CBSE Class 6 Science All Chapters Worksheet Set 06

Chapter 5: Separation of Substances

I. Fill in the blanks

Question 1. Sand can be separated from water by the process of _____________________________.
Answer: Sedimentation and decantation (or filtration)
In simple words: Heavier sand settles down at the bottom, and clear water can be poured out or filtered.

Exam Tip: Mention filtration for complete separation of fine suspended sand particles.

Question 2. Common salt is obtained from sea water by the process of __________________________.
Answer: Evaporation
In simple words: Sea water is trapped in shallow pools where heat from the sun evaporates the water, leaving behind solid salt crystals.

Exam Tip: Always remember that evaporation changes liquid into vapor, leaving dissolved solids behind.

Question 3. Husk is separated from rice by the process of _____________________________________.
Answer: Winnowing
In simple words: Wind blows away the lighter husk while the heavier rice grains fall straight down.

Exam Tip: Winnowing relies on the difference in the weight of components.

Question 4. Stones can be separated from rice by the process of ________________________________.
Answer: Handpicking
In simple words: Unwanted impurities like stones are picked out by hand due to their different size, shape, or color.

Exam Tip: Handpicking is useful when impurities are present in small quantities.

Question 5. Grains can be separated from stalks by __________________________________________.
Answer: Threshing
In simple words: Stalks are beaten to free the grain seeds.

Exam Tip: Threshing can be done manually or using mechanical threshers.

Question 6. To separate tea leaves from tea we use a _________________________________________.
Answer: Strainer (or filtration)
In simple words: A strainer acts as a barrier that allows liquid tea to pass through while holding back tea leaves.

Exam Tip: Filtration is the general scientific term for using a porous medium like a strainer or filter paper.

II. Answer in one word

Question 1. Name the method used to separate pebbles or stones from sand. _______________________.
Answer: Sieving
In simple words: Sieving allows fine sand to pass through holes while retaining larger pebbles on the sieve.

Exam Tip: Use sieving when components of a mixture have different sizes.

Question 2. Name the method used to separate oil from water. _______________________.
Answer: Decantation (using a separating funnel)
In simple words: Oil and water form two separate layers because they are immiscible, allowing the top layer to be poured off.

Exam Tip: Remember that oil and water are immiscible liquids.

III. Define the following

Question 1. Threshing
Answer: The process used to beat free grain seeds from harvested stalks. It is done by beating the stalks against a hard surface or by using bullocks and machines.
In simple words: Threshing separates grains from dried stalks.

Exam Tip: Key terms: harvesting, stalks, beating, grains.

Question 2. Handpicking
Answer: A method of separating slightly larger impurities like pieces of dirt, stone, and husk from wheat, rice, or pulses by hand.
In simple words: Picking out unwanted things manually.

Exam Tip: Applicable when quantity of impurity is small.

Question 3. Filtration
Answer: A method of separating insoluble solid particles from a liquid by passing the mixture through a porous material such as a filter paper or strainer.
In simple words: Using a filter to separate solid particles from liquids.

Question 4. Saturated solution
Answer: A solution in which no more of that substance (solute) can be dissolved at a given temperature.
In simple words: A liquid that has dissolved the maximum possible amount of a substance.

Exam Tip: Adding more solute results in it settling at the bottom without dissolving.

IV. Distinguish between

Question 1. Evaporation and condensation.
Answer:
Evaporation: The process of conversion of water into its vapor state.
Condensation: The process of conversion of water vapor back into its liquid state.
In simple words: Evaporation turns liquid to gas, while condensation turns gas to liquid.

Exam Tip: Both are reverse physical processes important in the water cycle.

Question 2. Sedimentation and decantation.
Answer:
Sedimentation: The process in which heavier insoluble components in a liquid settle down at the bottom over time.
Decantation: The process of pouring out the clear upper liquid gently without disturbing the settled sediment.
In simple words: Sedimentation lets heavy particles settle down; decantation pours off the clear liquid above.

Exam Tip: Decantation always follows sedimentation for separating mixtures of solids and liquids.

Question 5. How is common salt obtained from the sea water? Explain.
Answer: Sea water is collected in shallow pools and allowed to stand. Heat from the sun evaporates the water slowly, leaving behind wet solid salt. This raw salt is further purified to obtain common table salt.
In simple words: Sunlight evaporates sea water in shallow beds, leaving salt behind.

Exam Tip: Mention the role of sunlight and evaporation clearly.

VI. Draw and label the following diagrams.

Question 1. Process of filtration using a filter paper. (Ref. Pg. # 40 fig. 5.10)
Answer:
1. Fold a filter paper into a cone shape and place it inside a funnel.
2. Mount the funnel over a beaker using a stand.
3. Pour the mixture of solid and liquid slowly into the filter paper cone.
4. The clear liquid passes through as filtrate, and insoluble solid remains as residue on the filter paper.
In simple words: A filter paper cone inside a funnel separates solid impurities from liquid.

Exam Tip: Label: Funnel, Filter paper, Residue, Filtrate, Beaker, Stand.

Question 2. Process of Evaporation. (fig. 5.11 Pg. # 40)
Answer:
1. Take a beaker containing salt water and place it on a tripod stand with a wire gauze.
2. Heat the beaker using a burner.
3. Observe water converting into vapor and escaping into the air, leaving solid salt crystals at the bottom of the container.
In simple words: Heating salt water turns liquid water into vapor, leaving salt behind.

Exam Tip: Label: Beaker, Salt water, Burner, Tripod stand, Wire gauze, Water vapor.

CHAPTER - 7 GETTING TO KNOW PLANTS

FILL IN THE BLANKS

Question 1. The innermost part of a flower is called ____________________
Answer: Pistil (or carpel)
In simple words: The pistil is the female reproductive organ situated at the center of a flower.

Exam Tip: Pistil consists of stigma, style, and ovary.

Question 2. Plants synthesis food by the process of _____________________
Answer: Photosynthesis
In simple words: Plants use sunlight, water, and carbon dioxide to make their food.

Exam Tip: Chlorophyll is essential for trapping solar energy.

Question 3. Plants with green tender stems are called ___________________
Answer: Herbs
In simple words: Herbs are small plants with soft, green stems.

Question 4. The pattern of veins on the leaf is called ___________________
Answer: Venation
In simple words: The arrangement of veins on a leaf blade.

Exam Tip: Venation can be reticulate or parallel.

Question 5. The broad green part of the leaf is called ___________________
Answer: Lamina (or leaf blade)
In simple words: The flat, expanded green surface of the leaf.

Exam Tip: Most photosynthesis occurs across the lamina.

Question 6. The part of a leaf by which it is attached to the stem is called _____________
Answer: Petiole
In simple words: The stalk connecting the leaf to the stem.

Exam Tip: Some leaves do not have a petiole and are called sessile.

NAME THE FOLLOWING

Question 1. Any two creepers.___________________ ____________________
Answer: Pumpkin, Watermelon
In simple words: Plants with weak stems that spread along the ground.

Exam Tip: Creepers cannot stand erect on their own due to weak stems.

Question 2. Two types of root systems _______________________ ____________________
Answer: Taproot system, Fibrous root system
In simple words: The two main ways roots anchor plants in soil.

Exam Tip: Taproot has a main single root; fibrous roots have thin, similar-sized roots arising in a cluster.

Question 3. Three types of plants _______________ __________________ ______________
Answer: Herbs, Shrubs, Trees
In simple words: Classification of plants based on height, stem type, and branching.

Exam Tip: Additional categories include climbers and creepers.

Question 4. Two types of venation _____________________ ______________________
Answer: Reticulate venation, Parallel venation
In simple words: Net-like and parallel line arrangements of veins on leaves.

Exam Tip: Reticulate is generally found in dicots; parallel in monocots.

TRUE OR FALSE

Question 1. Ovary is a part of stem._____________
Answer: False (Ovary is part of the flower pistil)
In simple words: The ovary is located inside the flower, not on the stem.

Exam Tip: The ovary develops into a fruit after fertilization.

Question 2. The stem helps in holding the plant firmly in the soil.___________
Answer: False (Roots hold the plant firmly in the soil)
In simple words: Roots anchor the plant, while stems hold leaves, flowers, and fruits upright.

Exam Tip: Distinguish carefully between the functions of roots and stems.

Question 3. Leaves give out water vapour through the process of transpiration._______________
Answer: True
In simple words: Plants release excess water vapor into the air through stomata in leaves.

Exam Tip: Transpiration helps in cooling the plant and pulling water upward.

Question 4. Plants with weak stem that cannot stand upright and spread on the ground are called ______________
Answer: True (Statement describes creepers)
In simple words: Creepers crawl along the ground.

Question 5. Plants can carry out photosynthesis without carbon dioxide._______________
Answer: False
In simple words: Carbon dioxide is an essential raw material required for photosynthesis.

Exam Tip: Raw materials for photosynthesis: Carbon dioxide, water, sunlight, and chlorophyll.

DISTINGUISH BETWEEN THE FOLLOWING

Question 1. Taproot system and fibrous root system
Answer:
Taproot system: Consists of one primary main root growing straight down from which smaller lateral roots branch out. Found in plants with reticulate venation.
Fibrous root system: Does not have a primary main root; instead, a cluster of similar-sized thin roots arises from the base of the stem. Found in plants with parallel venation.
In simple words: Taproot has one main long root, while fibrous roots consist of a bunch of thin, bushy roots.

Exam Tip: There is a direct correlation between leaf venation and root type.

Question 2. Reticular venation and parallel venation
Answer:
Reticular venation: Veins form a net-like web design on both sides of the midrib.
Parallel venation: Veins run parallel to each other across the lamina or from base to tip.
In simple words: Reticular venation looks like a net, while parallel venation looks like lines side by side.

Exam Tip: Give examples like rose (reticular) and grass (parallel).

Question 3. Roots and stem
Answer:
Roots: Underground parts that absorb water and minerals from soil and anchor the plant firmly.
Stem: Aerial part that bears leaves, flowers, and fruits, conducting water and food throughout the plant.
In simple words: Roots stay underground and absorb water; stems stay above ground and support branches and leaves.

Exam Tip: Roots grow downwards (geotropic) and stems grow upwards (phototropic).

Question 4. Herbs, Shrubs and Trees
Answer:
Herbs: Short plants with green, soft, tender stems and few branches.
Shrubs: Medium-sized plants with hard, woody stems branching near the base.
Trees: Tall plants with very thick, hard, woody trunks and branches high above the ground.
In simple words: Herbs are small and soft, shrubs are bushy with woody stems, and trees are tall with thick trunks.

Exam Tip: Categorize based on height, stem hardness, and branching pattern.

CHAPTER: 8 Body Movements

I) Fill in the blanks :

Question 1. The bones are moved by alternate _________________ and of __________________ of two sets of muscles.
Answer: Contraction, relaxation
In simple words: Muscles pull bones by contracting and relaxing in pairs.

Exam Tip: Muscles can only pull bones, they cannot push.

Question 2. Snails move with the help of muscular ____________________________________.
Answer: Foot
In simple words: A snail glides smoothly using wave-like movements of its muscular foot.

Exam Tip: Mention the slimy mucus secreted to reduce friction.

Question 3. Fish swim by forming ____________________________ alternately on two sides of the body.
Answer: Loops (or curves)
In simple words: A fish curves its body first to one side and then to the other to push water backward and move forward.

Exam Tip: Fins help maintain balance and change direction.

Question 4. The body and legs of cockroaches have hard coverings forming on outer __________________________________.
Answer: Exoskeleton
In simple words: The outer hard skeleton protects internal body parts.

Exam Tip: Muscles are attached to this outer skeleton.

Question 5. Snakes ___________________________ on the ground by looping sideways.
Answer: Slither (or curve)
In simple words: Snakes push against the ground with loops of their body to move forward rapidly.

Exam Tip: Snakes have a long backbone and many connected ribs and muscles.

II) Distinguish between the following :

Question 1. Ball, socket joint and Hinge joint.
Answer:
Ball and socket joint: A joint where the rounded end of one bone fits into the hollow cup-shaped socket of another, allowing movement in all directions (e.g., shoulder, hip).
Hinge joint: A joint that allows back-and-forth movement in a single plane, much like a door hinge (e.g., knee, elbow).
In simple words: Ball and socket joints rotate in all directions, while hinge joints move back and forth like a door.

Exam Tip: Always give anatomical examples for each joint type.

Question 2. Bone and Cartilage.
Answer:
Bone: Hard, rigid skeletal structure that forms the framework of the body.
Cartilage: Soother, more flexible and elastic skeletal tissue found in joints and body parts like the earlobe and nose tip.
In simple words: Bones are hard and stiff, while cartilage is soft and flexible.

Exam Tip: Cartilage reduces friction between bones at joints.

III) Define

Question 1. Skeleton
Answer: The complete framework of bones and cartilage that gives shape, support, and protection to the human body.
In simple words: The hard framework of bones inside our body.

Exam Tip: Adult human skeleton has 206 bones.

Question 2. Ribcage
Answer: A bony cage formed by the ribs, backbone, and breastbone (sternum) that protects vital internal organs like the heart and lungs.
In simple words: The protective cage of bones around the chest.

Exam Tip: There are 12 pairs of ribs in humans.

Question 3. Joint
Answer: The point of connection between two or more bones in the body that allows different types of movements.
In simple words: Places where two bones meet.

Exam Tip: Joints can be movable, slightly movable, or fixed.

IV) Answer the following questions :

Question 1. Name the different types of joints in our body.
Answer: The main movable joints in our body are:
1. Ball and socket joint
2. Hinge joint
3. Pivotal joint
4. Fixed (immovable) joints
In simple words: Ball and socket, hinge, pivot, and fixed joints.

Exam Tip: List them clearly with brief examples.

Question 2. Write the adaptation of a bird.
Answer: Adaptations of birds for flying include:
1. Streamlined body to cut through air.
2. Bones are hollow and light (pneumatic bones).
3. Forelimbs are modified into wings.
4. Powerful breast muscles to flap wings.
In simple words: Hollow bones, wings, and streamlined bodies help birds fly easily.

Exam Tip: Mention structural modifications like feathers and wings.

CHAPTER: 9 THE LIVING ORGANISMS AND THEIR SURROUNDINGS

I. Fill in the blanks:

Question 1. Fish have ____________shaped body that helps them to move inside water.
Answer: Streamlined
In simple words: A boat-like tapered body shape reduces water resistance during movement.

Exam Tip: Streamlined shape is also seen in birds and airplanes.

Question 2. Small changes that take place in the body of a living organism over a short period to overcome to some problems due to changes in the surrounding are called ________________.
Answer: Acclimatization
In simple words: Adjusting quickly to temporary environmental changes like visiting high altitudes.

Exam Tip: Distinguish acclimatization from long-term evolutionary adaptation.

Question 3. In the mountain regions, the trees are normally ______________ shaped.
Answer: Cone (pyramidal)
In simple words: Cone-shaped trees allow snow and rain to slide off easily.

Exam Tip: Conifers often have needle-like leaves.

Question 4. The process of producing more of their own kind by the living organisms is called ________________.
Answer: Reproduction
In simple words: Giving birth to young ones of one's own species.

Exam Tip: Essential life process for the continuation of life on Earth.

Question 5. Frogs have ____________feet that help them to swim in water.
Answer: Webbed
In simple words: Skin between toes acts like paddles for swimming.

Exam Tip: Frogs are amphibians living both on land and in water.

Question 6. Dolphins and whales breathe through _______________.
Answer: Blowholes
In simple words: Marine mammals come to the water surface to breathe air through blowholes.

Question 7. The process of getting rid of wastes by the living organisms is called ________________.
Answer: Excretion
In simple words: Removing metabolic waste products from the body.

Exam Tip: Plants also excrete waste in the form of gums, resins, and oxygen.

Question 8. The stems of aquatic plants are long, ______________ and _____________.
Answer: Hollow, flexible
In simple words: Hollow stems help aquatic plants float and bend with water currents.

Exam Tip: Prevents stems from breaking under water flow.

Question 9. During respiration, organisms take in _____________ and give out ___________.
Answer: Oxygen, carbon dioxide
In simple words: Breathing in oxygen helps release energy from food, producing carbon dioxide.

Exam Tip: Respiration occurs continuously day and night in all living cells.

Question 10. Exchange of gases in plants take place through the tiny pores on the leaves called ___________________.
Answer: Stomata
In simple words: Microscopic pores on leaves for breathing and transpiration.

Exam Tip: Guard cells regulate the opening and closing of stomata.

II. Write true or false:

Question 1. Several kinds of plants and animals share the same habitat:
Answer: True
In simple words: A habitat supports diverse communities of interacting plants and animals.

Exam Tip: Ecosystems consist of biotic communities sharing a common habitat.

Question 2. The light brown skin of the lion helps it to become a predator in the grassland:
Answer: True
In simple words: Light brown color camouflages the lion in dry grassland grass.

Exam Tip: Camouflage helps predators hunt unnoticed.

Question 3. Desert animals like snakes and rats come during the day:
Answer: False (They stay in burrows during the hot day and come out at night)
In simple words: Desert animals are mostly nocturnal to escape daytime heat.

Exam Tip: Being nocturnal is a key behavioral adaptation in deserts.

Question 4. The animals which cannot adapt to changing abiotic factors of a region die out and only adapted ones survive:
Answer: True
In simple words: Survival of the fittest applies to environmental adaptation.

Exam Tip: Unadapted species face extinction or migration.

Question 5. Animals living in mountain regions have thick skin or fur:
Answer: True
In simple words: Thick fur protects animals from freezing mountain cold.

Exam Tip: Examples include yaks and snow leopards.

Question 6. Plants donot show respond to stimuli:
Answer: False (Plants do respond to stimuli like light, touch, and gravity)
In simple words: Mimosa leaves fold on touching, and stems bend toward sunlight.

Exam Tip: Phototropism and thigmotropism are plant responses.

Question 7. Some plants remove some of their waste products as secretions :
Answer: True
In simple words: Plants secrete gums, resins, and latex as waste products.

Exam Tip: Many plant secretions are commercially useful.

Question 8. Camels excrete large amount of urine and their dung is wet:
Answer: False (Camels excrete very little urine and dry dung to conserve water)
In simple words: Desert animals conserve water by producing concentrated urine.

Exam Tip: Camels are exceptionally adapted for water scarcity.

Question 9. Plants carry out photosynthesis only during the daytime and respiration only at night:
Answer: False (Photosynthesis occurs in daytime, but respiration occurs day and night)
In simple words: Respiration is a 24-hour life process in plants.

Question 1. Two terrestrial habitats.
Answer: Deserts, Grasslands (or Forests, Mountains)
In simple words: Habitats located on land.

Exam Tip: Terrestrial means land-based.

Question 2. Two aquatic habitats.
Answer: Oceans, Ponds (or Lakes, Rivers)
In simple words: Water-based habitats.

Exam Tip: Aquatic habitats include both freshwater and marine ecosystems.

Question 3. Two plants and two animals of mountain regions
Answer: Plants: Pine, Fir; Animals: Yak, Snow leopard
In simple words: Cold-tolerant organisms found in high altitudes.

Exam Tip: Mention organisms adapted to cold and snowy conditions.

Question 4. Four important abiotic factors needed for growth of plants
Answer: Sunlight, Water, Soil, Temperature (or Air)
In simple words: Non-living environmental factors essential for plant life.

Exam Tip: Abiotic means non-living components of a habitat.

Question 5. Breathing organs of fish and earthworms.
Answer: Fish: Gills; Earthworms: Moist skin
In simple words: Gills extract dissolved oxygen in fish; earthworms breathe through their skin.

Exam Tip: Different organisms have specialized respiratory organs adapted to their environment.

Question 6. Any three modes of reproduction by plants.
Answer: 1. Seeds
2. Stem cuttings (Vegetative propagation)
3. Spores (or roots/leaves)
In simple words: Plants reproduce through seeds, cuttings, and spores.

Exam Tip: Includes both sexual (seeds) and asexual (vegetative/spores) reproduction.

IV. Define the following:

Question i. Adaptation
Answer: The presence of specific body features or habits which enable a plant or animal to live in a particular habitat.
In simple words: Special body features that help organisms survive in their surroundings.

Exam Tip: Adaptations develop over long periods through evolution.

Question ii. Stimuli
Answer: Changes in our surroundings that make us respond to them.
In simple words: Environmental changes that trigger a reaction.

Exam Tip: Examples include light, heat, pain, and sound.

V. Distinguish between:

Question i. Biotic and abiotic factors.
Answer:
Biotic factors: All living components of a habitat, such as plants and animals.
Abiotic factors: All non-living components of a habitat, such as rocks, soil, air, water, and sunlight.
In simple words: Biotic means living things; abiotic means non-living things.

Exam Tip: Both biotic and abiotic factors interact to form an ecosystem.

Question ii. Terrestrial organisms and aquatic organisms.
Answer:
Terrestrial organisms: Organisms that live and breed on land (e.g., humans, lions, mango trees).
Aquatic organisms: Organisms that live and breed in water bodies (e.g., fish, whales, hydrilla).
In simple words: Terrestrial organisms live on land, while aquatic organisms live in water.

Exam Tip: Give clear examples of both groups.

VI. Draw, colour and label:

Question 1) a desert plant.
Answer:
1. Draw a succulent stem modified to store water.
2. Draw spines instead of broad leaves to reduce water loss.
3. Show extensive root systems spreading deep or wide underground.
In simple words: A cactus with a fleshy stem, spines, and roots.

Exam Tip: Label: Stem, Spines, Roots, Waxy coating.

Question 2) an aquatic plant
Answer:
1. Draw a submerged or floating plant like Lotus or Hydrilla.
2. Show long, hollow, flexible stems.
3. Show broad floating leaves with waxy upper surfaces.
In simple words: Water plant with flexible hollow stems and floating leaves.

Exam Tip: Label: Hollow stem, Floating leaf, Roots, Stomata on upper surface.

VII. PROJECT:
Stick pictures of any two plants and two animals belonging to each of the following habitats:

1. Deserts:
Answer: Plants: Cactus, Date Palm; Animals: Camel, Kangaroo rat.
In simple words: Organisms adapted to hot, dry desert conditions.

Exam Tip: Keep pictures neatly labeled for project work.

2. Mountain regions:
Answer: Plants: Pine, Fir; Animals: Yak, Snow Leopard.
In simple words: Organisms adapted to cold mountain climates.

Exam Tip: Note adaptations like thick fur and cone shapes.

3. Grasslands:
Answer: Plants: Acacia, Tall grasses; Animals: Lion, Zebra.
In simple words: Organisms living in open grassy plains.

Exam Tip: Highlight predator-prey relationships in grasslands.

4. Ponds/lakes:
Answer: Plants: Lotus, Hydrilla; Animals: Fish, Frog.
In simple words: Freshwater plants and animals.

Exam Tip: Focus on aquatic adaptations.

CHAPTER 10: MOTION AND MEASUREMENT OF DISTANCES

I Mention the type of motion taking place in:

Question 1. The horse pulling a cart
Answer: Rectilinear motion (translational motion)
In simple words: The cart moves forward in a straight line.

Exam Tip: The wheels show rotational motion, while the cart as a whole shows rectilinear motion.

Question 2. Earth moving around the sun in its orbit
Answer: Circular (or periodic/revolution) motion
In simple words: The Earth travels along a curved circular path around the sun.

Exam Tip: Also an example of periodic motion because it repeats in a fixed time interval (one year).

Question 3. A child playing with a top
Answer: Rotational motion
In simple words: The top spins around its own fixed axis.

Exam Tip: Rotational motion involves spinning around a fixed central axis.

Question 4. A coin moving over a carom board
Answer: Rectilinear motion
In simple words: The striker hits the coin, making it slide in a straight line.

Question 5. A ball fixed to string
Answer: Circular motion
In simple words: Whirling a ball on a string makes it move in a circle.

Exam Tip: Distance from the center remains constant.

Question 6. Motion of a branch of a tree when it shaken heavily.
Answer: Periodic (or oscillatory / random) motion
In simple words: The branch swings back and forth repeatedly.

Exam Tip: Oscillatory motion is a type of periodic motion.

II State True (T) or False (F) against the following statements :

Question a. Handspan cannot be used to measure length all over the world.
Answer: True (Because handspan varies from person to person)
In simple words: Standard units are needed because body parts vary in size.

Exam Tip: Handspan is a non-standard unit of measurement.

Question b. Ten millimeter is equal to 1 metre.
Answer: False (\(1000 \text{ mm} = 1 \text{ m}\), whereas \(10 \text{ mm} = 1 \text{ cm}\))
In simple words: One meter has one thousand millimeters, not ten.

Exam Tip: Memorize metric conversions: \(1 \text{ m} = 100 \text{ cm} = 1000 \text{ mm}\).

Question c. Motion and rest are different terms
Answer: True
In simple words: Motion is change of position with time; rest means staying in the same position.

Exam Tip: Rest and motion are relative terms.

Question d. To measure the diameter of tree, you can use measuring tap or thread.
Answer: True
In simple words: A flexible thread or tape is used to measure curved perimeters and diameters.

Exam Tip: Useful for measuring curved or irregular boundaries.

Question e. Kilometre is the SI unit of length.
Answer: False (Metre is the SI unit of length)
In simple words: The standard International System (SI) unit of length is the meter.

Exam Tip: Kilometers are used for large distances like road lengths.

Question f. Length of curved line cannot be measured by metre scare directly.
Answer: True (A thread must be used first to measure curved lines)
In simple words: A straight ruler cannot bend along a curved line.

Exam Tip: Use a thread along the curve and then measure the thread length with a scale.

III Fill in the blanks:

Question 1. 1000 times the length of a metre is called ___________.
Answer: Kilometre
In simple words: \(1 \text{ km} = 1000 \text{ m}\).

Exam Tip: 'Kilo' means one thousand.

Question 2. The 1/1000 part of a metre is called __________.
Answer: Millimetre
In simple words: One millimeter is one-thousandth of a meter.

Exam Tip: 'Milli' means one-thousandth.

Question 3. The motion which repeats itself after a fixed interval of time is called ________________ motion.
Answer: Periodic
In simple words: Motion that repeats regularly in equal time intervals.

Exam Tip: Examples include heartbeats and pendulum swings.

Question 4. The motion described by a violin string is _____________ motion.
Answer: Oscillatory (or vibratory)
In simple words: A plucked string vibrates back and forth rapidly.

Exam Tip: Vibratory motion is a rapid form of oscillatory motion.

CHAPTER: 11 Light, Shadows and Reflections

I) Fill in the blanks :

Question 1. _____________________________ helps us to see objects.
Answer: Light
In simple words: Light reflected from objects enters our eyes, allowing us to see them.

Exam Tip: Vision is impossible in complete darkness.

Question 2. Objects that give out or emit light of their own are called ___________________.
Answer: Luminous objects
In simple words: Objects that produce their own light, like the sun or a bulb.

Question 3. ______________________objects allow light to pass through them completely.
Answer: Transparent
In simple words: Glass and clear water let light pass through without obstruction.

Exam Tip: You can see clearly through transparent objects.

Question 4. ______________________ objects do not allow the light to pass through it at all.
Answer: Opaque
In simple words: Wood, metal, and cardboard block light completely.

Exam Tip: Opaque objects form shadows.

Question 5. _______________________ objects allow the light to pass through them partially.
Answer: Translucent
In simple words: Waxed paper and frosted glass let some light pass through.

Exam Tip: Objects viewed through translucent materials appear hazy.

Question 6. Light travels in a ______________________________.
Answer: Straight line (rectilinear propagation)
In simple words: Light rays travel straight and cannot bend around corners on their own.

Exam Tip: This property explains the formation of shadows and pin-hole camera images.

Question 7. _____________________ are formed when an opaque object comes in the path of light.
Answer: Shadows
In simple words: Dark patches formed when light is blocked by an opaque object.

Exam Tip: Requirements for a shadow: source of light, opaque object, and a screen.

Question 8. ______________________ and ____________________ objects are essential for the formation of shadows on a screen.
Answer: Source of light, Opaque object (and a screen)
In simple words: Light and an opaque object are needed to cast a shadow.

Exam Tip: A screen (like a wall or ground) is needed to view the shadow.

Question 9. A shadow cast by the heavenly bodies is called an ______________________.
Answer: Eclipse (or umbra/penumbra)
In simple words: Solar and lunar eclipses are shadow formations by planets, moons, and the sun.

Exam Tip: Solar eclipse occurs when the moon comes between the sun and Earth.

Question 10. Images formed by a pin-hole camera are ___________________________
Answer: Real and inverted (upside down)
In simple words: Pin-hole cameras produce upside-down images.

Exam Tip: Inversion happens because light travels in straight lines.

Question 11. We see ________________________ of the object in the mirror.
Answer: Reflection (or image)
In simple words: Mirrors reflect light to form clear images.

Exam Tip: Mirror images are laterally inverted (left appears right).

II) Answer in one or two words :

Question 1. Give two examples of opaque objects.
Answer: Wood, Metal sheet
In simple words: Materials that block light completely.

Exam Tip: Bricks, books, and rocks are also opaque.

Question 2. Give two examples transparent objects
Answer: Glass, Clean water
In simple words: Materials that allow clear vision through them.

Exam Tip: Air is also transparent.

Question 3. Give two examples of translucent objects.
Answer: Butter paper, Frosted glass
In simple words: Materials that allow partial light transmission.

Exam Tip: Oiled paper is a classic textbook example.

Question 4. Give two examples of luminous objects
Answer: Sun, Electric bulb
In simple words: Objects that emit their own light.

Exam Tip: Fireflies (glow-worms) are natural luminous animals.

Question 5. Give two examples of non-luminous objects.
Answer: Moon, Wooden chair
In simple words: Objects that do not emit their own light.

Exam Tip: The moon shines by reflecting sunlight, making it non-luminous.

III) Choose the correct Answer :

Question 1. [Mirror/glass] helps to change the direction of light that falls on it.
Answer: (Mirror) Mirror helps to change the direction of light that falls on it.
In simple words: Reflection from a mirror changes the path of light rays.

Exam Tip: Mirrors reflect light regularly.

Question 2. Images are [ same / different] from the shadow.
Answer: (different) Images are different from the shadow.
In simple words: Images show colors and details, whereas shadows are only dark shapes without details.

Question 3. Torch bulb is [ luminous / non - luminous object]
Answer: (luminous) Torch bulb is luminous.
In simple words: A glowing bulb produces its own light.

Exam Tip: Electrical energy converts to light and heat in a bulb.

Question 4. [opaque/transparent] objects cast shadows.
Answer: (opaque) Opaque objects cast shadows.
In simple words: Shadows require light blockage, which only opaque objects do.

Exam Tip: Transparent objects do not cast noticeable shadows.

Question 5. Coloured objects form [coloured / dark] shadows.
Answer: (dark) Coloured objects form dark shadows.
In simple words: All shadows are dark because they are simply absence of light.

Exam Tip: The color of the object does not affect the color of its shadow.

IV) Answer the following questions :

Question 1. How are shadows formed ?
Answer: Shadows are formed when an opaque object blocks the path of light, preventing light rays from reaching a screen placed behind the object.
In simple words: Blocking light with an opaque object creates a dark shadow.

Exam Tip: Mention the three necessary conditions: light source, opaque object, and screen.

Question 2. What is meant by reflection of light ?
Answer: The bouncing back of light rays from a shining or polished surface (like a mirror) is called reflection of light.
In simple words: Light bouncing off a surface like a ball off a wall.

Exam Tip: Smooth surfaces give regular reflection; rough surfaces give diffuse reflection.

Question 3. Explain with the help of an activity that light travels in a straight line.
Answer: Take three cardboard sheets with a small hole in the center of each. Align them upright in a straight line on a stand, and place a burning candle on one side. Look through the hole from the other end; the flame is visible. If any cardboard is disturbed out of alignment, the flame is no longer visible, proving light travels in a straight line.
In simple words: Aligning holes in cardboards lets us see a candle flame only when straight.

Exam Tip: This property is known as rectilinear propagation of light.

V) Define :

Question 1. Opaque objects
Answer: Objects that do not allow light to pass through them at all.
In simple words: Objects you cannot see through.

Exam Tip: They cast dark shadows.

Question 2. Shadows
Answer: Dark patches formed on a screen when an opaque object blocks light.
In simple words: Dark shapes formed when light is blocked.

Exam Tip: Shadows always form on the opposite side of the light source.

Question 3. Reflection of light
Answer: The phenomenon of bouncing back of light rays from a polished or shiny surface.
In simple words: Light bouncing off a mirror or shiny object.

Exam Tip: Enables us to see non-luminous objects.

VI) Distinguish between

Question 1. Transparent and translucent objects
Answer:
Transparent objects: Allow light to pass through them completely, allowing clear vision through them.
Translucent objects: Allow light to pass through them partially, resulting in hazy or blurred vision.
In simple words: Transparent lets you see clearly; translucent gives a hazy view.

Exam Tip: Give examples like clear glass (transparent) and oiled paper (translucent).

Question 2. Luminous and non luminous objects.
Answer:
Luminous objects: Objects that emit their own light (e.g., sun, stars, torch bulb).
Non-luminous objects: Objects that do not emit their own light, but shine by reflecting light from other sources (e.g., moon, book, chair).
In simple words: Luminous make their own light; non-luminous do not.

Exam Tip: Most objects in our surroundings are non-luminous.

CHAPTER 12: ELECTRICITY AND CIRCUITS

I. Fill in the blanks:

Question 1. An electric ______________ is a continuous path along which the current flows.
Answer: Circuit
In simple words: A complete pathway for electricity to flow.

Exam Tip: If the circuit breaks anywhere, current stops flowing.

Question 2. A circuit in which electricity does not flow is called an ______________ circuit.
Answer: Open (or incomplete)
In simple words: A broken pathway where electricity cannot pass.

Exam Tip: In an open circuit, bulbs do not glow.

Question 3. The source of electricity in an electric cell are the ______________ stored in it.
Answer: Chemicals
In simple words: Chemical energy inside a cell converts into electrical energy.

Question 4. Rubber is a good example of electric ______________.
Answer: Insulator
In simple words: Materials that do not allow electric current to pass through them.

Exam Tip: Insulators protect us from electric shocks.

Question 5. A device that is used to break of complete an electric circuit is called ______________.
Answer: Switch
In simple words: A switch turns appliances on or off by breaking or completing the circuit.

Exam Tip: A switch introduces an air gap when turned OFF.

Question 6. An electric cell has ______________ terminals.
Answer: Two (positive and negative)
In simple words: Every cell has a positive (+) and a negative (-) terminal.

Exam Tip: The metal cap is positive; the metal disc is negative.

Question 7. If the filament of a bulb breaks, it is said to be ______________.
Answer: Fused
In simple words: A broken filament stops electricity flow, so the bulb stops glowing.

Exam Tip: Fused bulbs have broken inner wire loops.

Question 8. An electric current is ______________ when no current flows through it.
Answer: Interrupted (or incomplete / zero)
In simple words: No electricity flows in an open or broken circuit.

Exam Tip: Circuit continuity is mandatory for current flow.

Question 9. Electric current flows from ______________ terminal to ____________ terminal of cell in the circuit.
Answer: Positive (+), negative (-)
In simple words: Conventional current flows from the positive terminal to the negative terminal.

Question 1. The source of electricity _____________________
Answer: Electric cell (or battery / generator)
In simple words: Devices that supply electrical energy.

Exam Tip: Cells convert chemical energy to electrical energy.

Question 2. Thin wire in a bulb which gives out light ____________________
Answer: Filament
In simple words: The coiled tungsten wire inside a bulb that glows when heated by electric current.

Exam Tip: Made of tungsten due to its very high melting point.

Question 3. The arrangement of providing a complete path for electricity to pass between two terminals of the electric cell ____________________
Answer: Electric circuit
In simple words: A closed pathway for current.

Exam Tip: Must connect both cell terminals without breaks.

Question 4. some times electric bulb does not glow even when electric switch is 'ON' then we say that bulb is ____________________
Answer: Fused
In simple words: A broken filament means the bulb is fused.

Exam Tip: Check if the filament is broken inside the glass.

Question 5. An electric appliance which makes or breaks an electric circuit ____________________
Answer: Switch
In simple words: A control device for opening and closing circuits.

Question a. Electric current can flow through metals.
Answer: True
In simple words: Metals are good conductors of electricity.

Exam Tip: Copper, aluminum, and iron conduct electricity well.

Question b. Instead of metal wires, a jute string can be used to make a circuit.
Answer: False (Jute is an insulator and cannot conduct electricity)
In simple words: Non-metals like jute do not conduct electricity.

Exam Tip: Only conductors can be used as connecting wires.

Question c. Electric current can pass through a sheet of thermocol.
Answer: False (Thermocol is an insulator)
In simple words: Thermocol blocks current flow.

Exam Tip: Insulators stop current transmission.

Question d. When current flows through a circuit, the circuit is called open circuit.
Answer: False (It is called a closed circuit)
In simple words: Current flows only in a closed circuit.

Exam Tip: Open circuits have zero current flow.

Question e. Electric current can easily flow through Copper.
Answer: True
In simple words: Copper is an excellent conductor of electricity.

Exam Tip: Widely used in electrical wiring.

Question f. When an electric circuit is closed, the electric current stops flowing through it.
Answer: False (Current flows continuously when a circuit is closed)
In simple words: A closed circuit allows current to flow.

Question 1. Choose a good conductor from the following materials.
a) Pencil lead
b) Thermocol
c) Wooden block
Answer: (a) Pencil lead
In simple words: Graphite in pencil lead conducts electricity.

Exam Tip: Graphite is a form of carbon that conducts electricity.

Question 2. Which of the following is not a good conductor of electricity.
a) Mercury
b) Copper
c) Plastic
d) Aluminum foil
Answer: (c) Plastic
In simple words: Plastic is an insulator, not a conductor.

Exam Tip: Plastics are used to insulate electrical wires and tools.

Question 3. Switch is 'OFF' when
a) circuit is complete
b) Circuit is not complete
c) Current is flowing in the circuit
d) Cell is fully charged
Answer: (b) Circuit is not complete
In simple words: An OFF switch breaks the circuit, stopping current flow.

Exam Tip: An open switch creates a gap in the circuit.

CHAPTER. 13 : FUN WITH MAGNETS

I. Fill in the blanks :

Question 1. A freely suspended _______________ always points in the north-south direction.
Answer: Bar magnet
In simple words: Freely suspended magnets align along Earth's magnetic north-south poles.

Exam Tip: This property is used in magnetic compasses.

Question 2. Similar poles of two magnets always ______________ each other.
Answer: Repel
In simple words: North-North or South-South poles push away from each other.

Exam Tip: Opposite poles attract; like poles repel.

Question 3. Bar magnet is an example of ______________ magnet.
Answer: Artificial (man-made)
In simple words: Magnets made by humans in laboratories or factories.

Exam Tip: Lodestone is an example of a natural magnet.

Question 4. A magnetic ______________ is used for finding geographic direction.
Answer: Compass
In simple words: A navigational tool with a magnetized needle pointing north-south.

Question 1. Bar magnet is more powerful than natural magnet.
Answer: True
In simple words: Artificial magnets are manufactured to be much stronger than natural stones.

Exam Tip: Alnico and neodymium are powerful artificial alloys.

Question 2. Magnetic poles always exist in pairs.
Answer: True
In simple words: North and south poles cannot be separated by breaking a magnet.

Exam Tip: Cutting a magnet creates two smaller complete magnets, each with two poles.

Question 3. Magnetic attraction is maximum in the middle of a bar magnet.
Answer: False (Attraction is maximum at the poles, near the ends)
In simple words: Magnetic strength is strongest at the two ends (poles).

Exam Tip: Iron filings cling mostly to the poles of a bar magnet.

Question 4. Magnetic Compass is used for finding magnetic directions.
Answer: True
In simple words: A compass needle aligns with Earth's magnetic field to show directions.

Exam Tip: The red-painted needle usually points toward the geographic north.

Question 5. Small pieces of wood are attracted by a strong magnet.
Answer: False (Wood is non-magnetic)
In simple words: Magnets only attract magnetic materials like iron, nickel, and cobalt.

Exam Tip: Wood, plastic, and paper are non-magnetic substances.

Question 6. A magnet can separate iron nails from a mixture of iron filings and iron nails.
Answer: False (Both iron nails and iron filings are magnetic and will both be attracted)
In simple words: A magnet attracts all iron objects, so it cannot separate one iron object from another.

Question 1. Classification of materials
Answer:
Magnetic materials: A shaving blade, steel cupboard, blade of knife, iron nail, sewing needle, paper clip, safety pin, iron spoon (steel/iron spoon).
Non-magnetic materials: A plastic ruler, brass button, piece of chalk, plastic mug, water, wooden stick, copper wire, eraser, cork, rubber band, tooth brush.
In simple words: Magnetic materials are attracted to magnets; non-magnetic materials are not.

Exam Tip: Metals like iron, steel, nickel, and cobalt are magnetic; most other substances are non-magnetic.

CHAPTER-15 AIR AROUND US

I. Fill in the blanks :

Question 1. Air is really not one substance but a __________________.
Answer: Mixture (of gases)
In simple words: Air is a mixture containing nitrogen, oxygen, argon, carbon dioxide, and water vapor.

Exam Tip: Air is a mixture, not a chemical compound.

Question 2. The component of air that supports burning is called ________________.
Answer: Oxygen
In simple words: Oxygen is essential for combustion and respiration.

Question 3. The aquatic animals use dissolved Oxygen in water for respiration, this is possible because Oxygen ________________ in water.
Answer: Dissolves
In simple words: Oxygen dissolves in water, allowing fish to breathe it.

Exam Tip: Aquatic life depends on dissolved oxygen.

Question 4. Nitrogen of the air is used on a large scale to manufacture ________________.
Answer: Fertilizers
In simple words: Nitrogen is used in industries to make plant fertilizers like urea and ammonia.

Exam Tip: Nitrogen makes up about 78 percent of the atmosphere.

Question 5. ________________ is the place in nature for gaseous exchange.
Answer: Atmosphere (or lungs / stomata)
In simple words: The atmosphere is the reservoir where living beings exchange oxygen and carbon dioxide.

Exam Tip: Plants and animals maintain the balance of oxygen and carbon dioxide in the air.

II. True or False statements :

Question 1. Air is a compound but not an element.
Answer: False (Air is a mixture of various gases, not a compound)
In simple words: Air is a physical mixture, not a chemical compound.

Exam Tip: Components of air retain their individual chemical properties.

Question 2. Air is an opaque material.
Answer: False (Air is transparent)
In simple words: We can see through air because it is transparent.

Exam Tip: Clean air has no color or odor.

Question 3. Air contains water vapour.
Answer: True
In simple words: Moisture is always present in the atmosphere as water vapor.

Exam Tip: Humidity levels vary depending on weather and location.

Question 4. The major part of air is Nitrogen.
Answer: True (About 78 percent)
In simple words: Nitrogen is the most abundant gas in our atmosphere.

Exam Tip: Oxygen is about 21 percent.

Question 5. Plants produce Oxygen through photosynthesis.
Answer: True
In simple words: Green plants release oxygen into the air during food production.

Exam Tip: Photosynthesis helps replenish atmospheric oxygen.

CHAPTER-16 GARBAGE IN, GARBAGE OUT

I. Fill in the blanks :

Question 1. Method of making compost using _____________ is called vermin composting
Answer: Redworms (earthworms)
In simple words: Redworms decompose organic kitchen waste into rich manure.

Exam Tip: Redworms cannot survive in very hot or very salty conditions.

Question 2. Converting plant and animals wastes into manure is called ____________.
Answer: Composting
In simple words: Natural breakdown of organic waste into nutrient-rich soil fertilizer.

Exam Tip: Helps reduce landfill waste.

Question 3. ____________ is an area where the garbage is collected.
Answer: Landfill
In simple words: A low-lying open area where municipal solid waste is dumped and covered with soil.

Exam Tip: Landfills help manage city garbage hygienically.

Question 4. We need to generate ____________ waste.
Answer: Less (minimal)
In simple words: Producing less waste protects our environment and conserves resources.

Exam Tip: Follow the 3 Rs: Reduce, Reuse, Recycle.

II. True or False Sentences :

Question 1. Paper can be recycled to get useful products.
Answer: True
In simple words: Old paper can be pulped and recycled into new paper products.

Exam Tip: Recycling paper saves trees and water.

Question 2. Drains get choked due to plastic thrown by us.
Answer: True
In simple words: Non-biodegradable plastics block drainage pipes and water flow.

Question 3. Plastics are eco-friendly.
Answer: False (Plastics are non-biodegradable and harm the environment)
In simple words: Plastics do not rot or decay easily, causing pollution.

Exam Tip: Avoid single-use plastics.

Question 4. Redworms eat up on green leaves on trees and make compost.
Answer: False (Redworms eat rotting organic waste, not living leaves on trees)
In simple words: Redworms decompose dead and decaying organic matter in soil.

Exam Tip: Redworms lack teeth and need soft, decomposed organic matter.

Question 5. Plastics give out harmful gases up on heating or burning.
Answer: True
In simple words: Burning plastics releases toxic fumes that pollute the air and cause health issues.

Exam Tip: Plastics should never be burned in open fires.