Summary of NCERT Class 9 Science – Chapter 1: Matter in Our Surroundings

Introduction to Matter

• Matter is anything that has mass and occupies space.

• Everything around us, including air, water, food, and living beings, is made up of matter.

Early Indian and Greek Philosophical Theories

• Indian Philosophers believed that matter is made up of five basic elements (Panch Tatva):

  • Air (Vayu)

  • Water (Jal)

  • Earth (Prithvi)

  • Fire (Agni)

  • Sky/Space (Aakash)

• Greek Philosophers such as Democritus proposed that matter is made up of tiny indivisible particles called atoms.

Physical Nature of Matter

Matter is Made Up of Particles

• All matter consists of small particles that cannot be seen with the naked eye.

• Evidence:

  • Dissolving salt or sugar in water: Even after dissolving, the volume does not change, indicating the presence of tiny particles.

Particles of Matter Have Space Between Them

• Example: When sugar or salt dissolves in water, it does not overflow, as the particles occupy the spaces between water molecules.

Particles of Matter Are Continuously Moving

• Evidence:

  • Diffusion – The intermixing of particles of two different substances on their own.

  • Example:

    • Fragrance of perfume spreads in a room without any stirring.

    • Ink spreads in water gradually.

Particles of Matter Attract Each Other

• Particles are held together by a force of attraction that varies between different types of matter.

• Example:

  • A rubber band can stretch but regains its shape due to the force of attraction between its particles.

  • Iron has stronger intermolecular forces than chalk, which breaks easily.

States of Matter

Matter exists in three major states:

1. Solid

2. Liquid

3. Gas

PropertySolidLiquidGasShapeFixedNo fixed shapeNo fixed shapeVolumeFixedFixedNo fixed volumeIntermolecular SpaceVery lessModerateLargeIntermolecular ForceStrongModerateWeakCompressibilityAlmost negligibleVery lowHighFluidityCannot flowCan flowCan flowKinetic EnergyLowModerateHigh

1. Solids

• Have a definite shape and volume.

• Particles are tightly packed and vibrate in their positions.

• Cannot be compressed easily.

• Examples: Ice, wood, iron, stone, plastic.

2. Liquids

• Do not have a definite shape but have a definite volume.

• Take the shape of their container.

• Particles have more kinetic energy than solids.

• Can flow and are called fluids.

• Examples: Water, milk, juice, oil.

3. Gases

• Do not have a definite shape or volume.

• Particles have high kinetic energy and move freely in all directions.

• Can be compressed easily.

• Examples: Oxygen, nitrogen, carbon dioxide, hydrogen.

Change of State of Matter

• Matter can change from one state to another by changing temperature or pressure.

1. Effect of Temperature

• Increase in temperature → Increases kinetic energy of particles → Overcomes force of attraction → Matter changes state.

Melting (Fusion)

• The process by which a solid changes into a liquid.

• The temperature at which a solid melts is called its melting point.

• Example: Ice melts at 0°C to form water.

Boiling (Vaporization)

• The process by which a liquid changes into a gas.

• The temperature at which a liquid boils is called its boiling point.

• Example: Water boils at 100°C to form steam.

Condensation

• The process by which a gas changes into a liquid when cooled.

• Example: Steam condenses back into water.

Freezing (Solidification)

• The process by which a liquid changes into a solid on cooling.

• Example: Water freezes into ice at 0°C.

2. Effect of Pressure

• Increasing pressure brings particles closer, which can change gases into liquids.

• Example: Liquefied Petroleum Gas (LPG) and Compressed Natural Gas (CNG) are stored under high pressure.

Sublimation

• Some solids directly convert into gas without changing into liquid.

• Example: Camphor, naphthalene balls, and dry ice.

Deposition

• Reverse of sublimation, where a gas changes directly into a solid.

• Example: Frost formation on cold surfaces.

Evaporation and Its Factors

What is Evaporation?

• Evaporation is the slow conversion of a liquid into gas at any temperature below its boiling point.

• Example: Water in an open container evaporates slowly.

Factors Affecting Evaporation

1. Surface Area – More surface area → Faster evaporation.

2. Temperature – Higher temperature → Faster evaporation.

3. Humidity – More humidity → Slower evaporation.

4. Wind Speed – Higher wind speed → Faster evaporation.

Cooling Effect of Evaporation

• Evaporation causes cooling because it takes away heat from the surroundings.

• Examples:

  • Sweating cools the body as sweat evaporates.

  • Desert coolers work better in dry weather.

  • Wet clothes dry faster under a fan.

Key Takeaways

1. Matter is made up of tiny particles that have space between them, are in motion, and attract each other.

2. Three states of matter – Solid, liquid, and gas – differ in shape, volume, particle arrangement, and energy.

3. Matter can change state due to changes in temperature and pressure.

4. Processes like melting, boiling, condensation, freezing, and sublimation show the interconversion of states of matter.

5. Evaporation is a surface phenomenon that depends on surface area, temperature, humidity, and wind speed.

6. Evaporation causes cooling, which is used in daily life (sweating, cooling of water in earthen pots, desert coolers).

Summary of NCERT Class 8 Science – Chapter 1: Crop Production and Management

Introduction

• Plants are the primary source of food for all living beings.

• Humans cultivate plants on a large scale to obtain food, a process called agriculture.

• Different crops are grown in different regions depending on climate, soil type, and water availability.

Types of Crops

Crops are classified based on the season in which they grow:

1. Kharif Crops (Rainy Season Crops)

• Sown in June–July, harvested in September–October.

• Require a lot of water (rainfall or irrigation).

• Examples: Paddy (rice), maize, cotton, jowar, bajra, soybean, groundnut.

2. Rabi Crops (Winter Season Crops)

• Sown in October–November, harvested in March–April.

• Require less water and cool temperatures.

• Examples: Wheat, barley, mustard, pea, gram.

Agricultural Practices

To cultivate crops efficiently, farmers follow various steps, known as agricultural practices:

1. Preparation of Soil

• The first step in farming is to prepare the soil to ensure proper aeration and nutrient mixing.

• It involves loosening and turning the soil to allow roots to penetrate easily.

• Methods used:

  • Ploughing (Tilling) – Done using ploughs, tractors, or traditional tools.

  • Levelling – Done using a leveller to make the soil even.

2. Sowing

• The process of planting seeds in the soil.

• Seeds must be healthy, of good quality, and free from diseases.

• Methods of Sowing:

  • Broadcasting – Manually scattering seeds.

  • Seed Drill – A modern tool for uniform seed placement.

  • Dibbling – Placing seeds at specific depths.

3. Adding Manure and Fertilizers

• Plants need nutrients to grow properly. These nutrients are provided by:

  • Manure – Organic, made from decomposed plant and animal waste.

  • Fertilizers – Chemical-based (e.g., Urea, NPK, Superphosphate).

ManureFertilizerNatural, organicSynthetic, chemical-basedProvides humusNo humusSlow in actionFast actionEco-friendlyCan cause pollution

4. Irrigation

• Watering the crops at different stages of growth.

• Sources of Irrigation: Wells, tubewells, canals, rivers, ponds.

• Traditional Irrigation Methods:

  • Moat (Pulley system) – Using buckets.

  • Chain Pump – Rotating chain to lift water.

  • Dhekli – A lever system to draw water.

  • Rahat (Water wheel) – Uses animals to draw water.

• Modern Irrigation Methods:

  • Sprinkler System – Sprays water like rain (used in uneven lands).

  • Drip Irrigation – Provides water drop by drop (used in dry regions).

5. Protection from Weeds

• Weeds are unwanted plants that grow with crops and compete for nutrients.

• Methods to Remove Weeds:

  • Manual Weeding – Using a tool called khurpi.

  • Weedicides – Chemicals like 2,4-D to kill weeds.

6. Harvesting

• Cutting and gathering mature crops.

• Methods:

  • Manual Harvesting – Using a sickle.

  • Mechanical Harvesting – Using harvesters and combines.

• Threshing – Separating grains from the stalk using a thresher or winnowing.

7. Storage of Grains

• Proper storage is essential to protect grains from pests, fungi, and moisture.

• Methods:

  • Drying grains before storage.

  • Stored in jute bags, silos, and granaries.

  • Pesticides and fumigation used for protection.

Animal Husbandry

• Along with crop farming, farmers also rear animals for milk, meat, eggs, and other products.

• Includes cattle farming, poultry farming, fish farming, and beekeeping.

1. Cattle Farming

• Dairy animals (cows, buffaloes) provide milk.

• Proper feeding and vaccination are essential.

2. Poultry Farming

• Involves rearing chickens, ducks, and turkeys for eggs and meat.

• Birds are vaccinated against diseases.

3. Fish Farming (Pisciculture)

• Fishes are bred and cultivated for commercial purposes.

• Types: Marine fishery and Inland fishery.

4. Beekeeping (Apiculture)

• Honey bees are reared for honey and wax.

• Beehives are maintained in proper conditions.

Key Takeaways

1. Agriculture is the process of growing plants for food.

2. Crops are classified into Kharif crops (rainy season) and Rabi crops (winter season).

3. Soil preparation is necessary before sowing seeds.

4. Manure and fertilizers provide essential nutrients to crops.

5. Irrigation is essential to supply water to crops.

6. Weeds must be removed to ensure healthy crop growth.

7. Harvesting and storage are crucial steps before distribution.

8. Animal husbandry supports farming by providing additional resources like milk, eggs, and honey.

Summary of NCERT Class 7 Science – Chapter 1: Nutrition in Plants

Introduction

• All living organisms need food for energy, growth, repair, and maintaining life processes.

• Nutrition is the process by which organisms obtain and utilize food.

• Nutrients are substances required by organisms for survival, such as carbohydrates, proteins, fats, vitamins, and minerals.

Modes of Nutrition

There are two main modes of nutrition in living organisms:

1. Autotrophic Nutrition – Organisms prepare their own food (e.g., plants, some bacteria).

2. Heterotrophic Nutrition – Organisms depend on others for food (e.g., animals, fungi, many bacteria).

Autotrophic Nutrition

• Plants are autotrophs as they prepare their own food using sunlight, water, and carbon dioxide through the process of photosynthesis.

• Green plants contain a pigment called chlorophyll, which helps in capturing sunlight.

Photosynthesis: The Process of Food Synthesis in Plants

• Definition: Photosynthesis is the process by which green plants synthesize their food using carbon dioxide (CO₂), water (H₂O), and sunlight to produce glucose (C₆H₁₂O₆) and oxygen (O₂).

• Chemical Equation of Photosynthesis: 6CO2+6H2O+Sunlight→C6H12O6+6O26CO_2 + 6H_2O + Sunlight → C_6H_{12}O_6 + 6O_26CO2​+6H2​O+Sunlight→C6​H12​O6​+6O2​

• Conditions Required for Photosynthesis:

  • Sunlight

  • Chlorophyll (found in chloroplasts)

  • Carbon dioxide (from the air)

  • Water (absorbed from soil)

Steps of Photosynthesis

1. Absorption of sunlight by chlorophyll in leaves.

2. Conversion of light energy into chemical energy.

3. Splitting of water molecules into hydrogen and oxygen.

4. Formation of glucose using carbon dioxide and hydrogen.

5. Oxygen is released as a byproduct.

Importance of Photosynthesis

• Produces oxygen necessary for respiration.

• Provides food for all living beings.

• Maintains balance of oxygen and carbon dioxide in the atmosphere.

Heterotrophic Nutrition

• Some plants cannot prepare their own food and depend on other organisms for survival.

• Types of heterotrophic plants:

1. Parasitic Plants

• These plants depend on a host plant for food and nutrients.

• Examples:

  • Cuscuta (Amarbel) – A yellow, thread-like plant that grows on other plants and absorbs their nutrients.

  • Mistletoe – Partially parasitic, as it performs photosynthesis but still absorbs water and minerals from the host.

2. Insectivorous Plants (Carnivorous Plants)

• These plants trap and digest insects to fulfill their nitrogen requirement.

• Examples:

  • Pitcher Plant – Has a pitcher-like structure with digestive enzymes to break down insects.

  • Venus Flytrap – Has leaves that snap shut when an insect lands on them.

3. Saprotrophic Plants

• These plants feed on dead and decaying matter.

• Examples:

  • Fungi such as mushrooms and bread mold.

  • Bacteria that decompose organic matter.

4. Symbiotic Plants (Mutualism)

• Two organisms live together and help each other.

• Examples:

  • Lichens – A partnership between algae (provides food) and fungi (provides water and shelter).

  • Rhizobium bacteria in leguminous plants – The bacteria fix nitrogen for the plant, and the plant provides nutrients to the bacteria.

Nutrient Absorption in Plants

• Soil provides water and minerals to plants.

• The roots of plants absorb minerals with the help of root hairs.

• Nitrogen fixation is done by Rhizobium bacteria found in leguminous plants (peas, beans, pulses).

• Farmers also use fertilizers and manure to enrich the soil.

Key Takeaways

1. Plants make their own food through photosynthesis, using sunlight, carbon dioxide, and water.

2. Chlorophyll is essential for capturing solar energy in green plants.

3. Heterotrophic plants depend on other organisms for food and nutrition.

4. Parasitic, insectivorous, saprotrophic, and symbiotic plants have different modes of survival.

5. Rhizobium bacteria help leguminous plants in nitrogen fixation.

6. Photosynthesis is crucial for life on Earth as it provides food and oxygen.