CBSE Class 6 Science All Chapters Worksheet Set 01

CHAPTER - 6 CHANGES AROUND US

I. FILL IN THE BLANKS

Question 1. The changes that can be reversed are called ________ changes.
Answer: reversible
In simple words: Changes that can be brought back to their original state are reversible changes.

Exam Tip: Remember that melting and freezing are classic examples of reversible changes.

Question 2. The changes that cannot be reversed are called ________ changes.
Answer: irreversible
In simple words: Changes that form completely new substances and cannot be undone are irreversible.

Exam Tip: Cooking and burning are always irreversible changes.

Question 3. On heating, the metals ________.
Answer: expand
In simple words: Heating causes solid objects like metals to increase in size or volume.

Exam Tip: Thermal expansion is the scientific term for this phenomenon.

Question 4. On cooling, the metals ________.
Answer: contract
In simple words: Cooling causes metals to decrease in size or volume.

Exam Tip: Contraction is the opposite of expansion.

Question 5. Burning of incense stick is an ________ change.
Answer: irreversible
In simple words: Once an incense stick is burnt, we cannot get back the original stick from its ash and smoke.

Exam Tip: Combustion reactions are permanent and irreversible.

Question 6. On heating metal rim ________ and fits into the wooden wheel.
Answer: expands
In simple words: The metal rim expands on heating, making it slightly larger so it can slip easily over the wooden wheel.

Question 7. Reversible changes are ________ in nature.
Answer: temporary
In simple words: Reversible changes do not last permanently and can be reversed.

Exam Tip: Contrast this with irreversible changes which are permanent.

II. CHOOSE THE CORRECT ANSWER

Question 1. Ripening of fruit is a ( reversible / irreversible ) change.
Answer: (irreversible) Ripening of fruit is an irreversible change.
Once a fruit ripens, it cannot be turned back into a raw fruit.
In simple words: Ripe fruit cannot become raw again.

Exam Tip: Growth and biological aging processes are always irreversible.

Question 2. In ( reversible / irreversible ) change we cannot get back the original components.
Answer: (irreversible) In irreversible change we cannot get back the original components.
New substances with different properties are formed permanently.
In simple words: Irreversible changes destroy the original materials permanently.

Exam Tip: Look for keywords like "cannot get back" to identify irreversible changes.

Question 3. Melting of ice is a ( reversible / irreversible ) change.
Answer: (reversible) Melting of ice is a reversible change.
Water obtained from melted ice can be frozen back into ice.
In simple words: Ice melts to water and water freezes back to ice.

Exam Tip: State changes of water are standard examples of physical reversible changes.

III. WRITE TRUE OR FALSE

Question 1. Growing of trees is an irreversible change.
Answer: True
In simple words: A grown tree cannot shrink back into a tiny seed.

Exam Tip: Biological growth is always irreversible.

Question 2. Formation of curd from milk is a reversible change.
Answer: False
In simple words: Once curd is formed from milk, we cannot get the milk back from curd.

Exam Tip: Chemical changes involving new taste and properties are irreversible.

IV. NAME THE FOLLOWING

Question 1. Name any two reversible changes.
Answer: Melting of ice and folding of paper.
In simple words: Changes that can be undone easily.

Exam Tip: State physical changes as examples.

Question 2. Name any two irreversible changes.
Answer: Burning of paper and cooking of food.
In simple words: Permanent changes that form new substances.

Exam Tip: Mention chemical or permanent physical transformations.

Question 3. Two methods to make a change happen.
Answer: Heating and applying force (or mixing substances).
In simple words: Energy or action is required to bring about a change.

Exam Tip: Temperature and pressure are common agents of change.

V. DISTINGUISH BETWEEN: Reversible and Irreversible changes

Question 1. Distinguish between Reversible and Irreversible changes.
Answer:

In simple words: Reversible can go back; irreversible cannot.

Exam Tip: Always present differences in tabular form for full marks.

VI. CLASSIFY THE FOLLOWING CHANGES INTO REVERSIBLE AND IRREVERSIBLE CHANGES

Question 1. Crumpling of paper, Burning of paper, Sawing of wood, Cooking of food, Change of water into water vapour, Ironing of clothes, Rusting of iron nails, Bud to flower.
Answer:
- Reversible changes: Crumpling of paper, Change of water into water vapour, Ironing of clothes.
- Irreversible changes: Burning of paper, Sawing of wood, Cooking of food, Rusting of iron nails, Bud to flower.
In simple words: Grouping changes based on whether they can be undone.

Exam Tip: Read each item carefully to check if the original material can be recovered.

CHAPTER - 7 GETTING TO KNOW PLANTS

I. FILL IN THE BLANKS

Question 1. The innermost part of a flower is called ________.
Answer: pistil
In simple words: The pistil is the female reproductive part located at the center of the flower.

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

Question 2. Plants synthesis food by the process of ________.
Answer: photosynthesis
In simple words: Green leaves make food using sunlight, water, and carbon dioxide.

Exam Tip: Chlorophyll is essential for this process.

Question 3. Plants with green tender stems are called ________.
Answer: herbs
In simple words: Herbs are small plants with delicate green stems.

Exam Tip: Coriander and grass are typical herbs.

Question 4. The pattern of veins on the leaf is called ________.
Answer: venation
In simple words: The arrangement of veins provides design and support to the 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: Lamina is the flat surface of the leaf where photosynthesis occurs.

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

Exam Tip: Not all leaves have a petiole; sessile leaves lack it.

Question 7. Plants with weak stem that cannot stand upright and spread on the ground are called ________.
Answer: creepers
In simple words: Creepers spread horizontally along the ground.

Exam Tip: Watermelon and pumpkin plants are common examples.

Question 8. Maize plant has ________ type of root.
Answer: fibrous
In simple words: Maize has a bunch of thin, fiber-like roots originating from the base of the stem.

Exam Tip: Monocots like wheat, maize, and grass have fibrous roots.

Question 9. ________ is the stored form of food in the plants.
Answer: Starch
In simple words: Plants store extra food in the form of starch.

Exam Tip: Iodine test is used to detect starch in leaves.

Question 10. ________ is the chemical used to indicate the presence of starch in the green leaves.
Answer: Iodine solution
In simple words: Iodine turns blue-black when it reacts with starch.

Exam Tip: Remember the color change: yellowish-brown to blue-black.

II. NAME THE FOLLOWING

Question 1. Any two creepers.
Answer: Watermelon and pumpkin.
In simple words: Plants crawling on the ground.

Exam Tip: Keep examples simple and familiar.

Question 2. Two types of root systems.
Answer: Taproot system and fibrous root system.
In simple words: The two main ways roots are structured in plants.

Exam Tip: Taproots have one main heavy root; fibrous roots have many equal-sized roots.

Question 3. The five types of plants.
Answer: Herbs, shrubs, trees, creepers, and climbers.
In simple words: Classification of plants based on size and habit.

Exam Tip: List all five categories accurately.

Question 4. Two types of venation.
Answer: Reticulate venation and parallel venation.
In simple words: Net-like and line-like vein patterns on leaves.

Exam Tip: Reticulate is found in dicots, parallel in monocots.

Question 5. Any two climbers.
Answer: Money plant and pea plant.
In simple words: Plants that take support of structures to climb up.

Exam Tip: Climbers use special organs like tendrils.

Question 6. Any two shrubs.
Answer: Rose and lemon.
In simple words: Medium-sized bushy plants with hard stems.

Exam Tip: Shrubs branch out near the base.

Question 7. Any two edible taproots.
Answer: Carrot and radish.
In simple words: Roots we eat as vegetables.

Exam Tip: Beetroot and turnip are also edible taproots.

III. WRITE TRUE OR FALSE

Question 1. Ovary is a part of stem.
Answer: False
In simple words: Ovary is the lower swollen part of the pistil in a flower.

Exam Tip: Ovary belongs to the flower, not the stem.

Question 2. The stem help in holding the plant firmly in the soil.
Answer: False
In simple words: Roots hold the plant firmly in the soil, not the stem.

Exam Tip: Stems conduct water and minerals upward, while roots anchor the plant.

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

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

Question 4. Weeds are unwanted plants.
Answer: True
In simple words: Unwanted plants growing alongside crops are called weeds.

Exam Tip: Weeds compete with crops for nutrients and water.

Question 5. Plants can carry out photosynthesis without carbon dioxide.
Answer: False
In simple words: Carbon dioxide is one of the essential raw materials for photosynthesis.

Exam Tip: Water, carbon dioxide, sunlight, and chlorophyll are all required.

Question 6. Chrysanthemum and sunflower are single flowers.
Answer: False
In simple words: Sunflowers and chrysanthemums are actually inflorescences made of many tiny flowers grouped together.

Question 7. Lemon plant is a herb.
Answer: False
In simple words: Lemon is a medium-sized bushy plant classified as a shrub.

Exam Tip: Lemon stems branch near the base, characteristic of shrubs.

IV. DEFINE THE FOLLOWING

Question 1. Herb
Answer: Plants with green, tender stems and short height, which usually do not have many branches, are called herbs.
In simple words: Small, delicate green plants.

Exam Tip: Mention green tender stem in your definition.

Question 2. Shrub
Answer: Medium-sized plants with hard stems that branch out near the base are called shrubs.
In simple words: Bushy plants with hard stems.

Exam Tip: Branching near the base distinguishes shrubs from trees.

Question 3. Tree
Answer: Very tall and large plants with a hard, thick brown stem called trunk and branches in the upper part are called trees.
In simple words: Large woody plants with a trunk.

Exam Tip: Mention the term 'trunk' in your answer.

Question 4. Creeper
Answer: Plants with weak stems that cannot stand upright and spread on the ground are called creepers.
In simple words: Plants that creep along the ground.

Question 5. Climber
Answer: Plants with weak stems that take support of neighboring structures or trees to climb up are called climbers.
In simple words: Plants that climb using support.

Exam Tip: Give examples like money plant or pea plant.

Question 6. Venation
Answer: The arrangement of veins on the lamina of a leaf is called venation.
In simple words: The design formed by veins on a leaf.

Exam Tip: State the two types (reticulate and parallel).

Question 7. Photosynthesis
Answer: The process by which green leaves prepare their food using water and carbon dioxide in the presence of sunlight and chlorophyll is called photosynthesis.
In simple words: Food-making process in plants using sunlight.

Exam Tip: Mention all four requirements: water, carbon dioxide, sunlight, chlorophyll.

Question 8. Transpiration
Answer: The process of loss of water in the form of water vapour from the stomata of leaves is called transpiration.
In simple words: Release of water vapor by plant leaves.

Exam Tip: Stomata are tiny pores responsible for this process.

V. DISTINGUISH BETWEEN THE FOLLOWING

Question 1. Taproot system and fibrous root system
Answer:

In simple words: Taproot has one main root; fibrous has a bunch of similar roots.

Exam Tip: Link taproot with dicots and fibrous with monocots for extra credit.

Question 2. Reticular venation and parallel venation
Answer:

In simple words: Reticulate is net-like; parallel runs in straight lines.

Exam Tip: Draw miniature diagrams to support your comparison table.

Question 3. Roots and stem
Answer:

In simple words: Roots stay underground; stem stays above ground and holds branches.

Exam Tip: Mention location (underground vs above ground) in the first point.

Question 4. Herbs, Shrubs and Trees
Answer:

In simple words: Herbs are small and green; shrubs are bushy; trees are tall and woody.

Exam Tip: Focus on stem type and height as the main criteria.

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 alternately contracting and relaxing.

Exam Tip: Muscles work in pairs to pull bones.

Question 2. Snails move with the help of a ________.
Answer: muscular foot
In simple words: Snails glide smoothly using their muscular foot.

Exam Tip: Mention muscular foot for exact credit.

Question 3. Fish swim by forming ________ alternately on two sides of the body.
Answer: loops (or curves)
In simple words: Fishes make rapid curves from side to side to push water and swim.

Question 4. Cockroaches have ________ pairs of legs and ________ pairs of wings to fly and walk.
Answer: three, two
In simple words: Cockroaches have 3 pairs of walking legs and 2 pairs of wings.

Exam Tip: Remember numbers: 3 pairs of legs, 2 pairs of wings.

Question 5. Snakes ________ on the ground by looping sideways.
Answer: slither
In simple words: Snakes push against the ground with loops of their body to move forward.

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

Question 6. Fish have ________ shaped body.
Answer: streamlined
In simple words: Streamlined bodies reduce resistance against water.

Exam Tip: Aeroplanes and boats also have streamlined shapes.

Question 7. The ________ in the earthworm's body helps it to get good grip on the ground.
Answer: bristles (setae)
In simple words: Tiny hair-like bristles help earthworms anchor to the soil.

Exam Tip: Earthworms extend and contract muscles alternately to move.

II. DISTINGUISH BETWEEN THE FOLLOWING

Question 1. Ball and socket joint / Hinge joint
Answer:

In simple words: Ball and socket moves everywhere; hinge moves like a door hinge.

Exam Tip: Always include examples in distinguish questions.

Question 2. Bones / Cartilages
Answer:

In simple words: Bones are hard; cartilages are flexible like the earlobe.

Exam Tip: Mention ear or nose tip as examples of cartilage.

III. DEFINE

Question 1. Skeleton
Answer: The framework of all the bones in the human body that gives shape and support is called the skeleton.
In simple words: The bony framework of our body.

Exam Tip: Adult human skeleton has 206 bones.

Question 2. Ribcage
Answer: The cone-shaped bony cage formed by the ribs, backbone, and breastbone that protects delicate organs like the heart and lungs is called the ribcage.
In simple words: Protective chest cage made of ribs.

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

Question 3. Joint
Answer: The points where two or more bones meet in the body are called joints.
In simple words: Places where bones join together.

Exam Tip: Joints allow various types of body movements.

IV. WRITE TRUE OR FALSE

Question 1. Ball and socket joint is found in the elbow.
Answer: False
In simple words: Elbow has a hinge joint, not a ball and socket joint.

Exam Tip: Shoulder has ball and socket; elbow has a hinge.

Question 2. The brain is enclosed within the skull bones.
Answer: True
In simple words: Skull protects our brain from injuries.

Exam Tip: Skull bones are fused and rigid.

Question 3. Cartilages are found in the bone joints.
Answer: True
In simple words: Cartilage cushions the ends of bones at joints.

Exam Tip: It prevents wear and tear of bones during movement.

Question 4. Lower jaw has fixed joints.
Answer: False
In simple words: Lower jaw is movable to help us talk and eat.

Exam Tip: Upper jaw has fixed joints, while the lower jaw is movable.

V. NAME THE FOLLOWING

Question 1. The joint found in the wrist:
Answer: Gliding joint
In simple words: Wrist bones slide past each other.

Exam Tip: Gliding joints allow bones to slide over one another.

Question 2. The medical device which show the shapes of the bones in our bodies:
Answer: X-ray machine
In simple words: X-rays photograph bones inside our body.

Exam Tip: Used to detect fractures.

Question 3. The delicate organs protected inside the ribcage:
Answer: Heart and lungs
In simple words: Vital organs housed securely inside the chest cavity.

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

Exam Tip: List them clearly with bullet points.

Question 2. State the functions of the skeleton in human body.
Answer: Functions of skeleton: (1) It gives shape and support to the body, (2) It protects delicate internal organs, and (3) It helps in body movements along with muscles.
In simple words: Provides shape, protection, and support for movement.

Exam Tip: Mention protection and support as key points.

Question 3. Write the adaptations of a bird.
Answer: Adaptations of birds: (1) Their bones are hollow and light (pneumatic bones), (2) Forelimbs are modified into wings for flying, (3) Their body is streamlined, and (4) Powerful chest muscles help flap wings.
In simple words: Light hollow bones and wings help birds fly easily.

Exam Tip: Hollow bones reduce body weight for flight.

CHAPTER - 9 THE LIVING ORGANISMS AND THEIR SURROUNDINGS

I. FILL IN THE BLANKS

Question 1. Fish have ________ shaped body that help them to move inside water.
Answer: streamlined
In simple words: Streamlining cuts through water smoothly.

Exam Tip: Essential aquatic adaptation.

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: acclimatisation
In simple words: Adjusting to temporary changes in weather or altitude.

Exam Tip: Contrast with long-term adaptation.

Question 3. In the mountain regions, the trees are normally ________ shaped.
Answer: cone (pyramidal)
In simple words: Conical shape helps snow slide off easily.

Exam Tip: Pine and fir trees are cone-shaped.

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 their own species.

Exam Tip: Essential characteristic of all living beings.

Question 5. Frogs have ________ feet that help them to swim in water.
Answer: webbed
In simple words: Webbed feet act like paddles in water.

Exam Tip: Frogs live both on land and in water (amphibians).

Question 6. Dolphins and whales breathe through ________.
Answer: blowholes
In simple words: Whales come to the water surface to breathe air through blowholes.

Exam Tip: They are mammals, not fish.

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

Exam Tip: Common life process in plants and animals.

Question 8. The stems of aquatic plants are long, ________ and ________.
Answer: hollow, light
In simple words: Hollow stems help aquatic plants float easily on water.

Exam Tip: Lotus and water lily have hollow stems.

Question 9. During respiration, organisms take in ________ and give out ________.
Answer: oxygen, carbon dioxide
In simple words: Breathing involves taking in oxygen and releasing carbon dioxide.

Exam Tip: Cellular respiration releases energy from food.

Question 10. Exchange of gases in plants take place through the tiny pores on the leaves called ________.
Answer: stomata
In simple words: Stomata are tiny openings for gas exchange.

Exam Tip: Located mostly on the underside of leaves.

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 many different species of plants and animals.

Exam Tip: Biodiversity exists within every habitat.

Question 2. The light brown skin of the lion helps it to become a predator in the grassland:
Answer: True
In simple words: Lion's color matches dry grassland grass, helping it hide while hunting.

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

Exam Tip: This avoids extreme daytime heat 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: Nature selects only those organisms that can adapt (survival of the fittest).

Exam Tip: Adaptation is crucial for survival.

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

Exam Tip: Fur traps body heat in cold climates.

Question 6. Plants do not show response to stimuli:
Answer: False
In simple words: Plants do respond to stimuli, e.g., Mimosa (touch-me-not) folds leaves when touched.

Exam Tip: Sunflower turning towards the sun is another example.

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.

Exam Tip: Plant excretion is different from animal excretion.

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

Exam Tip: Desert animals are adapted to conserve water.

Question 9. Plants carry out photosynthesis only during the daytime and respiration only at night:
Answer: False
In simple words: Plants respire 24 hours a day, but photosynthesize only in sunlight.

Exam Tip: Respiration is a continuous life process.

III. NAME THE FOLLOWING

Question 1. Two terrestrial habitats.
Answer: Deserts and grasslands.
In simple words: Habitats on land.

Exam Tip: Forests and mountains are also terrestrial.

Question 2. Two aquatic habitats.
Answer: Ponds and oceans.
In simple words: Water-based habitats.

Exam Tip: Rivers and lakes are freshwater aquatic habitats.

Question 3. Two plants and two animals of mountain regions.
Answer: Plants: Pine and fir; Animals: Snow leopard and yak.
In simple words: Cold climate flora and fauna.

Exam Tip: Mention both plants and animals clearly.

Question 4. Four important abiotic factors needed for growth of plants.
Answer: Sunlight, water, temperature, and soil.
In simple words: Non-living factors essential for plant growth.

Exam Tip: Abiotic means non-living components.

Question 5. Breathing organs of fish and earthworms.
Answer: Fish: Gills; Earthworms: Moist skin.
In simple words: How fish and earthworms take in oxygen.

Exam Tip: Gills for aquatic animals; skin for earthworms.

Question 6. Any three modes of reproduction by plants.
Answer: Seeds, stem cuttings, and roots (vegetative propagation).
In simple words: Ways plants produce new plants.

Exam Tip: Seeds are the most common mode.

IV. DEFINE THE FOLLOWING

Question 1. Adaptation
Answer: The presence of specific features or certain habits which enable a plant or animal to live in its surroundings is called adaptation.
In simple words: Special features that help plants and animals survive in their habitat.

Exam Tip: Adaptations develop over long periods.

Question 2. Stimuli
Answer: Changes in our surroundings that make us respond to them are called stimuli.
In simple words: Changes in environment that trigger a reaction.

Exam Tip: Plural of stimulus is stimuli.

V. DISTINGUISH BETWEEN

Question 1. Biotic and abiotic factors.
Answer:

In simple words: Biotic means living; abiotic means non-living.

Exam Tip: Bio means life, 'a' means without life.

Question 2. Terrestrial organisms and aquatic organisms.
Answer:

In simple words: Land animals vs water animals.

Exam Tip: Give examples for each category.

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 (straight line motion)
In simple words: Moving forward in a straight line.

Exam Tip: Motion along a straight path is rectilinear.

Question 2. Earth moving around the sun in its orbit
Answer: Circular motion (or periodic motion)
In simple words: Moving in a circular path around the sun.

Exam Tip: Periodic because it repeats in fixed time intervals.

Question 3. A child playing with a top
Answer: Rotational motion
In simple words: Spinning around a fixed axis.

Exam Tip: Tops rotate about their central axis.

Question 4. A coin moving over a carom board
Answer: Rectilinear motion
In simple words: Moving straight when struck.

Exam Tip: Striker and coins move in straight lines.

Question 5. A ball fixed to string
Answer: Circular motion
In simple words: Whirling a ball in a circle using a string.

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) motion
In simple words: Back and forth movement.

Exam Tip: Vibrations and oscillations are repetitive.

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
In simple words: Handspan varies from person to person, so it is not a standard unit.

Exam Tip: Standard units are needed for uniform measurement worldwide.

Question b. Ten millimeter is equal to 1 metre.
Answer: False
In simple words: 1000 millimetres make 1 metre (10 mm = 1 cm).

Exam Tip: Remember conversions: 1 m = 100 cm = 1000 mm.

Question c. Motion and rest are different terms of state of motion.
Answer: True
In simple words: An object can be at rest or in motion relative to its surroundings.

Exam Tip: Motion and rest are relative states.

Question d. To measure the diameter of tree, you can use measuring tape or thread.
Answer: True
In simple words: Curved or circular objects like tree trunks are measured using a thread and scale.

Exam Tip: Flexible measuring tools are best for curved surfaces.

Question e. Foot is the SI unit of length.
Answer: False
In simple words: Metre is the standard SI unit of length.

Exam Tip: SI stands for International System of Units.

Question f. Length of curved line cannot be measured by metre scale directly.
Answer: True
In simple words: Metre scale is straight, so we use a thread first to measure curves.

Exam Tip: Thread method is standard for measuring curved lines.

III. FILL IN THE BLANKS

Question 1. 1000 times the length of a metre is called ________.
Answer: kilometre
In simple words: 1 kilometre = 1000 metres.

Exam Tip: Used for measuring long distances.

Question 2. The 1/1000 part of a metre is called ________.
Answer: millimetre
In simple words: 1 metre = 1000 millimetres.

Exam Tip: Used for very small measurements.

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: Example: pendulum of a clock.

Question 4. The motion exhibited by a violin string is ________ motion.
Answer: oscillatory (or periodic)
In simple words: Vibrating strings move back and forth.

Exam Tip: Oscillation is a type of periodic motion.

Question 5. ________ is the SI unit of length.
Answer: Metre
In simple words: Standard unit for measuring length worldwide.

Exam Tip: Symbol for metre is m.

Question 6. ________ was the unit of length developed in ancient Egypt to measure length.
Answer: Cubit
In simple words: Length from elbow to the finger tip.

Exam Tip: Non-standard unit used historically.

Question 7. In 1790, the French created a standard unit of measurement called the ________.
Answer: metric system
In simple words: Standard system of measurement units.

Exam Tip: Brought uniformity in measurements.

IV. DEFINE THE FOLLOWING

Question 1. Motion
Answer: The change in position of an object with respect to its surroundings over time is called motion.
In simple words: Movement from one place to another.

Exam Tip: Mention change of position with time.

Question 2. Measurement
Answer: The comparison of an unknown quantity with some known standard quantity is called measurement.
In simple words: Finding the size or quantity using a standard unit.

Exam Tip: Measurement has two parts: a number and a unit.

V. DISTINGUISH BETWEEN

Question 1. Periodic motion and Non periodic motion.
Answer:

In simple words: Periodic repeats on time; non-periodic does not.

Exam Tip: Mention fixed time intervals as the key difference.

Question 2. Rectilinear motion and Circular motion.
Answer:

In simple words: Straight line vs circular path.

Exam Tip: Focus on the path of motion.

CHAPTER: 11 LIGHT, SHADOWS AND REFLECTIONS

I. FILL IN THE BLANKS

Question 1. ________ helps us to see objects with our eyes.
Answer: Light
In simple words: We cannot see anything in the dark without light.

Exam Tip: Light is essential for vision.

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.

Exam Tip: Example: Sun, glowing bulb.

Question 3. ________ objects allow light to pass through them completely.
Answer: Transparent
In simple words: We can see clearly through transparent objects.

Exam Tip: Example: Clear glass, pure water.

Question 4. ________ objects do not allow the light to pass through it at all.
Answer: Opaque
In simple words: Light cannot pass through opaque objects at all.

Exam Tip: Wood, metal, and cardboard are opaque.

Question 5. ________ objects allow the light to pass through them partially.
Answer: Translucent
In simple words: We can see through them partially or blurred.

Exam Tip: Example: Oiled paper, butter paper.

Question 6. Light travels in a ________.
Answer: straight line (rectilinear propagation)
In simple words: Light always moves in straight paths.

Exam Tip: This property is responsible for shadow formation.

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.

Exam Tip: Opaque objects cast dark shadows.

Question 8. ________, ________ and ________ are essential for the formation of shadows.
Answer: Source of light, opaque object, screen
In simple words: Three things needed for a shadow: light source, object, and screen.

Exam Tip: Without a screen, a shadow cannot be caught.

Question 9. A shadow cast by the heavenly bodies is called an ________.
Answer: eclipse
In simple words: Shadows of Earth and Moon cause eclipses.

Exam Tip: Solar and lunar eclipses are natural shadow phenomena.

Question 10. Images formed by a pin-hole camera are ________.
Answer: inverted (upside down)
In simple words: Images in a pinhole camera are upside down.

Exam Tip: Due to straight-line travel of light.

Question 11. We see ________ of the object in the mirror.
Answer: reflection (or image)
In simple words: Mirrors form reflections of objects placed in front of them.

Exam Tip: Reflection is bouncing back of light.

II. ANSWER IN ONE OR TWO WORDS

Question 1. Give two examples of opaque objects.
Answer: Wood and book.
In simple words: Objects that block light completely.

Exam Tip: Metals and stones are also opaque.

Question 2. Give two examples transparent objects.
Answer: Clear glass and pure water.
In simple words: Objects through which light passes clearly.

Exam Tip: Air is another transparent medium.

Question 3. Give two examples of translucent objects.
Answer: Butter paper and frosted glass.
In simple words: Objects that allow light to pass partially.

Exam Tip: Oiled paper is a classic school example.

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

Exam Tip: Stars and fireflies are also luminous.

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

Exam Tip: Moon shines by reflecting sunlight.

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.
Mirrors reflect light rays in a definite direction.
In simple words: Mirrors reflect and change light direction.

Exam Tip: Reflection occurs smoothly on polished surfaces like mirrors.

Question 2. Images are [ same / different] from the shadow.
Answer: (different) Images are different from the shadow.
Images show colors and details, whereas shadows are only dark outlines.
In simple words: Images have colors and details; shadows are just dark shapes.

Exam Tip: This is a very common exam question.

Question 3. Torch bulb is [ luminous / non - luminous] object.
Answer: (luminous) Torch bulb is a luminous object.
It produces its own light when switched on.
In simple words: It emits light on its own.

Question 4. [Opaque/Transparent] objects cast shadows.
Answer: (Opaque) Opaque objects cast shadows.
Only objects that block light form shadows.
In simple words: Blocking light creates shadows.

Exam Tip: Transparent objects do not cast prominent shadows.

Question 5. Coloured objects form [coloured / dark/white] shadows.
Answer: (dark) Coloured objects form dark shadows.
Shadows are always dark regardless of the color of the object.
In simple words: All shadows are black or dark.

Exam Tip: Color of an object does not affect shadow color.

Question 6. Images are formed because of [reflection of light/ obstruction of light]
Answer: (reflection of light) Images are formed because of reflection of light.
Mirrors form images by reflecting light rays.
In simple words: Reflection creates images; obstruction creates shadows.

Exam Tip: Do not confuse image formation with shadow formation.

IV. ANSWER THE FOLLOWING QUESTIONS

Question 1. How are shadows formed?
Answer: Shadows are formed when an opaque object comes in the path of light, blocking it from passing through.
In simple words: Blocking light creates a dark patch called a shadow.

Exam Tip: Mention light source, opaque object, and screen.

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

Exam Tip: Mirrors provide regular reflection.

Question 3. Explain with the help of an activity that light travels in a straight line.
Answer: Take a straight pipe or straw. Look at a lighted candle through it. You can see the flame. Now bend the pipe and look again; the flame is not visible. This proves that light travels in a straight line.
In simple words: You can only see light through a straight tube, not a bent one.

Question 1. Opaque objects
Answer: Objects that do not allow light to pass through them at all are called opaque objects.
In simple words: Objects that completely block light.

Exam Tip: Example: wood, iron sheet.

Question 2. Shadows
Answer: Dark patches formed on a screen when an opaque object blocks the path of light are called shadows.
In simple words: Dark silhouettes formed behind blocked light.

Exam Tip: Shadows require a light source, object, and screen.

Question 3. Reflection of light
Answer: The phenomenon of bouncing back of light rays from a shining or smooth surface is called reflection.
In simple words: Light bouncing back from a mirror.

Exam Tip: Enables us to see images in mirrors.

VI. DISTINGUISH BETWEEN

Question 1. Transparent and translucent objects
Answer:

In simple words: Transparent lets all light through; translucent lets some light through.

Exam Tip: Give clear glass and butter paper as respective examples.

Question 2. Luminous and non luminous objects
Answer:

In simple words: Luminous give off light; non-luminous do not.

Exam Tip: Moon is a classic non-luminous object reflecting sunlight.

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: Closed path for electric current to flow.

Exam Tip: A break in the path stops the current.

Question 2. A circuit in which electricity does not flow is called an ________ circuit.
Answer: open (or incomplete)
In simple words: Broken path through which current cannot flow.

Exam Tip: Bulb does not glow in an open circuit.

Question 3. The source of electricity in an electric cell are the ________ stored in it.
Answer: chemicals
In simple words: Cells convert stored chemical energy into electrical energy.

Exam Tip: When chemicals are used up, the cell stops working.

Question 4. Rubber is a ________ conductor of electricity.
Answer: bad (or insulator)
In simple words: Rubber does not allow electricity to pass through.

Exam Tip: Insulators protect us from electric shocks.

Question 5. A device that is used to break or complete an electric circuit is called ________.
Answer: switch
In simple words: Switch turns electricity ON or OFF.

Exam Tip: A switch makes or breaks the circuit.

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: Metal cap is positive; metal disc is negative.

Question 7. If the filament of a bulb breaks, it is said to be ________.
Answer: fused
In simple words: A fused bulb has a broken filament and will not glow.

Exam Tip: Current cannot pass through a fused bulb.

Question 8. An electric circuit said to be ________ when current flows through it.
Answer: closed (complete)
In simple words: Complete circuit allows current to flow.

Exam Tip: Closed circuit = ON state.

Question 9. Electric current flows from ________ terminal to ________ terminal of cell in the circuit.
Answer: positive, negative
In simple words: Conventional current flows from positive to negative terminal.

Exam Tip: Remember direction: positive to negative.

Question 10. In an electric cell, the metal cap is the ________ terminal while the metal disc is the ________ terminal.
Answer: positive, negative
In simple words: Cap is positive (+), disc is negative (-).

Exam Tip: Essential feature of dry cells.

II. NAME THE FOLLOWING

Question 1. Any two sources of electricity
Answer: Electric cell and electric generator (or battery/solar cell).
In simple words: Devices that supply electricity.

Exam Tip: Electric cells are portable sources.

Question 2. The thin wire in a bulb which gives out light
Answer: Filament
In simple words: Thin coiled wire inside a bulb that glows.

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: Complete loop for electricity.

Exam Tip: Must form a closed loop.

Question 4. Sometimes an electric bulb does not glow even when the electric switch is 'ON' then we say that the bulb is ________
Answer: fused
In simple words: Broken filament means the bulb is fused.

Exam Tip: Check the bulb if it doesn't glow in a working circuit.

Question 5. An electric appliance which makes or breaks an electric circuit
Answer: Switch
In simple words: Control device for electrical circuits.

Exam Tip: Essential for safe operation of appliances.

III. WRITE TRUE (T) OR FALSE (F)

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

Exam Tip: Copper and aluminum are widely used.

Question b. Instead of metal wires, a jute string can be used to make a circuit.
Answer: False
In simple words: Jute is an insulator and cannot conduct electricity.

Exam Tip: Only conductors can be used for wiring.

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

Exam Tip: Insulators stop current flow.

Question d. When current flows through a circuit, the circuit is called open circuit.
Answer: False
In simple words: A circuit with flowing current is a closed circuit.

Exam Tip: Open circuits do not allow 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: Used in household electrical wiring.

Question f. When an electric circuit is closed, the electric current stops flowing through it.
Answer: False
In simple words: Current flows when the circuit is closed.

Exam Tip: Closed means ON; current flows continuously.

IV. TICK THE CORRECT ANSWER

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

Exam Tip: Non-metals are generally insulators, but graphite is an exception.

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
Plastic is an insulator (bad conductor).
In simple words: Plastic does not conduct electricity.

Exam Tip: Used as covering on electrical wires for safety.

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
An OFF switch breaks the circuit.
In simple words: OFF switch makes the circuit incomplete.

Exam Tip: OFF means open circuit.

VI. DEFINE THE FOLLOWING

Question 1. Electricity
Answer: A form of energy resulting from the existence of charged particles is called electricity.
In simple words: Form of energy that powers electrical appliances.

Exam Tip: Essential form of modern energy.

Question 2. Switch
Answer: A simple device that is used to break or complete an electric circuit is called a switch.
In simple words: Device to turn current ON or OFF.

Exam Tip: Makes or breaks contact in a circuit.

Question 3. Electric circuit
Answer: A complete and closed path along which electric current flows from one terminal of a cell to another is called an electric circuit.
In simple words: Complete closed loop for electric current.

Exam Tip: Must include a source, wires, and a device.

VII. DISTINGUISH BETWEEN: Conductors and Insulators of electricity

Question 1. Conductors and Insulators
Answer:

In simple words: Conductors let electricity pass; insulators block it.

Exam Tip: Insulators are used for safety handles on tools.

X. VALUE BASED QUESTIONS

Question 1. What does this above sign warn people about?
Answer: It warns people of danger from high-voltage electricity.
In simple words: Warning sign for electrical danger.

Exam Tip: Skull and crossbones symbol indicates mortal danger.

Question 2. What values should you develop on knowing about the above warning?
Answer: We should develop cautiousness, alertness, and safety awareness regarding electrical installations.
In simple words: Be careful and maintain safe distance from electrical poles.

Exam Tip: Safety first is a crucial life value.

Question 3. Which source of electricity is safe for you for your classroom activities?
Answer: Electric cell (dry cell) is safe for classroom activities.
In simple words: Low voltage cells are safe and do not give shocks.

Exam Tip: Never use mains electricity for school experiments.

Question 4. Is it safe to touch electric switches and electric appliances with wet hands? Why?
Answer: No, it is dangerous because water conducts electricity and can cause a severe electric shock.
In simple words: Water conducts electricity, leading to dangerous shocks.

Exam Tip: Always dry hands before operating switches.

Question 5. Is air a good conductor of electricity?
Answer: No, dry air is a bad conductor (insulator) of electricity.
In simple words: Air does not conduct electricity under normal conditions.

Exam Tip: This prevents accidental shocks in open air.

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 geographic north-south.

Exam Tip: Used in making compasses.

Question 2. Similar poles of two magnets always ________ each other.
Answer: repel
In simple words: Like poles push each other away.

Exam Tip: North-North and South-South repel.

Question 3. Bar magnet is an example of ________ magnet.
Answer: artificial (or permanent)
In simple words: Man-made magnets are artificial magnets.

Exam Tip: Made from iron alloys.

Question 4. A ________ is used for finding geographic directions.
Answer: magnetic compass
In simple words: Compass needle points north-south to show directions.

Exam Tip: Essential tool for travelers and sailors.

Question 5. Unlike poles of two magnets always ________ each other.
Answer: attract
In simple words: Opposite poles pull towards each other.

Exam Tip: North-South attract.

Question 6. Bar magnets are always stored in pairs with their ________ poles on the same side.
Answer: opposite
In simple words: Storing with opposite poles facing together prevents demagnetization.

Exam Tip: Keep a piece of wood between them and soft iron keepers at ends.

Question 7. A magnetic compass always points in ________ direction.
Answer: north-south
In simple words: Compass needle aligns north-south.

Exam Tip: Red arrow typically points North.

Question 8. A magnet can lose its magnetism on ________, ________ and ________.
Answer: heating, hammering, dropping from height
In simple words: Rough handling destroys magnetic properties.

Exam Tip: Magnets must be handled with care.

II. WRITE TRUE OF FALSE

Question 1. Bar magnet is more powerful than natural magnet.
Answer: True
In simple words: Artificial magnets like bar magnets are stronger than lodestones.

Exam Tip: Made using strong electric fields or induction.

Question 2. Magnetic poles always exist in pairs.
Answer: True
In simple words: You cannot have a single isolated magnetic pole (monopole).

Exam Tip: Cutting a magnet creates two smaller complete magnets.

Question 3. Magnetic attraction is maximum in the middle of a bar magnet.
Answer: False
In simple words: Magnetic strength is maximum at the poles (ends), not in the middle.

Exam Tip: Iron filings cling mostly to the ends.

Question 4. Magnetic Compass is used for finding magnetic directions.
Answer: True
In simple words: Compass points north-south directions.

Exam Tip: Useful for navigation.

Question 5. Small pieces of wood are attracted by a strong magnet.
Answer: False
In simple words: Wood is non-magnetic and is never attracted to magnets.

Exam Tip: Only magnetic materials like iron and nickel are attracted.

Question 6. A magnet can separate iron nails from a mixture of iron filings and iron nails.
Answer: False
In simple words: Both are iron, so a magnet attracts both equally.

Exam Tip: Magnets attract all magnetic materials.

III. CLASSIFY THE GIVEN MATERIALS AS MAGNETIC OR NON-MAGNETIC SUBSTANCES

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

Exam Tip: Steel and iron are magnetic; wood, plastic, and brass are non-magnetic.

IV. DEFINE THE FOLLOWING

Question 1. Magnet
Answer: Any material that attracts iron and points in north-south direction when suspended freely is called a magnet.
In simple words: Object that attracts iron objects.

Exam Tip: Mention attraction of iron in the definition.

Question 2. Magnetite
Answer: A natural occurring iron ore that possesses magnetic properties is called magnetite.
In simple words: Natural magnetic rock.

Exam Tip: Also known as lodestone.

Question 3. Magnetic compass
Answer: A small instrument with a magnetized needle that pivots freely and points to the north-south direction is called a magnetic compass.
In simple words: Direction-finding instrument with a magnetic needle.

Exam Tip: Used for navigation.

V. DISTINGUISH BETWEEN: Magnetic and non magnetic substances

Question 1. Magnetic and non-magnetic substances
Answer:

In simple words: Magnetic materials get attracted; non-magnetic do not.

Exam Tip: Give examples of iron and plastic.

CHAPTER 14: WATER

I. FILL IN THE BLANKS

Question 1. The process by which plants evaporate water is called ________.
Answer: transpiration
In simple words: Plants release water vapour through leaves.

Exam Tip: Important part of water cycle.

Question 2. The water in oceans and sea is ________.
Answer: saline (salty)
In simple words: Ocean water contains high amounts of dissolved salts.

Exam Tip: Not fit for drinking directly.

Question 3. Water vapour gets added to the atmosphere by ________ and ________.
Answer: evaporation, transpiration
In simple words: Water enters the air via evaporation from water bodies and transpiration from plants.

Exam Tip: Both processes add water vapour to air.

Question 4. Water disappears from wet clothes by the process of ________.
Answer: evaporation
In simple words: Water turns into vapour and mixes in air.

Exam Tip: Speeds up in sunlight and wind.

Question 5. The source of water below the ground such as wells, tubewells, lakes etc. is known as ________.
Answer: groundwater
In simple words: Water stored underground.

Exam Tip: Replenished by rainwater seepage.

Question 6. In winter mornings, ________ is formed due to condensation of water vapour near the ground.
Answer: fog (or dew)
In simple words: Water vapour condenses into tiny droplets in cold air.

Exam Tip: Condensation occurs when air cools.

Question 7. Many tiny water droplets high up in the air, come together and fall down as ________ and ________.
Answer: rain, snow (or hail)
In simple words: Condensed water droplets fall as precipitation.

Exam Tip: Main source of freshwater on earth.

Question 8. The amount of the seepage of ________ into the ground affects the availability of ground water.
Answer: rainwater
In simple words: Rainwater seeping into soil maintains groundwater levels.

Exam Tip: Paved concrete roads reduce rainwater seepage.

Question 9. ________ part of the Earth is covered with water.
Answer: Two-thirds (or about 71%)
In simple words: Major portion of Earth is covered by oceans.

Exam Tip: Most of it is saline ocean water.

Question 10. Nearly ________ litres of water is transpired by wheat plants that give us one kilogram of wheat.
Answer: 500
In simple words: Crops require large amounts of water to grow.

Exam Tip: Highlights the importance of agricultural water management.

II. NAME THE FOLLOWING

Question 1. Two natural sources of water.
Answer: Rain and rivers (or oceans/lakes).
In simple words: Natural water reservoirs.

Exam Tip: Rain is the ultimate source of freshwater.

Question 2. Two fresh water bodies.
Answer: Rivers and ponds.
In simple words: Bodies of water with low salt content.

Exam Tip: Lakes and springs are also freshwater bodies.

Question 3. Two rainwater harvesting techniques.
Answer: Rooftop rainwater harvesting and storing in underground tanks (sumps).
In simple words: Collecting and storing rainwater for future use.

Exam Tip: Helps recharge groundwater.

Question 4. Four uses of water at home.
Answer: Drinking, cooking, washing, and bathing.
In simple words: Daily household activities requiring water.

Question 5. The two processes through which water vapour enters the air.
Answer: Evaporation and transpiration.
In simple words: Processes adding water vapour to atmosphere.

Exam Tip: Vital steps in the water cycle.

Question 6. Two adverse effects of floods.
Answer: Destruction of crops and damage to property and life.
In simple words: Heavy damage caused by overflowing water.

Exam Tip: Floods cause widespread loss.

Question 7. Two adverse effects of drought.
Answer: Scarcity of drinking water and drying up of crops.
In simple words: Lack of water leading to crop failure and famine.

Exam Tip: Opposite of floods.

III. WRITE TRUE OR FALSE

Question 1. Open wells are fed by ground water:
Answer: True
In simple words: Water seeps into the ground to feed open wells.

Exam Tip: Groundwater is accessed via wells.

Question 2. Life is possible on earth without water:
Answer: False
In simple words: Water is essential for the survival of all living beings.

Exam Tip: No life can exist without water.

Question 3. Saline water is fit for drinking and other domestic, agricultural and industrial needs:
Answer: False
In simple words: Saline water is salty and unfit for drinking or farming.

Exam Tip: Needs purification or desalination to be usable.

Question 4. Evaporation of water takes place at all times:
Answer: True
In simple words: Evaporation occurs continuously from all water surfaces.

Exam Tip: It happens faster in sunlight.

Question 5. Concrete land surfaces increases the seepage of rainwater into the ground:
Answer: False
In simple words: Concrete surfaces block rainwater seepage into soil.

Question 6. Heating of water makes evaporation faster.
Answer: True
In simple words: Higher temperature increases the rate of evaporation.

Exam Tip: Heat provides energy for water molecules to escape into air.

IV. DEFINE THE FOLLOWING

Question 1. Water cycle
Answer: The continuous circulation of water from Earth's surface to the atmosphere and back to Earth as precipitation is called the water cycle.
In simple words: Continuous movement of water between earth and sky.

Exam Tip: Involves evaporation, condensation, and precipitation.

Question 2. Rainwater harvesting
Answer: The method of collecting and storing rainwater from rooftops and open spaces for future use is called rainwater harvesting.
In simple words: Collecting rainwater for conservation.

Exam Tip: Helps improve groundwater levels.

V. DISTINGUISH BETWEEN: Evaporation and condensation

Question 1. Evaporation and Condensation
Answer:

In simple words: Evaporation turns water to gas; condensation turns gas to water.

Exam Tip: They are opposite processes.

VI. READ THE PARAGRAPH CAREFULLY (VALUE BASED QUESTIONS)

Question 1. Is Rahul right in brushing his teeth with the tap running? Why?
Answer: No, Rahul is not right because keeping the tap running wastes a large amount of precious drinking water.
In simple words: Keeping taps running wastes clean water unnecessarily.

Exam Tip: Water conservation is vital for future generations.

Question 2. What values did Rita show in her action?
Answer: Rita showed responsibility, environmental awareness, and care for natural resources.
In simple words: She showed care for saving water.

Exam Tip: Responsible citizenship includes conserving resources.

Question 3. Write a slogan on saving water.
Answer: Save water today, live tomorrow!
In simple words: Catchy phrase promoting water conservation.

Exam Tip: Keep slogans brief and impactful.

Question 4. State two major reasons leading to shortage of usable water on Earth.
Answer: Increasing population and wastage/pollution of water bodies.
In simple words: Rapidly rising demand and water pollution cause water shortages.

Exam Tip: Mention population growth and pollution.

Question 5. List any four ways by which you can help in conserving water at home.
Answer: (1) Turn off taps while brushing teeth, (2) Fix leaking taps promptly, (3) Use a bucket instead of a hose to wash cars, and (4) Reuse RO waste water for mopping.
In simple words: Simple steps to prevent water wastage at home.

Exam Tip: Practical tips score full marks.

CH-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 made of several gases mixed together.

Exam Tip: Nitrogen, oxygen, argon, carbon dioxide are components.

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

Exam Tip: Fire cannot burn without oxygen.

Question 3. The aquatic animals use dissolved ________ in water for respiration.
Answer: oxygen
In simple words: Fish breathe oxygen dissolved in water.

Exam Tip: Gills extract dissolved oxygen from water.

Question 4. ________ and ________ present inside the nose prevent dust particles from getting entry into the respiratory system.
Answer: Fine hair, mucus
In simple words: Hair and mucus in nose filter dust particles.

Exam Tip: Natural filtration system of our body.

Question 5. ________ and ________ are the gases which comprise 99% of the air.
Answer: Nitrogen, oxygen
In simple words: Nitrogen (78%) and oxygen (21%) make up 99% of air.

Exam Tip: Remember percentages: Nitrogen is about 78%, Oxygen is about 21%.

Question 6. ________ is the place in nature for gaseous exchange.
Answer: Atmosphere (or lungs/stomata)
In simple words: Atmosphere maintains the balance of gases.

Exam Tip: Photosynthesis and respiration balance atmospheric gases.

Question 7. Air in motion is called ________.
Answer: wind
In simple words: Moving air is called wind.

Exam Tip: Wind has speed and direction.

II. WRITE TRUE OR FALSE

Question 1. Air is a mixture but not an element.
Answer: True
In simple words: Air contains various gases physically mixed, not chemically bonded.

Exam Tip: Mixtures retain properties of individual components.

Question 2. Air is an opaque material.
Answer: False
In simple words: Air is transparent; we can see through it clearly.

Exam Tip: Transparent medium allows light to pass.

Question 3. Air contains water vapour.
Answer: True
In simple words: Humidity in air is due to water vapour.

Exam Tip: Amount of water vapour varies with place and season.

Question 4. The major part of air is nitrogen.
Answer: True
In simple words: Nitrogen makes up about 78% of air.

Exam Tip: Most abundant gas in atmosphere.

Question 5. Plants produce oxygen through photosynthesis.
Answer: True
In simple words: Green plants release oxygen during food making.

Exam Tip: Essential for breathing organisms.

Question 6. Carbon dioxide is produced during burning.
Answer: True
In simple words: Combustion releases carbon dioxide gas.

Exam Tip: Burning fuels adds carbon dioxide to air.

III. NAME THE FOLLOWING

Question 1. The gas which supports burning.
Answer: Oxygen
In simple words: Oxygen helps fires burn.

Exam Tip: Also called supporter of combustion.

Question 2. Any two properties of air.
Answer: Air occupies space and has weight.
In simple words: Air is matter with volume and mass.

Exam Tip: Basic physical properties of air.

IV. DEFINE: Atmosphere

Question 1. Atmosphere
Answer: The thick blanket of air that surrounds the Earth is called the atmosphere.
In simple words: Layer of air surrounding Earth.

Exam Tip: Held in place by Earth's gravity.

CHAPTER: 16 GARBAGE IN, GARBAGE OUT

I. FILL IN THE BLANKS

Question 1. Method of making compost using ________ is called vermicomposting.
Answer: red worms
In simple words: Composting using red worms is vermicomposting.

Exam Tip: Red worms break down organic kitchen waste efficiently.

Question 2. Converting plant and animals wastes into manure is called ________.
Answer: composting
In simple words: Natural recycling of organic waste into fertilizer.

Exam Tip: Enriches soil nutrients.

Question 3. ________ is an area where the garbage is collected.
Answer: Landfill
In simple words: Designated low-lying area for dumping city garbage.

Exam Tip: Covered with soil after filling.

Question 4. We need to generate ________ waste.
Answer: less (or minimum)
In simple words: Minimizing waste generation protects environment.

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

II. WRITE TRUE OR FALSE

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

Exam Tip: Saves trees and energy.

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

Exam Tip: Avoid single-use plastics.

Question 3. Plastics are eco-friendly.
Answer: False
In simple words: Plastics do not rot easily and pollute the environment.

Exam Tip: Plastics are non-biodegradable.

Question 4. Red worms eat up on green leaves on trees and make compost.
Answer: False
In simple words: Red worms feed on decaying organic waste in soil, not living green leaves on trees.

Exam Tip: They require moisture and rotting matter.

Question 5. Plastics give out harmful gases up on heating or burning.
Answer: True
In simple words: Burning plastics releases toxic gases into air.

Exam Tip: Plastics should never be burnt.

III. VALUE BASED QUESTIONS

Question 1. You have seen a rag picker sorting the plastic bags from a garbage heap having foul smell. Should you make faces at the rag picker while seeing him do the job? Why?
Answer: No, we should never make faces or disrespect rag pickers. They play a vital role in keeping our environment clean by recycling waste.
In simple words: Respect everyone; rag pickers help society by sorting waste.

Exam Tip: Dignity of labour should always be respected.

Question 2. Why is the garbage giving out the foul smell?
Answer: Garbage gives out foul smell due to the rotting and decomposition of organic waste by bacteria and fungi.
In simple words: Rotting organic waste produces bad odors.

Exam Tip: Microorganisms decompose organic matter.

Question 3. What do you think, the rag picker would do with those collected poly bags?
Answer: The rag picker would sell them to scrap dealers who send them to recycling units.
In simple words: Collected plastics are sold for recycling.

Exam Tip: Recycling reduces plastic pollution.

Question 4. What possible situations can arise if the poly bags are left there in the garbage?
Answer: Leftover poly bags can choke drains, pollute soil, get eaten by stray animals harming them, and remain undegraded for hundreds of years.
In simple words: Plastics choke drains, harm animals, and pollute soil.

Exam Tip: Non-biodegradable waste persists in nature.

Question 5. What values should you attribute for the society for minimizing poly bags pollution?
Answer: We should promote eco-friendly habits, use cloth or jute bags, and encourage recycling and waste segregation.
In simple words: Use cloth bags and reduce plastic usage.

Exam Tip: Environmental consciousness is an essential value.