbi, where he is hospitably received by Lord Munodi.  Gulliver observes that Lord Munodi’s estate is greener and more systematically built than the other part of the country as it follows the ancient methods of agriculture and construction.Further, he visits the ‘academyof projectors’ in Lagado where the scientists are busy in their researches and the teachers are involved in speculative learning. Then, he visits Glubdubbdrib where he gets a chance to communicate with the world’s great philosophers and tyrants who died several years ago. Finally,he travels to Luggnagg. The king makes arrangements for his departure to Japan from where he boards a ship back to England.In his final voyage, Gulliver takes up the post of the captain of the ship.

As most of his crewmen die because of sea sickness, he hires men from various islands who turnout to be rogues. Consequently, they leave Gulliver on a marooned island. On this island, Gulliver finds a race horses, called Houyhnhnms, governing the island with intelligence. They are being served by a race of wild human-like creatures called Yahoos.

Gulliver realises that the Houyhnhnms are the most virtuous race ontheearth, whereas the humans were full of vices. Therefore, he decides to live in the company of the Houyhnhnms forever. But, Gulliver is forced to leave the Houyhnhnmland. He decides to shun human company and live the rest of his lifeon a secluded island. But, the crew of a Portuguese ship, in command of Pedro de Mendez, discovers him and takes him to Lisbon. Gulliver rejects humans as he feels disgusted by their vices and the offensive odour of their bodies. Yet, the captain treats him hospitably and makes arrangements for his return to England. Gulliver reaches back home safely but maintains distance from his family members and spends most of the time in a stable with a pair of horses whom he treatsas companions and converses well with. Only after about five years, he start comingto terms with the mankind.PART I. A VOYAGE TO LILLIPUT· Gulliver gives a brief account of his early life and his studies.· At London, he works as an apprentice to Mr. Bates. Then, he goes to Leyden to study medicine.· On Mr. Bates’ recommendation, he worksas a surgeon at the Swallow.· After returning, Gulliver marries Mary Burton.· He sets sail on the Antelope from Bristol on May 4, 1699 with Captain William Prichard.·

Gulliver is shipwrecked because of a storm. He manages to swim safely to an unfamiliar island called Lilliput.· While sleeping, he is held captive by about six inch tall inhabitants of Lilliput.· Initially, he is seen as a threat by the Lilliputians. Gradually, they accept him as their ally. He helps them in their fight against Blefuscu and receives the title of ‘Nardac’ (the highest honour) for capturing the enemy fleets.· Flimnap and Skyresh Bolgolam plan a conspiracy against Gulliver. Four articles of impeachment are drawn against him.· Gulliver is secretly informed about his trial and punishments. He escapes to the island of Blefuscu.· Gulliver finds a boat floating in the sea. He repairs it and sets off to England.·

He is taken on board an English ship. He reaches England on April 13, 1702.· Gulliver earns a lot of wealth by selling the Lilliputian miniatures and shifts to a bigger house in Redriff.PART- II. A VOYAGE TO BROBDINGNAG· He sets off for his second voyage on the Adventure on June 20, 1702.· The ship encounters a storm. Some of thecrew men get down a strange island in search of water. But they escape at the sight of a giant, leaving Gulliver alone on the island called Brobdingnag.· Gulliver is seized by a giant and is carriedto his master. The master, a farmer, takes him to his home. Glumdalclitch, the farmer’s nine-year-old daughter, takes careof him.· Gulliver is made to perform in front of hisguests, in the market places and at the distant towns. The farmer earns great fortune. Slowly, Gulliver’s health starts deteriorating.· After a performance at the court, Gulliveris sold to the queen.·

Gulliver gets mistreated at the hands of the jealous dwarf who is punished for his mischief. He is also threatened by a monkey, flies and wasps.· He attempts to win the loyalty of the king and the queen by various means. The king refuses his proposal of revealing the secretof gun powder.· After various discourses with Gulliver about England, the king regards the English as a race of odious people.· Gulliver desires his liberty. An eagle lifts the box in which he lay and drops it in the sea.· Gulliver is rescued by the English crewmen. He reaches England on June 3, 1706.PART III. A VOYAGE TO LAPUTA, BALNIBARBI, LUGGNAGG, GLUBBDUBRIB, AND JAPAN · Gulliver sets sail to East Indies on August 5, 1706.· His sloop is captured by pirates. Gulliver is left alone in the sea in a small boat with scanty provisions. He goes to find refuge in a group of island.· Gulliver finds the island of Laputa, floating in the air and is taken onto it.· He finds the Laputians to be strange beings. They show interest only in the knowledge of mathematics and music.· Soon, Gulliver visits Balnibarbi where he is hospitably received by Lord Munodi.· Gulliver observes that the city, which follows new methods of agriculture and construction and, is in ruins, whereas Munodi’s estate, which still follows the ancient methods, is green and systematically built.· Gulliver leaves Lagado, the metropolis, after making many visits to the Academy ofLagado.·

He visits Glubbdubdrib where he gets a chance to converse with the dead philosophers and tyrants of the world by the magical powers of its governor.· Gulliver arrives at Luggnagg and stays at an apartment in the palace of the king.· Gulliver is told about the immortal beingsstruldbrugs. He learns about the disadvantages of immortality.· Gulliver wishes to leave. The king arranges for his journey to England with a Dutch crew.· He reaches England on April 16, 1710 and goes straight to his house in Redriff.PART IV. A VOYAGE TO THE COUNTRY OF THE HOUYHNHNMS· On September 7, 1710, Gulliver sets sail as the Captain of the Adventurer.· Many of his crew members die due to illness. He hires more crew members who conspire against him. They leave him on a deserted island, the land of the Houyhnhnms.· Gulliver is attacked by a group of abominable wild beast called Yahoos. He issaved by a Houyhnhnm, a horse, who takes him to his house. He stays with the family.· The Houyhnhnms are virtuous beings, with their actions guided by reason. After a careful examination of Gulliver’s behaviour, they consider him a rational being.· Gradually, Gulliver develops a great admiration for the Houyhnhnms and an equal disgust for his country men who are full of vices.· Gulliver has several discourses with his master Houyhnhnm. He decides to stay in the company of the Houyhnhnms forever.· Later, his master is forced to excommunicate Gulliver as he is a Yahoo.· Gulliver leaves the country. He shuns the company of human beings and decides to live in seclusion on an island.· He is found by the crew of Captain Pedro de Mendez’s ship and is taken to Lisbon.· The Captain arranges for his journey to Europe. Gulliver reaches home safely, but discards the company of his family members.· After five years, he is able to reconcile with the natural vices of human beings.

ThNks for ReaDiNG.. BY SUmIT BhADRa

THREE MEN IN A BOAT CLASS 9 SUMMARY

Three Men in a Boat (To Say Nothing of the Dog)

by Jerome K. Jerome was first published in 1889. It is the fictional story of three London friends and a dog taking a leisurelyboat trip up the River Thames, from Kingston-upon-Thames to Oxford. It is narrated by ‘J.’, whose companions are George (awarded no surname), William Samuel Harris and the dog, Montmorency.During a sociable evening in J.’s room, the three men convince themselves that they each have various illnesses. Their collectivediagnosis is overwork, and they prescribe themselves a fortnight’s holiday.

A stay in the country and a sea voyage are both ruled out, and they settle instead on a boating trip, travelling on the Thames by day and camping out in the hired boat at night.They set out the following Saturday. George must work in the City in the morning, and so arranges to join them laterthat day.

The other two, accompanied by the dog and a mountain of luggage, get a cab to Waterloo station, but are unable to find the correct train to Kingston. Eventuallythey bribe the driver of another train to take them there instead, one of the many humorous set-pieces that make the book more than a straightforward travelogue.

George completes the trio at Weybridge, with a dubious-looking parcel tucked underhis arm, which turns out to be a banjo and instruction book.The story is a tapestry of incidents that occur, anecdotes on various topics (including the unreliability of weather forecasts), loosely connected digressions (such as J. 's uncle’s inability to hang pictures), and descriptive pieces on the places that they pass.

It is in these descriptive pieces that the author’s original intention of writing a guidebook is most apparent. What he actually achieved was aclassic of British humorous writing. Although the book was written over a century ago, it has an enduring, timeless quality.

THE DIARY OF A YOUNG GIRL CLASS 10 SUMMARY

Diary of a Young Girl by Anne Frank

Summary

On her thirteenth birthday, Anne Frank’s parents give her a diary. She’s excited because she wants someone, or something, in which to confide all of her secret thoughts. Even though she has a richsocial life, she feels misunderstood by everyone she knows. Anne starts writing about daily events, her thoughts, school grades, boys, all that. But, within a month, her entire life changes.As Jews in German-occupied Holland, the Frank family fears for their lives.

When Anne’s sister, Margot, is called to appear before the authorities, which would almost surely mean she was being sent to a concentration camp, Anne and her family go into hiding. They move into a little section of Anne’s father’s office building that is walled off and hidden behind a swinging bookcase. The little diagram of the office building and “Secret Annex” along with the Thursday, July 9, 1942 entry gives us the layout.For two years, the Frank family lives in this Secret Annex. Mr. and Mrs. van Daan and their son Peter (who is a few years older than Anne) are also in hiding with the Franks.

Later, Mr. Dussel, an elderly dentistmoves in, and Anne has to share her bedroom with him. Anne’s adolescence is spent hidden from the outside world. She’s cooped up in tiny rooms, tiptoeing around during the day and becoming shell-shockedfrom the sounds of bombs and gunfire at night.Luckily, the Franks have tons of reading material and a radio.

Anne grows in her knowledge of politics and literature, and she puts tons of energy into studying and writing. At the same time, she grows further and further away from the other members of the Annex.We see a real change in Anne when she begins hanging out in the attic with Peter van Daan.

Around this time she starts having dreams about a boy she was in lovewith, another Peter, Peter Schiff. She sometimes even gets the two Peters confused in her head.She comes to see Peter (of the Annex) as much more than she first thought. She findshim sensitive and caring, and they talk about everything, including sex. Eventually their relationship changes.

Anne and Peter’s passion turns into a friendship and a source of comfort for them both.Another big change for Anne happens when the war seems to be ending. She hears that personal accounts such as her diary will be in demand after the war ends.We see a return to her earlier optimism as she begins editing her diary with vigor and excitement.Unfortunately, this does not last.

Even as Anne becomes more and more sensitive tothe suffering going on in the world, her ownsuffering becomes unbearable. She feels completely alone. She thinks everyone hates her. She feels constantly criticized. And there is no escape. At one point, she thinks it might have been better if she and her family had all died instead of hiding in the Annex. As Anne becomes harder on those around her, she also becomes harder on herself, berating herself for being mean to the other members of the Annex.There her diary ends.

Two short months after Anne’s fifteenth birthday, and two days after he last diary entry, the Secret Annex is raided. We don’t know Anne’s thoughts or feelings at that point or any time after, but we know things got worse.As you probably already know, Anne and the other members of the Annex were sentto various concentration camps. Anne’s father, Otto Frank, was the sole survivor.

The Photograph by Shirley Toulson Q/A Class 11

The Photograph by Shirley Toulson -
Question & Answers

1) What does the word ‘cardboard’ denote in the poem? Why has this wordbeen used?

Ans:The cardboard means a very stiff and thick paper, here the cardboard is a part of theframe that keeps the photograph intact. It's use in poem is ironical  It keeps the photograph of that 12 year old girl safe who herself was terribly transient  The player's mother had died some years ago.

2) What has the camera captured?

Ans:The camera had captured all the three girls alive in it. It has captured the pretty face of the poet's mother who as a girl of twelve at that time. It has also captured the smiling faces of the two girl cousins Betty and Dolly. They are holding the hands of the poet's mother.

3) What has not changed over the years? Does this suggest something to you?

Ans:The sea has not changed over the years. Itrings out the transient nature and its object. Time spares none. The pretty faces and the feet of the three girls are terribly transient or moral when compared to the ageless and unchangeable sea.

4) The poet’s mother laughed at the snapshot. What did this laugh indicate?

Ans:The poet's mother laughs at the snapshot which was taken years ago. In the photograph, she as well as her two little cousins stood at the each. She laughed at the ay all of them were dressed up for the beach. Perhaps they looked funny. Their laughter indicated the youthful spirit.

5) What is the meaning of the line “Both wry with the laboured ease or loss”

Ans:Both the mother and the poet suffered a great sense of loss. The mother has lost her childhood innocence and joyful spirit that the photograph has captured some years ago. For the poet, the smile of her mother has becomething of the past. She has silently resigned to her faith. Ironically both labour to bear their loss with ease.

6) What does "this circumstance" refer to?

Ans:The circumstance refers to the death of the poet's mother. The photograph of her dead mother brings sad nostalgic feelings in the past. But the poet has nothing to say at all about the circumstance. The silence of the poet makes the silence prevailing their still deeper.

7) The three stanzas depict three different phases. What are they?

Ans:In the first stanza, the poet's mother is shown as a twelve year old girl with pretty smiling face. Then she is paddling with her twogirl cousins. This face is before the poet's birth. The second face describes the middle aged mother laughing at her own snapshot. The third face describes the chilling pale of silence that the death of her mother has left of the past.

The Photograph by Shirley Toulson - Extra Questions

1) How does the poet contracts the girls terrible transience with the scene?

Ans:All the girls standing at the each have a terribly transient existence. They are mortal and suffer physical change with the passage of time. THe mother's sweet face and her smile has already disappeared for the last twenty or thirty years. But the vast sea remains unchanged or seemed to have less changed in their comparison.

2) "Both thrive with the laboured ease of loss" Describe the ironical situation.

Ans:Both the mother and the daughter suffer a sense of loss. The mother has lost her care free childhood. She can't have these moments of enjoyment again that she once experienced at the beach. She can't be a sweet smiling girl of twelve again. This is considered as the poet's loss too. She can't see the smiling face and experience the laughter again in life. The irony of the situation is that both of them struggle to ear the loss with tolerable ease.

3) Explain the line " the sea holiday as a past, mine is her laughter , Time spares none" .

Ans:Gone are the childhood days of mother and the sea holiday has become her past, the photograph flashes back to the scene that was captured about 30 years ago. Gone is a carefree laughter of the mother which was love at one time. But now, the laughter of her mother has eventually become a thing of past for the poet. She has silently resigned herself to the fate.

Questions for practice

Short answer type questions

1.What is the significance of the ‘cardboard’ frame?

2.What tone has the poetess adopted in the poem?

3.What comparison between the sea and human beings has been drawn in the second stanza?

4.What emotions do you associate with the mother looking at the photograph?

5.What emotions would you associate with Shirley as she looks at the photograph?

6.Why does the poetess seem to have nothing to say about the ‘circumstance’?

7.What is silenced and how has it silenced the poetess?

Long answer type questions

1.Each photograph is a memory. Justify the statement, in the light of the poem.

2.The past can be a source of inspiration as well as regret. Comment, based on any two chapters (prose, poem or drama) that you have read. One may be this poem. The otherwill require recall.

3.A photograph captures a moment in time. Discuss with reference to one of your favourite photographs.

4.If you were the poet, what title would you give to this poem and why.

5.You are the uncle who took the photograph of your mother. At her birthday this year, you came across a copy of this poem. Write aletter to your niece, Shirley, remembering the day at the beach.

6.When we look at something, it looks right back at us. Imagine that you are a photograph, (not necessarily the one in the poem). Write a diary entry commenting on the various people who have come into yourlife.

7.Discuss man’s relation to nature based on any two chapters you may have read (poems,prose, or drama).

8.You are a member of the Blossoms team at Bluebells. You have been assigned the task to interview students at various class levels and write an article about our relationship with our parents. Write the article referring to this poem in context.

9.We only realise the significance of something or someone in our lives, in their absence. Discuss with reference to the text and your real life..

The Photograph by Shirley Toulson Chapter Summary Class 11

The Photograph by Shirley Toulson - Chapter Summary

Short Synopsis

A photograph descries 3 stages. In the first stage, the photograph shows the poet's mother standing at the each enjoying her holiday ith her two girl cousins. She was 12 or so at that time. The second stage takes us twenty or thirty years later. The motehr wouldlaugh at the way she and her cousins Betty andDolly were dressed up for each holidays. In the third stage, the poet remembers the mother with  a heavy heart. The photograph revives a nostargic feeling in the poet.

Brief Summary

A Book by Shirley Toulson
The poet is looking at her mother's photograph which is indeed an old one. With it she can see how her mother looked when she was a little girl of twelve. THe photo shows her on  a beach with her two girl cousins ho are younger than her, holding her hand. It might have een windy at that time that their hair was flying on their faces when the uncle took the photograph.

All the three as smiling through their flying hair. Looking at the photograph, the poet says that her mother had a sweet face, but it was a time before the poet was born. The sea was washing their feet. The poet says that the sea has changed only a little but change has come about who's feet it was washing.After 30 or 40 years, the mother would take out the photograph andtake a look at it. By that time, she was marriedand had a daughter. She would laugh a little and says "Look at Betty and Dolly, see how they have dressed for the beach". By now, she can only remember those days. A huge change has come about her and she is no longer that small innocent girl of twelve.After some years, the poet's mother dies.

Now the poet remembers her mother's laughter, for her it is a thing of past.That's why she says "the sea holiday as her pastand mine is her laughter". Because just like the mother remembers her old days, now the poet can rememer her in that way only. However in course of time, the two of them learnt to live ith their losses. The pay of the losses had made a permanent impression in their wry faces. The poet says that her mother had been dead and no she feels herself in a situation that there is nothing to be said about but only emptiness. The silence of this situation sileances her. In other words, she is left speechless. The fate has killed all the feelings in her.

Thanks

BRIEF SUMMARY OF THE PORTRAIT OF A LADY CLASS 11

POTRAIT OF A LADY

In this story, Khushwant Singh draws a pen picture of his grand mother. He describes how he had spent his childhood with her in the village. He also describes the change that came in the relationship in the city. Ultimately, he describes the moving scene of her death.

Brief Summary

Khushwant Singh draws here an interesting portrait of his grandmother. He presents her as a tender, loving and deeply religious old lady. Singh says that his grandmother was an old woman. She was so old that her face was wrinkled that at the present it was difficult to believe she would ever had been young and pretty. Her hair was white as snow. She had a little stoop in her back. She could be seeing reciting her rosary all the time. The author says that "she was like the winter landscape in the mountains and exponce of pure white serenity breathing peace and contentment."A picture of author's grandfather was hung on the wall. He appeared too old and it was that he ever had a wife. He appeared to have only lots and lots of grandchildren. Singh was the only child at that time. His parents had gone to live in the city leaving him behind the village under the care of his grandmother. She would get him ready for school. And would also feed him with Chappathi. The School as attached with a temple. All the children sat in the verandah reciting alphabets while his grandmother is engaged reading holy scriptures. Finally in the evening, the author and the grandmother would walk back home feeding the dogs.

Khushwant Singh After a friendly relationship with his grandmother, he had to adopt a new life in the city. This itself was a turning point for the grandmother and the grandson. Both of them was sent for to settle down in the city with his parents. The author went to an English school but the grandmother never liked the way he was taught. Though Singh and his grandmother shared the same room, she was unable to help him. Apart from this, she was also disappointed that he was learning music that she considered not for gentlefolks.

In due course, Singh went up to a University and because of that, he was given a separate room.This indeed made the common link of their relationship snapped down completely. The grandmother agreed the fact and she used to spin the wheel from sunrise to sunset to compensate that. Only during the afternoon she would relax by feeding the sparrows with little pieces of bread. They were her best friends and the sparrows also liked her company.

Later, Singh went up abroad for higher studies which was for 5 long years. He had a doubt in his mind that whether his grandmother may survive or not until he come back. His also taught that it might e the last physical contact between them when she came in the railway station to see him off. After 5 years he came back, incredibly he was welcomed by his grandmother who was not grown  a single day older. Singh notices that even at this time when everyone is joyful about his return, grandmother's happiest moments was with her sparrows.Later in the evening there was a change in her attitude.She celebrated the return of her grandson y collecting some women of neighbourhood and beating drum for several hours. But in the morning, grandmother's health deteriorates and she reveals that she was nearing her end. So she decides that she is not going to waste a single moment by talking so she prayed.

Quite suddenly, the rosary falls from her hand and she exhaled her last breath and it was clear that she was no more. After making the preparations for the funeral, the family members went to fetch her body for the last journey. The golden blaze of light of the setting sun glittered her room. And to pay the last homage to the grandmother, thousands of sparrows gathered in and around her room. The sparrows never did cheered nor did they do anything normal. They don't even bother to notice the read pieces thrown at them. Along with her funeral, the sparrows flew away.

RANGE OF MEASUREMENT Q/A CLASS 11

RANGE OF MEASUREMENT

Q1: What is 0.000047 in scientific notation?

Answer: 4.7 x 10-5

Q2:
Q: Students X, Y and Z were asked by their teacher to measure the volume of water in a beaker.X wrote : 200; Y wrote : 200 mL and Z wrote : 200 Lm
Which one of these answers is correct?

Answer: The first one has no units. Therefore, we do not know what does it mean.The third is also not correct because there is no unit like Lm.The second one is the only correct answer because it denotes millilitre.

Q3: Convert 10 inches into meters.

Answer: We know that 1 inch = 2.54 cm (centimeters)

Q4: The micrometer (1 μm) is often called the micron.
(a) How many microns make up 1.0 km?
(b) How many microns are in 1.0 yd? (Given 1yd = 0.9144m)
Also mention significant figures while writing the final answers.

Answer:(a) Since 1km = 103m and 1 m = 106μmGiven 1.0 km has two significant figures,∴  1.0 km = 103m = (103m)(106μm) = 109μm = 1.0 x 109μm (maintaining two significant figures)(b) 1.0 yd = (0.91m)(106μm) = 9.1 × 105μm

Q5: Define parsec unit. Compute  1 parsec into meters (Given, 1 AU = 1.496 x 1011m).

Answer: 1 Parsec (parallactic second) is the distance at which one astronomical unit subtends an angle of 1 second of arc .According to parallax equation, r = l/θwhere l = 1 AU = 1.496 x 1011m andθ = 1'' = (π radians)(60 x 60 x 180)r = 1 parsec = 1.496 x 1011x 60 x 60 x 180/π = 3.08 x 1016m

Q6(cbse paper) : A laser signal is beamed towards a distant planet from the Earth and its reflection is received after seven minutes. If the distance between the planet and the Earth is 6.3 × 1010m, calculate the velocity of the signal.

Answer: Given, Distance (d) = 6.3 × 1010mduration time (t) = 7 min = 7 x 60 = 420 secsIf d is the distance of the planet, then total distance traveledby the signal is 2d.∴ velocity = (2d)/t = (2 x 6.3 × 1010m)/ 420 = 3 x 108m/s

Q7: If the mass of the sun is 2 × 1030kg and the mass of a proton is 2 × 10-27kg. If the sun wasmade only of protons, calculate the number of protons in the sun?

Answer:Given,Mass of the sun =2 × 1030kgMass of a proton = 2 × 10-27kg∴  Number of protons in the sun =(2 × 1030)÷ (2 × 10-27kg)=1057

Q8: Young’s modulus of a metal is 19 x1010N/m2. Express it in dyne/cm2.

Answer:Given Young's modulus E =  19 x 1010N/m2=19 x 1010kg m s-2x m-2(1 N = 1kg m/s2)E =  19 x 1010kg m-1s-2=  19 x 1010x 103g x (102cm)-1s-2E = 19 x 1010+3-2gcm-1s-2= 19 x 1011gcm-1s-2E = 19 x 1011(g cm s-2) cm-2=19 x 1011dyne cm-2

Q9: What are the four important characteristics of any unit standard?

Answer:
1.Permanence(invariability),
2.reproduce-ability.
3.Indestructibility
4.Invariability (The SI standards do not varywith time as they are based on the properties of atoms.)

Q10: What do you mean by the statement 'SI system of units are coherent system of units'?

Answer:It implies the units of derived quantities are obtained as multiples or sub-multiples of certain basic units.

Q11: Name any two methods that are usedto measure long distances?

Answer:
1.Parallax method
2.Laser pulse method
3.Radio-echo method (RADAR or SONAR)

Q12: What do you mean that SI system of units is a rationalized system?

Answer: It implies that the system makes use of one unit for one physical quantity,

THERMODYNAMICS Q/A CLASS 11

Thermodynamics

(Short Q & A)

Q1: Define Thermodynamics

Answer: It is a physical science that deals with quantitative relationbetween heat and mechanical energy. It is mainly based on three laws of thermodynamics.

Q2: Which law of thermodynamics evaluate thermodynamic parameters?

Answer: Third Law of Thermodynamics

Q3: Which Law of Thermodynamics deals with equivalence of different forms of energies?

Answer: First Law of Thermodynamics

Q4: State Zeroth Law.

Answer: It states "Two systems separately in thermal equilibrium with the thirdsystem are said to be in thermal equilibrium with each other."If system A and system B separately are in thermal equilibrium with another system,then system A and system B are also in thermal equilibrium with each other.

Q5: What is thermochemistry?

Answer: Thermochemistry is a branch of thermodynamics which deals with the relationships between chemical reactions and corresponding energy changes. It is based on 1st law of thermodynamics.

Q6: Name two laws of thermochemistry.

Answer: (i)  Lavosier and Laplace Law(ii) Hess's Law

Q7:Which Law of thermodynamics tells about direction of chemical change?

Answer: 2nd Law of thermodynamics.

Q8: What are the limitations of Laws of Thermodynamics?

Answer:
1.Laws are applicable at macroscopic level i.e. only to matter in bulk. It does not apply to individual molecules or atoms.

2.It does not tell anything about the rate of process will change nor tells about the time taken to reach equilibrium.

3.Concerns with the states (initial and final)but does not concern about the path.

4.It fails to explain to which extent heat willbe converted to work and vice versa.

Q9: What is a System? What are its different types?

Answer: The part of the universe under thermodynamic study is called a system. It is isolated fromthe rest of the universe by with a bounding surface.
Types of System are:
1. Open System
2. Closed System
3. Isolated System

Q10: Identify from the following which can be considered as open, closed or isolated system
i. ice in a closed beaker
ii. lime kiln
iii. Animals and Plants
iv. ice in thermos flask for first one hour.

Answer:
i. ice in a closed beaker : Closed System
ii. lime kiln : Open System
iii. Animals and Plants: Open System
iv. ice in thermos flask.: Isolated System

Q11(MCQ): Which of the following is the intensive property?

(a) temperature
(b) viscosity
(c) density
(d) all of these

Answer: (d) all of these

Q12(MCQ): Which of the folloing is an example of extensive property?

(a) temperature
(b) density
(c) internal energy
(d) surface tension

Answer: (c) internal energy

Q13: Define intensive property. Give its examples.

Answer: A property which is independent of the amount of substance(s) present in the systemis called intensive property

Examples are: temperature, pressure, density, viscosity, refractive index, concentration,specific heat, surface tension etc.

Q14: Which law of thermodynamics describes entropy?

Answer: Second Law.

Q15: Which law of thermodynamics is about the absolute zero temperature?

Answer: Third Law of Thermodynamics

Q16: What are state functions? Give examples of state functions?

Answer: The thermodynamic parameter which depend on the initial and final states of the system and are independent of how the change is accomplished are called statefunctions.

Examples are:
*.Internal Energy (U)
*.Enthalpy (H)
*.Entropy (S)
*.Pressure (P)
*.Potential Energy (PE)
*.Temperature (T)
*.Volume (V)

Q17(NCERT/NCERT): Choose the correct answer. A thermodynamic state function is a quantity
(i) used to determine heat changes
(ii) whose value is independent of path
(iii) used to determine pressure volume work
(iv) whose value depends on temperature only.

Answer: (ii) whose value is independent of path

Q18: What are path functions?

Answer: The system variables which depend upon the path of the system are called path functions or process functions.Examples are: work, heat and length.

Q19: Why is potential energy a state function while work is not?

Answer: An object at a particular height has fixed potential energy (mgh), irrespective of the fact how that object is brought to that height. Therefore potential energy depends on the final state and is a state function. Work done to bring that object to that height may be different i.e. whether it is picked up by lift or brought by a slope. Work is a path function.

Q20: How will you define thermodynamic process? What are its types?

Answer: The conversion of state of system from one to another is called a process. Various thermodynamic processes are:
*.Isothermal
*.Adiabatic
*.Isobaric
*.IsoChoric
*.CyclicIn addition,
a process may be classified as:
*.Reversible Process
*.Irreversible Process

Q21(MCQ): Thermodynamics is applicable to
(a) Only to microscopic systems
(b) Only to macroscopic systems
(c) Only to homogeneous systems
(d) Only to heterogeneous systems

Answer: (b) Only to macroscopic systems

Q22: What is a Isothermal Processes?

Answer: The processes in which the temperature remains fixed, are termed isothermal processes.The isothermal system is usually achieved by keeping the system in contact with a thermostat (i.e. constant temperature bath).In isothermal process, ΔT = 0 and ΔU = 0.

Q23: Define Adiabatic Process?

Answer: The process in which no heat can flow into or out of the system, is called adiabatic process.  It can be achieved by running the process in an insulated container like thermos-flask.For an adiabatic process Δq = 0

Q24(NCERT/MCQ): For the process to occur under adiabatic conditions, the correct condition is:
(i) ΔT = 0
(ii) ΔP = 0
(iii) q = 0
(iv) w = 0

Answer: (iii) q = 0Under adiabatic
conditions no heat transfertakes place, ∴ q = 0.

Q25: Define Isobaric Processes?

Answer: Isobaric  process is the one at which the process is carries out at constant pressure. e.g. water heating takes places inan open vessel under atmospheric pressure is an isobaric process.In an Isobaric process ΔP = 0

Q26: What is an Isochoric Process?

Answer: The process in which the volume remains constant is known as Isochoric process.e.g. a substance is heated in a non-expanding container will have an isochoric syste,In Isochoric process ΔV = 0 and ΔW = 0.

Q27: What factors determine the state of a thermodynamic system?

Answer: The factors are:*.Absolute Pressure (P) in pascals.*.Temperature (T) in Kelvins*.Volume (V) in cubic meters*.Number of moles (n) of working gas.

Q28: What is internal energy?

Answer: The internal energy (U or E) of a system is the total of all kinds of energy possessed bythe particles that make up the system.⇒ It is the sum of its translational, vibrational, rotational energies, chemical bond energy, nuclear energy possessed by sub-atomic particles, electronic energy and its potential energy due to its interaction with neighbouring molecules.It is a state property  and its absolute valuecannot be determined. We can determine the change in internal energy only.

Q29: What are the factors an internal energy of the system depends upon?

Answer:

1.Quantity of the gas or substance
2.Its chemical nature
3.Temperature, Pressure and Volume.

Q30: How can we say internal energy is a state function?

Answer: Consider 1 mole of water is heated from 273K to 373K, the change in energy is 7.52KJ. It is the same regardless of the form in which this energy is transferred to the water i.e. either by heating or by performing work or by another means.

Q31: Is internal energy is extensive or intensive property ?

Answer: The value of internal energy of a system depends on the mass of the matter contained in asystem, it is classed as an extensive property.

Q32: How work is defined in thermodynamics?

Answer: In thermodynamics, in general thework is done in expansion (or compression)of a gas. This is known aspressure-volume workorPV workor expansion work.For expansion work, W = - P× V joulesFor compression, work W =  P× Vjoules

Q33: What are the sign conventions used for Heat and Work?

Answer:
1.Heat flows into the system, q is +ve
2.Heat flows out of the system, q is –ve
3.Work is done on the system, w is +ve
4.Work is done by the system, w is –ve

Q34: Define First law of thermodynamics.
Answer: The total energy of an isolated system remains constant though it may change fromone form to another.Mathematically,  when work is done on thesystem,  ΔU = q + wAnd when work is done on  by the system, ΔU = q - w.
help from eduvictors

CLASS 11 LAWS OF CHEMICAL COMBINATIONS Q/A

Laws of Chemical Combinations

Q1: List the laws that are collectively called Laws of Chemical combinations.

Answer:

1. Law of Conservation of Mass
2. Law of Constant composition
3. Law of Multiple proportions
4. Law of reciprocal proportions
5. Law of Combining Volumes (Gay Lussac's law of Gaseous Volumes)
6. Avogadro Law

Q2: State Law of conservation of mass.

Answer: The law states, "In all physical and chemical changes, matter can neither be created nor be destroyed". Experimentally, it can be proved for both changes i,e. physical changes and chemical changes.

(a) When matter undergoes physical change e.g. a piece of ice cube in closed flask is heated. Ice cube gently melts to liquid state. Here,
 mass of ice in enclosed flask (before melting) = mass of water in the closed flask (after melting)

(b) When matter undergoes chemical change,
     Mass of reactants = Mass of products  + Mass of un-reacted reactants.

For exampLe. 100 g of mercury Oxide, is heated and is decomposed to produce, 92.6 g of mercury, and 7.4 g of oxygen.

        HgO (s)     →    Hg (l) + ½O₂
        100g         →    92.6g   + 7.4g


Q3:Who proposed law of conservation of mass.

Answer: Antoine Lavoiser in 1789

Q4: What mass of Silver Nitrate will react with 5.85g of sodium chloride to produce 14.35 g of Silver Chloride and 8.5g of Sodium Nitrate, if law of conservation of mass holds true?

Answer:  Let mass of Silver Nitrate (AgNO₃) in this reaction = x g

Law of conservation is true,
∴     AgNO₃ + NaCl     →   AgCl + NaNO₃
            x g    + 5.85g      =   14.35g + 8.5 g
⇒        x = 14.35g + 8.5 g - 5.85g = 17.0 g

Q5: What is the Law of Definite Proportions?

Answer: It states, "A given chemical substance (compound) always contains the same elements combined in a fixed proportion by weight”. It is also called law of constant composition.

For example, 1.0 gram of sodium chloride always contains 0.39 gram of sodium and 0.61 gram of chlorine, irrespective if it chemically combined or naturally found. Sodium chloride has definite proportions of sodium and chlorine; that is, it has definite proportion.

Q6: Who proposed the Law of Definite Proportions?

Answer: Louis Proust

Q7: What are the limitations of Law of Definite Proportions?

Answer:

1. The law does not hold true if the different isotopes of the element are involved in making chemical compound. e.g. For making CO₂ gas, C-12 combines with O in ratio C:O :: 12:32 while C-14 carbon isotope combines in ratio C:O::14:32.
2. The law is not applicable when elements combine in the same ratio but different compounds are formed. e.g. C₂H₅OH (ethyl alcohol) and CH₃OCH₃ (methol gas) are two different compounds but having same molecular formula i.e. C₂H₆O. In both compounds, the ratio of C:H:O by mass is same i.e. 12:3:8.

Q8: Is there any limitation of Law of Conservation of mass?

Answer: Yes. Law of conservation of mass holds true for most of the chemical equations, because heat energy dissipated or consumed is within error limits. For nuclear reactions, where a very large amount of energy is released, this law is not applicable.


Q9: When 1.375 g of CuO was reduced by H₂, 1.098 g of Cu was obtained. In another experiment, 1.178 g of Cu was dissolved in nitric acid and the resulting copper nitrate was converted into CuO by ignition The weight of CuO formed was 1.476 g. Show that in both these experiments the law of definite proportion holds true.

Answer:
In the first experiment:
        Weight of  CuO  = 1.375 g
         Weight of Cu     = 1.098 g
         Weight of O       = 1.375 - 1.098 = 0.277 g
Ratio of Cu:O             = 1.098 : 0.277  = 3.96 : 1

In the second experiment,
         Weight of CuO   = 1.476 g
         Weight of Cu      = 1.178 g
          Weight of O       = 1.476 – 1.178 = 0.298 g
     Ratio of Cu:O         = 1.178 : 0.298 = 3.96 : 1
In both experiments we obtain same Cu:O ratio i.e. 3.96:1. Hence law of definite proportions is applied here.

Q10: What is meant by the Law of multiple proportions?

Answer: Law of multiple proportions states, "If two elements chemically combine to give two or more compounds, then the weights of one element, which combine, with the fixed weight of the other element in those compounds, bear a simple multiple ratios to one another."

The law was proposed by Dalton based on his atomic theory.

e.g. 1g of Carbon(C) combines with oxygen and forms two compounds i.e. CO and CO₂. In CO, 1g of C combines with 1.33g of oxygen (O). And in CO₂, 1g of C combines with 2.66 g of O.
Weight of oxygen that combines with carbon are in ratio 1:2.

Q11: What was the importance of  Law of multiple proportions?

Answer: The law of multiple proportions was deduced from Dalton's atomic theory.  The law hold true was able to convince chemists the validity of atomic theory.

Q12: A metal combines with oxygen to form two oxides, having the following composition:
(i) 0.398 g of first metal oxide contains 0.318 g of metal.
(i) 0.716 g of second oxide contains 0.636 g of metal.
Show that the above data agrees with the law of multiple proportions.

Answer: Wt of oxygen in first oxide = 0.398 - 0.318 = 0.080 g
Wt of oxygen in second oxide = 0.716 - 0.636 = 0.080 g

For fixed mass of oxygen, (0.080g), metal forms oxides in the ratio = 0.318:0.636 = 1:2
Since 1:2 is a simple ratio, it agrees with the law of multiple proportions.

Q13: Hydrogen combines with oxygen and forms two compounds. In the first compound, hydrogen content is 5.93% while in the other compound it is 11.2%. Verify whether the data agrees with law of multiple proportions.

Answer: In 1st compound, Hydrogen = 5.93% ⇒ Oxygen = 100 - 5.93 = 94.07%
⇒ If 5.95 part of H combines with parts of Oxygen = 94.07
   1 part of Hydrogen combines with O = 94.07/5.93 = 15.86 parts.

In 2nd compound, Hydrogen composition = 11.2%, Oxygen composition = 88.8%
⇒ If 11.2 part of H combines with parts of Oxygen = 88.8
   1 part of Hydrogen combines with O = 88.8/11.2 = 7.9 parts.

The ratio of oxygen in parts that combine with 1 part of hydrogen = 15.86:7.9 = 2:1
Since 2:1 is a simple ratio, it is in agreement with Law of multiple proportions.

Q14: State Law of reciprocal proportions.

Answer: Law of reciprocal proportions states, "When two elements combine separately with a fixed mass of a third element, then the ratio of their masses in which they do so is either same or some whole number multiple of the ratio in which they combine with each other".

Q15: Who proposed law of reciprocal proportions.

Answer: Ritcher.

Q16: What is Gay Lussac’s Law of Gaseous Volumes or Combining Volumes?

Answer: The law of combining volumes was given by Gay Lussac in 1808. It is applicable only to gaseous reaction. According to this law, gases combine or are produced in a chemical reaction they do so in a simple ratio by volume provided all gases are at same temperature and pressure.


For example, two volumes of hydrogen react with one volume of oxygen gas to produce water. They bear a simple ratio 2:1

         2H₂(g)     + O₂ (g)  → 2H₂O (l)    
       2 volumes     1 volume  → 2 volumes
Law of combining volumes can be derived from Law of definite proportions when expressed in terms of volumes. Later Avagadro interpreted this law in terms of molecules. e.g. the ratio in the above equation 2:1:2 is called molar ratio of this gas reaction.

Q17: What is Avogadro's Law? 

Answer: According to this law, equal volumes of all gases under similar conditions of temperature and pressure contain equal number of molecules.

Avogadro's hypothesis reveals the following facts:

1. It introduces the fact molecules are polyatomic. 
2. It provided the basis for determining the relative masses of atoms.
3. One mole of all gases contain N_A number of molecules.
4. Mathematically at standards pressure and temperature (STP),  volume (V) ∝ n( no. of moles or molecules). i.e. V₁/n₁ = V₂/n₂ 
5. Volume of 1 mole of gas at STP (P  = 1 atm and T = 273K) = 22.4 litres.
6. Molecular mass of a gas = 2 × vapour density of gas.

Q18: A wooden log burns completely into ash. Justify conservation of mass is applied here.

Answer: Whenever a chemical change occurs, we consider mass of both reactants and products.
When a wooden log (its composition is mainly organic matter like hemi-sllulose, lignin etc.) burns and decomposes into Carbon-DiOxide gases, ash (Carbon) and water. Law of conservation of mass holds true here, the mass reactant (wood and oxygen) is equal to mass of products i.e. gases, water vapours released and ash.

Q19 (NCERT): The following data are obtained when dinitrogen and dioxygen react together to form different compounds:

   Mass of dinitrogen    Mass of dioxygen
(i)    14 g                       16 g
(ii)   14 g                       32 g
(iii)  28 g                       32 g
(iv)  28 g                       80 g

Which law of chemical combination is obeyed by the above experimental data? Give its statement.
Answer: For the fixed mass of dinitrogen at 28 g, the masses of dioxygen that combines
with the the fixed mass dinitrogen are  = 32 g, 64 g, 32 g, and 80 g.
i.e. 2:4:2:5. Since The masses of dioxygen bear a whole number ratio, hence, the given experimental data obeys the law of multiple proportions.

The law states that if two elements combine to form more than one compound, then the masses of one element that combines with the fixed mass of another element are in the ratio of small whole numbers.

Q20 (NCERT): If ten volumes of dihydrogen gas react with five volumes of dioxygen gas, how many volumes of water vapour would be produced?

Answer: Reaction of dihydrogen with dioxygen is:

         2H₂(g)     + O₂ (g)  → 2H₂O (l)
Now, two volumes of dihydrogen react with one volume of dihydrogen to produce two volumes of water vapour.
Applying law of combining volumes, the two gases combine in molar ratio 2:1:2.
Therefore, ten volumes of dihydrogen will react with five volumes of dioxygen to produce
ten volumes of water vapour.

Q21: What was Dalton's atomic theory?

Answer:

1. Matter is made up of extremely small, indivisible particles called atoms.
2. Atoms of same substance are identical in all respects, i.e., they possess same size, shape,
   mass, chemical properties, etc.
3. Atoms of different substances are different in all respects, i.e., they possess different
   sizes, shapes, masses, chemical properties, etc.
4. Atom is the smallest particle that takes part in chemical reactions.
5. Atoms of different elements may combine with each other in a fixed, simple, whole
   number ratio to form compound atoms.
6. Atoms can neither be created nor destroyed, i.e., atoms are indestructible.

Q22: What are main failures of  Dalton theory?

Answer: The main failures or limitation of Dalton’s atomic theory are:

1. It failed to explain anything about structure of the atom.
2. It could not explain how and why atoms of different elements combine with each other to form compound-atoms or molecules.
3. It failed to explain the nature of forces that bind together different atoms in a molecule.
4. It failed to explain Gay Lussac’s law of combining volumes.
5. It failed to account for the stability of atom after the discovery of sub-atomic particles.
6. It failed to understand the origin and nature of the characteristics of electromagnetic
   radiation absorbed or emitted by atoms.

taken from eduvictors

BY : SUMIT BHADRA (A.C.S)

CLASS 11 MOLE CONCEPT Q/A

 

CBSE Class 11 - Chemistry - CH1 - Mole Concept

taken from eduvictors

Q1: Define mole

Answer: A mole (or mol) is defined as the amount of substance which contains equal number of  particles (atoms / molecules / ions) as there are atoms in exactly 12.000g of carbon-12.

One mole of carbon-12 atom has a mass of exactly 12.000 grams and contains 6.02 × 10²³ atoms.

A mol is just a number like a dozen. A dozen equals to 12 eggs , a gross of Pencil equals to 144 Pencil. Similarly, mol is equal to 6.022 × 10²³(Avagadro constant). Mol is also known as chemist dozen.


The value 6.022 × 10²³ is known as Avogadro Constant (N_A), after the Italian scientist who first recognized the importance of the mass/number relationship


Q2: Why was there need to use this number called mole?

Answer: Atoms and molecules are extremely small in size and their numbers in even a small amount
of any substance is really very large. To handle such large numbers, a unit of similar magnitude is required.

In SI system, mole (symbol, mol) was introduced as seventh base quantity for the amount of a substance.


Q3: 1 mol of chlorine atom contains
(a) 6.022 × 10²³ atoms
(b) one  atom
(c) 35.5 g of Cl
(d) All of the above.

Answer: Both (a) and (b) are correct. 1 mol of Cl atom = 36.5 g of Cl (molar mass)
   = 6.02 × 10²³ atoms.


Q4: 1.0 mole of Chlorine molecule (Cl₂) contains
(i) how many number of molecules.
(ii) how many number of atoms.
(iii) how much it weighs.

Answer: (i) 1.0 mol of Cl₂ contains 6.022 × 10²³molecules.
(ii)  One molecule of Cl₂ contains 2 toms of Cl. ∴ Cl₂ contains 2 × 6.022 × 10²³ atoms
       i.e. 12.44 × 10²³ atoms

(iii) Molar mass of Cl is 35.5 gm/mol. 1.0 mol of Cl₂ weighs = 2 × 35.5 = 71.1 g

Mole in terms of number,

1 Mole of particle = 6.022 × 10²³ particles

Q5: Which of the following is correct option?
1.0 mole of NH₃ (ammonia) contains ...
(a) 6.022 × 10²³ molecules
(b) 4 mol of atoms
(c) 1 mol of Nitrogen atoms
(d) 3 × 6.022 × 10²³ of H atoms

Answer: All of the above options are correct.

Q6: What is atomic mass unit (amu)?

Answer: Atomic mass unit is defined as a mass exactly equal to one-twelfth the mass of one carbon-12 atom. One atomic mass unit also called one Dalton.

Mass of one mole of C-12 atoms = 12 g = mass of 6.022 × 10²³ C-12 atoms

1 amu = 1g per mol = 1/N_A = 1/ (6.022 × 10²³) = 1.66 × 10^-24g.

Q7: What is the mass of one ¹²C atom? Express it in grams as well as in amu.

Answer: one mole of C-12 atoms = 12 g = mass of 6.022 × 10²³ C-12 atoms
∴ mass of 1 C-12 atom =  12g ÷ 6.022 × 10²³ = 1.994 × 10^-23g
or   = 12g ÷ 6.022 × 10²³  = 12g × 1.66 × 10^-24g = 12 amu.

Q8: What is molar mass?

Answer: The mass of one mole of an element or one mole of compound is referred  as molar mass.
It is expressed as g mol^-1.

Example:
    molar mass of Mg  = 24 g mol^-1.
    molar mass of methane (CH₄) = (12 + 4) g mol^-1 = 16 g mol^-1.

Q9: What is Gram atomic mass or molar mass of an element?

Answer:  Gram atomic mass or molar mass of an element is mass of 1 mol of atoms or atomic mass expressed in grams. For example, atomic mass of Mg = 24u, therefore, molar mass of Mg is 24 grams per mol. Molar mass of an element is also called one gram atom.

Q10: What is Gram molecular mass or molar mass of molecular substance?

Answer: Gram molecular mass or molar mass of a molecular substance is the mass of 1 mol of molecules or molecular mass expressed is grams. For example, molecular mass of H₂O is 18u (2u + 16u), therefore, molar mass of H₂O is 18 g mol^-1. 

Mole in terms of mass,

No. of Moles = Mass ÷ Molar mass 

Q11: In 14g of N₂(nitrogen gas), calculate 
(i) number of moles (take molar mass of 28 g mol^-1)
(ii) number of molecules
(iii) number of atoms

Answer:
(i) No. of moles = 14g ÷ 28 g mol^-1 = 0.5 moles
(ii) No. of molecules = (number of moles) × N_A = 0.5 × 6.022 × 10²³ = 3.011 × 10²³ molecules
(iii) One molecule of N₂ contains 2 N atoms.
 No. of atoms  = 2 × 3.011 × 10²³ = 6.022 × 10²³ atoms = 1 N_A atoms.

Q12: One gram molecule H₂O contains how many moles of molecules and number of molecules?

Answer:  1 gram molecule H₂O = 1 mol of molecule H₂O = 6.022 × 10²³ molecules of  H₂O

Q13: How many moles of molecule are present in 15g of C₂H₄ (ethylene). Given atomic mass of C = 12.0 amu and of H = 1.0 amu.

Answer: Molecular mass of C₂H₄ = 2 × 12.0 amu + 4 × 1.0 amu = 24 + 4 = 28amu
∴ Molar mass of C₂H₄ = 28 g mol^-1
No. of moles of molecule C₂H₄ = mass ÷molar mass = 15 ÷ 28 = 0.536 mol.

Q14: Calculate number of bromide ions in 3 moles of  mercury(II) bromide.

Answer:  Mercury(II) bromide (HgBr₂) in ionic form in an aqueous solution is
       HgBr₂ →  Hg⁺² + 2Br^-1
 ∴ 1 molecule of HgBr₂ contains 2 Br^-1 ions.
 ⇒ 1 mol of HgBr₂ contains 2 mol Br^-1 ions.
  ∴ 3 molecule of HgBr₂ contains (2×3) = 6 Br^-1 ions. = 6 × 6.022 × 10²³   = 1.807 × 10²⁴ ions

Q15: What is Molar Volume?

Answer: One mole of any gas contains 22.4 liters at N.T.P or S.T.P. (0°C and 1atm/760 mm of Hg), the volume is called molar volume of standard molar volume. For molecular gases (e.g. CH₄), it is expressed  as gram molecular volume and for atomic gases (e.g. He gas), it is expressed as gram atomic volume.

e.g. One mol of CH₄ = 22.4 litres at STP gram molecular volume = 1 gram molecule of CH₄
       =  6.022 × 10²³  molecules of CH₄ = 16g of  CH₄

Mole in terms of molar volume, at STP

No. of Moles = Volume of gas (dm³) ÷ 22.4 (dm³ mol^-1)

Q16: What is the volume in litres at S.T.P. of 3 moles of hydrogen sulfide H₂S gas?
Answer: At S.T.P., 1 mole    = 22.4 litres molar volume
3 moles = 3 × 22.4 = 67.21 litres of Hydrogen Sulphide (H₂S).




Q17: A balloon is filled with He gas at N.T.P. The volume of the balloon is 2.24 dm³, find the amount of He gas in terms of moles is present.

Answer:  At N.T.P., 22.4 dm³ contains 1 mol of  Helium gas.
2.24 dm³ will have = 2.24 × 1/ 22.4 = 0.1 mol.




Q18: Calculate the molar mass of glucouse (C₆H₁₂O₆).

Answer:
   Atomic mass of C = 12u
   Atomic mass of H = 1 u
   Atomic mass of O = 16 u

 No. of C atoms glucouse = 6
 No. of H atoms glucouse = 12
 No. of O atoms glucouse = 6


Molar mass of glucouse = 6 × 12 + 12  × 1 + 6  × 16 = 180g
⇒ 1 mole  or 6.022 × 10²³ molecules of glucouse (C₆H₁₂O₆) weighs = 180g



Q19: A 12.0 g sample of gas occupies 19.2 L at STP. What is the molecular weight of this gas?

Answer: According to Avagadro's law, at n.t.p. 1 molar volume of gas = 22.4 L

At n.t.p. 19.2 L gas weighs = 12.0 g
At n.t.p. 22.4 L gas weighs = 12.0 x 22.4 /19.2 = 14.0g / mol




Q20(NCERT): Calculate the molecular mass of the following:
(i) H₂O
(ii) CO₂
(iii) CH₄

Answer:
Molecular mass is the sum of atomic masses of the elements present in a molecule. It is obtained by multiplying the atomic mass of each element by the number of its atoms and adding them together.

(i) Molecular mass of Water (H₂O) = (2× Atomic mass of H) + (1 × Atomic mass of Oxygen)
     = 2 × 1.008u + 1 × 16.00u = 2.016 u + 16.00 u = = 18.016 u  = 18.02 u

(ii) Molecular mass of CO₂ = (1 × Atomic mass of C ) + (2 × Atomic mass of O)
     =  1 × 12.011u + 2 × 16.00u = = 12.011 u + 32.00 u  = 44.01 u

(iii) Molecular mass of CH₄ = (1 × Atomic mass of C ) + (4 × Atomic mass of H)
     = 1  × 12.011u + 4 × 1.008u = = 12.011 u + 4.032 u = 16.043 u

Q21(NCERT): How much copper can be obtained from 100 g of copper sulphate (CuSO4)?
Answer: 1 mole of CuSO₄ contains  = 1 mole of Cu + 1 mol of S + 4 moles of O.
Molar mass of CuSO₄ = (63.5g) + (32.00g) + 4(16.00g)
       = 63.5 + 32.00 + 64.00 = 159.5 g

Since, 1 mole of CuSO4 contains 1 mole of Copper.

⇒ 159.5 g of CuSO4 contains 63.5 g of copper.
100g of CuSO4  will have Cu = (63.5 × 100) / 159.5 = 39.81g



Q22(NCERT): What will be the mass of one ¹²C atom in g?
Answer:  1 mole of carbon atoms = 6.022 × 10²³  atoms of carbon
                                = 12 g of carbon
 Mass of one ¹²C atom = 12 ÷  6.022 × 10²³  = 1.994 × 10^-23 g



Q23 (NCERT): Calculate the number of atoms in each of the following 
(i) 52 moles of Ar
(ii) 52 u of He 
(iii) 52 g of He.

Answer:
(i) 1 mole of Ar = 6.022 × 10²³ atoms of Ar
     52 mol of Ar = 52 × 6.022 × 10²³ atoms of Ar
              = 3.131 × 10²⁵  atoms of Ar

(ii) 1 atom of He = 4 u of He
 ⇒ 4 u of He = 1 atom of He
     1 u of He atom of He = 1/4 atoms of He
   52u of He atom of He = 52 × 1/4 =  13 atoms of He

(iii) 4 g of He = 6.022 × 10²³ atoms of He
      52 g of He atoms of He = 6.022 × 10²³ × 52 / 4 = 7.8286 × 10²⁴ atoms of He


BY : SUMIT BHADRA (A.C.S)