CBSE Class 6 Science All Chapters Worksheet Set 03

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 undone to get back the original substance are called 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 result in a new substance and cannot be changed back to the original form are irreversible.

Exam Tip: Burning and cooking are always irreversible changes.

Question 3. On heating, the metals ____________.
Answer: expand
In simple words: Heat causes 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 burns into ash and smoke, you cannot get the stick back.

Exam Tip: All combustion processes are irreversible.

Question 6. On heating metal rim ____________ and fits into the wooden wheel.
Answer: expands
In simple words: The metal rim expands when heated so it can easily slip over the wooden wheel before cooling and gripping it tightly.

Exam Tip: This is a practical application of thermal expansion in daily life.

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 temporary changes with permanent (irreversible) changes.

II. CHOOSE THE CORRECT ANSWER

Question 1. Ripening of fruit is a ( reversible / irreversible ) change.
Answer: irreversible
In simple words: A ripe fruit cannot be turned back into an unripe green fruit.

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 simple words: Irreversible changes form entirely new substances, so the original components are lost.

Question 3. Melting of ice is a ( reversible / irreversible ) change.
Answer: reversible
In simple words: Melted ice (water) can be frozen back into ice.

Exam Tip: Changes involving states of matter (melting, freezing, boiling) are typically reversible.

III. WRITE TRUE OR FALSE

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

Exam Tip: Biological growth is always permanent.

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

Exam Tip: Chemical changes like setting curd are irreversible.

IV. NAME THE FOLLOWING

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

Exam Tip: Keep simple, common examples ready for this question.

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

Exam Tip: Mention processes involving heat or chemical reactions.

Question 3. Two methods to make a change happen.
Answer: By heating, By applying force (or mixing substances).
In simple words: Ways to bring about a change include heating and mixing.

Exam Tip: Temperature and pressure/force are primary agents of change.

V. DISTINGUISH BETWEEN: Reversible and Irreversible changes

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

In simple words: Reversible changes can be undone, while irreversible changes are permanent.

Exam Tip: Always present differences in a tabular format with clear examples.

VI. CLASSIFY THE FOLLOWING CHANGES INTO REVERSIBLE AND IRREVERSIBLE CHANGES

Question 1. Crumpling of paper
Answer: Reversible change
In simple words: A crumpled paper can be straightened out again.

Exam Tip: Physical shape change without tearing is usually reversible.

Question 2. Burning of paper
Answer: Irreversible change
In simple words: Burning turns paper into ash and smoke, which cannot be converted back to paper.

Exam Tip: Combustion always results in an irreversible change.

Question 3. Sawing of wood
Answer: Irreversible change
In simple words: Once wood is cut into pieces and sawdust is formed, you cannot join them back into the original single log of wood.

Exam Tip: Cutting or breaking objects permanently alters them.

Question 4. Cooking of food
Answer: Irreversible change
In simple words: Cooked food cannot be turned back into raw ingredients.

Exam Tip: Cooking involves chemical changes.

Question 5. Change of water into water vapour
Answer: Reversible change
In simple words: Water vapour can be cooled down to condense back into liquid water.

Exam Tip: Evaporation and condensation are opposite, reversible processes.

Question 6. Ironing of clothes
Answer: Reversible change
In simple words: Ironed clothes can become crumpled again when worn or washed.

Question 7. Rusting of iron nails
Answer: Irreversible change
In simple words: Rust is a new substance formed on iron, and it cannot be turned back into pure iron easily.

Exam Tip: Rusting requires oxygen and moisture.

Question 8. Bud to flower
Answer: Irreversible change
In simple words: A bloomed flower cannot go back to being a closed bud.

Exam Tip: Natural growth stages are irreversible.

CHAPTER - 7 GETTING TO KNOW PLANTS

I. 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 located at the center of a flower.

Exam Tip: Learn the parts of a flower: sepals, petals, stamen, and pistil.

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

Exam Tip: Chlorophyll is essential for photosynthesis.

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

Question 4. The pattern of veins on the leaf is called ____________
Answer: venation
In simple words: Venation refers to the design made by veins on a leaf blade.

Exam Tip: The two main types are reticulate and parallel venation.

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

Exam Tip: This is where most photosynthesis takes place.

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 is the petiole.

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: Contrast creepers with climbers, which take support to climb up.

Question 8. Maize plant has ____________ type of root.
Answer: fibrous
In simple words: Maize, being a monocot, has a bunch of similar thin roots called fibrous roots.

Question 9. ____________ is the stored form of food in the plants.
Answer: Starch
In simple words: Plants store extra food as starch in their leaves, roots, or stems.

Exam Tip: Iodine test is used to detect the presence of starch.

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.

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

Exam Tip: Heavy fruits are usually borne by creepers on the ground.

Question 2. Two types of root systems.
Answer: Taproot system, Fibrous root system.
In simple words: The two major ways roots grow in plants.

Exam Tip: Taproot has one main heavy root; fibrous root has many thin branching roots.

Question 3. The five types of plants.
Answer: Herbs, Shrubs, Trees, Climbers, Creepers.
In simple words: Plant categories based on their size, height, and stem structure.

Exam Tip: Memorize these five categories thoroughly.

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

Exam Tip: Reticulate is a network; parallel runs side by side.

Question 5. Any two climbers.
Answer: Pea plant, Grapevine (or Money plant).
In simple words: Plants that climb up using support.

Exam Tip: Climbers have special structures like tendrils for support.

Question 6. Any two shrubs.
Answer: Rose, Lemon (or Tulsi).
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, Radish (or Beetroot, Turnip).
In simple words: Taproots that store food and are eaten by humans.

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 develops into a fruit after fertilization.

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 and hold leaves/branches.

Question 3. Leaves give out water vapour through the process of transpiration.
Answer: True
In simple words: Water is released into the air as vapor through stomata on leaves.

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

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

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

Exam Tip: Equation requires carbon dioxide, water, sunlight, and chlorophyll.

Question 6. Chrysanthemum and sunflower are single flowers.
Answer: False
In simple words: Flowers like sunflower and chrysanthemum 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 shrub with hard, woody stems branching near the base.

Exam Tip: Herbs have green, tender stems.

IV. DEFINE THE FOLLOWING

Question 1. Herb
Answer: Plants with green and tender stems, usually short in height and having few branches, are called herbs.
In simple words: Small, soft-stemmed plants like coriander or grass.

Exam Tip: Mention stem characteristics clearly.

Question 2. Shrub
Answer: Plants that have hard, woody stems with branches developing near the base of the stem are called shrubs.
In simple words: Medium-sized bushy plants like rose and lemon.

Question 3. Tree
Answer: Very tall plants having a hard, thick, brown stem (trunk) with branches arising high up on the stem are called trees.
In simple words: Large woody plants like mango or neem.

Exam Tip: The main stem is called a trunk.

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 crawl along the floor, such as pumpkins.

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 upwards using support, like pea plants.

Exam Tip: Mention the need for external support.

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

Exam Tip: Can be reticulate or parallel.

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

Exam Tip: Oxygen is released as a by-product.

Question 8. Transpiration
Answer: The loss of water in the form of water vapour from the aerial parts of a plant, mainly through stomata in leaves, is called transpiration.
In simple words: Evaporation of water from plant leaves.

Exam Tip: Stomata are tiny pores responsible for this.

V. DISTINGUISH BETWEEN THE FOLLOWING

Question 1. Taproot system and fibrous root system
Answer:

In simple words: Taproot has one main long root, while fibrous roots are a cluster of thin roots.

Exam Tip: Always link root systems to leaf venation in your answers.

Question 2. Reticular venation and parallel venation
Answer:

In simple words: Reticulate is net-like, and parallel is line-like.

Exam Tip: Mention the root correlation for top marks.

Question 3. Roots and stem
Answer:

In simple words: Roots stay underground and absorb water, while stems stay above ground and hold up the plant.

Exam Tip: Contrast their location and primary functions.

Question 4. Herbs, Shrubs and Trees
Answer:

In simple words: Herbs are small and soft, shrubs are medium and bushy, and trees are tall and woody.

Exam Tip: Focus on height and stem texture when comparing.

CHAPTER: 8 BODY MOVEMENTS

I. FILL IN THE BLANKS

Question 1. The bones are moved by alternate ____________ and ____________ of two sets of muscles.
Answer: contraction, relaxation
In simple words: Muscles pull bones by alternately shortening and lengthening.

Exam Tip: Muscles work in pairs to move bones.

Question 2. Snails move with the help of a ____________.
Answer: muscular foot
In simple words: Snails glide using a broad muscular foot.

Question 3. Fish swim by forming ____________ alternately on two sides of the body.
Answer: loops (or curves)
In simple words: Fish curve their body from side to side to push water and swim forward.

Exam Tip: Fins help maintain balance and steering.

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 legs for walking and 2 pairs of wings for flying.

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

Question 5. Snakes ____________ on the ground by looping sideways.
Answer: slither
In simple words: Snakes move forward by forming loops that push against the ground.

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

Question 6. Fish have ____________ shaped body.
Answer: streamlined
In simple words: A streamlined body tapers at both ends to cut easily through water.

Exam Tip: Boats and airplanes are also designed with 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 grip the soil.

Exam Tip: Earthworms contract and expand their body muscles to move.

II. DISTINGUISH BETWEEN THE FOLLOWING

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

In simple words: Ball and socket moves all around, while a hinge joint moves like a door in one direction.

Exam Tip: Mention the range of motion and anatomical examples.

Question 2. Bones / Cartilages
Answer:

In simple words: Bones are hard and rigid, while cartilages are soft and flexible.

Exam Tip: Give examples like the ear pinna for cartilage.

III. DEFINE

Question 1. Skeleton
Answer: The framework of all the bones in the human body that provides shape, support, and protection to internal organs is called the skeleton.
In simple words: The bony framework of the body.

Exam Tip: An adult human skeleton has 206 bones.

Question 2. Ribcage
Answer: The cage-like protective bony structure formed by the ribs, chest bone (sternum), and backbone is called the ribcage.
In simple words: Bony cage protecting the heart and lungs.

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

Question 3. Joint
Answer: The point where two or more bones meet in the body, allowing different types of movements, is called a joint.
In simple words: The meeting point between bones where movement occurs.

Exam Tip: Joints can be movable or immovable.

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: Shoulders and hips have ball and socket joints.

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

Exam Tip: Skull bones are fixed and immovable.

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 bones from rubbing against each other directly.

Question 4. Lower jaw has fixed joints.
Answer: False
In simple words: The lower jaw is movable, allowing us to talk and chew.

Exam Tip: Upper jaw is fixed to the skull.

V. NAME THE FOLLOWING

Question 1. The joint found in the wrist:
Answer: Gliding joint
In simple words: Wrists have gliding joints that allow bones to slide past each other.

Exam Tip: Gliding joints permit sideways and back-and-forth movement.

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

Exam Tip: X-rays pass through flesh easily but are blocked by dense bones.

Question 3. The delicate organs protected inside the ribcage:
Answer: Heart and lungs
In simple words: The ribcage shields vital organs like the heart and lungs.

Exam Tip: Essential protective function of the skeletal system.

V. ANSWER THE FOLLOWING QUESTIONS

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

Exam Tip: Learn one example for each joint type.

Question 2. State the functions of the skeleton in human body.
Answer: Functions of the skeleton are:
1. It provides a definite shape and support to the body.
2. It protects delicate internal organs (e.g., skull protects brain, ribcage protects heart and lungs).
3. It helps in body movements along with muscles.
4. Red blood cells are produced in the bone marrow.
In simple words: The skeleton supports, protects, and helps us move.

Exam Tip: List at least three points for full credit.

Question 3. Write the adaptations of a bird.
Answer: Adaptations of a bird include:
1. Their bodies are streamlined to reduce air resistance during flight.
2. Bones are hollow and light (pneumatic bones) to reduce body weight.
3. Forelimbs are modified into wings for flying.
4. Powerful chest muscles help flap wings during flight.
In simple words: Birds have lightweight hollow bones, wings, and streamlined bodies for flying.

Exam Tip: Mention hollow bones and wings as key flight adaptations.

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: Streamlined bodies help fish glide smoothly through water.

Exam Tip: Streamlining reduces fluid friction.

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 sudden environmental changes over a short time is acclimatisation.

Exam Tip: Do not confuse acclimatisation with long-term adaptation.

Question 3. In the mountain regions, the trees are normally ____________ shaped.
Answer: cone
In simple words: Cone-shaped trees help snow slide off easily.

Exam Tip: Conifers are typical of mountain habitats.

Question 4. The process of producing more of their own kind by the living organisms is called ____________.
Answer: reproduction
In simple words: Producing offspring is reproduction.

Exam Tip: Essential life process for species survival.

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 (amphibians) 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.

Exam Tip: Whales and dolphins are mammals, not fish; they have lungs.

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

Question 8. The stems of aquatic plants are long, ____________ and ____________.
Answer: hollow, light
In simple words: Hollow stems help aquatic plants float upright in water.

Exam Tip: Hydrophytes have spongy tissues with air spaces.

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

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 pore structures on leaves for gas exchange.

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 many different species of plants and animals.

Exam Tip: Biodiversity refers to this variety of life.

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 acts as camouflage in dry grassland.

Exam Tip: Camouflage helps predators sneak up on prey and prey hide from predators.

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

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: Only organisms adapted to environmental changes survive over time.

Exam Tip: This relates to the principle of survival of the fittest.

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

Exam Tip: Example: Yak has long hair to keep warm.

Question 6. Plants do not show respond to stimuli:
Answer: False
In simple words: Plants do respond to stimuli, such as bending towards sunlight or the touch-me-not plant closing its leaves.

Exam Tip: Mimosa pudica (touch-me-not) is a classic 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 products.

Exam Tip: Plant excretion is slower than 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.

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 photosynthesis occurs only in the presence of sunlight.

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

Exam Tip: Terrestrial means land-based.

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

Question 3. Two plants and two animals of mountain regions.
Answer: Plants: Pine, Fir; Animals: Snow leopard, Yak (or Mountain goat).
In simple words: Organisms adapted to cold, snowy mountain environments.

Exam Tip: Mention cold-tolerant species.

Question 4. Four important abiotic factors needed for growth of plants.
Answer: Sunlight, Water, Air (Carbon dioxide/Oxygen), Soil nutrients.
In simple words: Non-living factors essential for plant survival.

Exam Tip: Abiotic means non-living components of an ecosystem.

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: Earthworms breathe through their skin, so it must stay moist.

Question 6. Any three modes of reproduction by plants.
Answer: Seeds, Stem cuttings, Roots (or Spores, Buds).
In simple words: Different ways plants produce new plants.

Exam Tip: Includes both sexual (seeds) and vegetative propagation.

IV. DEFINE THE FOLLOWING

Question 1. Adaptation
Answer: The presence of specific body features or habits which enable a plant or animal to live in a particular habitat is called adaptation.
In simple words: Special features that help organisms survive in their environment.

Exam Tip: Adaptations develop over long periods through evolution.

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

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

V. DISTINGUISH BETWEEN

Question 1. Biotic and abiotic factors
Answer:

In simple words: Biotic means living things, and abiotic means non-living things.

Exam Tip: 'Bio' means life; 'a-' means without.

Question 2. Terrestrial organisms and aquatic organisms
Answer:

In simple words: Terrestrial live on land, while aquatic live in water.

Question 1. The horse pulling a cart
Answer: Rectilinear motion (and translational motion)
In simple words: Moving in a straight line along the road.

Exam Tip: Objects moving along a straight path exhibit rectilinear motion.

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

Exam Tip: Motion along a circular path at a fixed distance is circular motion.

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

Exam Tip: A spinning top rotates about its central axis.

Question 4. A coin moving over a carom board
Answer: Rectilinear motion
In simple words: Sliding in a straight line across the carom board.

Exam Tip: The striker moves in a straight line when hit properly.

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

Exam Tip: The string maintains a constant radius.

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 repeating at regular intervals.

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
In simple words: Handspans vary from person to person, so they are not a standard unit.

Exam Tip: Standard units are required for universal consistency.

Question b. Ten millimeter is equal to 1 metre.
Answer: False
In simple words: 1000 millimeters make 1 metre (\(1000\text{ mm} = 1\text{ m}\)).

Exam Tip: Remember conversion: \(1\text{ m} = 100\text{ cm} = 1000\text{ mm}\).

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 depend on the observer's frame of reference.

Question d. To measure the diameter of tree, you can use measuring tape or thread.
Answer: True
In simple words: A curved or circular tree trunk can be measured using a flexible thread and a ruler.

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: A straight metre scale cannot bend along a curve, so thread must be used first.

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

III. FILL IN THE BLANKS

Question 1. 1000 times the length of a metre is called ____________.
Answer: kilometre
In simple words: One thousand metres make one kilometre (\(1\text{ km} = 1000\text{ m}\)).

Exam Tip: Prefixes like 'kilo-' mean one thousand times.

Question 2. The 1/1000 part of a metre is called ____________.
Answer: millimetre
In simple words: One metre divided into 1000 parts gives one millimetre.

Exam Tip: Prefixes like 'milli-' mean one-thousandth.

Question 3. The motion which repeats itself after a fixed interval of time is called ____________ motion.
Answer: periodic
In simple words: Motion repeating at regular time intervals is periodic.

Exam Tip: Example: The ticking of a clock or motion of a simple pendulum.

Question 4. The motion exhibited by a violin string is ____________ motion.
Answer: oscillatory (or vibrational)
In simple words: Plucked strings vibrate back and forth rapidly.

Exam Tip: Vibration is rapid oscillation.

Question 5. ____________ is the SI unit of length.
Answer: Metre
In simple words: The standard international unit for measuring length is the metre.

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: Cubit was the length from the elbow to the fingertips.

Exam Tip: Ancient units were based on body parts.

Question 7. In 1790, the French created a standard unit of measurement called the ____________.
Answer: metric system
In simple words: The French introduced the metric system for uniform measurements.

Exam Tip: This created a unified global standard.

IV. DEFINE THE FOLLOWING

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

Exam Tip: Motion is always relative to an observer.

Question 2. Measurement
Answer: The comparison of an unknown quantity with a known fixed quantity of the same kind is called measurement.
In simple words: Finding out the size or quantity by comparing it with 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 at regular intervals, while non-periodic does not.

Exam Tip: Look for time regularity in periodic motion.

Question 2. Rectilinear motion and Circular motion
Answer:

In simple words: Rectilinear is straight-line motion, and circular is curved circular motion.

Exam Tip: Differentiate based on the trajectory path.

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: Light reflects off objects and enters our eyes, allowing us to see.

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 are luminous.

Exam Tip: Example: Sun, electric bulb, firefly.

Question 3. ____________ objects allow light to pass through them completely.
Answer: Transparent
In simple words: Transparent materials let all light pass through clearly, like glass.

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: Opaque objects block light completely and cast shadows.

Exam Tip: Example: Wood, metal, cardboard.

Question 5. ____________ objects allow the light to pass through them partially.
Answer: Translucent
In simple words: Translucent materials let some light pass through, blurring the view.

Exam Tip: Example: Butter paper, frosted glass.

Question 6. Light travels in a ____________.
Answer: straight line (rectilinear propagation)
In simple words: Light always travels in straight lines.

Exam Tip: This property is called rectilinear propagation of light.

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 are shadows.

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

Question 8. ____________, ____________ and ____________ are essential for the formation of shadows.
Answer: Source of light, Opaque object, Screen
In simple words: Three necessary things to form a shadow.

Exam Tip: Memorize these three mandatory components.

Question 9. A shadow cast by the heavenly bodies is called an ____________.
Answer: eclipse
In simple words: Solar and lunar eclipses are shadows cast by celestial bodies.

Exam Tip: Eclipses happen due to the straight-line propagation of light.

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

Exam Tip: This proves light travels in straight lines.

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: Mirror reflections 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 (or Stone, Cardboard).
In simple words: Objects that block light completely.

Exam Tip: Cannot see through them at all.

Question 2. Give two examples transparent objects.
Answer: Clear glass, Clean water (or Air).
In simple words: Objects that let light pass through clearly.

Exam Tip: Objects are clearly visible through them.

Question 3. Give two examples of translucent objects.
Answer: Butter paper, Frosted glass (or Waxed paper).
In simple words: Objects that let some light pass through.

Exam Tip: Vision through them is blurred.

Question 4. Give two examples of luminous objects.
Answer: Sun, Glowing electric bulb (or Torch, Candle flame).
In simple words: Objects that emit their own light.

Exam Tip: They are sources of light.

Question 5. Give two examples of non-luminous objects.
Answer: Moon, Tree (or Book, Chair).
In simple words: Objects that do not emit their own light.

Exam Tip: The 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
In simple words: Mirrors reflect light and change its direction.

Exam Tip: Reflection is bouncing back of light from shiny surfaces.

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

Exam Tip: Key difference: Images show colors/details; shadows are only dark silhouettes.

Question 3. Torch bulb is [ luminous / non - luminous] object
Answer: luminous
In simple words: A switched-on torch bulb produces its own light.

Exam Tip: Luminous objects generate light.

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

Exam Tip: Transparent objects do not cast noticeable shadows.

Question 5. Coloured objects form [coloured / dark/white] shadows.
Answer: dark
In simple words: Regardless of an object's color, its shadow is always dark/black because it blocks light.

Exam Tip: Shadows are simply areas where light does not reach.

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

Exam Tip: Obstruction of light creates shadows, not images.

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 the light from passing through and creating a dark patch on a screen behind it.
In simple words: Light is blocked by an opaque object, creating a dark shape.

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 shiny or polished surface (like a mirror) in the same medium 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 burning candle through the straight pipe; the flame is clearly visible. Now bend the pipe and try to look at the flame; the flame is not visible. This proves that light travels in a straight line.
In simple words: You can see a light through a straight tube, but not a bent tube, showing light travels in straight lines.

Exam Tip: This classic candle experiment demonstrates rectilinear propagation.

V. DEFINE

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 through which you cannot see anything and which cast shadows.

Exam Tip: Example: Wood, iron.

Question 2. Shadows
Answer: A dark patch formed behind an opaque object when it blocks the path of light is called a shadow.
In simple words: Dark shape 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 process of sending back light rays that fall on the surface of an object is called reflection of light.
In simple words: Light bouncing off surfaces.

Question 1. Transparent and translucent objects
Answer:

In simple words: Transparent lets all light through clearly, while translucent lets some light through with a blurred view.

Exam Tip: Compare clarity of vision through them.

Question 2. Luminous and non luminous objects
Answer:

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

Exam Tip: Remember the moon is 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 unbroken path for electric current is an electric circuit.

Exam Tip: Current flows only in a closed circuit.

Question 2. A circuit in which electricity does not flow is called an ____________ circuit.
Answer: open (or incomplete)
In simple words: An open circuit has a break, so electricity cannot flow.

Exam Tip: Bulbs do 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 produce electricity using chemicals stored inside them.

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

Question 4. Rubber is a ____________ conductor of electricity.
Answer: poor (or insulator)
In simple words: Rubber does not allow electricity to pass through, making it an insulator.

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: A switch turns appliances on or off by breaking or completing the circuit.

Exam Tip: Switches act as a drawbridge for electric current.

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 broken filament means the bulb is fused and won't glow.

Exam Tip: Fused bulbs create an open circuit.

Question 8. An electric circuit said to be ____________ when current flows through it.
Answer: closed (or complete)
In simple words: Current flows only in a closed circuit.

Exam Tip: Closed means unbroken loop.

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: + to -.

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: The top cap is positive (+), and the bottom flat disc is negative (-).

Exam Tip: Important terminal identification for electric cells.

II. NAME THE FOLLOWING

Question 1. Any two sources of electricity
Answer: Electric cell, Electric generator (or Solar cell, Battery).
In simple words: Devices that supply electrical energy.

Exam Tip: Cells and generators are common sources.

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

Exam Tip: Made of tungsten metal due to its 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 complete loop for electricity is an electric circuit.

Exam Tip: Must form a closed loop from + to -.

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: A broken filament prevents the bulb from glowing even when switched on.

Exam Tip: Check for a broken filament inside the glass bulb.

Question 5. An electric appliance which makes or breaks an electric circuit
Answer: Switch
In simple words: A switch controls the flow of electricity in a circuit.

Exam Tip: Essential control component in electrical setups.

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, aluminum, and iron are good conductors.

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 to wire circuits.

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

Exam Tip: Insulators do not allow current to pass.

Question d. When current flows through a circuit, the circuit is called open circuit.
Answer: False
In simple words: When current flows, the circuit is closed (complete), not open.

Exam Tip: Open circuits do not carry current.

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

Exam Tip: Commonly used in electrical wiring.

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

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 (carbon) is a non-metal 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 and does not conduct electricity.

Exam Tip: Plastics are used to cover 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
In simple words: An OFF switch breaks the circuit, making it 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 (like electrons) is called electricity.
In simple words: A 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: A device to turn electrical devices on and off.

Exam Tip: Controls current flow safely.

Question 3. Electric circuit
Answer: A complete, unbroken path that allows electric current to flow from one terminal of a cell through appliances and back to the other terminal is called an electric circuit.
In simple words: A closed loop for electric current.

Exam Tip: Must form a continuous conductive path.

VII. DISTINGUISH BETWEEN: Conductors and Insulators of electricity

Question 1. Distinguish between Conductors and Insulators.
Answer:

In simple words: Conductors let electricity flow through them, while insulators block electricity.

Exam Tip: Insulators keep us safe from electric shocks.

VIII. EXPLAIN THE DIRECTION OF ELECTRIC CURRENT IN AN ELECTRIC CIRCUIT WITH THE HELP OF A DIAGRAM.

Question 1. Explain the direction of electric current in an electric circuit.
Answer: In an electric circuit, electric current flows from the positive (+) terminal of the electric cell to the negative (-) terminal through wires and appliances (like a bulb).
In simple words: Current flows from the positive terminal to the negative terminal of a battery.

Exam Tip: Always draw arrows from + to - in circuit diagrams.

X. VALUE BASED QUESTIONS

Question 1. What does this above sign [Skull and crossbones danger sign] warn people about?
Answer: It warns people about high-voltage electricity and the danger of fatal electric shocks.
In simple words: It warns of danger from high-voltage electricity.

Exam Tip: Never touch electrical poles or transformers.

Question 2. What values should you develop on knowing about the above warning?
Answer: We should develop alertness, cautiousness, and respect for safety rules regarding electricity.
In simple words: Developing safety awareness and caution around electricity.

Exam Tip: Safety first in all electrical matters.

Question 3. Which source of electricity is safe for you for your classroom activities?
Answer: Electric cells (dry cells) are safe for classroom activities because they provide low voltage.
In simple words: Dry cells/batteries are safe for school experiments.

Exam Tip: Never use household mains electricity for school science experiments.

Question 4. Is it safe to touch electric switches and electric appliances with wet hands? Why?
Answer: No, it is not safe because water is a conductor of electricity and can cause a severe electric shock.
In simple words: Wet hands can conduct electricity and give you a shock.

Exam Tip: Always dry your hands before touching switches.

Question 5. Is air a good conductor of electricity?
Answer: No, dry air is an insulator (poor conductor) of electricity.
In simple words: Air does not normally conduct electricity.

Exam Tip: This is why sparks don't jump across ordinary gaps easily.

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: A freely hanging magnet aligns itself along the earth's north-south direction.

Exam Tip: This property is used to make magnetic compasses.

Question 2. Similar poles of two magnets always ____________ each other.
Answer: repel
In simple words: Like poles push each other away (North-North or South-South).

Exam Tip: Repulsion is a sure test for magnetism.

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

Exam Tip: Contrast with natural magnets like lodestone (magnetite).

Question 4. A ____________ is used for finding geographic directions.
Answer: magnetic compass
In simple words: A compass uses a magnetized needle to show directions.

Exam Tip: The needle always points North-South.

Question 5. Unlike poles of two magnets always ____________ each other.
Answer: attract
In simple words: Opposite poles pull towards each other (North-South).

Exam Tip: Unlike poles pull together.

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

Exam Tip: Use a wooden piece and keepers to store bar magnets safely.

Question 7. A magnetic compass always points in ____________ direction.
Answer: north-south
In simple words: Compass needles align north-south.

Exam Tip: Essential navigational tool.

Question 8. A magnet can lose its magnetism on ____________, ____________ and ____________.
Answer: heating, hammering, dropping from height
In simple words: Rough handling, heating, or dropping can destroy a magnet's power.

Exam Tip: Magnets must be handled with care.

II. WRITE TRUE OR FALSE

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

Exam Tip: Man-made magnets are designed for stronger magnetic fields.

Question 2. Magnetic poles always exist in pairs.
Answer: True
In simple words: You cannot have an isolated north pole or south pole; they always come in pairs.

Exam Tip: If you cut a magnet in half, each piece gets both north and south poles.

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

Exam Tip: Iron filings cling mostly to the poles.

Question 4. Magnetic Compass is used for finding magnetic directions.
Answer: True
In simple words: A compass indicates directions using magnetism.

Exam Tip: Widely used by sailors and travellers.

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 by magnets.

Exam Tip: Only magnetic materials (iron, nickel, cobalt) 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 iron nails and iron filings are magnetic, so a magnet cannot separate them from each other.

Exam Tip: Magnets attract all magnetic materials equally.

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

Question 1. Classify the given substances into magnetic and non-magnetic.
Answer:

In simple words: Magnetic materials are attracted to magnets (like iron and steel), while non-magnetic materials are not.

Exam Tip: Remember iron, nickel, and cobalt are magnetic.

IV. DEFINE THE FOLLOWING

Question 1. Magnet
Answer: Any material that attracts objects made of iron, nickel, and cobalt is called a magnet.
In simple words: An object that pulls iron items towards itself.

Exam Tip: Magnets have two poles: North and South.

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

Exam Tip: Considered the first natural magnet discovered by humans.

Question 3. Magnetic compass
Answer: A small instrument containing a magnetized needle that pivots freely and points in the north-south direction is called a magnetic compass.
In simple words: A tool used for finding directions using a magnetic needle.

Exam Tip: Essential navigation device.

V. DISTINGUISH BETWEEN: Magnetic and non magnetic substances

Question 1. Distinguish between Magnetic and non-magnetic substances.
Answer:

In simple words: Magnetic substances are pulled by magnets, whereas non-magnetic substances are not.

Exam Tip: Mention iron as the primary example of magnetic substances.

CHAPTER 14: WATER

I. FILL IN THE BLANKS

Question 1. The process by which plants evaporate water is called ____________.
Answer: transpiration
In simple words: Release of water vapor by plants is called transpiration.

Exam Tip: Plants release huge amounts of water into the atmosphere this way.

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

Exam Tip: Saline water is unfit for direct drinking and agriculture.

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

Exam Tip: These two processes drive the water cycle.

Question 4. Water disappears from wet clothes by the process of ____________.
Answer: evaporation
In simple words: Water from wet clothes turns into vapor and mixes with air.

Exam Tip: Heat from the sun speeds up evaporation.

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 is called groundwater.

Exam Tip: Replenished by rainwater seeping into the ground.

Question 6. In winter mornings, ____________ is formed due to condensation of water vapour near the ground.
Answer: fog
In simple words: Water vapor condenses on dust particles in cold air to form fog.

Exam Tip: Condensation turns gas into liquid.

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 like rain or snow.

Exam Tip: Precipitation returns atmospheric water to 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 underground maintains groundwater levels.

Exam Tip: Concrete flooring reduces this seepage.

Question 9. ____________ part of the Earth is covered with water.
Answer: Two-thirds (or about 71%)
In simple words: Most of Earth's surface is covered with water.

Exam Tip: Remember: ~71% water, ~29% land.

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

Exam Tip: Highlights the importance of water in agriculture.

II. NAME THE FOLLOWING

Question 1. Two natural sources of water.
Answer: Rain, Oceans (or Rivers, Lakes, Springs).
In simple words: Natural water reservoirs on Earth.

Exam Tip: Rain is the primary source of fresh water.

Question 2. Two fresh water bodies.
Answer: Rivers, Ponds (or Lakes, Streams).
In simple words: Water bodies with low salt content suitable for drinking.

Exam Tip: Only a tiny fraction of Earth's water is fresh water.

Question 3. Two rainwater harvesting techniques.
Answer: Rooftop rainwater harvesting, Groundwater recharge (boring/pits).
In simple words: Methods to collect and store rainwater.

Exam Tip: Crucial for water conservation.

Question 4. Four uses of water at home.
Answer: Drinking, Cooking, Bathing, Washing clothes.
In simple words: Common domestic uses of water.

Exam Tip: Basic daily necessities.

Question 5. The two processes through which water vapour enters the air.
Answer: Evaporation, Transpiration.
In simple words: How water gets into the atmosphere.

Exam Tip: Core components of the water cycle.

Question 6. Two adverse effects of floods.
Answer: Loss of human and animal life, Destruction of crops and property.
In simple words: Damage caused by excessive water and flooding.

Exam Tip: Floods disrupt normal life completely.

Question 7. Two adverse effects of drought.
Answer: Scarcity of drinking water, Crop failure leading to famine.
In simple words: Hardships caused by lack of rain and water.

Exam Tip: Droughts cause severe food and water shortages.

III. WRITE TRUE OR FALSE

Question 1. Open wells are fed by ground water:
Answer: True
In simple words: Water from underground aquifers fills open wells.

Exam Tip: Groundwater is the source for wells and borewells.

Question 2. Life is possible on earth without water:
Answer: False
In simple words: Water is essential for all living organisms to survive.

Exam Tip: No water means no life.

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

Exam Tip: Desalination is needed to make saline water usable.

Question 4. Evaporation of water takes place at all times:
Answer: True
In simple words: Water evaporates from open surfaces at all temperatures.

Exam Tip: Even cold water evaporates slowly.

Question 5. Concrete land surfaces increases the seepage of rainwater into the ground:
Answer: False
In simple words: Concrete prevents rainwater from seeping into the ground, reducing groundwater levels.

Exam Tip: Urbanization reduces groundwater recharge.

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 the air.

IV. DEFINE THE FOLLOWING

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

Exam Tip: Involves evaporation, condensation, and precipitation.

Question 2. Rainwater harvesting
Answer: The collection and storage of rainwater from rooftops or open spaces for future use or to recharge groundwater is called rainwater harvesting.
In simple words: Collecting and storing rainwater for later use.

Exam Tip: Essential method to combat water scarcity.

V. DISTINGUISH BETWEEN: Evaporation and condensation

Question 1. Distinguish between Evaporation and Condensation.
Answer:

In simple words: Evaporation turns water into vapor, while condensation turns vapor back into water drops.

Exam Tip: They are opposite processes.

VI. READ THE PARAGRAPH CAREFULLY: (Value based questions)
Rahul is brushing his teeth in the bathroom keeping the water tap running. Then Rita, his sister, comes up and puts off the tap and tells him to put 'on' the tap only when he does the rinsing.

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 huge amount of precious drinking water.
In simple words: Leaving the tap running wastes clean drinking water.

Exam Tip: Always turn off taps when not in active use.

Question 2. What values did Rita show in her action?
Answer: Rita showed responsibility, environmental awareness, and care for conserving water.
In simple words: Rita showed responsibility towards water conservation.

Exam Tip: Conserving resources is a civic duty.

Question 3. Write a slogan on saving water.
Answer: Save water today, survive tomorrow! (or "Every drop counts.")
In simple words: Catchy phrase promoting water conservation.

Exam Tip: Keep slogans short and impactful.

Question 4. State two major reasons leading to shortage of usable water on Earth.
Answer: 1. Increasing population and water wastage.
2. Deforestation and reduction in groundwater recharge due to concrete construction.
In simple words: Overuse and wastage along with poor groundwater recharge cause water shortages.

Exam Tip: Mention population growth and wastage.

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 and pipes immediately.
3. Use a bucket for bathing instead of a running shower.
4. Use leftover RO wastewater or washing water for gardening.
In simple words: Simple daily habits to save water at home.

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 other gases.

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

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

Exam Tip: Fire goes out without oxygen.

Question 3. The aquatic animals use dissolved ____________ in water for respiration.
Answer: oxygen
In simple words: Aquatic animals 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: Nose hair and mucus filter dust out of inhaled air.

Exam Tip: Natural filtration mechanism of our respiratory system.

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: Nitrogen is ~78% and oxygen is ~21%.

Question 6. ____________ is the place in nature for gaseous exchange.
Answer: Atmosphere (or lungs/stomata)
In simple words: The atmosphere allows gas exchange for living organisms.

Exam Tip: Atmosphere surrounds the Earth.

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

Exam Tip: Wind is caused by uneven heating of the earth.

II. WRITE TRUE OR FALSE

Question 1. Air is a mixture but not an element.
Answer: True
In simple words: Air is a mixture of several gases.

Exam Tip: Components retain their individual properties.

Question 2. Air is an opaque material.
Answer: False
In simple words: Air is transparent, allowing us to see through it clearly.

Exam Tip: Transparent medium around us.

Question 3. Air contains water vapour.
Answer: True
In simple words: Air always contains varying amounts of moisture or water vapor.

Exam Tip: Humidity refers to water vapor content in air.

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

Exam Tip: Nitrogen is the most abundant gas in the atmosphere.

Question 5. Plants produce oxygen through photosynthesis.
Answer: True
In simple words: Plants release oxygen as a by-product during photosynthesis.

Exam Tip: This replenishes oxygen in the atmosphere.

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

Exam Tip: Combustion produces carbon dioxide and water vapor.

III. NAME THE FOLLOWING

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

Exam Tip: Essential for combustion.

Question 2. Any two properties of air.
Answer: 1. Air occupies space.
2. Air exerts pressure.
In simple words: Air has weight and takes up space.

Exam Tip: Fundamental physical properties of air.

IV. DEFINE: Atmosphere

Question 1. Define Atmosphere.
Answer: The blanket of air that surrounds the Earth is called the atmosphere.
In simple words: The layer of air enveloping the 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: Red worms help break down kitchen waste into rich manure.

Exam Tip: Red worms cannot survive in extreme heat or cold or salty environments.

Question 2. Converting plant and animals wastes into manure is called ____________.
Answer: composting
In simple words: Turning organic waste into fertilizer is composting.

Exam Tip: Natural recycling of organic waste.

Question 3. ____________ is an area where the garbage is collected.
Answer: Landfill
In simple words: Low-lying areas where city garbage is dumped and covered are landfills.

Exam Tip: Landfills help manage municipal solid waste.

Question 4. We need to generate ____________ waste.
Answer: less
In simple words: We should minimize waste generation to protect the 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: Recycling paper saves trees.

Question 2. Drains get choked due to plastic thrown by us.
Answer: True
In simple words: Non-biodegradable plastics choke drains and sewers.

Exam Tip: Plastics do not rot or decompose easily.

Question 3. Plastics are eco-friendly.
Answer: False
In simple words: Plastics are non-biodegradable and harm the environment.

Exam Tip: Plastics cause long-term pollution.

Question 4. Red worms eat up on green leaves on trees and make compost.
Answer: False
In simple words: Red worms live in soil/composting pits and eat dead plant matter, not leaves on living trees.

Exam Tip: Red worms require moisture and decaying organic matter.

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

Exam Tip: Never burn plastic bags.

III. VALUE BASED QUESTIONS
You have seen a rag picker sorting the plastic bags from a garbage heap having foul smell.

Question 1. Should you make faces at the rag picker while seeing him do the job? Why?
Answer: No, we should never mock rag pickers because they perform a vital service by collecting recyclable materials and helping clean up our environment.
In simple words: We should respect rag pickers for helping recycle waste.

Exam Tip: Dignity of labor should always be respected.

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

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 (kabadiwallahs) who send them to recycling units.
In simple words: They sell them to recycling centers to earn a living.

Exam Tip: Plastic recycling reduces waste pileup.

Question 4. What possible situations can arise if the poly bags are left there in the garbage?
Answer: If left in garbage, poly bags can choke drains, pollute soil, poison animals that eat them, and remain undecayed for hundreds of years.
In simple words: Plastic bags cause pollution, choke drains, and harm stray animals.

Exam Tip: Avoid single-use plastic bags completely.

Question 5. What values should you attribute for the society for minimizing poly bags pollution?
Answer: We should promote values like eco-friendliness, social responsibility, cleanliness, and the use of cloth or jute bags instead of plastic bags.
In simple words: Using cloth bags and minimizing plastic use helps protect the environment.

Exam Tip: Say no to plastic bags and yes to cloth bags.