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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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 Q. What is the atomic number of carbon?
Answer: The atomic number of carbon is 6. Q. What is the distribution of electrons in various shells for carbon? Answer: The distribution of electrons in various shells for carbon: K(2),L(4) Q. How many valence electrons will carbon have? Answer: 4 Q. Why carbon form covalent compound? Answer: carbon form covalent compound because : (i) Carbon cannot gain four electrons forming C4– anion because it would be difficult for the nucleus with six protons to hold on to ten electrons. , that is, four extra electrons. (ii) Carbon cannot lose four electrons forming C 4+ Cation because it requires a large amount of energy to remove four electrons leaving behind a carbon Cation with six protons in its nucleus holding on to just two electrons. Q. Why is carbon tetravalent ? Answer: Carbon atom has 4 electrons in the outermost shell.It needs 4 more electrons to complete its octet. Therefore , carbon is tetravalent . For rest solved questions visit: Wonder family of Carbon and its compound Posts with label 10th Carbon and its Compounds Solved
HEREDITY AND EVOLUTION SOLVED EXERCISES QUESTIONS [Biology Term-2 CHAPTER - 13] VERY SHORT ANSWER QUESTIONS (1 mark) 1. Who proposed the theory of inheritance of acquired characters. Answer: J.B. Lamarck. 2. State one of the evolutionary forces leading to the origin of a new species according to the synthetic theory of evolution. Answer: Origin of new species is based on natural selection acting on genetic variations that appear among the members of a population. 3. Give an example of a vestigial organ present in human body. Answer: Vermiform appendix. 4. What is the evolutionary significance of the fossil Archaeopteryx? Answer: Archaeopteryx is the connecting link between reptiles and birds. It has both reptilian on features and avian(bird-like) features. 5. Who proposed the double helical model of DNA? Answer: Watson and Crick. 6. Who proposed the theory of natural selection? Answer: Charles Darwin. 7. What is retro virus? Answer: A virus with RNA as the genetic material eg: HIV is a retro virus. 8. What is a genetically modified organism (GMO)? Answer: The organism that contains a segment of foreign DNA. 9. Name any two genetic diseases. Answer: Hemophilia and colour blindness. 10. One of the examples of two analogous organs can be the wing of parrot and a) Flippers of whale. c)Foreleg of horse b) Front leg of frog d)Wing of housefly Answer: Wing of housefly SHORT ANSWER QUESTIONS (2 marks) 1. What are transgenic organisms? Which property of DNA is used as a tool in genetic engineering? Answer: The organisms that contain a segment of foreign DNA are known as transgenic organisms.The complimentary property of the nucleotides of DNA.is the most powerful tool in genetic engineering. 2. Explain how the sex of the child is determined at the time of conception in human beings. Answer: Male human beings have XY sex-chromosomes and female human beings have XX sex-chromosomes. If a sperm carrying x-chromosome fertilizes with the ovum, then sex of the baby will be female. If a sperm carrying y-chromosome fuses with the ovum, the sex of the baby will be male. 3. By comparing the similarity of nucleotide sequences in DNA of different kinds of organisms, evolutionary relationships can be established. a) Arrange the following according to their evolutionary closeness (You may use your knowledge of classification also) Cockroach, mango tree, gorilla, fish. b) Whose DNA among the following do you think is most similar to that of humans. Answer: (a) cockroach – fish – gorilla ( b) Gorilla 4. Mention the ways by which variant genotypes are produced in organism? Answer: a) gene mutation b) Crossing over c) Hybridization 5. In human beings blue eye colour is recessive to brown eye colour . If a brown eyed man has a blue eyed mother then find a) What are the possible genotypes of his father? b) What is the genotype of the man and his mother? Answer: BB , Bb B. Man: Bb, mother: bb 6. What are fossils? Of what interest are fossils to the evolutionary biologists? Answer: A fossil is the remnant or impression of an organism that lived in the Remote past. Use of Fossils a) Phylogeny, the evolutionary history can be reconstructed from the fossils. b) The fossil record has helped in building the broad historical sequence of biological evolution. SHORT ANSWER QUESTION (3 marks) 1. a) Who isolated DNA for the first time from pus cells? b) Why is DNA called polynucleotide? c) Name two purine nitrogenous bases found in a DNA molecule. Answer: a) F.Meishcer, named it nuclein. b)DNA is called polynucleolide because it is a polymer or long chain of nucleolide. c)Purine:- Adenine and Guanine. 2. a) Who put forward the double helical model of DNA? b) What are the three chemically essential parts of nucleotides constituting a DNA? Answer: a) Watson and Crick. b)Nucleotide constituting –DNA Nitrogen bases (Purines and Pyrimidines), Pentose sugar(Deoxyribose sugar) and a phosphate molecule. 3.Guinea pig having black colour when crossed with guinea pig having same colour produced 80 offspring, out of which 60 were black and 20 were white. Now,find out: a)What is the possible genotype of the guinea pigs? b)Which trait is dominant and which trait is recessive? c)What is this cross called as and what is its phenotypic ratio? Answer: a) Bb x Bb b)Black is dominant and white is recessive. c) Monohybrid cross, phenotypic ratio=3:1 4. Write a brief account on . Who disproved this theory? Answer: salient points of Lamarck‘s theory: 1.The use and disuse of an organ leads to acquiring of change in the features of that organ. 2. These changes are inherited by the offspring. 3. Favourable variations result in evolution of new species. August Weisman disproved this theory. 5. Distinguish between acquired and inherited traits giving one example of each. Answer: Acquired traits 1) A trait (or characteristic) of a organism which is not inherited‘ but develops in response to the environment is called an acquired trait. (2) The acquired traits of an organism cannot be passed on to its future generations. e.g. low weight‘ of beetle, cut tail‘ of a mouse. Inherited traits 1) A trait (or characteristic) of an organism which is caused by a change in its genes (or DNA) is called an inherited trait. 2) The inherited traits of an organism are passed on to its future generations. e.g. red colour of beetles, fur coat of guinea pigs. 6. Why did Mendel chosen pea plant for his experiments? T-II 2015 Answer: Mendel chose pea plant for his experiments because it is: (a) Easy to grow (b) Short lifespan (c) Easily distinguishable characters (d) Larger size of flower (e) Self-pollinated. HEREDITY AND EVOLUTION [SOLVED][Biology Term-2] Click Here 10th Science SA-2 Chapter wise Test Papers Links 1. Carbon and Its Compounds 6. The Human Eye and the Colorful World 2. Periodic Classification of Elements 7. Our Environment 3. How Do Organisms Reproduce? 8. Management of Natural Resource 4. Heredity and Evolution 9. Science Sample papers 5. Light - Reflection and Refraction 10. X Science NCERT SOLUTIONS 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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