Science Textbook for Class IX PDF (NCERT)

SCIENCE TEXTBOOK FOR CLASS IX 2024-25 0964 – SCIENCE ISBN 81-7450-492-3 Textbook for Class IX First Edition February 2006 Phalguna 1927 ALL RIGHTS RESERVED Reprinte...

SCIENCE TEXTBOOK FOR CLASS IX 2024-25 0964 – SCIENCE ISBN 81-7450-492-3 Textbook for Class IX First Edition February 2006 Phalguna 1927 ALL RIGHTS RESERVED Reprinted q No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, November 2006, November 2007, recording or otherwise without the prior permission of the publisher. January 2009, December 2009, q This book is sold subject to the condition that it shall not, by way of trade, be lent, re- November 2010, December 2011, sold, hired out or otherwise disposed of without the publisher’s consent, in any form of binding or cover other than that in which it is published. October 2012, October 2013, q The correct price of this publication is the price printed on this page, Any revised December 2014, December 2015, price indicated by a rubber stamp or by a sticker or by any other means is incorrect February 2017, December 2017, and should be unacceptable. December 2018, October 2019, January 2021 and November 2021 OFFICES OF THE PUBLICATION DIVISION, NCERT Revised Edition NCERT Campus October 2022 Ashwina 1944 Sri Aurobindo Marg New Delhi 110 016 Phone : 011-26562708 Reprinted 108, 100 Feet Road March 2024 Chaitra 1946 Hosdakere Halli Extension Banashankari III Stage Bengaluru 560 085 Phone : 080-26725740 PD 520T SU Navjivan Trust Building P.O.Navjivan © National Council of Educational Ahmedabad 380 014 Phone : 079-27541446 Research and Training, 2006, 2022 CWC Campus Opp. Dhankal Bus Stop Panihati Kolkata 700 114 Phone : 033-25530454 CWC Complex Maligaon Guwahati 781 021 Phone : 0361-2674869 Publication Team Head, Publication : Anup Kumar Rajput Division ` 155.00 Chief Editor : Shveta Uppal Chief Production : Arun Chitkara Officer Chief Business : Amitabh Kumar Manager (In charge) Printed on 80 GSM paper with NCERT Production Assistant : Prakash Veer Singh watermark Published at the Publication Division Cover by the Secretary, National Council of Educational Research and Training, Nidhi Wadhwa Sri Aurobindo Marg, New Delhi 110 016 Layout and Illustrations and printed at SDA Print ‘N’ Pack, D-19, Digital Expressions Sector-B1, Tronica City Industrial Area, Loni, District Ghaziabad- 201 102 (U.P.) 2024-25  FOREWORD The National Curriculum Framework (NCF) 2005, recommends that children’s life at school must be linked to their life outside the school. This principle marks a departure from the legacy of bookish learning which continues to shape our system and causes a gap between the school, home and community. The syllabi and textbooks developed on the basis of NCF signify an attempt to implement this basic idea. They also attempt to discourage rote learning and the maintenance of sharp boundaries between different subject areas. We hope these measures will take us significantly further in the direction of a child- centred system of education outlined in the National Policy on Education (1986). The success of this effort depends on the steps that school principals and teachers will take to encourage children to reflect on their own learning and to pursue imaginative activities and questions. We must recognise that, given space, time and freedom, children generate new knowledge by engaging with the information passed on to them by adults. Treating the prescribed textbook as the sole basis of examination is one of the key reasons why other resources and sites of learning are ignored. Inculcating creativity and initiative is possible if we perceive and treat children as participants in learning, not as receivers of a fixed body of knowledge. These aims imply considerable change in school routines and mode of functioning. Flexibility in the daily time-table is as necessary as rigour in implementing the annual calendar so that the required number of teaching days are actually devoted to teaching. The methods used for teaching and evaluation will also determine how effective this textbook proves for making children’s life at school a happy experience, rather than a source of stress or boredom. Syllabus designers have tried to address the problem of curricular burden by restructuring and reorienting knowledge at different stages with greater consideration for child psychology and the time available for teaching. The textbook attempts to enhance this endeavour by giving higher priority and 2024-25 space to opportunities for contemplation and wondering, discussion in small groups, and activities requiring hands-on experience. The National Council of Educational Research and Training (NCER T) appreciates the hard work done by the textbook development team responsible for this book. We wish to thank the Chairman of the advisory group in science and mathematics, Professor J.V. Narlikar and the Chief Advisor for this book, Professor Rupamanjari Ghosh, School of Physical Sciences, Jawaharlal Nehru University, New Delhi, for guiding the work of this committee. Several teachers contributed to the development of this textbook; we are grateful to them and their principals for making this possible. We are indebted to the institutions and organisations which have generously permitted us to draw upon their resources, material and personnel. We are especially grateful to the members of the National Monitoring Committee, appointed by the Department of Secondary and Higher Education, Ministry of Human Resource Development under the Chairmanship of Professor Mrinal Miri and Professor G.P. Deshpande, for their valuable time and contribution. As an organisation committed to systemic reform and continuous improvement in the quality of its products, NCERT welcomes comments and suggestions which will enable us to undertake further revision and refinement. Director New Delhi National Council of Educational 20 December 2005 Research and Training (iv) 2024-25 RATIONALISATION OF CONTENT IN THE TEXTBOOK In view of the COVID-19 pandemic, it is imperative to reduce content load on students. The National Education Policy 2020, also emphasises reducing the content load and providing opportunities for experiential learning with creative mindset. In this backdrop, the NCERT has undertaken the exercise to rationalise the textbooks across all classes. Learning Outcomes already developed by the NCERT across classes have been taken into consideration in this exercise. Contents of the textbooks have been rationalised in view of the following: Overlapping with similar content included in other subject areas in the same class Similar content included in the lower or higher class in the same subject Difficulty level Content, which is easily accessible to students without much interventions from teachers and can be learned by children through self-learning or peer-learning Content, which is irrelevant in the present context This present edition, is a reformatted version after carrying out the changes given above. 2024-25 2024-25  TEXTBOOK DEVELOPMENT COMMITTEE CHAIRMAN, ADVISORY GROUP FOR TEXTBOOKS IN SCIENCE AND MATHEMATICS J.V. Narlikar, Emeritus Professor, Chairman, Advisory Committee Inter Uni- versity Centre for Astronomy & Astrophysics (IUCCA), Ganeshbhind, Pune University, Pune CHIEF ADVISOR Rupamanjari Ghosh, Professor, School of Physical Sciences, Jawaharlal Nehru University, New Delhi MEMBERS Anjni Koul, Lecturer, Department of Education in Science and Mathematics (DESM), NCERT, New Delhi Anupam Pachauri, 1317, Sector 37, Faridabad, Haryana Anuradha Gulati, TGT, CRPF Public School, Rohini, Delhi Asfa M. Yasin, Reader, Pandit Sunderlal Sharma Central Institute of Vocational Education, NCERT, Bhopal Charu Maini, PGT, DAV School, Sector 14, Gurgaon, Haryana Dinesh Kumar, Reader, DESM, NCERT, New Delhi Gagan Gupta, Reader, DESM, NCERT, New Delhi H.L. Satheesh, TGT , DM School, Regional Institute of Education, Mysore Madhuri Mahapatra, Reader, Regional Institute of Education, Bhubaneswar, Orissa Puran Chand, Joint Director, Central Institute of Educational Technology, NCERT, New Delhi S.C. Jain, Professor, DESM, NCERT, New Delhi Sujatha G.D., Assistant Mistress, V.V.S. Sardar Patel High School, Rajaji Nagar, Bangalore S.K. Dash, Reader, DESM, NCERT, New Delhi Seshu Lavania, Reader, Department of Botany, University of Lucknow, Lucknow Satyajit Rath, Scientist, National Institute of Immunology, JNU Campus, New Delhi Sukhvir Singh, Reader, DESM, Regional Institute of Education, Ajmer, Rajasthan Uma Sudhir, Eklavya, Indore MEMBER-COORDINATOR Brahm Parkash, Professor, DESM, NCERT, New Delhi 2024-25  A CKNOWLEDGEMENTS The National Council of Educational Research and Training is grateful to the members of the Textbook Development Team, whose names are given separately, for their contribution in the development of the Science textbook for Class IX. The Council also gratefully acknowledges the contribution of the participating members of the Review Workshop in the finalisation of the book: P.K. Bhattacharya, Professor, DESM, NCERT; Anita Julka, Reader, DEGSN, NCERT; Tausif Ahmad, PGT, New Era Sr. Sec. School, New Delhi; Samarketu, PGT in Physics, JNV, MESRA, Ranchi; Meenakshi Sharma, PGT in Biology, SVEM, Ankleshwar, Gujarat; Raji Kamlasanan, PGT in Biology, DTEA SNSU School, R.K. Puram, New Delhi; Meenambika Menon, TGT in Science, Cambridge School, Noida; Lalit Gupta, TGT in Science, Govt. Boys Sr. Sec. School No. 2, Uttam Nagar, New Delhi; Manoj Kumar Gupta, Lecturer in Chemistry, Mukherji Memorial Sr. Sec. School, Shahdara, Delhi; Vijay Kumar, Vice-Principal, Govt. Sarvodaya, Co. Edu. Sr. Sec. School, Anand Vihar, Delhi; Kanhaya Lal, Principal (Retd.), Deptt. of Education, GNCT of Delhi, Delhi; K.B. Gupta, Professor (Retd.), NCERT, New Delhi; Kuldeep Singh, TGT in Science, JNV, Meerut; R.A. Goel, Principal (Retd.), Delhi; Sumit Kumar Bhatnagar, Department of Education, GNCT of Delhi, Delhi. Acknowledgements are due to M. Chandra, Professor and Head, Department of Education in Science and Mathematics, NCERT, New Delhi for providing all academic and administrative support. The Council also gratefully acknowledges the support provided by the APC Office of DESM, administrative staff of DESM; Deepak Kapoor, Incharge Computer Centre, DESM; Saima, DTP Operator; Mohd. Qamar Tabrez, Copy Editor; Mathew John and Randhir Thakur, Proofreaders. The efforts of the Publication Department, NCERT are also highly appreciated. 2024-25  CONTENTS FOREWORD iii RATIONALISATION OF CONTENT IN THE TEXTBOOK V Chapter 1 MATTER IN OUR SURROUNDINGS 1 Chapter 2 IS MATTER AROUND US PURE? 14 Chapter 3 ATOMS AND MOLECULES 26 Chapter 4 STRUCTURE OF THE ATOM 38 Chapter 5 THE FUNDAMENTAL UNIT OF LIFE 49 Chapter 6 TISSUES 60 Chapter 7 MOTION 72 Chapter 8 FORCE AND LAWS OF MOTION 87 Chapter 9 GRAVITATION 100 Chapter 10 WORK AND ENERGY 113 Chapter 11 SOUND 127 Chapter 12 IMPROVEMENT IN FOOD RESOURCES 140 ANSWERS 152– 154 2024-25  THE CONSTITUTION OF INDIA PREAMBLE WE, THE PEOPLE OF INDIA, having solemnly resolved to constitute India into a 1 [SOVEREIGN SOCIALIST SECULAR DEMOCRATIC REPUBLIC] and to secure to all its citizens : JUSTICE, social, economic and political; LIBERTY of thought, expression, belief, faith and worship; EQUALITY of status and of opportunity; and to promote among them all FRATERNITY assuring the dignity of the individual and the 2[unity and integrity of the Nation]; IN OUR CONSTITUENT ASSEMBLY this twenty-sixth day of November, 1949 do HEREBY ADOPT, ENACT AND GIVE TO OURSELVES THIS CONSTITUTION. 1. Subs. by the Constitution (Forty-second Amendment) Act, 1976, Sec.2, for "Sovereign Democratic Republic" (w.e.f. 3.1.1977) 2. Subs. by the Constitution (Forty-second Amendment) Act, 1976, Sec.2, for "Unity of the Nation" (w.e.f. 3.1.1977) 2024-25