Text Book Solutions All Class

Q.1. True/False

(i) Digestion of starch starts in the stomach.

False

(ii) The tongue helps in mixing food with saliva.

True

(iii) The gall bladder temporarily stores bile.

True

(iv) The ruminants bring back swallowed grass into their mouth and chew it for some time. 

True

(v) We chew the food with the teeth and break it down mechanically into small pieces. 

True

(vi) Large intestine receives digested and absorbed food. 

False

Q.2. Fill in the blanks.

(i) The main steps of nutrition in humans are ____, ____, ____, ____ and ____.

ingestion, digestion, absorption, assimilation and egestion.

(ii) The largest gland in the human body is ____.

liver

(iii) The stomach releases hydrochloric acid and ____ juices which act on food.

digestive

(iv) The inner wall of the small intestine has many finger-like outgrowths called ____.

villi

(v) Amoeba digests its food in the food ____.

vacuole

(vi) We chew the food with the ____ and break it down mechanically into small pieces.

teeth

Answer the following Questions

Q.3. Where are fats digested in the body?

Fats are primarily digested in the small intestine.

Q.4. What kills bacteria that enter along with the juices to act?

The acid kills many bacteria that enter along with the juices to act. This process helps to maintain a safe environment for digestion and prevents the growth of harmful bacteria.

Q.5. Where are faeces formed in the human body?

Faeces are formed in the human body in large intestine.

Q.6. Where food is absorbed in our body?

Absorption of food takes place in small intestine.

Q.7. Where faeces are stored?

Faeces are stored in rectum.

Q.8. What does saliva do to food in our mouth?

The saliva breaks down the starch into sugars.

Q.9. What is rumen?

 Rumen is a large, sac-like structure found in ruminants, such as cattle and deer.

Q.10. What does animal nutrition include?

Animal nutrition includes nutrient requirement, mode of intake of food and its utilisation in the body.

Q.11. What are the different modes of feeding in animals?

Different modes of feeding in animals include:

• Scraping – removing food from surfaces.
• Chewing – breaking down food into smaller pieces.
• Sucking – drawing in liquids, like nectar.
• Capturing and swallowing – catching prey whole.
• Filtering – sifting tiny food particles from water.

Q.12. What are ruminant animals?

The grazing animals like cows, buffaloes and deer are known as ruminants.

Q.13. What do pancreatic juices digest?

 The pancreatic juice plays a crucial role in digestion by acting on:

• Carbohydrates – breaking them down into simpler sugars.
• Fats – converting them into fatty acids and glycerol.
• Proteins – transforming them into amino acids.

Overall, pancreatic juice helps in simplifying these food components for better absorption in the body.

Q.14. What do you mean by rumination? 

 Rumination is a process that occurs in certain animals, known as ruminants. It involves the following steps:

• Animals quickly swallow their food, which is often grass.
• The food is stored in a part of the stomach called the rumen.
• Later, the partially digested food, known as cud, returns to the mouth.
• The animal then chews the cud thoroughly before swallowing it again.

This process helps in the digestion of tough plant materials, particularly cellulose, which many animals, including humans, cannot digest effectively

Q.15. What are the main steps involved in the process of respiration in animals? 

​The main steps of respiration in animals include inhalation, where oxygen is taken into the body; gas exchange in the lungs or tissues, where oxygen is exchanged for carbon dioxide; and exhalation, where carbon dioxide is expelled from the body. This process is crucial for supplying oxygen to cells and removing waste gases.

Q.1. True or False

(i) The SI unit of speed is kilometre per hour.

False
Explanation: The SI unit of speed is metre per second (m/s).

(ii) Candle clocks were used to measure time in ancient India.

False
Explanation: Candle clocks were used in other cultures; India used Ghatika-yantras.

(iii) In non-uniform motion, the speed of the object remains the same.

False
Explanation: In non-uniform motion, the speed changes.

(iv) All pendulums of the same length have the same time period at the same location.

True
Explanation: Time period depends only on the length, not the mass.

(v) Distance is measured in metres and time in seconds.

True
Explanation: These are standard SI units.

Q.2. Fill in the blanks.
(i)  The metallic ball is called the ____ of the pendulum.

bob
The term ‘bob’ refers to the weight or mass at the end of a pendulum, which swings back and forth during oscillation.

(ii) The symbols of all units are written in ____.

singular
Unit symbols are conventionally written in singular form to maintain consistency and clarity in scientific communication.

(iii) The time taken by the pendulum to complete one oscillation is called its ____.

time period
The ‘time period’ is defined as the duration it takes for a pendulum to return to its original position after completing one full swing.

(iv) One microsecond is one ____ of a second.

millionth
A microsecond is a unit of time equal to one millionth (10^-6) of a second, commonly used in scientific contexts.

(v) A nanosecond is one ____ of a second.

billionth
A nanosecond is a unit of time equal to one billionth (10^-9) of a second, often used in computing and telecommunications.

(vi) The distance-time graph for the motion of an object moving with a constant speed is a ____.

straight line
A straight line on a distance-time graph indicates uniform motion, where the distance covered is directly proportional to time.

Answer the following Questions 

Q.3. Give an example of oscillatory motion.

The to and fro motion of a simple pendulum is a clear example of oscillatory motion. 
Here’s a brief overview:

• A simple pendulum consists of a small weight, known as the bob, attached to a string or thread.
• When the bob is pulled to one side and released, it swings back and forth around its mean position.
• This back-and-forth movement is repeated in a regular pattern, making it a periodic motion.

Q.4. What is uniform motion?

An object that moves in a straight line at a constant speed is described as being in uniform motion. 
This means:

• The speed does not change over time.
• The distance covered is proportional to the time taken.
• The motion can be represented by a straight line on a distance-time graph.

Q.5. An object moving along a straight line with a constant speed is said to be in uniform motion.

Vehicle A is moving faster. The speed of a vehicle is determined by the distance it covers in a specific time frame. 
Key points include:

• A vehicle that travels a greater distance in the same time interval has a higher speed.
• For example, if Vehicle A covers 100 metres in 5 seconds and Vehicle B covers 80 metres in the same time, Vehicle A is faster.
• Speed can vary; the same vehicle may move faster or slower at different times.

Q.6. What is distance-time graph?

A distance-time graph visually represents how far an object travels over time. Key points include:

• It shows the speed of an object.
• A straight line indicates constant speed.
• If the line is curved, the object’s speed is changing.

Q.7. What is oscillatory motion?

The to and fro motion of an object is known as oscillatory motion.

Q.8. What is non-uniform motion?

Non-uniform motion occurs when an object’s speed changes while moving along a straight line. 
Key points include:

• The speed is not constant.
• Motion can vary from slow to fast.
• It contrasts with uniform motion, where speed remains constant.

Q.9. What is the basic unit of speed?

The basic unit of speed is the metre per second (m/s).

Q.10.  A simple pendulum takes 32 s to complete 20 oscillations. What is the time period of the pendulum?

Number of oscillations = 20
Total time taken to complete 20 oscillations = 32 s
Time period = Total time taken/Number of oscillations = 32/20 = 1.6s

Q.11. When pendulum is said to have one complete oscillation?

The pendulum is said to have completed one oscillation when its bob, starting from its mean position B, moves to A, to C and back to B.

Q.12. Explain how in ancient time a day, a month and a year were measured?

Our ancestors observed that many natural events occur at regular intervals:

• The day was defined as the time between one sunrise and the next.
• A month was measured from one new moon to the next.
• A year was determined by the time it takes for the Earth to complete one revolution around the sun.

Q.13. The distance between two stations is 240 km. A train takes 4 hours to cover this distance. Calculate the speed of the train.

Distance between two stations = 240 km
Time taken to cover this distance = 4 hours
Speed = Distance/Time Taken = 240/4 = 60km/h

Q.14. Salma takes 15 minutes from her house to reach her school on a bicycle. If the bicycle has a speed of 2 m/s, calculate the distance between her house and the school.

Time taken = 15 min = 15 x 60 = 900 seconds
Speed = 2 m/s
Distance = Speed x Time
= 2 x 900 = 1800 m = 1800/1000 = 1.8 km

Q.15. What is speedometer?

A speedometer is a device that measures and displays the speed of a vehicle.

• It is commonly found on the dashboards of cars, motorcycles, and scooters.
• The speed is usually shown in kilometres per hour (km/h).
• Speedometers help drivers maintain safe speeds while driving.

Q.16. What are quartz clocks?

Quartz clocks are timekeeping devices that use an electric circuit powered by one or more cells.

• They are known for their high accuracy in measuring time.
• Quartz clocks have largely replaced older clock technologies.
• The precision of quartz clocks is significantly better than traditional clocks.

Q.1. True/False

(i) Metals are poor conductors of heat.
Ans: False

Metals are good conductors of heat.

(i) Land breeze occurs during the night.

Ans: True

At night, cooler land air moves towards the warmer sea.

(i) Dark-colored clothes absorb less heat than light-colored clothes.

Ans: False

Dark-colored clothes absorb more heat.

(i) Water vapor released by plants is called transpiration.
Ans: True

It is a natural process where plants release water into the air.

(i) Radiation requires air or water to transfer heat.
Ans: False

Radiation can occur in empty space, such as sunlight.

Q.2. Fill in the blanks.

(i)  The hotness of an object is determined by its ____.

temperature

(ii) Temperature is measured in degree ____.

celsius

(iii) A cold steel spoon is dipped in a cup of hot milk. It transfers heat to its other end by the process of ____.

conduction

(vi) Dark colored clothes are preferred during ____.

winter

(v) Poor conductors are known as ____.

insulators

Answer the following Questions 

Q.3. Does the transfer of heat by radiation require any medium?

The transfer of heat by radiation does not require any medium.

Q.4. What is the concern associated with the use of mercury thermometers?

There is a lot of concern over the use of mercury in thermometers. Mercury is a toxic substance and is very difficult to dispose of if a thermometer breaks.

Q.5. How water get heated when kept on flame?

When water is heated, the water near the flame gets hot. Hot water rises up. The cold water from the sides moves down towards the source of heat. This water also gets hot and rises and water from the sides moves down. This process continues till the whole water gets heated. This mode of heat transfer is known as convection.

Q.6. Which device is used to measure temperature?

Thermometer is used to measure temperature.

Q.7. How does heat flow from one object to another?

Heat flows from a hotter object to a colder object.

Q.8. Do all hot bodies radiate heat?

Yes, all hot bodies radiate heat.

Q.9. How does heat transfer in solids?

In solids, generally, the heat is transferred by the process of conduction.

Q.10. What is Conduction?

The process by which heat is transferred from the hotter end to the colder end of an object is known as conduction.

Q.11. Explain the process of conduction with an example.

Conduction is the transfer of heat in solids through direct contact. In this process, heated particles vibrate and pass energy to nearby particles. For example, when a metal pan is placed on a flame, heat travels from the bottom to the entire surface, making the pan hot. Metals are used for cooking because they are good conductors of heat.

Q.12. What is convection and how does it affect coastal areas?

Convection is heat transfer in liquids and gases where warm particles rise and cool ones sink. In coastal areas, during the day, land heats up faster than sea, causing a sea breeze. At night, land cools faster, creating a land breeze. These breezes are examples of convection currents and provide comfort in coastal climates.

Q.13. Describe radiation and give two real-life applications.

Radiation is the transfer of heat through invisible waves, without needing a medium. For example, the Sun heats the Earth through radiation. Another example is the warmth felt near a fire. Light-colored clothes reflect radiation, keeping us cool, while dark-colored clothes absorb heat, keeping us warm in winter.

Q.14. How does the water cycle help in redistributing water on Earth?

The Sun’s heat drives the water cycle through evaporation, condensation, precipitation, and seepage. Water evaporates from oceans and lakes, forms clouds, and falls back as rain or snow. Some of this water seeps underground to become groundwater. This cycle keeps water circulating and available across regions.

Q.15. What are ice stupas and how do they help conserve water in Ladakh?

Ice stupas are cone-shaped ice structures built in Ladakh to store water in winter. Stream water is frozen in these shapes and melts slowly in spring, providing water for farming. They help solve water scarcity in dry, mountainous areas and are an example of traditional knowledge used for modern conservation.

Q1: What is the main reason for the development of pimples during adolescence?

a) Lack of sleep

b) Increase in oily secretions from the skin

c) Excessive washing of the face

​d) Change in diet

Answer: b) Increase in oily secretions from the skin

Q2: What is the term used to describe the natural signs that the body is preparing for adulthood?

a) Puberty

b) Maturity

c) Secondary sexual characteristics

d) Adolescence

Answer: c) Secondary sexual characteristics

Q3: At what age does adolescence typically begin?

a) 5–6 years

b) 10–12 years

c) 13–14 years

d) 19–20 years

Answer: b) 10–12 years

Q4: What does the onset of the menstrual cycle in girls indicate?

a) Beginning of adolescence

b) The start of puberty

c) Both a and b

d) End of childhood

Answer: c) Both a and b

Q5: Which of the following is a secondary sexual characteristic in boys?

a) Development of breasts

b) Voice deepening

c) Menstruation

d) None of the above

Answer: b) Voice deepeningFill in the Blanks:

Q1: The stage of life when the body undergoes changes to prepare for adulthood is called __________.

Answer: adolescence

Q2: The growth of facial hair in boys is one of the __________ sexual characteristics that occur during adolescence.

Answer: secondary

Q3: The natural process in adolescent girls that involves the release of blood is called __________.

Answer: menstruation

Q4: During adolescence, boys and girls experience growth in __________ in the pubic region and underarms.

Answer: hair

Q5: __________ refers to the time period when the body undergoes internal and external changes to reach reproductive capability.

Answer: PubertyTrue/False Questions:

Q1: Adolescence is marked only by physical changes in the body.

Answer: False

Q2: The onset of menstruation is an important internal change in adolescent girls.

Answer: True

Q3: Acne is a common skin condition that may develop due to increased oily secretions during adolescence.

Answer: True

Q4: Boys and girls develop the same type of secondary sexual characteristics during adolescence.

Answer: False

Q5: The menstrual cycle is an indicator of a girl’s reproductive health.

Answer: TrueVery Short Answer Questions:

Q1: What are secondary sexual characteristics?

Answer: Secondary sexual characteristics are features that distinguish males from females and mark the onset of puberty, such as voice changes in boys and breast development in girls.

Q2: What is menstruation?

Answer: Menstruation is the monthly discharge of blood from the uterus of a non-pregnant female, marking the beginning of reproductive health.

Q3: Why do boys experience voice changes during adolescence?

Answer: The voice box grows, leading to a deeper, hoarser voice, which is one of the secondary sexual characteristics in boys.

Q4: How does physical activity help adolescents?

Answer: Physical activity helps in developing strength, building stamina, and maintaining a healthy body during adolescence.

Q5: What is the role of hormones during adolescence?

Answer: Hormones regulate growth, development, and emotional changes during adolescence and are crucial for reproductive maturity.Long Answer Questions:

Q1: Explain the physical and emotional changes that occur during adolescence.

Answer: Adolescence is marked by rapid physical growth, including changes in height, weight, and the development of secondary sexual characteristics. Boys experience deepening of the voice, growth of facial hair, and increased muscle mass. Girls experience breast development, wider hips, and the onset of menstruation. Emotional changes include mood swings, increased sensitivity, and a desire for independence, as adolescents explore their identities and relationships with others.

Q2: How can adolescents manage emotional changes effectively?

Answer: Adolescents can manage emotional changes by engaging in activities like sports, music, or art to channel their emotions positively. Talking to trusted adults, practicing mindfulness, and maintaining a balanced lifestyle can also help manage mood swings and emotional stress.

Q3: What are the key nutritional needs of adolescents, and why are they important?

Answer: Adolescents need a balanced diet rich in proteins, carbohydrates, fats, vitamins, and minerals to support their rapid growth and development. Nutrients like calcium are essential for bone growth, while iron is important for the formation of blood. A healthy diet helps adolescents perform well physically and mentally.

Q4: What is the significance of the menstrual cycle in adolescent girls?

Answer: The menstrual cycle marks the onset of reproductive health in adolescent girls. It indicates the body’s readiness for reproduction and is a natural process that occurs roughly every 28-30 days. The cycle also helps maintain overall hormonal balance and contributes to the girl’s growth and development.

Q5: Discuss the impact of substance abuse during adolescence and the importance of saying ‘NO’ to harmful substances.

Answer: Substance abuse during adolescence can have long-term physical, mental, and emotional consequences, including addiction, damage to organs, and impaired cognitive development. It is crucial for adolescents to resist peer pressure and make healthy choices, as avoiding harmful substances promotes better health and well-being.

Q.1. True/False

(i) Rusting of iron is a physical change.

False
Explanation: It is a chemical change where new substance (rust) is formed.

(ii) Evaporation of water is a reversible change.

True
Explanation: Water vapor can condense back into liquid.

(iii) All physical changes are reversible.

False
Explanation: Some physical changes, like chopping wood, are irreversible.

(iv) Burning of magnesium ribbon produces a white powder.

True
Explanation: It forms magnesium oxide, a new substance.

(v) Bioluminescence produces light without heat.

True
Explanation: It is a chemical change found in fireflies.

Q.2. Fill in the blanks.

(i) Cutting a log of wood into pieces is a ____ change.

physical

This is a physical change because it alters the form of the wood without changing its chemical composition.

(ii) Condensation is a ____ change.

physical
Condensation is a physical change as it involves a change in the state of matter from gas to liquid without altering the substance’s chemical identity.

(iii) When carbon dioxide is passed through lime water, it turns milky due to the formation of ____.

Calcium Carbonate
The milky appearance is due to the formation of calcium carbonate, which occurs when carbon dioxide reacts with lime water.

(iv) Two methods by which rusting of iron can be prevented are ____ and ____.

painting or greasing, galvanisation
Painting or greasing creates a barrier against moisture, while galvanisation involves coating iron with zinc to prevent rust.

(v)  Changes in which only ____ properties of a substance change are called physical changes.

physical
Physical changes involve alterations in physical properties such as shape, size, or state, without changing the substance’s chemical identity.

(vi)  A medicine is the end product of a chain of ____.

chemical reactions
Medicines are created through a series of chemical reactions that transform raw materials into effective therapeutic agents.

Answer the following Questions

Q3. What is the white substance formed when lime water reacts with carbon dioxide?

Calcium carbonate.

Q4. What kind of change is chopping vegetables?

Irreversible physical change.

Q5. Name the three requirements of the fire triangle.

Fuel, oxygen, and heat (ignition temperature).

Q6. Which process breaks down rocks into soil over time?

Weathering.

Q7. What kind of change is melting wax?

Physical change.

Q8. What happens when magnesium ribbon is burnt in air?

When magnesium ribbon is burnt in air, it reacts with the oxygen present to form magnesium oxide. This process produces a bright flame and results in a white powder.

• The reaction can be summarised as:
• Magnesium (Mg) Oxygen (O₂) → Magnesium oxide (MgO)
• Heat and light are also released during this reaction.

Q.9. What do you understand by chemical change?

A change in which one or more new substances are formed is called a chemical change.

Q.10. Why formation of manure from leaves is a chemical change?

Formation of manure from leaves is a chemical change because:

• The composition of the resulting manure is different from that of the original leaves.
• New substances are created during the decomposition process.
• This transformation involves a series of chemical reactions

Q.11. Why tearing of paper into pieces is a physical change?

Tearing a piece of paper is a physical change because:

• Only the shape and size of the paper are altered.
• No new substance is created during this process.

Q.12. What is rusting?

If a piece of iron is left in the open for some time, it acquires a film of brownish substance. This substance is called rust the process is called rusting.
The process of rusting can be represented by the following equation: Iron (Fe) + Oxygen (O₂, from the air) + water (H₂O) → rust (iron oxide Fe₂O₃)

Q.13. Explain why burning of wood and cutting it into small pieces are considered as two different types of changes.

Burning of wood
Burning is a non-reversible chemical change because when we burn wood new substances are formed as the carbon in the wood reacts with oxygen in the air to create ash and smoke, and energy in the form of light and heat.
Cutting of wood it into small pieces
Cutting of wood into small pieces are physical change as no new substance is formed. Only shape and size changes when wood is cut into small pieces.

Q.14. What is a physical change?

A physical change occurs when a substance alters its physical properties without forming a new substance. Key characteristics include:

• Changes can involve shape, size, colour, and state of the substance.
• These changes are generally reversible.
• No new substances are created during a physical change.

Q.15. Explain the changes that occur when a candle burns.

When a candle burns, both physical and chemical changes take place. The wax melts (physical change), evaporates, and then the vapor burns in air to form carbon dioxide and water (chemical change). Melting and re-solidifying wax are reversible, but the burning process is irreversible and forms new substances.

MCQ Questions

Q1: Which metal is commonly used to make food packaging materials as it is cheaper, and its thin sheets can be folded easily into any shape?

a) Aluminium

b) Copper

c) Iron

d) Gold

Ans: a) Aluminium

Q2: Which of the following metals catches fire when it comes in contact with water?

a) Copper

b) Aluminium

c) Zinc

d) Sodium

Ans: d) Sodium

Q3: Which of the following properties do most metals possess?

a) Malleability

b) Dullness

c) Non-conductivity

d) Brittle

Ans: a) Malleability

Q4: Which of these metals is known for being the most malleable and ductile?

a) Gold

b) Copper

c) Iron

d) Aluminium

Ans: a) Gold

Q5: What is the property that enables metals to produce a ringing sound when struck?

a) Malleability

b) Sonority

c) Ductility

d) Lustre

Ans: b) Sonority

Fill in the Blanks

Q1: Materials that allow electricity to flow through them easily are called __________.

Ans: conductors

Q2: The property of metals by which they can be beaten into thin sheets is called __________.

Ans: malleability

Q3: Metals react with oxygen to produce __________ which are basic in nature.

Ans: metal oxides

Q4: The process of formation of rust on objects made of iron is called __________.

Ans: rusting

Q5: The property by which materials can be drawn into wires is called __________.

Ans: ductility

True/False Questions

Q1: All metals are hard and lustrous.

Ans: False

Q2: Non-metals are generally poor conductors of heat and electricity.

Ans: True

Q3: Metals do not react with oxygen.

Ans: False

Q4: The rusting of iron can be prevented by applying a protective layer of zinc.

Ans: True

Q5: Magnesium burns with a dazzling white flame and forms a white powder when exposed to oxygen.

Ans: True

Very Short Answer Questions

Q1: What is the process by which metals like iron develop brown deposits?

Ans: This process is called rusting, and it occurs when iron comes into contact with both air and water.

Q2: What is the property of metals that allows them to be beaten into thin sheets?

Ans: Malleability

Q3: Why are materials like copper and aluminium used in electrical wiring?

Ans: Because they are good conductors of electricity.

Q4: What happens when magnesium reacts with oxygen?

Ans: Magnesium burns with a dazzling white flame and forms magnesium oxide.

Q5: What is the nature of magnesium oxide when dissolved in water?

Ans: Magnesium oxide forms a basic solution when dissolved in water.

Long Answer Questions

Q1: Explain the properties of metals and non-metals and how they differ.

Ans: Metals are generally lustrous, malleable, ductile, and good conductors of heat and electricity. They form basic oxides when they react with oxygen. Non-metals, on the other hand, are usually non-lustrous, brittle, and poor conductors of heat and electricity. They form acidic oxides when they react with oxygen and do not have the properties of malleability and ductility.

Q2: Why are gold and silver used in jewellery, and why are only a few metals suitable for this purpose?

Ans: Gold and silver are highly malleable and ductile, allowing them to be shaped into intricate designs and thin sheets. They are also resistant to corrosion, making them ideal for jewellery. However, not all metals possess these qualities, as some are too hard or reactive to be used for jewellery.

Q3: Describe the process of rusting and the methods used to prevent it.

Ans: Rusting is the process where iron reacts with oxygen and water, forming brown deposits on its surface. To prevent rusting, methods such as painting, oiling, greasing, or applying a protective layer of zinc (galvanisation) are used. These methods prevent exposure to air and water, which are necessary for rust formation.

Q4: How do the properties of metals and non-metals influence their uses in everyday life?

Ans: The properties of metals, such as conductivity, malleability, and ductility, make them useful in applications like electrical wiring, construction, and manufacturing tools. Non-metals, though poor conductors, are essential in biological processes, like oxygen for respiration and carbon for life forms, and are also used in the production of fertilizers and water purification.

Q5: What is the significance of the Iron Pillar of Delhi, and what does it tell us about ancient Indian metallurgy?

Ans: The Iron Pillar of Delhi is a remarkable example of ancient Indian metallurgy. Despite facing exposure to wind, rain, and intense weather for over 1600 years, it shows very little rust. This indicates advanced techniques in metalworking that allowed for resistance to rusting, demonstrating the high level of skill in metallurgy in ancient India.

Q.1. True/False

(i) The human body is a good conductor of electricity.

True
Explanation: That is why touching live wires is dangerous.

(ii) An incandescent lamp will not glow if connected with the wrong terminals.

False
Explanation: It glows regardless of which terminal is connected to which side.

(iii) Circuit diagrams use symbols to show real components in a circuit.

​True
Explanation: Standard symbols make diagrams easy to understand.

(iv) A battery produces alternating current (AC).

False
Explanation: Batteries produce direct current (DC).

(v) LEDs can work even if the positive and negative terminals are reversed.

False
Explanation: LEDs only work when connected in the correct direction.

Q.2. Fill in the blanks.

(i) Longer line in the symbol for a cell represents its ____ terminal.

positive
The longer line in the symbol for a cell indicates the positive terminal, while the shorter line represents the negative terminal.

(ii) The combination of two or more cells is called a ____.

battery
A battery is formed when two or more cells are connected together to provide a higher voltage or capacity.

(iii) When current is switched ‘on’ in a room heater, it ____.

produces heat

• When the current is switched on in a room heater, it:
• Produces heat as the electric current flows through the wire.

(iv) The safety device based on the heating effect of electric current is called a ____.

fuse
A fuse is designed to protect electrical circuits by melting and breaking the circuit when excessive current flows, preventing damage or fire.

Answer the following Questions 

Q.3. What is electric current?

Electric current is the flow of electrons through a conductor, such as a wire.

• It is measured in amperes.
• Electric current can produce heat when it flows through a wire.
• This heating effect is used in many appliances, like heaters and toasters.
• When current flows, it can also create a magnetic field, making wires behave like magnets.

Q.4. Write some uses of battery.

Battery Uses

• Torches for lighting
• Transistors for amplifying signals
• Toys for operation
• TV remote controls for convenience

Q.5. What is filament?

In the bulb there is a thin wire, called the filament, which glows when an electric current passes through it.

Q.6. What are the uses of heating effect of electric current?

The heating effect of electric current is utilised in various electrical appliances, including:

• Immersion heaters
• Hotplates
• Irons
• Geysers
• Electric kettles
• Hair dryers

Q.7. Name any two effects of electric current.

The two effects of electric current are:
(i) Heating effect of electric current
(ii) Magnetic effect of the electric current

Q.8. What is an

An electric circuit is a closed path that allows electricity to flow between the two terminals of an electric cell. Key points include:

• The circuit must be closed for current to flow.
• A bulb will only glow when the current is flowing through the circuit.
• If the circuit is open (e.g., when a switch is off), no current flows.

In the bulb, a thin wire called the filament glows when electric current passes through it. If the filament is broken, the circuit becomes incomplete, and the bulb will not glow.

Q.9. Explain the symbol of electric cell.

In the symbol of an electric cell, the representation consists of:

• The longer line indicates the positive terminal.
• The thicker, shorter line represents the negative terminal.

Q.10. Why a fused bulb does not glow?

A fused bulb does not glow due to a break in its filament. This break interrupts the flow of current between the bulb’s terminals. As a result:

• The circuit becomes incomplete.
• No current passes through the filament.
• Thus, the bulb remains unlit.

Q.11. Sometimes the cells are placed side by side. Then how are the terminals of the cells connected?

Cells are typically connected using:

• A thick wire or a metal strip that links the positive terminal of one cell to the negative terminal of the next.
• This connection allows the cells to work together as a battery.

Q.12. What is a switch, and how does it control an electric circuit?

A switch is a device that either completes (ON) or breaks (OFF) a circuit. When the switch is ON, the circuit is closed, and current flows, making the device work. When OFF, the circuit opens, stopping the current. Switches can be placed anywhere in the circuit and are essential for safe control of electricity.

Q.13. Explain the importance of circuit diagrams and list three symbols used.

Circuit diagrams help represent electric circuits using symbols, making them easy to understand and communicate. They are important in designing, testing, and explaining circuits. Common symbols include:

Q.14. Describe the difference between an incandescent lamp and an LED.

An incandescent lamp has a filament that glows when current passes through it and can work in either direction of connection. An LED does not have a filament; it only glows when connected correctly, with the longer wire to the positive terminal and the shorter wire to the negative. LEDs are energy-efficient and long-lasting.

Q.15. What are conductors and insulators? Give examples and their uses.

Conductors are materials that allow electricity to pass easily, like copper and aluminum, used in wires and plugs. Insulators block current and include rubber, plastic, and glass. They are used to cover wires, make switches, and ensure electrical safety by preventing shocks.

Multiple Choice Questions

Q1: What is the primary goal of science as mentioned in the chapter?

a) To memorize facts

b) To explore the world through curiosity and experiments

c) To study historical events

d) To prove theories

Answer: b) To explore the world through curiosity and experiments  View Answer

ExperimentingQ2: Which of the following is an example of a reversible change?

a) Burning of paper

b) Breaking of a rock

c) Melting of ice

d) Rusting of iron

Answer: c) Melting of ice  View Answer

Q3: What inspired the early scientific exploration of flight?

a) Observing the movement of the sun

b) Experimenting with electricity

c) Watching planes fly

d)  Studying the wings of birds

Answer: b) Studying the wings of birds  View Answer

Exploration of FlightQ4: What does science help us do according to the chapter?

a) Answer only factual questions

b) Develop new technologies

c) Understand and explore the environment

d) Memorize important dates

Answer: c) Understand and explore the environment  View Answer

Q5: What does the chapter suggest about human activities and nature?

a) They are not connected

b) They are linked and affect the environment

c) Human activities have no impact on nature

d) Human activities only affect animals

Answer: b) They are linked and affect the environment  View Answer
Fill in the Blanks

Q1. Science is not just about discovering facts but also about _______ curiosity and asking questions.
Answer: welcoming  View Answer

Q2. The process of light and shadows helped early humans to measure _______.
Answer: time  View Answer

Measuring TimeQ3. Materials are classified based on their _______ such as conductivity or malleability.
Answer: properties  View Answer

Q4. Animals breathe and circulate _______ to all parts of their body for survival.
Answer: nutrients  View Answer

Q5. The phenomenon of eclipses is caused by the _______ cast by Earth or Moon.
Answer: shadows  View Answer

Eclipse and Tilt of EarthTrue/False Questions

Q1: Science is about memorizing facts and repeating them.

Answer: False

Science is not just memorizing facts; it is about observing, experimenting, asking questions, and understanding how things work in the natural world.

Q2: Human activities are connected to the natural world and impact the environment.

Answer: True

Human actions like farming, building, and pollution affect the environment, showing that humans and nature are closely linked.

Q3: The chapter encourages only studying the properties of materials and not asking any questions.

Answer: False

The chapter encourages curiosity and asking questions to explore and understand the properties of materials, not just studying them passively.

Science is about CuriosityQ4: The position of shadows in the Sun was used by early humans to measure time.

Answer: True

Early humans observed how shadows changed position during the day to estimate time before clocks were invented.

Q5: The study of light and shadows does not help in understanding the Earth’s movements.

Answer: False

Light and shadows help us understand Earth’s rotation and revolution because the changes in sunlight cause day and night and seasons.

Short Answer Questions

Q1. Explain how science is a continuous process of discovery.
Answer: Science is ongoing because every discovery leads to new questions and experiments. It never stops as we keep exploring deeper into nature.

Q2. What is the difference between reversible and irreversible changes?
Answer: Reversible changes can be undone and return to their original form, like ice melting and then freezing again. Irreversible changes cannot be undone, like a fruit ripening or a battery running out of power.

Q3. Why is it important to step outside the classroom to learn science?
Answer: Experiencing the world through activities and experiments helps us understand science better than just reading, making learning hands-on and meaningful.

Q4. How do human activities link to environmental challenges?
Answer: Human actions affect nature and society, and science helps us understand this connection to work toward a sustainable future.

Our EnvironmentQ5. What role do light and shadows play in our daily life and in science?
Answer: Light and shadows help us see, tell time, and explain natural phenomena like eclipses and day-night cycles.Long Answer Questions

Q1. Explain why science is considered both a process and a way of thinking.
Answer:

• Science is not just a collection of facts but a continuous process of asking questions and seeking answers.
• It involves curiosity, experiments, observations, and logical reasoning.
• Scientists observe patterns in nature and try to understand why and how things happen.
• This method of thinking encourages openness to new ideas and revising old ones based on evidence.
• Hence, science helps us develop critical thinking and problem-solving skills.

Q2. Describe how different fields of science are interconnected and why this is important.
Answer:

• Fields like physics, chemistry, biology, and earth sciences often overlap in their studies.
• For example, biology uses chemistry to understand life processes, while earth science involves physics to explain natural phenomena.
• Discoveries in one field can lead to questions and new findings in others.
• This interconnectedness helps provide a more complete understanding of the world.
• It encourages collaborative learning and innovation across disciplines.

Q3. Why is hands-on learning through experiments and activities emphasized in science education?
Answer:

• Experiments help students experience scientific concepts practically rather than just reading theory.
• Hands-on learning develops observation, analysis, and critical thinking skills.
• It allows learners to see results firsthand and understand cause-effect relationships.
• Such activities spark curiosity and make learning enjoyable and memorable.
• They also prepare students to think like scientists and solve real-world problems.

Q4. Discuss the role of science in addressing environmental challenges and promoting sustainability.
Answer:

• Science helps us understand how human activities impact the environment.
• It provides tools and knowledge to reduce pollution and conserve natural resources.
• Through science, we can develop renewable energy, waste management, and eco-friendly technologies.
• It raises awareness about climate change and biodiversity loss.
• Ultimately, science guides us toward creating a sustainable and balanced relationship with nature.

Q5. How do light and shadows help us understand time and natural phenomena like eclipses?
Answer:

• Early humans used the length and position of shadows cast by the Sun to measure time during the day.
• Light enables us to see objects, and shadows show the shape and position of these objects.
• The Earth and Moon cast shadows that cause eclipses, which are important astronomical events.
• Studying light and shadows helps explain day and night cycles caused by Earth’s rotation.
• This understanding connects everyday experiences with larger cosmic events.

Multiple Choice Questions

Q1: What is the primary goal of science as mentioned in the chapter?

a) To memorize facts

b) To explore the world through curiosity and experiments

c) To study historical events

d) To prove theories

Answer: b) To explore the world through curiosity and experiments  View Answer

ExperimentingQ2: Which of the following is an example of a reversible change?

a) Burning of paper

b) Breaking of a rock

c) Melting of ice

d) Rusting of iron

Answer: c) Melting of ice  View Answer

Q3: What inspired the early scientific exploration of flight?

a) Observing the movement of the sun

b) Experimenting with electricity

c) Watching planes fly

d)  Studying the wings of birds

Answer: b) Studying the wings of birds  View Answer

Exploration of FlightQ4: What does science help us do according to the chapter?

a) Answer only factual questions

b) Develop new technologies

c) Understand and explore the environment

d) Memorize important dates

Answer: c) Understand and explore the environment  View Answer

Q5: What does the chapter suggest about human activities and nature?

a) They are not connected

b) They are linked and affect the environment

c) Human activities have no impact on nature

d) Human activities only affect animals

Answer: b) They are linked and affect the environment  View Answer
Fill in the Blanks

Q1. Science is not just about discovering facts but also about _______ curiosity and asking questions.
Answer: welcoming  View Answer

Q2. The process of light and shadows helped early humans to measure _______.
Answer: time  View Answer

Measuring TimeQ3. Materials are classified based on their _______ such as conductivity or malleability.
Answer: properties  View Answer

Q4. Animals breathe and circulate _______ to all parts of their body for survival.
Answer: nutrients  View Answer

Q5. The phenomenon of eclipses is caused by the _______ cast by Earth or Moon.
Answer: shadows  View Answer

Eclipse and Tilt of EarthTrue/False Questions

Q1: Science is about memorizing facts and repeating them.

Answer: False

Science is not just memorizing facts; it is about observing, experimenting, asking questions, and understanding how things work in the natural world.

Q2: Human activities are connected to the natural world and impact the environment.

Answer: True

Human actions like farming, building, and pollution affect the environment, showing that humans and nature are closely linked.

Q3: The chapter encourages only studying the properties of materials and not asking any questions.

Answer: False

The chapter encourages curiosity and asking questions to explore and understand the properties of materials, not just studying them passively.

Science is about CuriosityQ4: The position of shadows in the Sun was used by early humans to measure time.

Answer: True

Early humans observed how shadows changed position during the day to estimate time before clocks were invented.

Q5: The study of light and shadows does not help in understanding the Earth’s movements.

Answer: False

Light and shadows help us understand Earth’s rotation and revolution because the changes in sunlight cause day and night and seasons.

Short Answer Questions

Q1. Explain how science is a continuous process of discovery.
Answer: Science is ongoing because every discovery leads to new questions and experiments. It never stops as we keep exploring deeper into nature.

Q2. What is the difference between reversible and irreversible changes?
Answer: Reversible changes can be undone and return to their original form, like ice melting and then freezing again. Irreversible changes cannot be undone, like a fruit ripening or a battery running out of power.

Q3. Why is it important to step outside the classroom to learn science?
Answer: Experiencing the world through activities and experiments helps us understand science better than just reading, making learning hands-on and meaningful.

Q4. How do human activities link to environmental challenges?
Answer: Human actions affect nature and society, and science helps us understand this connection to work toward a sustainable future.

Our EnvironmentQ5. What role do light and shadows play in our daily life and in science?
Answer: Light and shadows help us see, tell time, and explain natural phenomena like eclipses and day-night cycles.Long Answer Questions

Q1. Explain why science is considered both a process and a way of thinking.
Answer:

• Science is not just a collection of facts but a continuous process of asking questions and seeking answers.
• It involves curiosity, experiments, observations, and logical reasoning.
• Scientists observe patterns in nature and try to understand why and how things happen.
• This method of thinking encourages openness to new ideas and revising old ones based on evidence.
• Hence, science helps us develop critical thinking and problem-solving skills.

Q2. Describe how different fields of science are interconnected and why this is important.
Answer:

• Fields like physics, chemistry, biology, and earth sciences often overlap in their studies.
• For example, biology uses chemistry to understand life processes, while earth science involves physics to explain natural phenomena.
• Discoveries in one field can lead to questions and new findings in others.
• This interconnectedness helps provide a more complete understanding of the world.
• It encourages collaborative learning and innovation across disciplines.

Q3. Why is hands-on learning through experiments and activities emphasized in science education?
Answer:

• Experiments help students experience scientific concepts practically rather than just reading theory.
• Hands-on learning develops observation, analysis, and critical thinking skills.
• It allows learners to see results firsthand and understand cause-effect relationships.
• Such activities spark curiosity and make learning enjoyable and memorable.
• They also prepare students to think like scientists and solve real-world problems.

Q4. Discuss the role of science in addressing environmental challenges and promoting sustainability.
Answer:

• Science helps us understand how human activities impact the environment.
• It provides tools and knowledge to reduce pollution and conserve natural resources.
• Through science, we can develop renewable energy, waste management, and eco-friendly technologies.
• It raises awareness about climate change and biodiversity loss.
• Ultimately, science guides us toward creating a sustainable and balanced relationship with nature.

Q5. How do light and shadows help us understand time and natural phenomena like eclipses?
Answer:

• Early humans used the length and position of shadows cast by the Sun to measure time during the day.
• Light enables us to see objects, and shadows show the shape and position of these objects.
• The Earth and Moon cast shadows that cause eclipses, which are important astronomical events.
• Studying light and shadows helps explain day and night cycles caused by Earth’s rotation.
• This understanding connects everyday experiences with larger cosmic events.