| Latest Science NCERT Notes and Solutions (Class 6th to 10th) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 6th | 7th | 8th | 9th | 10th | ||||||||||
| Latest Science NCERT Notes and Solutions (Class 11th) | ||||||||||||||
| Physics | Chemistry | Biology | ||||||||||||
| Latest Science NCERT Notes and Solutions (Class 12th) | ||||||||||||||
| Physics | Chemistry | Biology | ||||||||||||
Latest Class 9th Science NCERT Concepts & Solutions
1. Matter In Our Surroundings
This chapter introduces the fundamental concept of matter, defined as anything that has mass and occupies space. It explores the physical nature of matter, explaining that it is made up of tiny, constantly moving particles. The chapter details the distinct properties of the three states of matter—solid, liquid, and gas—based on the varying forces of attraction and kinetic energy between their particles. Key processes of inter-conversion of states are discussed, including melting (solid to liquid), boiling (liquid to gas), sublimation (solid directly to gas), condensation (gas to liquid), and freezing (liquid to solid), illustrating how matter changes its state with changes in temperature and pressure.
2. Is Matter Around Us Pure?
This chapter classifies matter into pure substances and mixtures. Pure substances, which have a fixed chemical composition, are further divided into elements and compounds. Mixtures, which consist of two or more substances mixed in any proportion, are classified as homogeneous (uniform composition, e.g., salt solution) and heterogeneous (non-uniform composition, e.g., sand and water). It introduces various techniques for separating the components of mixtures, such as evaporation, filtration, distillation, chromatography, and crystallisation, based on the different physical properties of the components. The chapter also distinguishes between true solutions, suspensions, and colloidal solutions based on particle size and stability.
3. Atoms And Molecules
This fundamental chemistry chapter introduces the building blocks of matter: atoms (the smallest unit of an element) and molecules (the smallest unit of a compound). It discusses the foundational laws of chemical combination: the Law of Conservation of Mass and the Law of Constant Proportions. The chapter explains the postulates of Dalton's atomic theory, which provided the first scientific basis for the concept of the atom. It introduces crucial quantitative concepts like atomic mass, molecular mass, and the mole concept, which defines a mole as a specific quantity ($\textsf{1 mole} = 6.022 \times 10^{23} \textsf{ particles}$) that connects the mass of a substance to the number of its particles.
4. Structure Of The Atom
This chapter delves into the internal structure of the atom, revealing that it is not indivisible. It traces the historical development of atomic models, from J.J. Thomson's "plum pudding" model to Rutherford's discovery of the nucleus and Bohr's model of discrete energy shells. The chapter describes the three fundamental subatomic particles: negatively charged electrons, positively charged protons, and neutral neutrons. It defines atomic number (Z) as the number of protons and mass number (A) as the total number of protons and neutrons. The concepts of isotopes (atoms of the same element with different mass numbers) and isobars (atoms of different elements with the same mass number) are also explained.
5. The Fundamental Unit Of Life
This foundational biology chapter establishes the cell as the basic structural and functional unit of all living organisms. It introduces the discovery of the cell by Robert Hooke and the formulation of the Cell Theory. The chapter provides a detailed overview of the components of a cell, differentiating between plant and animal cells. Key structures discussed include the selectively permeable cell membrane, the rigid cell wall (in plants), the control centre or nucleus containing genetic material, and the jelly-like cytoplasm. It also explains the functions of various specialized cell organelles like mitochondria (powerhouse), endoplasmic reticulum, Golgi apparatus, lysosomes, and vacuoles.
6. Tissues
In multicellular organisms, cells with similar structure and function group together to form tissues. This chapter explores the different types of tissues in plants and animals. Plant tissues are classified into meristematic tissues (responsible for growth) and permanent tissues (specialized for various functions). Permanent tissues include simple tissues like parenchyma and complex tissues like xylem (conducts water) and phloem (transports food). Animal tissues are categorised into four main types: epithelial tissue (for protection and covering), connective tissue (for support and binding, e.g., blood and bone), muscular tissue (for movement), and nervous tissue (for transmitting signals).
7. Motion
This physics chapter introduces the formal description of motion along a straight line. It distinguishes between scalar quantities like distance and speed, and vector quantities like displacement and velocity. The concept of acceleration is introduced as the rate of change of velocity. The chapter emphasizes the graphical representation of motion using distance-time and velocity-time graphs to analyze an object's movement. It culminates in the derivation and application of the three fundamental equations of motion for uniformly accelerated linear motion: $\textsf{v = u + at}$, $\textsf{s = ut} + \frac{1}{2}\textsf{at}^2$, and $\textsf{2as} = \textsf{v}^2 - \textsf{u}^2$.
8. Force And Laws Of Motion
This chapter delves into the cause of motion: force. It explains the concept of a balanced and unbalanced force and introduces Newton's three laws of motion, which form the bedrock of classical mechanics. Newton's First Law defines inertia, Newton's Second Law provides the quantitative relationship between force, mass, and acceleration ($\textsf{F = ma}$), and Newton's Third Law states that for every action, there is an equal and opposite reaction. The important concept of momentum ($\textsf{p = mv}$) is introduced, leading to the principle of the Conservation of Momentum, which governs interactions like collisions.
9. Gravitation
Gravitation is the universal force of attraction between any two objects with mass. This chapter introduces Newton's Universal Law of Gravitation ($\textsf{F} = \textsf{G}\frac{\textsf{m}_1\textsf{m}_2}{\textsf{r}^2}$). It explains the concept of free fall and defines the acceleration due to gravity ($\textsf{g}$). A key distinction is made between mass (the amount of matter in an object, which is constant) and weight (the force of gravity on an object, which varies). The chapter also explores pressure in fluids, introducing the concept of buoyancy and Archimedes' principle, which explains why objects float or sink.
10. Work And Energy
This chapter defines work in its scientific sense, where work is done only when a force produces a displacement ($\textsf{Work} = \textsf{Force} \times \textsf{Displacement}$). It introduces energy as the capacity to do work. The chapter focuses on two main forms of mechanical energy: kinetic energy ($\textsf{KE} = \frac{1}{2}\textsf{mv}^2$), the energy of motion, and potential energy, the energy stored due to position or configuration. It establishes the fundamental Law of Conservation of Energy, stating that energy can only be transformed from one form to another, not created or destroyed. Finally, power is defined as the rate at which work is done or energy is transferred.
11. Sound
This chapter explores the physics of sound, defining it as a mechanical, longitudinal wave that requires a medium (solid, liquid, or gas) for its propagation. It explains how sound is produced by vibrating objects, creating a series of compressions and rarefactions. Key characteristics of sound waves are defined, including wavelength ($\lambda$), frequency ($\nu$) (which determines pitch), and amplitude (which determines loudness). The chapter discusses the reflection of sound, which leads to phenomena like echoes, and covers the range of human hearing (approximately 20 Hz to 20,000 Hz), introducing the concepts of infrasound and ultrasound.
12. Improvement In Food Resources
Addressing the challenge of feeding India's large and growing population, this chapter discusses strategies to improve food production from both plant and animal sources. For crops, it covers three main areas: crop variety improvement (through techniques like hybridisation), crop production management (nutrient management, irrigation, and cropping patterns), and crop protection management (controlling weeds, pests, and diseases). It also delves into animal husbandry, discussing scientific management practices for cattle farming (for milk), poultry farming (for eggs and meat), and fish farming (pisciculture), all with a focus on achieving higher yields sustainably.