![]() Very Short Answer type (1 mark) questions 1. What are oxidizing agents? Give one example. 2 State two advantages of vegetative propagation. 3 A green plant receives 50,000J of energy from the sun in the form of sunlight. How much energy will it capture and convert to food energy? Short Answer-I type (2 mark) questions 1Why do we need to look for alternatives sources of energy other than fossil fuels? Give two reasons. 2 Give reasons for the following- (a)Sky appears dark instead of blue to an astronaut in space. (b)Planets do not twinkle 3 What is placenta? Write its two functions. Short Answer II type (3 mark) questions 1 Define addition reaction. Write its one industrial application. Which of the following hydrocarbons undergo addition reaction? C3H4, C4H10, CH4, C2H4. 2 (a) Mention the fundamental property of element which formed the basis of Modern periodic table and state Modern periodic law. (b) Mention the period to which Na, Mg and Al belong to. Justify their position in the periodic table. 3 Draw the longitudinal section of a flower and label the part which (a) develops into fruit (b) produces pollens (c) is sticky and receives the pollens (d) is colourful and attracts the insects 4 A Mendelian experiment consisted a cross of round and yellow seed plant with wrinkled and green seed plant. The progeny had all round seeds but almost half of them had green seeds. Write the genetic make up (genotype) of the following- (a) parent plant with round and yellow seeds (b) parent plant with wrinkled and green seeds (c) progeny with round and green seeds 5 How can the age of fossils be estimated? 6 An object 3cm in length is held 25cm away from a converging lens of focal length 15 cm. Find (i) the position (ii) size (iii) nature of the image formed. 7. Ramesh is not able to see distant objects clearly. Name the eye defect he is suffering from? How can this defect be corrected? Draw the ray diagram to show image formation(i) by the eye with defect (ii) by the corrected eye 8 Seema is a student of class X. She read in her textbook that certain compounds used as refrigerants and in the deodorants are harmful to the ozone layer. She got concerned as she knew about the importance of the ozone layer in the atmosphere. She also talked to her teacher about her interest in spreading awareness about ozone depletion. Now answer the following questions: (a) Write the full form of the compounds which harm the ozone layer. (b) Mention the function of the ozone layer. (c)How can Seema spread awareness about the ozone layer in her school? Mention any two activities that may help her in doing it. Long Answer II type (5 mark) questions 1. (a) Explain the mechanisms of the cleansing action of soaps. (b) Detergents are effective in hard water but soaps are not. Why? 2. (a) Draw the ray diagrams for the image formation by a concave mirror when the object is at (i) infinity (ii) between F and C (iii) between P and F (b)Explain why we prefer to use a convex mirror as a rear view mirror in vehicles? (c) Write any two uses of a concave mirror. 3 (a) An object is placed at a distance of 15cm from a convex mirror of focal length 20 cm. Find the position and nature of the image. (b) Define refractive index. Light enters from air to diamond having refractive index 2.42. Find the speed of light in the diamond. The speed of light in vacuum is 3 × 10^8m/s. X CBSE Board Question Papers 2013 English_Com. Hindi Course_A Mathematics Science Social_Science ![]()
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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 ?
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Q. What are the different ways in which individuals with a particular trait may increase in a population?
Answer: The different ways in which individuals with a particular trait may increase in a population are following : Food availability – Individuals with a particular trait may have extra abundance of food in their environment. They will naturally increase in number. Genetic drift – Individuals with a particular trait may increase in a population due to genetic drift. In it, there is a seasonal or accidental decline in population. The survivors have certain combination of traits which increase in number with increase in population Natural selection – The particular trait which has survival value is picked up by natural selection. It increases in population through differential reproduction. Q. What do they tell us about the process of evolution? Answer: Fossils provide a direct evidence of evolution and are called written documents of evolution. They directly indicate the presence of different types of organisms in different ages. The path of evolution is known by arranging the fossils in a proper sequence age wise. The early fossils are the simple organisms. Later on different complex forms arose, flourished and died down. They are replaced by newer forms. Q. state the analogy between wings of a bird and a butterfly. What does it indicate? Answer: They are analogous because both bats and birds adapted to flight. Bat being a mammal has the finger extension type wing and bird being aves with the full forelimb extending the wing. As structure both the wings are different, so are considered as analogous organ. Q. Why did Mendel choose pea plant for his experiments? Answer: Mendel chooses pea plant because: a. Presence of observable traits with contrasting forms. b. Produces many offspring in one cross. c. Short life cycle. d. Ease in cross pollination. e. Plants were sexually reproducing with bisexual flowers. f. Hybrids were perfectly fertile Q. Why is vegetative propagation practiced for growing some types of plants? Answer: Vegetative propagation is generally performed in higher plants of ornamental, horticultural, medicinal and other economic importance. It is practiced for growing these plants because (i) Good qualities of a variety can be maintained indefinitely. (ii) Vegetative propagation gives a genetically uniform population. (iii) Vegetative propagation is a quicker method of raising of crops. (iv) It is the only known method of multiplication of seedless plants Q. Leaves of Bryophyllum fallen on the ground produce new plants whereas the leaves of Jasmine do not, why? Answer: In Bryophyllum, vegetative propagation occurs through leaves. Buds occur in notches of Bryophyllum leaf. However, when the leaf falls down and comes in contact with the soil, the buds spout and produce plantlets. Q. What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem? Where will the magnification maximum? Solution : The accumulation of harmful chemicals in the body of living organisms at different trophic levels in a food chain is called biological magnification. Yes, the concentration of these harmful chemicals will be different at different levels of the ecosystem. It will be maximum at the last trophic level which is mostly the top carnivores (quaternary consumers). Q. What are analogous organs? Explain with examples. Solution: The organs which are similar in function or appearance but differ in structure and development are called analogous organs. The wings of a bird and an insect are developmentally and structurally different from each other. Skeleton, flesh and feathers support bird's wings. The insects have a fold of membrane as wing, which is associated with few muscles. Wings of birds and insects are structurally different but perform the same function of flying. They are therefore, termed as analogous organs. Q. Mrs. Kumar is pregnant for the last three months and she goes for regular check-up to her doctor. During her last visit, the doctor asked Mrs. Kumar to get an ultrasound done. Both Mr. and Mrs. Kumar went to a radiologist and got the ultrasound done. Once the ultrasound is over, Mr. Kumar asked the doctor whether the baby in the womb is a boy or a girl. (a) What should the doctor reply to the couple? (b) Is it ethical to determine the sex of a child? (c) What should government do to discourage sex determination? Solution : (a) The doctor should not tell the sex of the foetus. (b) No, it is not ethical to determine the sex of a child. (c) The government should ban the process of sex determination and should punish or fine whosoever does so. Q. (a) Why is vegetative propagation practised for growing some types of plants? (b) Name the different parts of a flower that has germ cells. (c) List any two agents of pollination. Answer: (a) Some plants like banana, seedless grapes, rose, which cannot produce viable seeds, can be easily grown by vegetative propagation. To get genetically identical copies and to maintain and preserve a stock of selected varieties, vegetative propagation is the only means. It is an easier less expensive and rapid method of propagation (b) Style and ovule both have germ cells. (c) Wind and water Q. What happens to the pollen which falls on a suitable stigma? Explain. Answer: The pollen grains absorb water and sugar from the surface of stigma and swell up. A tube grows out of the pollen grain and travel through the style to reach the ovary. The pollen tube carrying two male gametes which liberated inside the embryo sac. One male gamete fuses with the egg to form zygote. The other male gamete fuses with the secondary nucleus to form the endosperm, which provides nourishment to the growing embryo. Q.How many 'X' chromosomes are present in body cells of humans in a: (i) Male (ii) Female? (iii) Describe the role of sex chromosomes in deciding the sex of the child. Solution : (i) In the body cells of human males one X and one Y chromosome is present. 50 percent male gametes (sperms) carry X-chromosome and the remaining 50 percent carry Y-chromosome. (ii) The body cells of human female carry two X-chromosomes. Females produce gametes (ova) with similar type of chromosomes, all carry one X-chromosome. (iii) Sex chromosomes in males are XY type while in female they are XX type. When a sperm carrying X- chromosome fertilizes an egg, the zygote develops into a female (XX condition). When sperm carrying Y chromosome fertilizes an egg, the zygote develops into a male (XY condition). Q. What is meant by tissue culture? How this technique is performed? In which area this technique is finding its application. Solution : The production of plants by cells or tissues or organs in a synthetic medium is called tissue culture. This technique is also Know as micro propagation technique. The synthetic medium used in this technique contains all the nutrients and hormones which are required for the growth. A cell or tissue is transferred into suitable synthetic medium under sterile conditions. The tissue often develops into a fast growing cellular mass called callus. The callus is transferred to another medium for growth and differentiation that forms plantlets. The plantlets can be transplanted into soil or pots where they can be grown to maturity. Tissue culture technique is being popularly used for production of ornamental plants like Orchids, Dahlia and Carnation. |
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