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• Tara Chand ( Coordinator) • Shabnam Johry • Tanushri Saxena • Renu Kathpalia McGraw Hill Education (India) Private Limited NEW DELHI McGraw Hill Education Offices New Delhi New York St Louis San Francisco Auckland Bogotá Caracas Kuala Lumpur Lisbon London Madrid Mexico City Milan Montreal San Juan Santiago Singapore Sydney Tokyo Toronto Published by McGraw Hill Education (India) Private Limited, P-24, Green Park Extension, New Delhi 110 016. General Science: For Civil Services Preliminary Examination—Paper I, 2e Copyright © 2014, 2013, McGraw Hill Education (India) Private Limited. No part of this publication may be reproduced or distributed in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise or stored in a database or retrieval system without the prior written permission of the publishers. The program listings (if any) may be entered, stored and executed in a computer system, but they may not be reproduced for publication. This edition can be exported from India only by the publishers, McGraw Hill Education (India) Private Limited. Print Edition ISBN (13): 978-93-513-4353-0 ISBN (10): 93-513-4353-7 E-book Edition ISBN (13): 978-93-392-1391-6 ISBN (10): 93-392-1391-2 Managing Director: Kaushik Bellani Deputy General Manager—Test Prep and School: Tanmoy Roychowdhury Publishing Manager—Test Prep: K N Prakash Assistant Sponsoring Editor—Bhavna Malhotra Asst Manager (Developmental Editing): Anubha Srivastava Asst Manager—Production: Medha Arora Senior Production Executive: Dharmender Sharma Product Specialist: Vikas Sharma General Manager—Production: Rajender P. Ghansela Manager—Production: Reji Kumar Information contained in this work has been obtained by McGraw Hill Education (India), from sources believed to be reliable. However, neither McGraw Hill Education (India) nor its authors guarantee the accuracy or completeness of any information published herein, and neither McGraw Hill Education (India) nor its authors shall be responsible for any errors, omissions, or damages arising out of use of this information. This work is published with the understanding that McGraw Hill Education (India) and its authors are supplying information but are not attempting to render engineering or other professional services. If such services are required, the assistance of an appropriate professional should be sought. Typeset at Script Makers, 19, A1-B, DDA Market, Paschim Vihar, New Delhi 110063 and text and cover printed at Cover Designer: K. Anoop ABOUT THE AUTHORS Dr Tara Chand A former Dean of St Stephen’s College, University of Delhi, Dr Tara Chand taught Physics in that college for over 36 years. He did his B.Sc (Hons), M.Sc and Ph.D from the University of Delhi and his post-doctoral research at the renowned Fermilab, Chicago, USA. Dr Tara Chand has been the overall coordinator of McGraw Hill’s bestselling manual General Studies: Paper I for Civil Services Preliminary Examination since its inception in 1985. He has also contributed the Physics portion in the manual. He closely follows the recent trends in the pattern of the General Studies Paper. Dr Shabnam Johry D Shabnam Johry is an Associate Professor of Chemistry at St. Stephen’s College, University of Delhi. She holds a Ph.D. in Organic Chemistry from the University of Delhi. Dr Johry enjoys the honour of being the first lady student of St. Stephen’s College to join the faculty of this esteemed institution, and has a teaching experience of over 30 years in this college. Dr Tanushri Saxena D Tanushri Saxena is an Associate Professor of Zoology in Swami Shraddhanand College of the University of Delhi where she has been teaching for the past 20 years. She received her bachelor’s and master’s and PhD degrees from the University of Delhi. She is a member of Indian Society of General and Comparative Endocrinology and Asia and Oceania Society of Comparative Endocrinology (Tokyo). Dr Renu Kathpalia Dr Renu Kathpalia is an Associate Professor in the Department of Botany, Kirori Mal College, University of Delhi where she has been teaching for the past 22 years. She did her M.Phil. and Ph.D from the University of Delhi. PREFACE TO THE SECOND EDITION T he second, revised edition of General Science for Civil Services Preliminary Examination Paper I has a total of nearly 260 new MCQs distributed over the various sections. There are also solved questions related to General Science from last years’ question papers (GS Paper I). Each part has been dealt with by a subject expert related to the topic. The text is carefully calibrated to meet the needs of the aspirants and the MCQs are chosen after due thought. It is hoped that this new edition will strengthen the fundamentals of aspirants in various aspects of General Science and will ensure good scores in the examination. Our best wishes to the readers and we wish them all the best in their endeavours! T C ARA HAND S J HABNAM OHRY T S ANUSHRI AXENA R K ENU ATHPALIA PREFACE TO THE FIRST EDITION S cience is one of the important areas tested in the Civil Services Preliminary Examination. This book has been written not only to help aspirants acquire sound knowledge and understanding of general science, but also to make this study stimulating, interesting and relevant. It presents important and new developments in science in a way that makes it easier for aspirants to understand. Different parts of this book have been handled by the respective subject expert so that each section is endowed with academic rigour. The new section introduced in the syllabus, namely, ‘General Issue on Environmental Ecology, Biodiversity and Climate Change’ has been comprehensively dealt with by three authors who are experts on these subjects. A section has been devoted to ‘New Technologies’, a topic which has assumed importance in recent years. This book presupposes only the knowledge of science typically attained in a secondary school (tenth class) course. The text is concise and does not contain any unnecessary details. A glossary of key terms is also included in each section so that revision at a glance will be easy. Each part is supplemented with multiple choice questions (MCQs) for testing mastery of the concepts. These questions have been framed keeping in mind the trend of application-oriented nature of questions being asked in the examination. The pattern of MCQs followed in the question papers of the years 2011 and 2012 has been adhered to in this book. The unique feature of this book is that it deals with science involved in everyday life. The aspirants will enjoy it because while preparing for their examination they will become aware of the science behind various phenomena occurring around them all the time. They will also be equipped with information about the latest technologies. The simple and student-friendly presentation will make this book a reliable and trusted friend for aspirants preparing for the UPSC preliminary examination and also various state service examinations. We hope they will enjoy and benefit from the experience of learning general science as it is presented in this book. Our best wishes are with them for success in their endeavours. T C ARA HAND S J HABNAM OHRY T S ANUSHRI AXENA R K ENU ATHPALIA ABOUT THE CIVIL SERVICES EXAMINATION The Civil Services examination comprises two successive stages: (i) Civil Services (Preliminary) Examination (Objective Type) for the selection of candidates for Main Examination; and (ii) Civil Services (Main) Examination (Written and Interview) for the selection of candidates for the various services and posts. Scheme and subjects for the Preliminary and Main Examination. A. Preliminary Examination The Examination shall comprise two compulsory Papers of 200 marks each. Note: (i) Both the question papers will be of the objective type (multiple choice questions). (ii) The question papers will be set both in Hindi and English. However, questions relating to English Language Comprehension Skills of Class X level will be tested through passages from English language only without providing Hindi translation thereof in the question paper. B. Main Examination The written examination will consist of the following papers: Qualifying Papers: Paper A: (One of the Indian Language to be selected by the candidate from the Languages included in the Eighth Schedule to the Constitution). 300 Marks Paper B: English 300 Marks The papers on Indian Languages and English (Paper A and Paper B) will be of Matriculation or equivalent standard and will be of qualifying nature. The marks obtained in these papers will not be counted for ranking. Papers to be counted for merit Paper I: Essay 250 Marks Paper II: General Studies–I 250 Marks (Indian Heritage and Culture, History and Geography of the World and Society) Paper III: General Studies –II 250 Marks