Saturday, 21 January 2017

The story of my life summry SA2 class10

By Muhammad Sahanawaj

The Story of my Life: Summary (Chapter 15-22) 
Chapter 15 
Helen spent the next summer and winter with her family in Alabama. Staying at home made her forget about the controversy over ‘The Frost King’. Helen was scared that people would discover that the ideas were not her own. To help her, Helen’s teacher Anne Sullivan encouraged her to write the story of her own life in the form of an assignment. Helen was 12 years old at that time and used to write for a magazine called Youth's Companion. Her visit to President Cleveland’s inauguration, to Niagara Falls, and to the World’s fair were the big events of 1893. Although she couldn’t see the Falls, Helen said that their power had a big impact on her. Helen claimed that beauty and music were like goodness and love to her.
Chapter 16 
By the time Helen was 13, she could fingerspell and read in raised print and Braille. He could not only speak in English, but also a little bit of French. Helen began her formal schooling and preparation for college in for college by taking Latin and Math lessons.  She initially liked Math more, but later grew to love Latin too.
Anne Sullivan taught Helen based on her interests until now. She used to teach her what she wanted to know and provided her with experiences. However, when preparing for college, Helen worked systematically and things that did not gratify her immediately. She had to achieve her goal of receiving formal education.  
Chapter 17 
In October 1894, Helen went to the Wright-Humason School for the Deaf in New York City for two years. Miss Sullivan accompanied her and attended the school as her interpreter. Helen studied arithmetic, physical geography, French and German at the school. The school was chosen because it was the best for continuing the development of Helen’s speech and lip reading skills. Helen and her teachers were disappointed as her lip-reading and speech skills were not what they had hoped and expected to be despite the practice. Helen did not like Math. In spite of the setbacks, her admiration for geography and languages helped her form fond memories of her stay in New York.  The only thing she liked about New York was Central Park. The daily walks in Central park and closeness to nature were the two things that helped her get closer to her former life in her country.
Chapter 18 
In 1896, Helen went to Cambridge school for Young Ladies to be prepared to get into Radcliffe. It was her first experience of attending classes with girls who could hear and see. At the Cambridge School too, Miss Sullivan was to attend the classes with Helen as her interpreter. The teachers had never taught someone like Helen. The subjects that Helen learnt in the first year were English history, English literature, German, Latin, arithmetic, Latin composition and occasional themes. Miss Sullivan tried her best to spell into Helen’s hands everything that was in the books. Although Helen’s sponsors in London and Philadelphia worked to have the textbooks embossed in raised print for Helen to read, the books were not ready in time to suit Helen’s purpose. The Principal and the German teacher learnt to fingerspell so that Miss Sullivan could take a break. Although they were not as fluent as Miss Sullivan, Principal Gilman took over teaching Helen English Literature for the remaining part of the year.  
Chapter 19 Summary
Helen looked forward to her second year at Gilman’s school. However, she was confronted with unexpected difficulties that year which caused her a great deal of frustration.  She had to study mathematics without the needed tools. The classes were larger and it was not possible for the Cambridge teachers to give her special instructions. Anne Sullivan had to read all the books to her. Helen had to wait in order to buy a Braille writer so that she could do her algebra, geometry and physics.
When the embossed books and the other apparatus arrived, Helen’s difficulties began to disappear and she began to study with confidence. However, Mr. Gilman thought that Helen was overworked and was breaking down. He insisted that I was overworked, and that I should remain at his school three years longer. He made changes in her studies. A difference of opinion between Mr. Gilman and Miss Sullivan resulted in Helen’s mother withdrawing Helen and Mildred from the Cambridge school. Helen went on to continue her studies under a tutor. Helen found it easier to study with a tutor than receive instructions in class.
When Helen took her exam in June 1899, she faced many difficulties, as the administrative board of Radcliffe did not realize how difficult they were making her examinations. They did not understand the peculiar difficulties Helen had to go through. However, Helen, with her grit and determination, overcame them all.                  
Chapter 20 
Helen Keller took the entrance exams for Radcliffe College in 1899 just after her 19th birthday. She became the first blind-deaf college student in the fall of 1900.  She had thought of college romantically, that it would be a time to reflect and think about her subjects. However, her college life was different from her fellow students. She had to use her hands to listen rather than take down notes. The speed at which the lectures took place made it difficult for Keller to understand and remember everything that was taught.
Ms. Keller and Ms. Sullivan worked hard at Radcliffe College. Ms. Sullivan attended all of Ms. Keller's classes and helped with reading. Radcliffe was not prepared for deaf or blind students at that time. Many of the other students had never met a deaf and blind person. Although she enjoyed college, Ms. Keller thought that schedules of the students were too hectic and gave no time to sit and think. She also wrote, "we should take our education as we would take a walk in the country, leisurely, our minds hospitably open to impressions of every sort."
Chapter 21 
In this chapter, Helen Keller goes back to tell readers about her initial experiences with reading. Helen first read when I was seven years old. That was her first connected story in May 1887. There were only a few books in raised print, which Helen read repeatedly until a time when the words were so worn and pressed that she could scarcely make them out.
During her visit to Boston, she was allowed to spend a part of each day at the Institution library, and here she used to wander from bookcase to bookcase and take down whatever her “fingers lighted upon”. When she discovered the book ‘Little Lord Fauntleroy,’ Miss Sullivan read it to her and the book became Helen’s “sweet and gentle companion” throughout her childhood.
From there she read many books and she loved "Little Women" because it gave her a sense of kinship with girls and boys who could see and hear. She also loved ‘The Jungle Book’ and ‘Wild ‘Animals I Have Known’ as she felt a genuine interest in the animals themselves, they being “real animals and not caricatures of men”.  She was fascinated by Greek literature and it was Iliad that made Greece her “paradise”. According to her, great poetry did not need an interpreter but a responsive heart. Macbeth and King Lear impressed her most among Shakespeare’s works. She read the Bible for years “with an ever-broadening sense of joy and inspiration”. She said she loved it as she loved no other book.
Helen also expresses her love for history apart from her love for literature. The first book that gave her a real sense of the value of history was Swinton's "World's History," which she received on her thirteenth birthday. Among the French writers, she liked Molière and Racine best. Literature was Helen’s Utopia, where she faced no barrier of the senses. The things that she had learned and the things that were taught to her seemed of ridiculously little importance compared with their "large loves and heavenly charities."
Chapter 22 
Books and reading were not the only things that Helen enjoyed. When Helen was not reading, she enjoyed outdoor activities. She liked swimming, canoeing, and sailing. She also loved trees and used to feel close to them so much so that she believed she could hear their sap flow and see the sun shining on the leaves. Helen felt that each one of us had the ability to understand the impressions and the emotions experienced by mankind from the beginning. Blindness or deafness could not rob us of our memory in the subconscious about the green earth. This, she termed as the sixth sense which can see, feel and hear.   

Thursday, 19 January 2017

Carbon and its compound class10 allen notes

Science Class 10 Notes for Carbon and its Compounds

1. Bonding in Carbon

Carbon form covalent bonds.

Formation of covalent bond : Covalent bond formation involves sharing of electrons between bonding atoms which may be either same or different.

Covalency : The number of electrons contributed by an atom for sharing is known as its covalency.

Characteristics of covalent compounds :

(i) These compounds are molecular in nature (i.e. they exist as single molecules)

(ii) These are insoluble in water and soluble in benzene, kerosene and petrol etc.

(iii) These compounds are poor conductor of electricity.

2. Allotropy in Carbon

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The property due to which an element exists in two or more forms, which differ in their physical and some ofthe chemical properties is known as “Allotropy” and the various forms are called “Allotropes”.

Carbon exists in two allotropic form (i) crystalline (ii) amorphous. The crystalline forms are diamond and graphite whereas the amorphous forms are coal, charcoal, lamp black etc.
Fullerenes form another class of carbon allotropes. The first one to be identified was C-60, which has carbon atoms arranged in the shape of a football.
3. Unique Nature of Carbon

Catenation : The property of elements to form long chains or rings by self linking of their own atoms- through covalent bonds is called catenation. The extent of catenation depends upon the strength of the bonds between the atoms involved in catenation.

4. Saturated and Unsaturated Carbon Compounds

In saturated compounds the valencies of all the carbon atoms are satisfied by single bonds between them.

While in the unsaturated compounds, the valencies of all the carbon atoms are not satisfied by single bonds, thus in order to satisfy their valencies, they form double or triple bond between the carbon atoms.

5. Straight chain compounds : The compounds which contain straight chain of carbon atoms e.g. normal butane (C4H10), normal pentane (5H12) etc.

6. Branched chain compounds : Those compounds which are branched.

e.g. iso-butane (C4H10), isopentane (C5H12), neopentane (C5H12) etc.

7. Closed chain compounds or Ring compounds :

Cyclic compounds are called closed chain or ring compounds e.g. cyclohexane (C6H12), cyclopentane (C5H10), cyclobutane (C4H8), cyclopropane (C3H6) etc.

8. Hydrocarbons

All those compounds which contain just carbon and hydrogen are called hydrocarbons.

9. Functional Group

The atom or group of atoms which determine the properties of a compound is known as functional group. e.g. —OH (alcohol), —CHO (aldehyde), > C = C < (alkene), — C C — (alkyne) etc.

10. Homologous Series

A series of compounds in which the same functional group substitutes hydrogen in a carbon chain is called a homologous series.

e.g. CH3C1 and C2H5C1 differ by a —CH2 unit.

11. Nomenclature

Chemists developed a set of rules, for naming organic compounds based on their structures which is known as IUPAC rules.

The IUPAC name of an organic compounds consists of three parts.

Prefix – word root – Suffix

Word Root : A word root indicates the nature of basic carbon skeleton.

In case a functional group is present, it is indicated in the name of the compound with either as a prefix or as a suffix.

While adding the suffix to the word root the terminal ‘e’ of carbon chain is removed If the carbon chain is unsaturated then the final `ane’ in the name of the carbon chain is substituted by ‘en& or yne’ respectively for double and triple bonds.


12. Chemical Properties of Carbon Compounds :

(i) Combustion : Carbon compound undergo combustion reaction to produce CO2 and H20 with the evolution of heat and light.

CH4 +O2 > CO2 + 2O + heat and light

(ii) Oxidation :


The substance which are used for oxidation are known as oxidising agent.

e.g alkaline KMnO4

Saturday, 7 January 2017

Heridity and Evolution nòtes

Heredity and Evolution Notes

For Class 10 Formulas Download PDF


1. The transmission of characters from parent to their off springs is known as heredity.

The study of heredity and variations is known as genetics.

♦ Clones are those organisms which are the carbon copies of one another.

♦ Variation in sexually reproducing organisms are caused due to the following factors like environment, crossing over and recombination of genes and mutation.

♦ The first study of inheritance was done by Gregor Mendel on garden pea.

♦ Paired condition of chromosomes is known as diploid.

♦ Unpaired condition of chromosomes is known as haploid.

♦ DNA (Deoxyribo Nucleic Acid), RNA (Ribo Nucleic Acid) is the genetic material in all organisms.

2. Mendel’s laws of inheritance are

(i) Law of Dominance
(ii) Law of Segregation (Law of purjty of gametes)
(iii) Law of Independent Assortment

3. Genotype is the composition of genes present in an organism and the characteristic which is visible in an organism is called its phenotype.

4. When two parents cross (or breed) to produce progeny (or offsprings), then their progeny is called F1-generation (First Filial Generation) and when the first generation progeny cross among themselves to prod or second Filial Generation.

♦ Mendel conducted his famous experiments on garden pea (Pisum sativum).

♦ He used a number of contrasting characters like round / wrinkled seeds, tall/ short plants, white/ violet flowers and so on.

5. During Monohybrid Cross

♦ When tall pea plants are crossed with short pea plants then in Fi generation only tall plants were obtained.

♦ F2 progeny ofFi tall plants are not all tall but one quarter of them are short indicating that both tallness and shortness traits were inherited in F1 but only tallness trait was expressed due to dominance.

♦ In dihybrid cross two pairs of contrasting characters were considered. Tall plant with round seeds were crossed with short plant with wrinkled seeds. In Fi tall plants with round seeds were obtained. On selfing these F, plants with F2 produced tall plants with round seeds, short plant with wrinkled seeds and some new combinations (tall plant }
with wrinkled seeds and short plant with rounds seeds) were also obtained. The tall/short trait and round wrinkled traits are independently inherited.

♦ The expression of a particular trait is controlled by gene.

6. DNA is the source of making protein in a cell.

The section of DNA that provides information for one protein is called gene.

7. Physical and Chemical Basis of Heredity

Mendel (1866) said that heredity was controlled by particles, called germinal units, or factors.

8 Sex determination is the process by which the sex of a person is determined.

All human chromosomes are not paired. 22 pairs are called autosomes. Women have a perfect pair of sex chromosomes XX. But men have a mismatched pair XY.

9. Evolution
It is the sequence of gradual changes which take place in the primitive organisms over millions of years in which new species are produced

A. The evidences of evolution are :
i. Homologous organs,
ii. Analogous organs, and
Fossils

B. Theories of Evolution

Jean Baptiste Lamarck gave the first theory of evolution.

Darwin’s Theory of Evolution

Charles Robert Darwin (1809-1882) explained the evolutionary principle in his famous book “The origin of species”. The theory proposed by him is popularly known as theory of natural selection or Darwinsim.

The main features of the theory of natural selection are as follows:
(i) Over production
(ii) Limited food and space
(iii) Struggle for Existence
(iv) Variations
(v) Natural Selection or Survival of the Fittest

10. Speciation : The process by which new species develop from the existing species is known as speciation.

The factors which leads to speciation are :
♦ Geographical isolation
♦ Genetic drift and
♦ Variations

11. Classification Evolutions are of three types :-
(i) Convergent Evolution
(ii) Divergent Evolution
(iii) Para

Electricity notes class10 by allen notes

Science Notes for Class 10
Chapter 12 Physcis Electricity pdf
1.   Positive and negative charges: The charge acquired by a glass rod when rubbed with silk is
called positive charge and the charge acquired by an ebonite rod when rubbed with wool is called negative charge.
2.   Coulomb: It is the S.I. unit of charge. One coulomb is defined as that amount of charge which repels an equal and similar charge with a force of 9 x 109 N when placed in vacuum at a distance of 1 meter from it.
Charge on an electron = -1.6 x 10-19 coulomb.
3.   Static and current electricities: Static electricity deals with the electric charges at rest while the current electricity deals with the electric charges in motion.
4.   Conductor: A substance which allows passage of electric charges through it easily is called a
‗conductor‘. A conductor offers very low resistance to the flow of current. For example copper,silver, aluminium etc.
5.   Insulator: A substance that has infinitely high resistance does not allow electric current to flow through it. It is called an ‗insulator‘. For example rubber, glass, plastic, ebonite etc.
6.   Electric current: The flow of electric charges across a cross-section of a conductor constitutes an electric current. It is defined as the rate of flow of the electric charge through any section of a conductor.     Electric currentharge/Time or I = Q/t Electric current is a scalar quantity.
7.   Ampere: It is the S.I. unit of current. If one coulomb of charge flows through any section of a conductor in one second, then current through it is said to be one ampere.
1 ampere = 1 coulomb/1 second    or      1 A = 1C/1s = 1Cs-1
1 milliampere =   1 mA = 10-3 A
1 microampere = 1µA = 10-6 A
8.   Electric circuit: The closed path along which electric current flows is called an ‗electric circuit‘.
9.   Conventional current: Conventionally, the direction of motion of positive charges is taken as the direction of current. The direction of conventional current is opposite to that of the negatively charged electrons.
10. Electric field: It is the region around a charged body within which its influence can be experienced.
11. Electrostatic potential: Electrostatic potential at any point in an electric field is defined as the amount of work done in bringing a unit positive charge from infinity to that point. Its unit is volt. Positive charges move from higher to lower potential regions. Electrons, being negatively charged, move from lower to higher potential regions.
12. Potential difference between two points: The Potential difference between two points in an electric field is the amount of work done in bringing a unit positive charge from one to another. Potential difference = Work done/Charge  or   V = W/Q
13. One volt potential difference: The Potential difference between two points in an electric field is said to one volt if one joule of work has to be done in bringing a positive charge of one coulomb from one point to another. 1 volt = 1 joule/1 coulomb  or  1 V = 1J/1C
14. Galvanometer: It is device to detect current in an electric circuit.
15. Ammeter: It is device to measure current in a circuit. It is always connected in series in a circuit.
16. Voltmeter: It is a device to measure potential difference. It is always connected in parallel to the component across which the potential difference is to be measured.
17. Ohm’s law: This law states that the current passing through a conductor is directly proportional to the potential difference cross its ends, provided the physical conditions like temperature, density etc. remains unchanged. V α I  or  V = RI
18. Resistance: It is a property of a conductor by virtue of which it opposes the flow of current through it. It is equal to the ratio of the potential difference applied across its ends and the current flowing through it. Resistance = Potential difference/Current or    R = V/I
19. Ohm: It is the S.I. unit of resistance. A conductor has a resistance of one ohm if a current of one ampere of current passing a conductr having apotential difference of one volt.

Electricity Important Question of class10

Questions from CBSE Board Paper 2014 for 2015

Q. A wire of resistivity  ρ  is stretched to double its length. How does it affect the (a) resistance (b) resistivity?
Solution:

(a) wire is stretched to double its length
So, New length of wire   l'= 2l
New Area of cross section or thickness  of wire   A'= A/2
New  resistance = r =( ρ x 2l) /(A/ 2)  = 4ρl/ A = 4 R
 Hence, new resistance = 4r
(b) the resistivity is a property of a material and thus is a constant.
So, in this case, by increasing the length of the wire we are not altering its resistivity. It will remain the same, ρ

Q. A wire of resistance 10 ohm is bent in the form of a closed circle. What is the effective resistance between the two points at the end of any diameter of the circle?

Solution:  A wire of resistance 10 ohm is bent in the form of a closed circle
So, R1 = R2 = 5 Ohm form a parallel loop
R' = (R1  R2)/(R1+ R2) = (5x5 )/(5+5) = 2.5 Ohm

Q. List two safety measures commonly used in electric circuits. Explain the main function of each. [CBSE 2014]

Ans: Two safety measures commonly used in electric circuits and appliances are
(i) Electric Fuse: An electric fuse is connected in series it protects the circuit from overloading and prevents it from short circuiting.

(ii) Proper earthing of all electric circuit in which any leakage of current in an electric appliance is transferred to the ground and people using the appliance do not get the shock.

Q. With the help of a circuit diagram prove that when a number of resistors are connected in  parallel the reciprocal of the equivalent resistance of the combination is equal to the sum of the reciprocals of the individual resistances of the resistors.
Find the resistance between A and B in the following network [CBSE 2014]

Solution:   The resistance between a to and B to C = R1=  2 + 2 = 4 ohm
R2 = 4 Ohm
The resistance between A and B =R' = (R1  R2)/(R1+ R2)  = 4x4/(4+4) = 2 Ohm
Q. (a) How does the resistance of a wire change when
(i) its length is tripled ?
(ii) its radius is tripled ?
(iii) its material is changed to one whose resistivity is three times ?
(b) List two reasons why nichrome is used for making heating element of electrical appliances. [CBSE 2014]

Solution: (a)
(i) We know that resistance of wire is directly proportional to length of wire
So,if  its length is tripled the resistance increases 3 times

(ii) We know that resistance of wire is inversely proportional to area of cross section of wire
New radius = 3r  so,New area increases 9 times
Thus the resistance of a wire decreases 9 times
(ii) R = Pl/A
new resistivity p'   = 3p
New Resistance R' = 3Pl/A = 3R
Thus, the resistance of wire increases 3 times

(b) Nichrome is used for making heating element of electrical appliances because:
(i) Nichrome does not oxidize, i. e. burn easily at high temperatures as it has higher melting and boiling point than metals.
(ii) Nichrome has higher resisistivity and consequently a higher resistance. Therefore, it will resist the flow of charges more, and lead to development of heat faster

Q. Mention one reason why tungsten is used for making filament of electric lamp. [CBSE 2014]
Ans: tungsten does not oxidize, i. e. burn easily at high temperatures as it has higher melting and boiling point than metals

Q. List two characteristics of the material to be used in fuse wire. Name the material it is made of. A fuse is always connected in series in an electric circuit ? Justify this statement giving reason [CBSE 2014]
Answer:
two characteristics of the material to be used in fuse wire
(a) Low melting and boiling point (b) high electric resistance

Fuse is generally made up of  an alloy of tin and lead

In series connection the current for the entire house pass through the fuse. So, when fuse melts , it breaks down the entire home circuit and no current flows to the household circuitry. Thus, a fuse is always connected in series

Q. A circuit has a line of 5 A. How many lamps of rating 40 W; 220 V can si