For 9th grade students, Science Class 9 NCERT Solution play a significant role in their academic journey. These solutions contain complete answers to the in-text and chapter-end questions in the Science textbook, making it easier for students to comprehend the concepts and apply them to the questions. The Science textbook covers three primary branches of science: Physics, Chemistry, and Biology, and the NCERT Solutions cover all the chapters of these subjects.
The language used in the Science Class 9 NCERT Solution is simple and easy-to-understand, presented in a step-by-step manner to help students grasp the concepts logically. By referring to these solutions, students can identify their weak areas and revise the concepts regularly to perform better in their examinations.
The NCERT Solutions for Class 9 Science help students prepare effectively for their examinations by providing them with a comprehensive set of solutions. These solutions serve as a vital resource for students who may find it difficult to locate the answers to the questions on their own. Students can use these solutions to build a solid foundation in Science and achieve academic success.
Science Class 9 NCERT Solution
- Chapter 1 Matter in Our Surroundings
- Chapter 2 Is Matter Around Us Pure
- Chapter 3 Atoms and Molecules
- Chapter 4 Structure of the Atom
- Chapter 5 The Fundamental Unit of Life
- Chapter 6 Tissues
- Chapter 7 Diversity in Living Organisms
- Chapter 8 Motion
- Chapter 9 Force and Laws of Motion
- Chapter 10 Gravitation
- Chapter 11 Work, Power And Energy
- Chapter 12 Sound
- Chapter 13 Why Do we Fall Ill
- Chapter 14 Natural Resources
- Chapter 15 Improvement in Food Resources
Science Class 9 Important Points Chapter Wise
Chapter 1: Matter in Our Surrounding
The first chapter of the Class 9 Science textbook, entitled Matter in Our Surroundings, exposes students to the idea of matter, as well as to its various states and physical characteristics. These are some key topics this chapter covered:
- Matter is anything that has mass and occupies space.
- It is composed of atoms and molecules, which are little particles.
- Solid, liquid, and gas are the three distinct states of matter. The arrangement of a substance’s particles determines its state.
- Shape, volume, density, and compressibility are some of matter’s properties.
- The variation in the intermolecular forces between the constituents of matter contributes to state changes. Melting, freezing, evaporation, condensation, and sublimation are a few of the several forms of transformations.
- Surface area, temperature, humidity, and wind speed are just a few of the variables that affect how quickly water evaporates.
- Air pressure affects a liquid’s boiling point. Because of this, water boils more slowly at high altitudes.
- When a solid transforms into a gas without first becoming liquid, this is known as sublimation.
- This chapter introduces the idea of the Kinetic Theory of Matter, which describes how matter behaves in terms of its constituent particles.
Chapter 2: Is Matter Around Us Pure?
- A pure substance is made up of only one type of particles with definite properties.
- A mixture contains two or more pure substances mixed in varying proportions.
- Mixtures can be homogeneous or heterogeneous.
- Homogeneous mixtures have uniform composition and appearance, while heterogeneous mixtures have non-uniform composition and appearance.
- Homogeneous mixtures of two or more components are called solutions.
- The concentration of a solution is measured by the amount of solute dissolved in a given amount of solvent.
- Solids in a mixture can be separated from liquids using filtration or centrifugation.
- Chromatography is a technique used to separate the components of a mixture based on their solubility in a particular solvent.
- Distillation is a technique used to separate the components of a mixture based on their boiling points.
- Crystallisation is a technique used to obtain pure solids from their impure solutions by cooling the solution slowly.
- Impurities can be detected by using various methods like melting point determination, boiling point determination, and chromatography.
- Different methods are used to purify water like boiling, filtration, chlorination, etc.
- Common techniques used for purification of metals are liquation, distillation, electrolysis, and zone refining.
Chapter 3: Atoms and Molecules
- Atoms and molecules that are too small for the human eye to see make up matter.
- As they cannot be formed, destroyed, or further divided, atoms are the fundamental building units of matter.
- According to Dalton’s atomic theory, molecules are created when atoms join in a particular ratio to form compounds.
- An element’s molecules are identical, and they can be combined to create a compound’s molecules.
- The total atomic masses of every atom in a molecule make up the substance’s molecular mass.
- According to Avogadro’s law, equal volumes of all gases at the same temperature and pressure contain an equal number of molecules.
- The quantity and types of atoms that make up a molecule are represented by the chemical formula of a compound.
- An element’s valency is determined by how many electrons it must receive or lose in order to establish a stable configuration.
- Whereas covalent compounds are created when atoms share electrons, ionic compounds are created when electrons are transferred from one atom to another.
- Atoms of the same element that have variable numbers of neutrons but the same number of protons are called isotopes.
- The mass number is the total amount of protons and neutrons in an atom, whereas an element’s atomic number is the quantity of protons in its nucleus.
- The number of particles in 12 grammes of carbon-12, which is used as a unit of measurement for substance amounts, is equal to one mole.
Chapter 4: Structure of the Atom
- The concept of an atom was first proposed by John Dalton in the early 19th century.
- Protons, neutrons, and electrons are the three primary subatomic particles that make up an atom.
- Protons are positively charged particles present in the nucleus of an atom, while neutrons are neutral particles also present in the nucleus.
- Electrons are negatively charged particles that revolve around the nucleus in shells or energy levels.
- The atomic number of an element is the number of protons present in its nucleus.
- The mass number of an atom is the sum of the number of protons and neutrons present in its nucleus.
- The electrons in an atom are arranged in different shells or energy levels, with each shell having a specific energy level.
- The maximum number of electrons that can be accommodated in a shell is given by 2n^2, where n is the number of the shell.
- The quantity of electrons in an atom’s outermost shell is known as an element’s valency.
- The octet rule states that elements tend to gain, lose, or share electrons to attain a stable configuration of 8 electrons in their outermost shell.
- Atoms of the same element that have variable numbers of neutrons but the same number of protons are called isotopes.
- The discovery of isotopes led to the revision of the atomic mass of some elements, which is the weighted average of the masses of all the naturally occurring isotopes of an element.
Chapter 5: The Fundamental Unit of Life
- The smallest structural and functional units of life, cells are the building blocks of all living things.
- Robert Hooke used a simple microscope to make the first observation of cells in 1665. These reminded him of the little apartments in a monastery, therefore the term “cells,” he gave them.
- The first person to view living cells with a microscope was a Dutch scientist named Anton van Leeuwenhoek.
- Prokaryotic and eukaryotic cells can be divided into two groups. Eukaryotic cells are complex and have nuclei, whereas prokaryotic cells are simple and lack a nucleus.
- The cell is surrounded by a thin, pliable membrane called the cell membrane, which isolates the interior of the cell from the external environment.
- Several organelles are found in the cytoplasm, a jelly-like fluid that fills the cell.
- The most significant organelle in eukaryotic cells is the nucleus. DNA, which carries genetic data and regulates a cell’s actions, is present in it.
- The nucleolus, a tiny, compact structure within the nucleus, is responsible for producing ribosomes.
- Protein synthesis is carried out by microscopic organelles called ribosomes.
- Cells manufacture energy through a process called respiration, which is carried out by mitochondria, which are organelles.
- The organelles known as chloroplasts are located in plant cells and are in charge of photosynthesis, which is how plants produce their own food.
- Moreover, plant cells have a stiff cell wall formed of cellulose that serves as the cell’s structural support.
- Both asexual and sexual reproduction are possible in cells. Sexual reproduction involves two parents and produces kids with a combination of genetic features from both parents as opposed to asexual reproduction, which only involves one parent and produces identical offspring.
Chapter 6: Tissues
- Tissue is a group of similar cells that perform a particular function in an organism.
- Tissues are of four types: epithelial, connective, muscular, and nervous.
- Epithelial tissue covers the surface of the body and lines the internal organs and cavities.
- Connective tissue provides support, protection, and framework to the organs and tissues.
- Muscular tissue helps in movement and locomotion.
- Nervous tissue is responsible for communication and coordination between various body parts.
- Meristem is a type of tissue that helps in the growth of the plant.
- Permanent tissues are the ones that have attained maturity and cannot divide further.
- Parenchyma, collenchyma, and sclerenchyma are examples of plant tissues.
- The study of tissues is called histology.
Chapter 7: Diversity in Living Organism
- Diversity in Living Organisms is the study of the vast variety of living organisms that exist on our planet.
- The classification of living organisms is based on their structural and functional characteristics.
- The two major classification systems are the traditional classification system and the modern classification system.
- Carolus Linnaeus is known as the father of taxonomy and is credited with developing the traditional classification system.
- The modern classification system is based on the evolutionary relationships among living organisms and is called the phylogenetic classification system.
- The five kingdoms of living organisms are Monera, Protista, Fungi, Plantae and Animalia.
- Viruses are not considered living organisms as they cannot reproduce on their own and require a host cell to do so.
- Bacteria are unicellular organisms and are classified under the kingdom Monera.
- Protists are mostly unicellular eukaryotic organisms and are classified under the kingdom Protista.
- Fungi are heterotrophic organisms that feed on dead and decaying matter and are classified under the kingdom Fungi.
- Plants are multicellular eukaryotic organisms that have chlorophyll and perform photosynthesis. They are classified under the kingdom Plantae.
- Animals are multicellular eukaryotic organisms that are heterotrophic and have specialized tissues and organs. They are classified under the kingdom Animalia.
- The classification of organisms helps in the identification and study of different organisms and their relationships with each other.
- The classification system is important in conservation efforts as it helps in identifying endangered species and their habitats.
Chapter 8: Motion
- Motion refers to the change in position of an object with respect to its surroundings.
- The distance travelled by an object in a given time is known as speed, while the rate of change of displacement is known as velocity.
- The rate at which velocity changes in relation to time is referred to as acceleration.
- The three equations of motion relate to the displacement, initial velocity, final velocity, time taken and acceleration of an object.
- Uniform motion is when an object travels with a constant speed while non-uniform motion is when the object travels with a varying speed.
- Graphical representation of motion can be made using distance-time and velocity-time graphs.
- Galileo’s experiment demonstrated that objects of different masses fall at the same rate in the absence of air resistance, whereas air resistance can greatly affect the motion of objects.
- Newton’s laws of motion state that an object at rest will remain at rest and an object in motion will continue to move with uniform velocity unless acted upon by an external force.
- The second law of motion states that the force acting on an object is directly proportional to the rate of change of its momentum.
- Every action has an equal and opposite reaction, according to the third rule of motion.
- Friction is a force that opposes the relative motion between two surfaces in contact and can be both beneficial and harmful.
- Air resistance is a form of friction that opposes the motion of objects through air.
- The force of gravity is a universal force of attraction between any two objects with mass, and its strength is determined by the mass and distance between the objects.
Chapter 9: Force and Law of Motion
- Force is a physical quantity that changes or tends to change the state of motion of an object.
- The SI unit of force is Newton (N), and it is measured using a device called a spring balance.
- Unless acted upon by an outside force, an object will continue to be in its condition of rest or uniform motion in a straight line, according to Newton’s first law of motion.
- The first law is also called the law of inertia. An object’s ability to resist changes in its state of motion is known as inertia.
- The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass, according to Newton’s second rule of motion.
- Mathematically, F = ma, where F is the net force, m is the mass of the object, and a is its acceleration.
- The second law is also known as the law of acceleration.
- The acceleration is moving in the same general direction as the net force.
- With every action, there is an equal and opposite response, states Newton’s third rule of motion.
- The third law explains why two objects in contact always experience equal and opposite forces.
- The law of action and reaction is another name for the third law.
- The force that prevents motion between two surfaces in contact is known as the force of friction.
- Friction can be static or kinetic, depending on whether the surfaces are at rest or in motion.
- Air resistance is a type of friction that opposes the motion of objects through the air.
- The force of gravity is the force of attraction between two objects with mass.
- Gravity is the reason why objects fall to the ground and why planets orbit around the sun.
Chapter 10: Gravitation
- The pull between any two objects in the universe is known as gravity.
- The force of gravity is inversely proportional to the square of the distance between objects and directly proportional to their mass.
- Sir Issac Newton made the initial discovery of the gravitational law in 1687.
- The gravitational force is measured with a tool called a spring balance and has the SI unit of Newton (N).
- The acceleration a body experiences as a result of gravity is known as the acceleration due to gravity.
- Near the surface of the Earth, the acceleration caused by gravity is 9.8 m/s2.
- The gravitational pull on an object is measured by its weight.
- An object’s weight varies depending on its location and gravitational field intensity.
- The amount of matter that makes up an item is its mass, which is constant regardless of location or gravitational field intensity.
- Due to the moon’s weaker gravitational field than the Earth’s, an object’s weight on the moon is one-sixth that of the object’s weight on the Earth.
- Astronauts in space feel as though they are weightless since there is no external force supporting them.
- The gravitational attraction between the planets and the sun causes their orbital motion.
- On Earth, tides are caused by the gravitational pull of the earth.
- The orbital motion of satellites around the Earth is also impacted by gravitational pull.
- The minimal velocity necessary for an object to escape the gravitational field of a planet or other celestial body is known as the escape velocity.
- The planet’s mass and radius affect the escape velocity.
- By putting more space between two things, the gravitational attraction between them can be weakened.
Chapter 11: Work and Energy
- The product of the force acting on an object and the distance it travels while being moved by the force is known as work.
- Joule is the SI unit of work .
- Work might be zero, negative, or in between.
- When the force being applied and the motion are moving in the same direction, positive work is being done.
- When the force being applied and the motion’s direction are in opposition, negative work is being done.
- Zero work is done when the force applied and the direction of motion are perpendicular to each other.
- Power is the rate at which work is done, and it is defined as the amount of work done per unit time.
- The SI unit of power is Watt (W).
- Energy is the ability of an object to do work.
- Energy can be classified into two types: kinetic energy and potential energy.
- The energy an object possesses as a result of its motion is known as kinetic energy.
- The formula for kinetic energy is KE = 1/2mv2, where m is the mass of the object and v is its velocity.
- Potential energy is the energy possessed by an object due to its position or state.
- The equation for potential energy is PE = mgh, where m is the object’s mass, g is its gravitational acceleration, and h is its height above the ground.
- Energy cannot be created or destroyed; it can only be changed from one form to another, according to the rule of conservation of energy.
- The total energy of a system remains constant unless an external force acts on it.
- The work-energy theorem states that the net work done on an object is equal to the change in its kinetic energy.
- The principle of conservation of mechanical energy states that the total mechanical energy of a system remains constant if only conservative forces act on it.
- Conservative forces are those forces that do not dissipate energy as heat.
- Non-conservative forces are those forces that dissipate energy as heat, such as friction.
- The efficiency of a machine is the ratio of output work to input work, and it is always less than 1.
Chapter 12: Sound
- Energy in the form of sound causes our ears to experience hearing.
- Sound waves travel in a straight line through a medium.
- The speed of sound waves in air is approximately 340 m/s.
- The frequency of a sound wave is the number of complete vibrations it makes per second, and it is measured in Hertz (Hz).
- The amplitude of a sound wave is the maximum displacement of the particles of the medium from their equilibrium position.
- A sound wave’s amplitude determines how loud it is.
- A sound’s frequency and pitch are correlated.
- The range of frequencies that the human ear can hear is from 20 Hz to 20,000 Hz.
- Different animals have various audible frequency ranges.
- A sound wave’s strength is measured in decibels and is the amount of energy it contains per unit of space (dB).
Chapter 13: Why Do We Fall Ill?
- Health is a complete state of physical, mental, and social well-being.
- Disease is a state of an organism’s reduced functioning for a variety of causes.
- Pathogens are organisms that cause disease, including bacteria, viruses, fungus, and protozoa.
- Infectious and non-infectious diseases can be categorised.
- Pathogens that are contagious from person to person are what cause infectious diseases.
- Non-infectious diseases are brought on by things like heredity, way of living, and environmental factors.
- Air, water, food, direct contact, and indirect contact are all possible ways for infectious diseases to spread.
- Immunity is an organism’s capacity to fend against illnesses and infections.
- Natural or artificial means can be used to develop immunity.
- Via pathogen exposure, immunisation, and antibody transfer from the mother, one can develop natural immunity.
- Proteins called antibodies are created by the immune system to combat particular infections.
- Disease prevention, diagnosis, and treatment are all included in health care.
- The transmission of infections can be stopped by using good personal hygiene and sanitation techniques like handwashing, clean water, and proper waste disposal.
- A strong immune system can be maintained with the right diet, exercise, and rest.
- Mental health is an important aspect of overall health, and it can be affected by factors such as stress, trauma, and mental disorders.
Chapter 14: Natural Resources
- Resources that can be used by humans are known as natural resources.
- Renewable and non-renewable resources can be categorised into two groups.
- Resources like water, wind, and solar energy are examples of renewable resources since they can be regenerated naturally.
- Minerals and fossil fuels are examples of non-renewable resources because they are limited and cannot be regenerated after usage.
- The creation of oxygen, the storage of carbon dioxide, the production of timber, and the provision of wildlife habitat are just a few of the numerous ecological, economic, and social advantages that forests offer.
Chapter 15: Improvement in Food Resources
- Growing crops and raising animals for food and other things is called agriculture.
- Crop production, which entails the cultivation of plants for food, fibre, and other goods, is impacted by elements like climate, soil, water availability, and pest control.
- The technique of irrigation involves providing water to crops, and it can boost crop production in places with little rainfall.
- Fertilizers are compounds that give plants vital nutrients and can boost agricultural yields and soil fertility.
- Pesticides are chemicals that are used to manage pests including weeds, fungi, and insects. They can also shield crops from harm.
- Crop rotation, integrated pest control, and organic farming are examples of activities that fall under the category of sustainable agriculture. These strategies strive to increase crop yields while reducing their detrimental effects on the environment.
- Breeding, feeding, and disease control are all part of the practise of raising animals for food, fibre, and other goods, which is known as animal husbandry.
- A significant source of nourishment and income for many people, dairy farming entails the production of milk and other dairy products.
- Poultry farming is a significant source of protein and entails raising chickens, ducks, and other birds for their meat and eggs.
- Fisheries are significant sources of protein and revenue because they entail the raising and harvesting of fish and other aquatic species.
Frequently Asked Questions
Q. What are NCERT Solutions for Class 9 Science?
NCERT Solutions for Class 9 Science are a set of comprehensive answers to the in-text and chapter-end questions in the Science textbook for students studying in the 9th grade.
Q. Why are NCERT Solutions for Class 9 Science important?
In order to help students understand the ideas and apply them to the questions, NCERT Answers for Class 9 Science are crucial since they offer comprehensive answers to the questions in the Science textbook. With the aid of these solutions, students can pinpoint their areas of weakness and successfully get ready for exams.
Q. What topics are covered in NCERT Solutions for Class 9 Science?
NCERT Solutions for Class 9 Science cover three primary branches of science: Physics, Chemistry, and Biology. The solutions cover all the chapters of these subjects in the Science textbook.
Q. Are NCERT Solutions for Class 9 Science written in an easy-to-understand language?
Truly, the language used in the NCERT Answers for Class 9 Science is straightforward and clear, making it simpler for pupils to understand the concepts and apply them to the questions.
Q. Can students use NCERT Solutions for Class 9 Science to revise for their examinations?
Yes, students can use NCERT Solutions for Class 9 Science to revise the concepts regularly and retain the information, which will help them perform better in their examinations.
Q. Are NCERT Solutions for Class 9 Science free?
Yes, you can easily find and get the NCERT Answers for Class 9 Science online for free.