NCERT Solutions for Class 9 Science

Get here the Updated NCERT Solutions for Class 9 Science all chapters in Hindi and English Medium free for academic session 2020–2021. UP Board Solutions for Class 9 Science in Hindi Medium or English Medium are also available for free download.

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NCERT Solutions for Class 9 Science

Class: 9Science – विज्ञान
Contents:NCERT Solutions in Hindi and English Medium

9th Science Solutions in English & Hindi Medium

Free download links for Class 9 Science NCERT Solutions and UP Board Solutions in PDF format free are given below. All the solutions are updated for new academic session 2020-21 for UP Board, Delhi Board, MP Board, Gujrat Board, Uttarakhand Board, etc., who are following NCERT Books 2020-2021 for their final board exams.

Class 9 Science Main Points & NCERT Solutions

Chapter 1. Matter in Our Surroundings

Class 9 Science Chapter 1 describes Physical Nature of matter like matter is made up of particle and the size of these particles. It further explains the characteristics of the particle of matter like they have space between them, they are moving with some kinetic energy, and they attract each other with a particular force. We all know that there are three states of matter – Solid, Liquid and Gas. In Chemistry Chapter 1 of Class 9 Science, we will go through the properties of matter in different states. Changing of state with the application of temperature, pressure, or other factors are also important for the exams.

Chapter 2. Is Matter Around Us Pure

Class 9 Science Chapter 2 explains about all types of substances, whether it is pure or a mixture of two or more pure substances. Homogeneous and heterogeneous mixture and their properties are frequently asked in school exams of class 9 Science. We have to learn here about how many types of solutions are there, how to prepare these solutions and how to find the concentration of a given solution. After doing this, we will be able to understand about Suspension and Colloidal also. Properties of Suspension and Colloidal are also crucial as exams point of view. Separating the components from the mixture using various methods are given at the end of this chapter. We can apply these ways in day to day life to understand in a better way.

Chapter 3. Atoms and Molecules

Class 9 Science Chapter 3 deals with Law of Chemical Combination, Law of Conservation of Mass and Law of Constant Proportion. Here, we will study that Atoms and Molecules are the fundamental building blocks of all matter. What is an atom? How big are they? What are the ancient or modern symbols of atoms? These type of questions are new for standard nine students. Atomic Mass and their symbols usually start from grade 9 and play an important role in higher classes. We should understand carefully about important Molecules and their valency along with the knowledge of ions – cation or anion. Using Criss-cross method, writing the formula of any compound is the most important part of Chemistry Chapter 3 of Class 9 Science. Questions based on Molecular mass and Mole concepts are also crucial for the class test or school terminal exams.




Chapter 4. Structure of the Atom

Class 9 Science Chapter 4 is based on sub-atomic particle like a proton – p, neutron – n and electron – e. It also explains the various steps of the discovery of the structure of atoms and its subparts. Structure of Atom includes the atomic models of J. J. Thomson, Rutherford and Bohr. Rutherford’s experiment, its observation and conclusion are considered as important topics of Chemistry Chapter 4 of Class 9 Science. We have to learn here about Valency, Atomic Number, Mass Number and their correlation with each other. We should understand the difference between Isotopes and Isobars to remove any confusion in further classes.

Chapter 5. The Fundamental Unit of Life

Class 9 Science Chapter 5 is the first chapter of Biology in standard 9. This chapter tells us how Robert Hooke discovered the cell using a slice of cork. Cells are too small to see through naked eyes, but we can see the cell by microscope making temporary mounts of peels of onions. Here, we will be able to know about cells in the human body like Bone cells, Blood cells, Smooth muscles cells, Nerve cells, etc. The structural organisation of a cell, Plasma membrane and its phenomena with Isotonic, Hypotonic and Hypertonic solutions are briefly described in grade 9 Science, Chapter 5 Biology section. We should know about the function of Cell wall, Nucleus and Cytoplasm in a cell. A complete description of Plant cell and Animal cell with their components like Golgi Apparatus, Lysosomes, Mitochondria, Plastid, Vacuoles and Cell division is the main point of this chapter to study.

Chapter 6. Tissues

Class 9 Science Chapter 6 describes about the plant and animal tissues. Plant tissues include the explanation about Meristematic tissue – for the growth of plants and Permanent tissue – permanent in shape, size and function (simple and complex permanent tissues). Animal tissues cover the topics related to Epithelial tissue (also known as covering or protective tissue), Connective tissue, Muscular tissue and Nervous tissue. Nerve cells or Neurons are the fundamental units of the nervous system. Nervous tissues are made up of these Neurons. Neurons are the longest cells in the human body. An individual nerve cell may be up to a metre long.

Chapter 7. Diversity in Living Organisms

Class 9 Science Chapter 7 explains about the classification of the living being in a systematic order. We will study here that the classification of life forms will be closely related to their evolution. Biologists, Ernst Haeckel, Robert Whittaker and Carl Woese, have tried to classify all living organisms into called kingdoms. The classification Whittaker divided all the living being into five kingdoms as Monera, Protista, Fungi, Plantae and Animalia. Further classification is done by naming the sub-groups Phylum or Division, Class, Order, Family, Genus and Species. In Class 9 Science Chapter 7, we have to compare the living being within the same kingdom or some time with the other kingdom also. In the end, we will study the Nomenclature – systematic naming of living organisms.




Chapter 8. Motion

Class 9 Science Chapter 8 includes all the terms which describe the motion of an object. Most of the topics are based on the motion on a straight line or uniform motion. During the study of uniform or non-uniform motion, we will learn to find the average speed or speed during a specific duration. Chapter 8 of Class 9 Science contains many numerical problems in Physics following the three equation of motion. We should understand about the difference between velocity and speed as well as distance and displacement. Graphical representation of motion and the derivation of three equations of motion with a graphical method are frequently asked in school examination. Concepts of uniform circular motion and numerically based on it are also important for exams.

Chapter 9. Force and Laws of Motion

Class 9 Science Chapter 9 starts with focusing on the balanced and unbalanced force. Later on, it includes the impact of Friction force and Inertia also. The main motive to study Chapter 9 of Class 9 Science is to understand the laws of motion under the influence of force. Here, we will start from First law of motions and Inertia of body. Later on Second law of motion along with the law of conservation of momentum. We have to do all the intext questions and exercises questions based on particular on laws of motions and momentum. In the end, there are many reasoning questions based on the Third law of motion are given to understand about the law of Action-Reaction.

Chapter 10. Gravitation

Class 9 Science Chapter 10 is based on the concepts of Gravitation, Universal Law of Gravitation and Gravity. We should know that every object is attracted by other objects with a variable gravitational pull according to what the Gravitational Law states. The relation between Universal Gravitational Constant G and Gravitational Acceleration g is also important for terminal exams or class test. Chapter 10 of Class 9 Science also states about the difference between Mass and Weight considering the values of g. We know that G is constant, but the value of gravity varies according to the varying radius of Earth. Value of g is maximum at poles and least at the equator due to the elliptical structure of Earth. Concepts of Buoyancy, Buoyant force, Pressure and Thrust, Archimedes’ principle of floatation and Relative Density are the topic for exam preparation.



Chapter 11. Work and Energy

Class 9 Science Chapter 11 explains that Work and Energy are the same things only the states are changed. Work is concerted to different from of Energy or from Energy we can do work. Questions based on constant force and uniform motions are given as intext questions. Mechanical Energy is basically divided into two kinds as Kinetic Energy and Potential Energy. Kinetic Energy of an object is due to its motion whereas Potential Energy is due to its current position. The sum of Potential and Kinetic Energy is considered as Mechanical Energy. The other forms of energies are Heat Energy, Chemical Energy, Electrical Energy and Light Energy. The Law of Conservation of Energy, Work done, Power and Commercial unit of Energy are the main topics for numerical practice. The relation between 1 Unit and Joules are important for derivation as well as for numerical problems.

Chapter 12. Sound

Class 9 Science Chapter 12 deals with the production and motion of sound. We know that sound travels with different speed in different materials but does not travel in the vacuum as it needs a material medium to travel. Characteristic of a sound wave or Longitudinal wave and concepts of Compression and Rarefaction with Frequency, Amplitude and Speed is important for this segment of class 9 Science. We should also know about the Intensity, Softness, Loudness, Low and High Pitch of sound waves. Most of the numerical in Chapter 12 of Class 9 Science is based on speed, wavelength and frequency. Reflection of sound, including the concept of Echo, are important for conceptual questions. At the end of chapter 12 of 9th Physics, the concepts of Reverberation, instruments based on multiple reflections of sound, range of hearing, Sonar and application of Ultra-Sound waves are given for practice.

Chapter 13. Why do We Fall ill?

Class 9 Science Chapter 13 is focused on Health and related terminology of Health. We will study what Health is, what are the criteria for a healthy person or a disease-free person, and more similar queries. We will also try to know what are the main causes of disease and what is the difference between Acute and Chronic disease. Many diseases may be Infectious or Non-infectious. Mean of spreading, precaution from being ill, the principle of treatment and cure of disease are the concepts given to understand.




Chapter 14. Natural Resources

Class 9 Science Chapter 14 is mainly focused on the Natural Resources available on Earth. Topics for study are the role of the atmosphere in climate control, the appearance of areas of low and high pressure, the direction in which air would flow at night or in the day, causes of rain and means of pollution. We have to study about the availability of water resources and the method of prevention from being polluted. In the end, we will read about biochemical cycles like the water cycle, nitrogen cycle, carbon cycle, oxygen cycle and the greenhouse effect.

Chapter 15. Improvement in Food Resources

Class 9 Science Chapter 15 is based on various methods of improvement of food resources. Improvement of various crops like wheat, rice, maize, millets, etc. yield and improvement of crop variety are an exciting topic to read. Crop production management includes nutrient management like Compost and vermi-compost, Green manure, etc. manure and fertilisers. Irrigation, cropping pattern, crop production management, storage facility, animal husbandry, cattle farming, poultry farming, egg and broiler and fish production are the main points of focus.

Class 9 Science Solutions for 2020-21

We have updated all the NCERT Solutions 2020-21 for new session in PDF form. PDF file related to all chapters are given on the chapter’s page. If you are facing in downloading these pages, please contact us for help. NCERT Solutions Offline Apps 2020-2021 are also based on latest NCERT Books 2020-21. Download these apps for offline use. If you have downloaded these apps once, there is no need of internet connection later on.



Feedback & Suggestions

Along with the solutions of each chapter, in the same section assignments, Previous years questions with solutions are also given. Important questions according to the latest NCERT Syllabus 2020-21 from popular books Lakhmir Singh and Manjit Kaur, S Chand, Pradeep’ fundamental book, Together with Science, U – Like and other important books will be included in the assignments. NCERT Books Solutions for UP Board are also included in Hindi and English Medium. If you need answers of questions related to any chapter, please upload through Discussion FORUM, we will provide solutions with in 48 hours.



Important Questions on Class 9 Science

स्विमिंग पूल में गोताखोर पानी काट पाता है। इससे पदार्थ का कौन-सा गुण प्रेक्षित होता है?
जल के कणों के बीच दूरी अधिक होने के कारण आकर्षण बल कम होता है। इसलिए स्विमिंग पूल में गोताखोर पानी काट पाता है।
किसी भी पदार्थ की अवस्था परिवर्तन के दौरान तापमान स्थिर क्यों रहता है?
पदार्थ की अवस्था परिवर्तन के दौरान दी गयी ऊष्मा (गुप्त ऊष्मा), पदार्थ के कणों की बीच आणुविक बन्धो को तोड़ने में खर्च होती है। इसीलिए अवस्था परिवर्तन के दौरान दी गयी ऊष्मा पदार्थ का तापमान नहीं बढ़ा पाती।
Describe Pure substance with example.
Pure Substance: A pure substance consists of a single of matter or particles and cannot be separated into other kind of matter by any physical process. Pure substances always have the same colour, taste and texture at a given temperature and pressure. For example, pure water is always colourless, odorless and tasteless and boils at 373 K at normal atmospheric pressure.
Convert into mole: 12g of oxygen gas.
32 g of oxygen gas = 1 mole
Then, 12g of oxygen gas = 12/32 mole = 0.375 mole
What are the limitations of Rutherford’s model of the atom?
According to Rutherford’s model of an atom, electrons revolve around the nucleus in fixed orbits. But, an electron revolving in circular orbits will not be stable because during revolution, it will experience acceleration. Due to acceleration, the electrons will lose energy in the form of radiation and fall into the nucleus. In such a case, the atom would be highly unstable and collapse.
यदि किसी परमाणु में इलेक्ट्रॉनों की संख्या 8 है और प्रोटॉनों की संख्या भी 8 है तब, (a) परमाणु की परमाणु संख्या क्या है? (b) परमाणु का क्या आवेश है?
(a) हम जानते हैं कि, परमाणु संख्या = प्रोटॉनों की संख्या
अतः, परमाणु की परमाणु संख्या = 8

(b) परमाणु का आवेश = प्रोटॉनों की संख्या – इलेक्ट्रॉनों की संख्या = 8 – 8 = 0
अतः, परमाणु पर कोई आवेश नहीं है और परमाणु उदासीन है।

कोशिका की खोज किसने और कैसे की?
कोशिका की खोज सर्वप्रथम राबर्ट हुक ने की। उन्होंने 1665 में कॉर्क की पतली छीलन को अपने बनाए गए सूक्ष्मदर्शी में देखा जिसमें मधुमखी के छत्ते जैसे छोटी छोटी कोठरियाँ दिखायी दी जिन्हे उन्होंने (सेल) कोशिका नाम दिया।
लाइसोसोम को आत्मघाती थैली क्यों कहते हैं?
लाइसोसोम के अंदर अत्यंत शक्तिशाली पाचक रस होते है जो कोशिका के अंदर प्रवेश करने वाले विषाक्त, विजातीय पदार्थो को तो नष्ट करते ही है, कोशिका के ठीक से कार्य न करने वाले अंगको को भी नष्ट करके उसे साफ करने का कार्य करते है। कभी-कभी पूरी कोशिका ही बीमार हो जाती है और ठीक से कार्य नहीं करती, तब पूरी कोशिका को ही नष्ट करने के लिए, लाइसोसोम फट जाते हैं और एंजाइम अपनी ही कोशिकाओं को पाचित कर देते हैं। इसलिए लाइसोसोम को कोशिका की आत्मघाती थैली भी कहते हैं।
बहुकोशिक जीवों में ऊतकों का क्या उपयोग है?
बहुकोशिक जीवों में ऊतक भोजन का पाचन, स्वसन, उत्सर्जन, परिसंचरण, गमन तथा जनन आदि कार्य करते हैं।
उस ऊतक का नाम बताएँ जो हमारे शरीर में गति के लिए उत्तरदायी है।
पेशी ऊतक शरीर को गति प्रदान करते है। पेशी ऊतक में एक विशेष प्रकार का प्रोटीन होता है जिसके संकुचन एवं प्रसार के कारण गति होती है।
अपने चारों ओर फैले जीव रूपों की विभिन्नता के तीन उदाहरण दें।
जीवों में तीन प्रकार विभिन्ता प्रायः देखी जाती हैं:
आकार: कुछ जीव जैसे बैक्टीरिया अतिसूक्ष्म होते है तो दूसरी ओर ह्वेल जैसे जीव कई मीटर तक लम्बे होते हैं।
जीवन काल: कुछ जीवों जैसे मच्छर का जीवन काल अति न्यून होता है जबकि कुछ पौधे सैकड़ों साल जिन्दा रहते है।
रंग: कुछ जीव रंगहीन (पारदर्शी तक) होते है तो कुछ विभिन्न आकर्षक रंगों युक्त होते हैं।
वर्गीकरण के विभिन्न पदानुक्रमों में किस समूह में सर्वाधिक समान लक्षण वाले सबसे कम जीवों को और किस समूह में सबसे ज्यादा संख्या में जीवों को रखा जाएगा?
सर्वाधिक समान लक्षणों वालें सबसे कम संख्या वाले वर्ग को जाति (स्पसीज) कहते है क्योंकि वर्गीकरण में यह निम्नतम स्तर पर है। जबकि सर्वाधिक संख्या वालें समूह की जगत कहते है क्योंकि वर्गीकरण में यह उच्चतम स्तर पर है।
विस्थापन के लिए निम्न में कौन सही है? (a) यह शून्य नहीं हो सकता है। (b) इसका परिमाण वस्तु के द्वारा तय की गई दूरी से अधिक है।
(a) और (b) दोनों में से कोई भी सत्य नहीं है। क्योंकि यह शून्य हो सकता है तथा इसका परिमाण वस्तु के द्वारा तय की गई दूरी से कम या बराबर होता है।
Why is it advised to tie any luggage kept on the roof of a bus with a rope?
When the bus accelerates and moves forward, it acquires a state of motion. However, the luggage kept on the roof, owing to its inertia, tends to remain in its state of rest. Hence, with the forward movement of the bus, the luggage tends to remain at its original position and ultimately falls from the roof of the bus. To avoid this, it is advised to tie any luggage kept on the roof of a bus with a rope.
Gravitational force acts on all objects in proportion to their masses. Why then, a heavy object does not fall faster than a light object?
All objects fall on ground with constant acceleration, called acceleration due to gravity (in the absence of air resistances). It is constant and does not depend upon the mass of an object. Hence, heavy objects do not fall faster than light objects.
पानी की सतह पर रखने पर कोई वस्तु क्यों तैरती या डूबती है?
यदि वस्तु का घनत्व पानी के घनत्व से कम है या बराबर है तो वस्तु पानी पर तैरती रहेगी अन्यथा वस्तु पानी में डूब जाएगी।
या
यदि वस्तु का भार उसके द्वारा विस्थापित जल के भार से कम या बराबर है तो वस्तु पानी में तैरेगी अन्यथा डूब जाएगी।
A battery lights a bulb. Describe the energy changes involved in the process.
Battery converts chemical energy into electrical energy. This electrical energy is further converted into light and heat energy.
A person holds a bundle of hay over his head for 30 minutes and gets tired. Has he done some work or not? Justify your answer.
The person holding a bundle of hay get tired because his muscular energy is converting into thermal energy. There is no displacement at all, so he had no work. As Work done = Force × displacement.
मान लीजिए आप अपने मित्र के साथ चंद्रमा पर गए हुए है। क्या आप अपने मित्र द्वारा उत्पन्न ध्वनि को सुन पाएँगे?
ध्वनि तरंगों को चलने के लिए द्रव्यात्मक माध्यम (जैसे: लोहा, ताँबा, वायु आदि) की आवश्यकता होती है। चंद्रमा पर वायुमंडल नहीं है। इसलिए अपने मित्र द्वारा उत्पन्न ध्वनि को माध्यम के आभाव में हम नहीं सुन पाएँगे।
प्रतिरक्षीकरण क्या है?
एक बार रोग होने पर उसी रोग से बचने की विधि को प्रतिरक्षीकरण कहते हैं। इस प्रक्रिया में रोगाणुओं (कमजोर रोगाणुओं) को शरीर में प्रवेश कराया जाता है। जब रोगाणु प्रतिरक्षा तंत्र पर पहली बार आक्रमण करते हैं तो प्रतिरक्षा तंत्र रोगाणुओं के प्रति क्रिया करता है और फिर इसका विशिष्ट रूप से स्मरण कर लेता है। इस प्रकार जब वही रोगाणु या उससे मिलता – जुलता रोगाणु संपर्क में आता है तो पूरी शक्ति से उसे नष्ट कर देता है। इससे पहले संक्रमण की अपेक्षा दूसरा संक्रमण शीघ्र ही समाप्त हो जाता है।
वायुमंडल एक कंबल की तरह कैसे कार्य करता है?
वायु ताप का कुचालक होता है। अतः, दिन के समय वायुमंडल होने के कारण सूर्य से आने तापमान का कुछ ही भाग पृथ्वी तक आ पता है और रात के समय ऊष्मा को बाहरी अंतरिक्ष में जाने से रोकता है। इस प्रकार वायुमंडल, पृथ्वी के औसत तापमान को दिन और रात से समय पुरे वर्ष लगभग नियत बनाए रखता है।
What are the advantages of inter-cropping and crop rotation?
Inter-cropping and crop rotation both play an important role in increasing the yield of crops. Inter-cropping helps in preventing pests and diseases to spread throughout the field. It also increases soil fertility, whereas crop rotation prevents soil depletion, increases soil fertility, and reduces soil erosion. Both these methods reduce the need for fertilizers. It also helps in controlling weeds and controls the growth of pathogens and pests in crops.