Test Paper Chapter 14, NATURAL RESOURCES
Q1. Why is the atmosphere essential for life? Q2. Why is water essential for life? Q3. How are living organisms dependent on the soil? Are organisms that live in water totally independent of soil as a resource? Q4. You have seen weather reports on television and in news paper. How do you think we are able to predict the weather? Q5. We know that many human activities lead to increasing levels of pollution of air, water bodies and soil. Do you think that isolating these activities to specific and limited areas would help in reducing pollution? Q6. Write a note on how forests influence the air, soil and water resources. Q7. What is ‘Water Cycle’ ? Explain the process of water cycle. Q8. Write a short note on ‘Nitrogen Fixation’ Q9.Explain the ‘Nitrogen Cycle Q10. Discuss the consequences of the increase in the concentration of Carbon dioxide and other Green House gases in the atmosphere CBSE Summative & Formative Assignment based on CCE Test Paper Biology Term-2 CCE Test Paper Biology Chapter Natural Resources ix Biology-1 Download File CCE Test Paper Biology Chapter Natural Resources ix Biology-2 Download File CBSE NCERT Class 9th natural resources Solved Board Questions Download File
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IX Atomic Structure ( a fundamental particles) Discovery of Electron 9th Atomic Structure (Discovery of a fundamental particle protons) 9th Atoms and Molecules 9th Structure of Atoms Practice paper and sample paper based On Atomic structure Rutherford Experiment and Discovery of Nucleus Lord Rutherford (1911) and his coworkers performed an experiment. They bombarded a very thin, gold fail with Alpha particles from a radioactive source. They observed that most of the particles passed straight through the foil undeflected. But a few particles were deflected at different angles. One out of 4000 Alpha particles was deflected at an angle greater than 150. Conclusion Following conclusions were drawn from the Rutherford’s Alpha Particles scattering experiment. 1. The fact that majority of the particles went through the foil undeflected shows that most of the space occupied by an atom is empty. 2. The deflection of a few particles over a wide angle of 150 degrees shows that these particles strike with heavy body having positive charge. 3. The heavy positively charged central part of the atom is called nucleus. 4. Nearly all of the mass of atom is concentrated in the nucleus. 5. The size of the nucleus is very small as compared with the size of atom. Defects of Rutherford Model Rutherford model of an atom resembles our solar system. It has following defects: 1. According to classical electromagnetic theory, electron being charged body will emit energy continuously. Thus the orbit of the revolving electron becomes smaller and smaller until it would fall into the nucleus and atomic structure would collapse. 2. If revolving electron emits energy continuously then there should be a continuous spectrum but a line spectrum is obtained. Bohr’s Atomic Model Neil Bohr (1913) presented a model of atom which has removed the defects of Rutherford Model. This model was developed for hydrogen atom which has only proton in the nucleus and one electron is revolving around it. Postulates of Bohr’s Atomic Model The main postulates of Bohr’s Model are given below: 1. Electrons revolve around the nucleus in a fixed orbit. 2. As long as electron revolves in a fixed orbit it does not emit and absorb energy. Hence energy of electron remains constant. 3. The orbit nearest to the nucleus is the first orbit and has lowest energy. When an electron absorbs energy it jumps from lower energy orbit to higher energy orbit. Energy is emitted in the form of radiations, when an electron jumps from higher energy orbit to lower energy orbit. The unit of energy emitted in the form of radiations is called quantum. It explains the formation of atomic spectrum. Downloadable study material: Click Here Structure of atom for CBSE class 9(IX)
Solved Summative Assessment Paper Solved some important questions for coming CBSE Exam How was the neutron discovered? How was the proton discovered? How was the Electron discovered? Extra mark’s Notes, "Atomic Structure" How was the Nucleus discovered? Structure of an Atom IX Chemistry assignment-1 Structure of an Atom IX Chemistry assignment-2 How to identify the group and period of element ?
Electronic configuration is the arrangement of electrons in an atom in different shells and sub-shells. The modern periodic table has elements arranged according to their electronic configurations.From left to right i.e. in a period,the arrangment is such that each subsequent electron added is to the same shell. Electronic Configuration is the Period e.g Configuration of Li atomic number. 3, is 1s2 ,2s1 Configuration of Be atomic no. 4, is 1s2 ,2s2 Configuration of B atomic no. 5, is 1s2 ,2s2,2p1 Configuration of C atomic no. 6, is 1s2 ,2s2 ,2p2 and so on till Neon,the last element. This addition of each subsequent electron results in a completely new configuration and as such the chemical properties of the subsequent element change gradually..At the end of each row, a drastic shift occurs in chemical properties. Electronic Configuration is the Group From top to down in a column,i.e.in a group, each subsequent electron is added to the new shell,but in same sub-shell. e.g. In the 1st group, Configuration of H atomic number.1,is 1s1 Configuration of Li atomic no. 3, is 1s2 ,2s1 Configuration of Na atomic no. 11, is 1s2 ,s2,2p6 ,3s1 Configuration of K atomic no. 19, is 1s2 ,2s2 ,2p6,3s2 ,3p6,4s1 and so on till Neon,the last element. The number of valence shell electrons in an atom would determine the way it will interact with other atoms, and therefore determine its chemical properties. Further study visit10th Periodic Classification of Elements (10 pages) 7th_cbse_sample_paper_chapter_simple_interest Download File 7th_Profit_loss__simple_interest Download File 7th_maths_percentage_cbse_test_paper-1 Download File 7th_maths_percentage_cbse_test_paper-2 Download File Educational link by jsunil tutorial 7th math's Term-I 7th math's Term-II CBSE Class VII Science 7th Science CBSE Practice Test paper 7th Science CBSE Solved Test paper CHEMISTRY sample paper set 1 for class XI
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