SAMPLE QUESTIONS ENGLISH (COMMUNICATIVE) (101) CLASS X _SUMMATIVE ASSESSMENT II (2013-14)29/10/2013 Q Read the passage given below carefully. 10 marks
“DAIJA” It was Monday morning when the phone rang. It was my mother. After talking for a minute, she said “I am giving the phone to someone. Talk to her." "Hello," came a familiar voice and I immediately knew who was at the other end. I was very happy to hear that voice. It had been too long. "Daija! How are you? When did you come there?" "Just yesterday. I am fine. How are you?" said Daija Daija was my grandparents' helping hand for many years. She came to work for them almost 51 years ago. My mother was just seven years old then. Daija came unannounced. She had heard that my grandparents were looking for a maid and she travelled for two days to apply for the job. She was around 20 years old then. Daija was puny. She frequently laughed out loud. Her husband had left her for another woman but this had not embittered her about life. Slowly, she became part of the family. Her real name was Kamlaben but my mother would call her “Daija" affectionately and it stuck to her for the rest of her life. Her personality was such that she became the life of every festival and get-together. She was a good dancer and though she did not have a good voice she enjoyed singing too. When my mother was married and moved to another town, Daija cried more than my grandmother. When my mother was pregnant she came to live with her. Every winter, we used to go to our grandparents’ place for holidays and she became our playmate. She would hide some special food from my grandmother to give us later. My grandmother could not do without her. When my grandfather died 10 years ago, she became my grandmother's sole companion. They had disagreements but that didn't bother either of them. But once grandfather was gone, Daija started feeling insecure. My grandmother, who was six years older than Daija, was also not keeping well. Daija would take care of her but who would take care of Daija? She was already 72. One day, she came to my mother and took out about Rs. 6,000, which she had saved. She said "Kamala, please secure a place for me in an old age home. I may not be staying here for a long time." My mother dismissed her but that act remained in her mind. Sometimes, she would discuss Daija’s future with my father. Daija, too old by now to do everything herself, had other maids helping her. She was now the task manager. At times, we could not differentiate her from our grandmother. She was as influential. Then, one day after 45 years, without warning, her husband came to visit her. She had no feelings. She had not seen him for all these years. The other woman had passed away leaving her grown-up son, who was earning decent lives for themselves. The husband himself had made a name in palmistry. Now he was expecting her to come back. She was not sure. He left without an answer. It took her a long time to decide. She finally decided to go .The day she left, a vacuum was created in our lives. There was no one to take her place. Today, we miss her laughs, her unconditional love and her spontaneity. She still visits my grandmother on every festival. These days, Daija has been travelling around with her husband, and his son takes care of her. Some people like Daija leave a void in lives, and are always remembered. Q On the basis of your reading of the above passage, complete the following statement briefly. 1 x 6 = 6 marks 1. Daija came to their house _____________________________________. 2. Daija’s personality was ________________________________________. 3. Her husband had _____________________________________________. 4. The narrator could not differentiate between Daija and her grandmother because_____________________. 5. Daija wanted to go to an old age home because_________________________. 6. She eventually decided to _____________________________. Q Answer the following questions briefly. 1 mark a) What was Daija‟s husband doing? Q Find words from the passage which mean the same as the words given below: 1 x 3 = 3 marks a) space b) avoided c) readiness Q Read the following passage carefully: 5 marks Have you heard people saying that the 'rupiah makes the world go round? Do you know the story of the rupee? The word rupee comes from the Sanskrit term ‘ Rupya’ or ‘ Rupa’ which means silver. The very early coins before the second century BC, were all made of silver but the coins were neither of any standard weight nor had any face or value printed on them. It was Sher Shah Suri who first gave the name “rupia” to the silver coins. The last silver coins were minted in 1940 with the face of King George VI on them. In 1942 the silver coin was replaced by a cupro-nickel coin for the first time. Money was invented by man to get power but now money has become more powerful than man. All over the world, money and power go together. The more money a person has, the more successful he is judged to be. A rich man is accepted by society even if he is corrupt or evil. Man works hard to earn more and more money and saves a lot of it. He thinks that money will give him more freedom to enjoy himself and to have lots of fun. He thinks he will not be anyone's slave but be his own master. But soon he becomes the slave of money. The more he has, the more he wants. He is never satisfied with what he has got but always wants something more even though he knows that in the end, he cannot carry anything with him. Money can buy everything but it cannot buy peace or happiness or a ticket to heaven. Read the following questions and write the option you consider the most appropriate in your answer sheet: (a) The early coins were made of………………………. (i) copper (ii) gold (iii) silver (iv) lead (b) The cupro-nickel coins came into existence in the year…………………………… (i) 1924 (ii) 1942 (iii) 1429 (iv) 1294 (c)Today money is…………………….. (i) less powerful than man (ii) equal to man (iii) more powerful than man (iv) none of the above (d) Society willingly accepts……………………... from a rich man. (i) honesty (ii) corruption (iii) bribery (iv) none of the above (e) The word satisfied can be replaced by……………………… (i) contended (ii) happy (iii) fulfilled (iv) overjoyed SECTION B 25 Marks Q Notice: Your school has planned an inter class debate competition. Write a notice for the school notice-board informing students of the competition giving details like date, time venue, contact person etc in 50-60 words. 3 marks Q You have to rush for your tuition class, and nobody is at home. Leave a message for your mother informing her about the same. 3 marks OR Your mother promised you to buy a new I-Pad or any gadget, on achieving a good result. You are waiting the good result, as well as the I-Pad. Explain your anticipation in a diary – entry. Q Recently your colony has witnessed and suffered acute water shortage. As the Secretary of your RWA, write a letter to the Chairman DJB highlighting the problem and suggesting ways to solve the issue. Or Write a letter to your younger brother, who has got admission in a hostel, emphasizing the importance of a good breakfast. 5 marks Q It was a dark night. There was no one at home suddenly it started raining. I could hear the distant howling of the wild cats and suddenly ……. 5 marks Q It was a dark night. There was no one at home suddenly it started raining. I could hear the distant howling of the wild cats and suddenly ……. 5 marks Q The students of today are becoming ‘Couch Potatoes’ due to their excess T.V. viewing habit. This has a negative effect not only and their health, but overall personality. Write an article, expressing your views on the same. 5 marks Q Write a speech, to be given in the morning assembly, talking about the importance of education in one’s life. 5 marks Section - C: Grammar 20 Marks Q Read the paragraph given below and fills in the blanks with the help of options that follow. 4 marks Humans have always thought of the moon as living. In earlier times, it was seen that it had always been changing. Since it was the brightest star in the dark sky, humans watched and wondered why it i) Humans (ii) always afraid of the dark, so the bright light (iii) both welcome and mysterious. Today, we still feel fear or mystery when we (iv) ......... at the moon. It is these feelings which keep the old superstitions about the moon alive. (i) (a) change (b) is changing (c) changed (d) was changing (ii) (a) had (b) have been (c) were (d) got (iii) (a) were (b) was (c) had (d) has (iv) (a) looks (b) looking (c) look (d) looked Q Complete the following passage by filling up the blanks. Write the correction in your answer sheet. 4 marks Pollution (a)……………. the destroying of environment. It (b)……………………. to the degeneration of soil, air water. Soil, air and water (c)……………………been degraded by waste, smoke and chemicals. In metro cities problem (d)…………………….become very serious. Smoke from chimneys and automobiles (e)……………………… polluting the air. The acid rain (f)………………………. to degeneration of buildings. Government should take strict measures if it (g)……………………… to protect the earth. Man's greed and selfishness (h)………………………….the major causes of pollution. Q Rearrange the following jumbled words to make meaningful sentences and write the same in the answer sheet. 1 x 4 = 4 marks (a) in/other animals/elephant/an/excels/ intelligence (b) displays/ he/ his intelligence/little actions/in his (c) with a difficulty/a way out/whenever/with/his intelligence/faced/he finds (d)one/the/of/loved/most/animals/world/in/the Q The following paragraph has not been edited. There is one error in each line. Identify the error in each line, and write it along with the word that comes before and the word that comes after in your answer sheet. The first one has been done as an example. 4 marks Example: On reaching his room he entire broke he entirely broke down, and became a prey for the most i. ________ violent agitation. The vulgarity of those twins, and ii. ________ the gross materialism of Mrs. Otis, was naturally iii. ________ extremely annoying, but what really distress him iv. ________ most was that he had been unable to wear the suit of mail. Q Read the following conversation between two friends, Ginnie and Dimpi and complete the paragraph that follows. 4 marks Ginnie: Why have you not brought my dress? Dimpi: I haven’t brought it because I had gone to my cousin's house with my mother, so I forgot to keep it. Ginnie: Don't give me lame excuses. I want to know the truth. Dimpi: I am sorry Ginnie. I was playing with my friends till late. I forgot that you needed it today. Ginnie asked Dimpi (a) ………………….. .Dimpi said that she (b) …………………………. Ginnie (c) …………………………… and further added that (d)…………………… Dimpi said that he was sorry and further added that she was playing with her friends and she had forgotten that she needed it that day. SECTION – D: LITERATURE 25 Marks Q Read the extract given below and answer the questions that follow by writing the correct option in the answer sheet. 1 x 3 = 3 marks Gainst death and all oblivious enmity shall you pace forth, your paradise shall still find room. Even in the eyes of all posterity, That wear this world out to the ending doom. a) Why would the young man be remembered by the future generations? i) Because he is very brave ii) Because he is very philanthropic iii) Because he has written immortal verses iv) Because he is very religions b) What does the poet mean by ending doom? i) The day when war would come to an end. ii) The day when the whole mankind will die iii) The day when the whole earth will be destroyed iv) The day on which God will decide the fate of all mortal beings. c) What is the tone of these lines? i) Pessimistic ii) Sad iii) Confident iv) optimistic Q Read the following extract carefully and answers the questions that follow by choosing the most appropriate alternative from those given below: “I’ve seen a weekend cottage near Darking that I should rather like to buy,” said Miss Mebbin with seeming irrelevance. “Six hundred and eighty, freehold. Quite a bargain, only I don’t happen to have the money.” 1 x 3 = 3 marks a) Who is Miss Mebbin talking to? b) Why is Miss Mebbin talking about the cottage when she can’t afford to buy it? c) What does the phrase ‘seeming irrelevance’ here means? Q Read the extract given below and answer the questions that follow: 1 x 3 = 3 marks “What are they coming for? They haven’t been here for ages.” (a) Who is coming? (b) Why are they coming? (c) Why haven’t they been here for ages? Q Answer the following in about 50-60 words each. 2 x 3 = 6 marks a.) “We do many things, sir‟. Explain this statement with reference to the context. b.) Why had the tiger turned to eating of small animals? c.) Why did the postmaster call Ali a pest? Q Answer any one of the following in about 125 words. 5 marks ‘Tough day’s never last but tough people do’. Explain this statement with reference to the two boys. OR Do you admire the frog for his intelligence or criticize him for his cruelty? Explain, with suitable examples
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Discovery of Electron Who discovered the electron? Electron was discovered by J. J. Thomson in 1897 when he was studying the properties of cathode ray. What is cathode ray? J. J. Thomson constructed a glass tube which was partially evacuated i.e. much of the air was pumped out of the tube. Then he applied a high electrical voltage between two electrodes at either end of the tube. He detected that a stream of particle (ray) was coming out from the negatively charged electrode (cathode) to positively charged electrode (anode). This ray is called cathode ray and the whole construction is called cathode ray tube. The schematic of a cathode ray tube Conclusion s: o Cathode rays consist of electrons. o Electrons are the basic unit s of all atoms. Properties of cathode ray particle 1. They travel in straight lines. 2. They are independent of the material composition of the cathode. 3. Applying electric field in the path of cathode ray deflects the ray towards positively charged plate. Hence cathode ray consists of negatively charged particles. J. J. Thomson measured the charge-by-mass-ratio (e/m) of cathode ray particle using deflection in both electric and magnetic field. e/m =−1.76×108 coulomb per gram The cathode ray particle turned out to be 2000 times lighter than hydrogen. Although we got e/m ratio for electron from J.J. Thomson’s Cathode Ray Tube experiment, we still don’t know the exact charge (e) for electron. American physicist Robert Millikan designed an experiment to measure the absolute value of the charge of electron which is discussed below. Millikan Oil Drop Experiment In 1909, American physicist R. Millikan measured the charge of an electron using negatively charged oil droplets. The measured charge (e) of an electron is −1.60×10−19 Coulombs. Using the measured charge of electron, we can calculate the mass of electron from e/m ratio given by J. J. Thomson’s cathode ray experiment. e/m=−1.76×108 Coulomb-per-gram m=e−1.76×108 Putting e=−1.60×10−19 Coulomb, m=9.1×10−28 gram. What we have learned Electron was discovered by J. J. Thomson in Cathode Ray Tube (CRT) experiment. Electrons are negatively charged particles with charge-to-mass ratio −1.76×108 C/gm The charge of an electron was measured by R. Millikan in Oil drop experiment. Charge of an electron is −1.60×10−19 C Mass of an electron is 9.1×10−28 gram. Electron is approximately 2000 times lighter than hydrogen. Discovery of Proton 
Q.What is refraction of light? What are the laws of refraction? Ans: Deviation of ray of light from its original path when it travels from one transparent homogeneous medium to another transparent homogenous medium is called the refraction of light. There are two laws of refraction :- (I ) incident ray, reflected ray and normal lie in the same plane. (ii) The ratio of sine of angle of incidence and sine of angle of refraction is constant i.e. Sin i / Sin r = n. This is also called as Snell’s law. Q. Define Refractive Index: Ans: It is the ratio of speed of light in vacuum to the speed of light in medium is called Refractive index. Q. Give the ratio of velocities of two light waves travelling is vacuum and having wave lengths 4000A0 and 8000A0. Ans: In Vacuum, light of all the wave lengths travel with the same velocity i.e. 3 X 108 m/sec. Q.. For what angle of incidence, the lateral shift produced by parallel sided glass plate is zero? Ans: For <i = 0. Q. What are the factors on which the lateral shift depends? Ans: Thickness of the refracting medium, angle of incidence and its refractive index Q. What is the value of Relative refractive index of air? Ans: One. Q. If speed of light in vacuum = 3 x 108 m/sec and Refractive index of water = 4/3, What is the speed of light in water? Ans: Refractive index of water = Speed of light in vacuum / Speed of light in water; 4/3 = (3 x 108 m/sec )/ (Speed of light in water) Speed of light in water = (3 x 108 m/sec) x ¾ = 9/4 x 108m/sec = 2.25 x 108 m/sec. Q. For the same angle of incidence in media P, Q and R, the angles of refraction are 350, 250, 150 respectively. In which medium will the velocity of light be minimum? Ans: According Snell’s law n = Sin i / Sin = C / V For given angle of incidence (i), V will be minimum, when angle of refraction <r is minimum In given data it is for medium R. Q. A coin in a glass beaker appears to rise as the beaker is slowly filled with water. Why? Ans: It happens on account of refraction of light. A ray of light starting from the coin goes from water to air and bends away from normal. Therefore, bottom of the beaker on which the coin lies appears to be raised.
Q. State Modern Periodic Law. Name the two elements of first period. Q.Two element X, Y and Z belong to 17th group but to 2nd,3rd and 4th period respectively. Number of valence electrons in Y is 7. Find the number of valence electrons in X and Z. Q. How does the metallic character of the elements vary (i) in a group (ii) in a period of the modern periodic table ? Q. Na, Mg, Al and P belong to 3rd period but are placed in first, second, thirteenth and fifteenth group. Number of shells occupied in Mg is three. What is the number of occupied shells in Na, Al and P. Give reason for your answer. Q. What is the number of elements in first , second and third period of the periodic table? Give reason for your answer. Q. Arrange the following elements in the descending order of atomic size and give a reason for your answer. Mg, Cl, P, Ar (Atomic numbers of the above elements are 12, 17, 15, 18 respectively. Q. Mention any two trends exhibited by elements when we go from left to right across the period of periodic table. Q. Given below are the atomic radii of some elements of second period.
Arrange these elements in the increasing order of their atomic number . Give reason for your answer. Q. “Elements in Periodic Table show periodicity of properties” List any four such properties. Q. (a) Atomic number of Mg and Al are 12 and 13 respectively. Write their electronic configuration. (b) Mention the period of the Modern Periodic Table to which the above two elements belong. Give reason for your answer Q. (a) State the Modern periodic law. (b) What is the total number of periods and groups in Modern Periodic Table Q. From the part of a periodic table, answer the following questions
(a) Atomic number of oxygen is 8. What would be the atomic number of, Fluorine ? (b) Out of ‘X’ and ‘Q’ which element has larger atomic size. Give reason for your answer Fluorine. (c) Out of ‘Y’ and ‘Z’ which element has smaller atomic size. Give reason for your answer. Q. (a) Atomic radius of hydrogen is 37pm. Express it in meters. (b) How does atomic size vary in a group and in a period ? Q. (a) What are metalloids ? Write any two examples. (b) Given below are some of the elements of first group Li, Na, K (Their atomic numbers are 3,11,19 respectively and they belong to 2nd 3rd and 4th period respectively) Arrange these in the decreasing order of metallic character exhibited by them. Q. Nitrogen (atomic number 7) and phosphorous (atomic number 15) belong to group 15 of the Periodic Table write the electronic configuration of these two elements. Which of these will be more electronegative and why ? Q. (a) State modern Periodic Law. (b) What are groups and periods in periodic Table? Q. (a) “Silicon is classified as a metalloid.” Justify this classification. (b) Name two more such metalloids. (c) In which part of the Periodic Table we can look for metalloids. On which side of these we can get non- metals ? Q. The following table shows the positions of six elements A, B, C,D,E and F in the modern periodic table
(a) Which element will form only covalent compounds ? (b) Which element is a metal with valency two ? (c) Out of D and E , which one has a bigger atomic radius ? Give reason for your answers. Q. State the modern periodic law. How many groups and periods are there in the modern periodic table Q. Out of the two elements X and Y which has bigger atomic radius ? Give reason to justify your answer. (i) X has atomic number 18 and atomic mass 40 (ii) Y has atomic number 20 and atomic mass 40 Q. Given below is a part of the periodic table.
(a) What happens to the atomic size? Justify your answer. (b) what happens to the metallic character of the elements ? (b) (i) Take about 3mL of Ethanol in a test tube and warm it gently in a water bath. (ii) Add a 5% solution of alkaline potassium permanganate drop by drop to the solution. (iii) What happens to the colour of KMnO4 added initially and then in excess? Give reason. Name the product of this reaction. Q. (a) How does the tendency to gain electrons change as we go down a group ? Give reason. (b) Given below is a part of the periodic table. How does the valency vary, as we move vertically downward from Li to Fr. Give reason?
Q. The electronic configuration of three elements X, Y and Z are given below.
(i) Which element belongs to the second period ? (ii) Which element belongs to the eighteenth period ? (iii) Which element belongs to the second group? (iv) What is the valency of Y ? (v) Y and Z, are they metal or a non – metal ? Q. (a) Element „Y‟ with atomic number 3 combines with element „A‟ with atomic number 17, what would be the formula of the compound ? (b) What is electronic configuration of element with atomic number 10 ? What will be its valency ?
Chapter : 05 : Periodic Classification of Elements [Main Page]
Questions From Board Paper Solved Questions Paper CBSE Questions Bank Mendeleev’s Periodic table and its properties [E-Notes] Dobereiner Triads I Newland’s law of Octaves [ E-Notes] CBSE Study Accelerator Full E-Notes CBSE Guess Question Solved Question Paper Solved Assignment CBSE Practice Worksheet CBSE Guess Test paper CBSE Test Paper VALUE BASED QUESTIONS Support Material 2012-13 for Class X-XII VALUE BASED QUESTIONS Support Material 2013-14 for Class X-XII VALUE BASED QUESTIONS [Jsunil Tutorial] 2013-14 for Class X-XII GEOMETRICAL REPRESENTATION OF QUADRATIC EXPRESSION Consider the quadratic expression, y = ax2 + bx + c, a ≠0 & a,b,c ∈R then : (i) The graph between x,y is always a parabola. If a > 0, then the shape of the parabola is concave upwards & if a < 0 then the shape of the parabola is concave downwards. (ii) The graph of y = ax2 (Let the roots of the equation ax + bx + c can be divided into 6 categories which are as follows : 2α + bx + c = 0 be and β)   Mirror formula is the relationship between object distance (u), image distance (v) and focal length. 1/v + 1/u = 1/f In Triangle ABC and Triangle A’B’C <A = <A’ = 900 <C =<C ( vert. opp. <s] Triangle ABC ~Triangle A’B’C [AA similarity] => AB /A’B’ = AC/A’C ----(I) Similarly, In Triangle ABC and A’B’C <A = <A’ = 900 <C =<C ( vert. opp. <s] Also, in Triangle ABC ~Triangle A’B’C [AA similarity] AB /A’B’ = AC/A’C ----(1) Similarly, In DFPE ~ A’B’F EP /A’B’ = PF/A’F AB /A’B’ = PF/A’F [ AB=EP] ----(II) From(i) &(ii) AC/A’C = PF/A’F => A’C/AC = A’F/PF => (CP-A’P)/(AP- CP) = (A’P – PF)/PF Now, PF = -f ; CP = 2PF = -2f ; AP = -u ; and A’P = -v Put these value in above relation: [(-2f) –(-v)] /(-u)-(-2f) = {(-v) –(-f) }/(-f) => uv = fv +uf => 1/f = 1/u + 1/v you may also see (a) Mirror formula (b) Mirror Formula
 Derivation or Proof-of- the relation between focal length and radius of curvature(X) physics [R=2f]
Consider a ray of light AB, parallel to the principal axis, incident on a spherical mirror at point B. The normal to the surface at point B is CB and CP = CB = R, is the radius of curvature. The ray AB, after reflection from mirror will pass through F (concave mirror) or will appear to diverge from F (convex mirror) From the figure, According to law of reflection,< i = <r <i = <q [Since, AB IICP] => <r= <q So, In D BCF, CF = BF ----(i) If the aperture of the mirror is small, B lies close to P, BF = PF (ii) From (i) and (ii) CF = FP Now, PC = PF + FC = 2 PF or R = 2f  Atom: It is the smallest particle of an element which may or may not have independent existence. The atoms of certain elements such as hydrogen, oxygen, nitrogen, etc .do not have independent existence whereas atoms of helium, neon, argon, etc. do have independent existence. Thus we can say that all elements are composed of atoms. IUPAC (International Union of Pure and Applied Chemistry) approves names of elements. Many of the symbols are the first one or two letters of the element’s name in English. The first letter of a symbol is always written as a capital letter (uppercase) and the second letter as a small letter (lowercase) For example : (i) hydrogen, H (ii) aluminium, Al and not AL (iii) cobalt, Co and not CO. Symbols of some elements are formed from the first letter of the name and a letter, appearing later in the name. Examples are: (i) chlorine, Cl, (ii) zinc, Zn etc. Other symbols have been taken from the names of elements in Latin, German or Greek. For example, the symbol of iron is Fe from its Latin name ferrum, sodium is Na from natrium, potassium is K from kalium. Therefore, each element has a name and a unique chemical symbol. Molecule: A molecule is the smallest or the simplest structural unit of an element (or) a compound which contains one (or) more atoms. It retains the characteristics of an element. A molecule can exist freely and it is a combined form of bonded units whereas an atom is a singular smallest form of non bonded unit. Molecules are of two types, namely homo atomic molecules and hetero atomic molecules. Homo atomic molecules: These are the molecules which are made up of atoms of the same element. For example hydrogen gas consists of two atoms of hydrogen (H2).Similarly oxygen gas consists of two atoms of oxygen (O2). HETERO ATOMIC MOLECULES : The hetero atomic molecules are made up of atoms of different elements. They are also classified as diatomic, triatomic, or polyatomic molecules depending upon the number of atoms present. H2O, NH3, CH4, etc., are the examples for hetero atomic molecules. Atomicity: The number of atoms present in one molecule of an element is called the atomicity of an element. Depending upon the number of atoms in one molecule of an element, molecules are classified into monoatomic, diatomic, triatomic or poly atomic molecules containing one, two, three, or more than three atoms respectively. Mon atomic molecules: Helium (He) Neon (Ne) Metals Di atomic molecules: Hydrogen H2 Chlorine Cl2 Tri atomic molecules: Ozone (O3) Poly atomic molecules: phosphorous P4 Sulphur S8 Atomicity = Molecular Mass/Atomic mass MORE TO KNOW : Isotopes ⇒ These are the atoms of same element with same atomic number (Z) but different mass number (A). Example (17Cl35,17Cl37 ) Isobars ⇒ These are the Atoms of the different element with same mass number but different atomic number. Example (18Ar40, 20Ca 40 ) Isotones ⇒ These are the atoms of different elements with same number of neutrons Example : (6C13, 7N14 ) AVOGADRO’S HYPOTHESIS : Amedeo Avogadro put forward hypothesis and is based on the relation between number of molecules and volume of gases that is “volume of a gas at a given temperature and pressure is proportional to the number of particles”. Avogadro’s Law: Equal volumes of all gases under the same conditions of temperature and pressure. contain the equal number of molecules. TEST YOUR UNDERSTANDING SKILL (a) Find the atomicity of chlorine if its atomic mass is 35.5 and its molecular mass is 71 (b) Find the atomicity of ozone if its atomic mass is 16 and its molecular mass is 48 WHAT IS AN ION? An ion is a charged particle and can be negatively or positively charged. A negatively charged ion is called an ‘anion’ and the positively charged ion, a ‘cation’. For example, sodium chloride (NaCl). Its constituent particles are positively charged sodium ions (Na+) and negatively charged chloride ions (Cl–). Ions may consist of a single charged atom or a group of atoms that have a net charge on them. A group of atoms carrying a charge is known as a polyatomic ion e.g. Calcium oxide (Ca+2 O-2) RELATIVE ATOMIC MASS (RAM): Relative atomic mass of an element is the ratio of mass of one atom of element to the 1/12th part of mass of one atom of carbon. Relative atomic mass is a pure ratio and has no unit. If the atomic mass of an element is expressed in grams, it is known as gram atomic mass. e.g., Gram atomic mass of hydrogen = 1g ; Gram atomic mass of carbon = 12g Gram atomic mass of nitrogen = 14g ; Gram atomic mass of oxygen = 16g Atomic mass is expressed in atomic mass unit (amu). One atomic mass unit is defi ned as 1/12th part of the mass of one atom of carbon. Chemical Formulae: The chemical formula is a symbolic representation of a compound of its composition. Valency : The combining power (or capacity) of an element is known as its valency. Valency can be used to find out how the atoms of an element will combine with the atom(s) of another element to form a chemical compound. RELATIVE MOLECULAR MASS (RMM) : The relative molecular mass of an element or a compound is the ratio of mass of one molecule of the element or a compound to the mass of 1/12 th part of mass of one atom of carbon. Relative Molecular mass is a pure ratio and has no unit. If the molecular mass of a given substance is expressed in gram, it is known as gram molecular mass of that substance. Molecular mass is the sum of the masses of all the atoms present in one molecule of the compound or an element. Test your numerical skill : Problem: Find the gram molecular mass of water (H2O) Solution: Þ 2(H) = 2 x 1 = 2 and 1(O) = 1 x 16 = 16 Gram molecular mass of H2O = 2 + 16 = 18g Problem: Find the gram molecular mass of carbon dioxide Solution: Þ (CO2) 1(C) = 1 x 12 = 12 and 2(O) = 2 x 16 = 32 Gram molecular mass of CO2 = 12 + 32 = 44 g MOLE CONCEPT While performing a reaction, to know the number. of atoms (or) molecules involved, the concept of mole was introduced. The quantity of a substance is expressed in terms of mole. Definition of mole : Mole is defined as the amount of substance that contains as many specifi ed elementary particles as the number of atoms in 12g of carbon-12 isotope. One mole is also defined as the amount of substance which contains Avogadro number (6.023 x 1023) of particles. MORE TO KNOW Avogadro number: Number of atoms or molecules or ions present in one mole of a substance is called Avogadro number. Its value is 6.023 x 1023. Therefore, one mole of any substance = 6.023 x 1023 particles may be atoms, molecules, ions For e g. One mole of oxygen atoms represents 6.023 x 1023 atoms of oxygen and 5 moles of oxygen atoms contain 5 x 6.023x1023 atoms of oxygen. To find the number of moles, the following formulae are useful 1. When the mass of the substance is given: Use this formula : Number of moles = given mass/ atomic mass (a). Calculate the number of moles in (i) 81g of aluminium ii) 4.6g sodium (iii) 5.1g of Ammonia (iv) 90g of water (v) 2g of NaOH Solution: (i) Number of moles of aluminium = given mass of aluminium / atomic mass of aluminium = 81/27 = 3 moles of aluminium [Rest Question do yourself] (b) Calculate the mass of 0.5 mole of iron Solution: mass = atomic mass x number of moles = 55.9 x 0.5 = 27.95 g Do yourself : Find the mass of 2.5 mole of oxygen atoms [ Mass = molecular mass x number of moles] 2. Calculation of number of particles when the mass of the substance is given: Number of particles =( Avogadro number x given mass)/gram molecular mass Problem: Calculate the number. of molecules in 11g of CO2 Solution: gram molecular mass of CO2 = 44g Number of molecules = (6.023 x 1023 x 11) / 44 = 1.51 x 1023 molecules Do yourself: Calculate the number of molecules in 360g of glucose 3. Calculation of mass when number of particles of a substance is given: Mass of a substance = (gram molecular mass x number of particles)/6.023 x 1023 Problem: Calculate the mass of 18.069 x 1023 molecules of SO2 Solution: Gram molecular mass SO2 = 64gm The mass of 18.069 x 1023 molecules of SO2 = (64x18.069 x 1023)/ (6.023 x 1023) = 192 g Do yourself: (a) Calculate the mass of glucose in 2 x 1024 molecules (b) Calculate the mass of 12.046 x 1023 molecules in CaO 4. Calculation of number of moles when you are given number of molecules: Problem: Calculate the number moles for a substance containing 3.0115 x 1023 molecules in it. Solution: Number of moles = [Number of molecules/(6.023 x 1023)] = ( 3.0115 x 1023)/( 3.0115 x 1023) =0.5 moles Do yourself: (a) Calculate number of moles in 12.046x 1022 atoms of copper (b) Calculate the number of moles in 24.092 x 1022 molecules of water. Problem: Calculate the number of aluminum ions present in 0.051 g of aluminum oxide. (Hint: The mass of an ion is the same as that of an atom of the same element. Atomic mass of Al=27 u) Solution: Mass of the 1 mole of Al2 O3 = 2x27 + 3x16 = 102gm The number of ions present in 102 gm of aluminum oxide = 6.023 x 1023 ion The number of ions present in 0.051g of aluminum oxide= (6.023 x 1023 ion x 0.051g)/ 102 gm = 6.023 x 1023 ion x0.0005 = 3.0115 x 1020 ions In Al2 O3, Aluminium and oxygen are in ratio 2:3 So, The number of aluminum ions present(Al3+) in 0.051g of aluminum oxide = 2 x 3.0115 x 1020 ions =6.023 x 1020 ion DOWNLOAD FULL E-NOTES
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OTBA Study material by CBSE for classes IX & XI
Open Text Material for Class IX DOWNLOAD Open Text Material for Class XI DOWNLOAD Additional for PSA PSA SAMPLE QUESTION PAPER FOR CLASS IX AND XI CLICK HERE SUPPORT MATERIAL WITH FOR PSA WITH ANSWER CLASS IX AND XI Problem Solving Assessment Question Paper 2013 : Class-IX Problem Solving Assessment Question Paper 2013 :Class XI Courtesy:CBSE  The basic structural and functional unit of an organism The basic structural and functional unit of an organism is called cell. Cells are like bricks that are assembled to make a building. Similarly, cells are assembled to make the body of every organism. This is why cell are called the basic structural and functional unit of an organism. Discovery of cell: Robert Hooke in 1665 observed slices of cork (a part of the bark of a tree) under a simple magnifying device. He Robert Hooke observed under a microscope there are many partitioned boxes or compartments like a honeycomb. Hooke coined the term ‘cell’ for each box. A hen’s egg can be seen easily. Is it a cell or a group of cells? It is a single cell. A white blood cell (WBC) in human blood is another example of a single cell. How do scientists observe and study the living cells? Scientists used microscopes which magnify objects. Stains (dyes) are used to colour parts of the cell to study the detailed structure. Kinds of organism: Organisms which are made up of a single cell are called unicellular where as Organisms made up of more than one cell is called multicellular. Cell Theory : Cell Theory was elaborated by a German botanist Schleiden and Zoologist Schwann The Cell Theory states that: 1) All organisms are made up of one or more cells and the products of those cells. 2) All cells carry out life activities ( require energy, grow, have a limited size). 3) New cells arise only from other living cells by the process of cell division. Tissue: The group of cells that are similar in structure and functions is called tissue. like nervous tissue in animal and Vascular tissue in plant. Cells have different shape of Cells according to function they perform in body: Generally, cells are round, spherical or elongated (red blood) . Some cells are long and pointed at both ends. They exhibit spindle shape (muscle cells) . Cells sometimes are quite long. Some are branched like the nerve cell or a neuron. Guard cell in leaves are kidney shaped. White blood cells change their shape and move like amoeba. Which part of the cell gives it shape? Cell membrane provides shape to the cells of plants and animals. Cell wall is an additional covering over the cell membrane in plant cells. It gives shape and rigidity to cells. The size of cells in living organisms may vary . The smallest cell is 0.1 to 0.5 micrometre in bacteria. The largest cell measuring 170 mm ×130 mm, is the egg of an ostrich. Nerve cell is the longest cell and blood cells are the smallest cell in our body Cell Structure Protoplasm: The entire content of a living cell is known as protoplasm. It includes the cytoplasm and the nucleus. Protoplasm is called the living substance of the cell. Plasma membrane: The cytoplasm and nucleus are enclosed within the cell membrane together called the plasma membrane. Cell membrane: The outer boundary of the cell is the cell membrane. It is composed of proteins and carbohydrates. Functions of Cell membrane: The cell membrane gives shape to the cell. The cell membrane separates cells from one another and also the cell from the surrounding medium. The cell membrane is porous and allows the movement of substances or materials both inward and outward. This is why it is called selectively permeable membrane. Cell wall: There is also another thick additional covering of animal cell called the cell wall. This is because plant cell need protection against variations in temperature, high wind speed, atmospheric moisture, etc. Full E-Notes for CBSE & NCERT class 8th given below
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