JAC Board Class 9 Science: Matter in Our Surroundings

• Class 9 Science for the JAC Board covers a wide range of topics in Physics, Chemistry, and Biology.
• The curriculum aims to provide a foundational understanding of scientific principles.
• Students are expected to learn through a combination of theoretical knowledge and practical experiments.

Matter in Our Surroundings

• Matter is anything that occupies space and has mass.
• Matter exists in three states: solid, liquid, and gas.
• Solids have a definite shape and volume.
• Liquids have a definite volume but no definite shape; they take the shape of their container.
• Gases have neither a definite shape nor a definite volume; they fill the entire container.
• Matter is made up of small particles called atoms and molecules.
• The force of attraction between particles is strongest in solids, less in liquids, and negligible in gases.
• Changes in temperature and pressure can change the state of matter (e.g., melting, boiling, condensation, freezing, sublimation, deposition).
• Sublimation is the process where a solid directly changes into a gas without passing through the liquid state.
• Evaporation is the process where a liquid changes into a gas below its boiling point.
• Evaporation causes cooling.
• Factors affecting evaporation: surface area, temperature, humidity, and wind speed.

Is Matter Around Us Pure?

• A pure substance consists of a single type of particle.
• Mixtures are composed of two or more substances mixed together in any proportion.
• Mixtures can be homogeneous or heterogeneous.
• Homogeneous mixtures have a uniform composition throughout (e.g., sugar solution, air).
• Heterogeneous mixtures have a non-uniform composition (e.g., sand and water, muddy water).
• Solutions, suspensions, and colloids are types of mixtures.
• A solution is a homogeneous mixture where the solute is dissolved in the solvent (e.g., salt in water).
• The concentration of a solution is the amount of solute present in a given quantity of solvent or solution.
• Suspension is a heterogeneous mixture in which solid particles are spread throughout the liquid without dissolving (e.g., chalk powder in water).
• Colloids appear homogeneous but are actually heterogeneous mixtures (e.g., milk, fog, blood).
• Tyndall effect is the scattering of light by colloidal particles.
• Methods for separating mixtures: evaporation, centrifugation, decantation, sublimation, chromatography, distillation, and fractional distillation.
• Chromatography is based on differing movement of different substances in a mixture on a stationary phase.
• Distillation is used to separate miscible liquids with different boiling points.
• Fractional distillation is used when the difference in boiling points is less.

Atoms and Molecules

• An atom is the smallest particle of an element that can take part in a chemical reaction.
• A molecule is a group of two or more atoms chemically bonded together.
• Elements are substances made up of only one kind of atom (e.g., hydrogen, oxygen, iron).
• Compounds are substances made up of two or more different kinds of atoms chemically combined in a fixed ratio (e.g., water, carbon dioxide).
• Ions are charged particles formed when an atom gains or loses electrons.
• Cations are positively charged ions.
• Anions are negatively charged ions.
• Chemical formulas represent the composition of a molecule using symbols of elements and subscripts to indicate the number of atoms of each element.
• Molecular mass is the sum of the atomic masses of all the atoms in a molecule.
• Mole concept: 1 mole of any substance contains Avogadro's number (6.022 x 10^23) of particles.
• Molar mass is the mass of 1 mole of a substance.

Structure of the Atom

• Atoms are made up of electrons, protons, and neutrons.
• Electrons are negatively charged particles that revolve around the nucleus.
• Protons are positively charged particles located in the nucleus.
• Neutrons are neutral particles also located in the nucleus.
• The number of protons in an atom is called its atomic number (Z).
• The total number of protons and neutrons in an atom is called its mass number (A).
• Isotopes are atoms of the same element with the same atomic number but different mass numbers.
• Isobars are atoms of different elements with the same mass number but different atomic numbers.
• Electronic configuration describes the arrangement of electrons in different energy levels or shells around the nucleus (e.g., K, L, M, N shells).
• Valence electrons are the electrons in the outermost shell, which determine the chemical properties of an atom.
• Valency is the combining capacity of an atom.

The Fundamental Unit of Life

• The cell is the basic structural and functional unit of life.
• Cells are classified as prokaryotic or eukaryotic.
• Prokaryotic cells are simple cells without a well-defined nucleus and membrane-bound organelles (e.g., bacteria).
• Eukaryotic cells are complex cells with a well-defined nucleus and membrane-bound organelles (e.g., plant and animal cells).
• Cell organelles: cell membrane, cell wall, nucleus, cytoplasm, endoplasmic reticulum, Golgi apparatus, lysosomes, mitochondria, plastids, vacuoles.
• Cell membrane controls the movement of substances in and out of the cell.
• Cell wall (in plant cells) provides support and protection.
• Nucleus contains the genetic material (DNA) and controls cell activities.
• Cytoplasm is the fluid-filled space inside the cell.
• Endoplasmic reticulum (ER) is involved in protein and lipid synthesis.
• Golgi apparatus processes and packages proteins and lipids.
• Lysosomes contain enzymes for intracellular digestion.
• Mitochondria are the powerhouses of the cell, producing ATP.
• Plastids (in plant cells) include chloroplasts (for photosynthesis), chromoplasts, and leucoplasts.
• Vacuoles store water, nutrients, and waste products.
• Cell division: mitosis (for growth and repair) and meiosis (for sexual reproduction).

Tissues

• A tissue is a group of similar cells performing a specific function.
• Plant tissues: meristematic (actively dividing) and permanent (non-dividing).
• Meristematic tissues: apical, lateral, and intercalary.
• Permanent tissues: simple (parenchyma, collenchyma, sclerenchyma) and complex (xylem, phloem).
• Animal tissues: epithelial, connective, muscular, and nervous.
• Epithelial tissue covers body surfaces and lines body cavities.
• Connective tissue supports and connects different tissues and organs (e.g., blood, bone, cartilage).
• Muscular tissue is responsible for movement.
• Nervous tissue transmits electrical signals.

Diversity in Living Organisms

• Classification is the arrangement of organisms into groups based on similarities and differences.
• Hierarchy of classification: kingdom, phylum (for animals) / division (for plants), class, order, family, genus, species.
• Five-kingdom classification: Monera, Protista, Fungi, Plantae, and Animalia.
• Monera includes prokaryotic organisms (e.g., bacteria).
• Protista includes unicellular eukaryotic organisms (e.g., protozoa, algae).
• Fungi includes heterotrophic organisms with chitinous cell walls (e.g., mushrooms, molds).
• Plantae includes multicellular, photosynthetic organisms (e.g., plants).
• Animalia includes multicellular, heterotrophic organisms (e.g., animals).
• Principles of nomenclature: binomial nomenclature (genus and species names).
• Viruses are acellular organisms that require a host to reproduce.

Motion

• Motion is the change in position of an object with respect to time.
• Distance is the total length of the path traveled by an object.
• Displacement is the shortest distance between the initial and final positions of an object.
• Speed is the rate of change of distance.
• Velocity is the rate of change of displacement.
• Acceleration is the rate of change of velocity.
• Uniform motion: object covers equal distances in equal intervals of time.
• Non-uniform motion: object covers unequal distances in equal intervals of time.
• Equations of motion: v = u + at, s = ut + (1/2)at^2, v^2 = u^2 + 2as
• Graphical representation of motion: distance-time and velocity-time graphs.
• Uniform circular motion is motion in a circle with constant speed.

Force and Laws of Motion

• Force is a push or pull that changes or tends to change the state of rest or motion of an object.
• Balanced forces do not cause a change in motion.
• Unbalanced forces cause a change in motion.
• Newton's first law of motion (law of inertia): An object remains in a state of rest or of uniform motion unless acted upon by an external unbalanced force.
• Inertia is the tendency of an object to resist changes in its state of motion.
• Newton's second law of motion: Force is directly proportional to the rate of change of momentum (F = ma).
• Momentum is the product of mass and velocity (p = mv).
• Newton's third law of motion: For every action, there is an equal and opposite reaction.
• Conservation of momentum: In the absence of an external force, the total momentum of a system remains constant.

Gravitation

• Gravitation is the force of attraction between any two objects in the universe.
• Universal law of gravitation: F = G(m1m2)/r^2, where G is the universal gravitational constant.
• Acceleration due to gravity (g) is the acceleration experienced by an object due to the Earth's gravitational pull.
• Weight is the force with which an object is attracted towards the Earth (W = mg).
• Mass is the amount of matter in an object.
• Weight varies from place to place, but mass remains constant.
• Free fall is the motion of an object under the influence of gravity alone.
• Thrust is the force acting on an object perpendicular to the surface.
• Pressure is thrust per unit area (P = F/A).
• Buoyancy is the upward force exerted by a fluid on an object immersed in it.
• Archimedes' principle: When an object is partially or fully immersed in a fluid, it experiences an upward force equal to the weight of the fluid displaced by it.
• Relative density is the ratio of the density of a substance to the density of water.

Work and Energy

• Work is said to be done when a force causes displacement of an object.
• Work = Force x Displacement (W = Fs cos θ).
• Energy is the capacity to do work.
• Kinetic energy is the energy possessed by an object due to its motion (KE = (1/2)mv^2).
• Potential energy is the energy possessed by an object due to its position or configuration (PE = mgh).
• Law of conservation of energy: Energy can neither be created nor destroyed, but it can be transformed from one form to another.
• Power is the rate of doing work (P = W/t).
• Units of work and energy: Joule (J).
• Unit of power: Watt (W).

Sound

• Sound is a form of energy that produces a sensation of hearing.
• Sound is produced by vibrations.
• Sound requires a medium for propagation (e.g., solid, liquid, gas).
• Sound cannot travel through a vacuum.
• Longitudinal waves: particles of the medium vibrate parallel to the direction of propagation of the wave.
• Transverse waves: particles of the medium vibrate perpendicular to the direction of propagation of the wave.
• Sound travels as longitudinal waves.
• Characteristics of sound waves: wavelength, frequency, amplitude, time period, velocity.
• Frequency is the number of vibrations per second (measured in Hertz, Hz).
• Amplitude is the maximum displacement of a particle from its mean position.
• Loudness depends on the amplitude of the sound wave.
• Pitch depends on the frequency of the sound wave.
• Ultrasound is sound with a frequency greater than 20,000 Hz.
• Infrasound is sound with a frequency less than 20 Hz.
• Applications of ultrasound: medical imaging, sonar.
• Echo is the repetition of sound due to reflection.
• Reverberation is the persistence of sound due to multiple reflections.

Why Do We Fall Ill?

• Health is a state of being well enough to function physically, mentally, and socially.
• Disease is a condition that impairs the normal functioning of the body.
• Causes of diseases: pathogens (viruses, bacteria, fungi, protozoa), malnutrition, genetic disorders, environmental factors.
• Infectious diseases are caused by pathogens and can spread from one person to another (e.g., common cold, tuberculosis, malaria).
• Non-infectious diseases are not caused by pathogens and cannot spread from one person to another (e.g., diabetes, cancer).
• Modes of transmission of infectious diseases: air, water, contact, vectors (e.g., mosquitoes).
• Prevention of diseases: maintaining hygiene, sanitation, vaccination.
• Principles of treatment: reducing the effects of the disease and killing the pathogens.
• Antibiotics block biochemical pathways important for bacteria.
• Viruses live inside host cells, making treatment more difficult.

Natural Resources

• Natural resources are substances or materials occurring in nature that can be used for economic gain.
• Air, water, and soil are essential natural resources.
• Air pollution: caused by pollutants such as smoke, dust, and gases.
• Water pollution: caused by pollutants such as sewage, chemicals, and industrial waste.
• Soil pollution: caused by pollutants such as pesticides, fertilizers, and solid waste.
• Biogeochemical cycles: the movement of nutrients through the ecosystem (e.g., water cycle, carbon cycle, nitrogen cycle, oxygen cycle).
• Greenhouse effect: the trapping of heat by gases in the atmosphere, leading to global warming.
• Ozone layer depletion: caused by chlorofluorocarbons (CFCs) and other ozone-depleting substances.
• Water is essential for life.
• Soil formation depends on weathering.
• Biodiversity is the variety of life forms found in a region.
• Conservation of natural resources: reducing pollution, recycling, afforestation, sustainable development.