Text Book Solutions All Class

Multiple Choice Questions

Q.1. According to ancient philosophers matter consists of: 
(a) Three constituents 
(b) Four constituents 
(c) Five constituents 
(d) Six constituents.

Correct Answer is Option (c)
Matter is made up of five constituents also called tatvas (air, water, earth, fire and sky).

Q.2. Dry ice is:
(a) Solid ammonia
(b) Solid carbon dioxide
(c) Solid sulphur dioxide
(d) Normal ice

Correct Answer is Option (b)
Dry ice is solid carbon dioxide (CO₂).

Q.3. Which of the following statements is not correct for liquid state?
(a) Particles are loosly packed in the liquid state
(b) Fluidity is the maximum in the liquid state
(c) Liquids can be compressed
(d) Liquids take up the shape of any container in which these are placed

Correct Answer is Option (b)
Fluidity is maximum in the gaseous state and not in the liquid state.

Q.4. Which of the following will sublime? 
(a) Common salt 
(b) Sugar 
(c) Camphor 
(d) Potassium nitrate

Correct Answer is Option (c)
Camphor, ammonium chloride, Phenophthelene sublimes i.e. change from solid to gaseous state directly without passing through liquid state upon heating.

Q.5. When the liquid starts boiling, the further heat energy which is supplied: 
(a) Is lost to the surrounding as such 
(b) Increases the temperature of the liquid 
(c) Increases the kinetic energy of the particles in the liquid 
(d) Is absorbed as latent heat of vaporisation by the liquid

Correct Answer is Option (d)
Heat is absorbed as latent heat of vapourisation. As long as liquid is not boiled, the heat energy which is supplied increases the kinetic energy of particles present in water. Once the liquid starts boiling the heat energy is used to brinchange in the state (liquid-gas). It is known as latent heat of vapourisation.

Fill in the Blanks
1. Matter is made up of small_________.

Correct Answer is Particles

2. The forces of attraction between the particles are _______ in solids, ______ in liquids and _________ in gases.

Correct Answer is Maximum, intermediate, minimum

3. __________ is the change of gaseous state directly to solid state without going through liquid state, and vice-versa.

Correct Answer is Deposition or Desublimation. 

4. Evaporation causes __________.

Correct Answer is Cooling

5. Latent heat of fusion is the amount of heat energy required to change 1 kg of solid into liquid at its ________.

Correct Answer is Melting point

6. Solid, liquid and gas are called the three _______ of matter.

Correct Answer is States

7. The smell of perfume gradually spreads across a room due to ______.

Correct Answer is Diffusion

8. Rapid evaporation depends on the ______ area exposed to atmosphere.

Correct Answer is Surface

9. As the temperature of a system increases, the pressure of the gases ______.

Correct Answer is Increases

10. As the volume of a specific amount of gas decreases, it’s pressure _______.

Correct Answer is Increases

11. As the temperature of a gas decreases, It’s volume ______.

Correct Answer is Decreases

12. Gas molecules at higher temperatures have more _______ than at cooler temperatures.

Correct Answer is Kinetic energy

13. A sponge has minute ________, in which ________ is trapped.

Correct Answer is holes, air.

14. The pressure inside of a sealed tube if you raise the temperature go ______

Correct Answer is Up

15. Forces of attraction in liquids are _______ than in solid.

Correct Answer is Weaker

16. Latent heat of ________ is the amount of heat energy required to change 1 kg of solid into liquid at its melting point.

Correct Answer is fusion

Very Short Answer Questions

Q.1. Name one property which is shown by naphthalene and not by sodium chloride.

Naphthalene undergoes sublimation upon heating i.e. it directly changes into vapours. Whereas Sodium chloride (common salt) does not undergo sublimation. It melts on strong heating.

Q.2. A rubber band changes its shape when stretched. Can it be regarded as solid?

Rubber is a solid. It has elastic property due to which it undergoes change in shape when pressure is applied and regains its original shape when pressure is released.

Q.3. Gases can be compressed but solids cannot. Explain.

In gases, interparticle spaces are quite large. On applying pressure, these spaces decrease and the molecules of gas come closer. As a result, the gases can be compressed. Whereas in solids, particles are compactly packed leaving negligible interparticle space thus solids cannot be compressed.

Q.4. Define latent heat of vaporization.

Latent heat of vaporization is the heat energy required to change 1 kg of a liquid to gas at atmospheric pressure at its boiling point.

Q.5. What happens to the heat energy which is supplied to the solid once it has started melting?

Once the solid has started melting heat energy absorbed is consumed in bringing about the change in state from solid to liquid (overcoming the force of attraction between the particles of solids). The heat absorbed is known as latent heat of fusion.

Q.6.The freezing point of water is 0°C. What is the corresponding temperature on the Kelvin scale?

Temperature on Kelvin scale = 0°C+273 = 273K.

Q.7. Are the melting point temperature of the solid state and the freezing point temperature of the liquid state of a substance different?

No, these are the same. For example, melting point of ice and freezing point of water are both 0°C or 273 K.

Q.8. A substance is in liquid state at room temperature and changes into gas upon heating. What will you call its gaseous state?

The gaseous state of the substance is called vapour. Gaseous state of a substance which exists as liquid also is known as vapour.

Q.9. When a crystal of copper sulphate is placed at the bottom of a beaker containing water, the colour of water slowly becomes blue, why?

Copper sulphate on dissolution in water releases (Cu²⁺ ions) and SO₄^2– ions. Due to diffusion of Cu²⁺ ions the colour of water slowly becomes blue.

Q.10. The boiling point of ethyl alcohol is 78°C. What is the corresponding temperature on kelvin scale?

Temperature on kelvin scale = 78 + 273 = 351 K

Crossword Puzzle

Across
1. BEC stands for Bose-Einstein-______
3. The state consists of super energetic and super excited particles
8. Conversion of solid to vapour is called ______
Down
2. This is the phenomenon of change of a liquid into vapours at any temperature below its boiling point
4. SI unit of Temperature
5. CNG stands ____ natural gas
6. It is the amount of water vapour present in air.
7. LPG stands for ______petroleum gas.

Answer: 

1. Condensation
2. evaporation
3. plasma
4. kelvin
5. Compressed
6. Humidity
7. liquefied
8. sublimation

Multiple Choice Questions (MCQs)

Instruction: Select the correct option for each question.

1. Pressure is defined as:
   a) Force × area
   b) Force / area
   c) Area / force
   d) Mass × acceleration
   Answer: b) Force / area
   Pressure is the force applied per unit area (only the perpendicular component counts).
2. Why do broader bag straps feel more comfortable than narrow ones for the same load?
   a) They reduce the force
   b) They increase pressure
   c) They decrease pressure by increasing area
   d) They change the weight
   Answer: c) They decrease pressure by increasing area
   Same force spread over a larger area gives lower pressure.
3. SI unit of pressure is:
   a) Newton (N)
   b) Joule (J)
   c) Pascal (Pa)
   d) Watt (W)
   Answer: c) Pascal (Pa)
   1 Pa = 1 N/m².
4. Liquid pressure at a point depends mainly on:
   a) Shape of container
   b) Color of liquid
   c) Height (depth) of the liquid column
   d) Total volume of liquid
   Answer: c) Height (depth) of the liquid column
   Greater height above the point means greater pressure.
5. Which activity shows that liquids exert pressure on the walls?
   a) Balloon inflating
   b) Water jetting sideways from holes in a bottle
   c) Magnet attracting iron
   d) Ice melting
   Answer: b) Water jetting sideways from holes in a bottle
   Sideways jets show lateral pressure on walls.
6. Atmospheric pressure is the pressure exerted by:
   a) Water only
   b) Rocks of Earth
   c) Air around us in all directions
   d) Only wind
   Answer: c) Air around us in all directions
   Air molecules press on surfaces from every side.
   Atmospheric Pressure
7. Air moves from a region of:
   a) Low pressure to high pressure
   b) High pressure to low pressure
   c) High temperature to low temperature only
   d) Low density to high density only
   Answer: b) High pressure to low pressure
   Wind is air flowing from high to low pressure.
8. During the day at the coast, a sea breeze blows because:
   a) Sea heats faster than land
   b) Land heats faster; air rises over land creating low pressure
   c) Air pressure over sea is always low
   d) Earth stops rotating
   Answer: b) Land heats faster; air rises over land creating low pressure
   Cooler, high-pressure air from sea flows toward land.
9. High-speed winds between two hanging balloons make them move closer because:
   a) Gravity increases
   b) Pressure between them increases
   c) Pressure between them decreases due to fast air
   d) They gain electric charge
   Answer: c) Pressure between them decreases due to fast air
   Outside higher pressure pushes them together.
10. Lightning is produced when:
    a) Sun heats clouds
    b) Charges in clouds and ground discharge suddenly
    c) Wind speed becomes zero
    d) Air becomes very cold
    Answer: b) Charges in clouds and ground discharge suddenly
    Charge separation in clouds leads to a bright discharge (lightning).

Fill in the Blanks

Instruction: Fill in the blanks with the correct word based on the chapter.

1. Pressure = __________ / area.
   Answer: force
   Only the perpendicular (normal) force is used for pressure.
2. Overhead water tanks are placed high to increase water __________ in the pipes.
   Answer: pressure
   Greater height of water column gives higher outlet pressure.
3. 1 pascal (Pa) equals 1 __________ per square metre.
   Answer: newton
   1 Pa = 1 N/m².
4. Liquids exert pressure at the bottom and also on the __________ of a container.
   Answer: walls
   Pressure acts in all directions.
5. At sea level, typical atmospheric pressure is about 1,013 __________ or 1,013 __________.
   Answer: mb; hPa
   1 mb = 1 hPa = 100 Pa.
6. Air flows from regions of high pressure to regions of __________ pressure.
   Answer: low
   This movement is wind; it stops when pressures equalize.
7. Daytime coastal wind from sea to land is called a __________ breeze.
   Answer: sea
   Nighttime reverse flow is land breeze.
8. Lightning conductors safely carry electric charge into the __________.
   Answer: ground
   They protect buildings by providing a safe path.
9. The calm, low-pressure center of a cyclone is called the __________.
   Answer: eye
   Surrounded by a ring of strongest winds and rain.
10. A sudden rise of sea water pushed by cyclone winds onto land is called a storm __________.
    Answer: surge
    It can flood coastal areas severely.

Cyclone

Very Short Answer Questions

Instruction: Answer the following questions in one line.

1. Why are dam walls broader at the base?
   Answer: Because water pressure increases with depth, so the base must withstand greater sideways pressure.
2. Why aren’t we crushed by atmospheric pressure?
   Answer: Internal body fluids and gases exert equal pressure outward, balancing outside pressure.
3. What causes a sea breeze?
   Answer: Low pressure over warmer land draws in cooler, high-pressure air from the sea.
4. What simple safety rule helps prevent roofs from blowing off in storms?
   Answer: Keep some doors/windows open to equalize inside and outside pressure.
5. What is a thunderstorm?
   Answer: A storm with thunder and lightning due to charge separation in tall clouds.

Dams are build borader at Base

Short Answer Questions

Instruction: Answer the following questions in 2–3 lines.

1. Explain, with an example, how area affects pressure in daily life.
   Answer: Narrow bag straps exert higher pressure (same force on smaller area) causing discomfort, while broad straps reduce pressure and feel comfortable.
2. How does height of a liquid column affect pressure? Mention one application.
   Answer: Greater height gives greater pressure at the bottom (P ∝ depth). Overhead tanks are placed high to supply good water pressure.
3. Describe briefly how winds are formed.
   Answer: Uneven heating creates pressure differences; air flows from high to low pressure. Larger pressure differences produce stronger winds.
4. How does lightning form inside storm clouds?
   Answer: Updrafts and downdrafts make ice and water drops rub and separate charges; a sudden discharge between regions (or to ground) produces lightning.
5. Why are cyclones dangerous? Give two reasons.
   Answer: They bring high-speed winds that damage structures and a storm surge that floods coasts; heavy rains also cause floods and landslides.

Match the Following

Instruction: Match Column A with the correct option in Column B.

Correct Matches:

1. Pascal (Pa) — b) SI unit of pressure
   Explanation: 1 Pa = 1 N/m².
2. Sea breeze — c) Daytime wind from sea toward land
   Explanation: Due to lower pressure over warm land.
3. Balloon experiment — e) Fast air lowers pressure between objects, pushing them together
   Explanation: High-speed air reduces pressure; outside pressure moves balloons inward.
4. Lightning conductor — d) Provides safe path to ground for electric charge
   Explanation: Protects buildings during lightning strikes.
5. Eye of a cyclone — a) Calm center with lowest pressure
   Explanation: Surrounding eyewall has strongest winds and rain.

Q1. Multiple Choice Questions (MCQs)

Instruction: Select the correct option for each question.

1. In science, a force is defined as:
   a) Only a push
   b) Only a pull
   c) A push or a pull
   d) Energy of motion
   Answer: c) A push or a pull
   Any push or pull on an object is called a force.
2. Which of these is NOT an effect of force?
   a) Change of shape
   b) Change of direction
   c) Production of light
   d) Start/stop motion
   Answer: c) Production of light
   Force changes motion or shape; producing light is not a direct effect of force.
3. Forces always involve:
   a) Only one object
   b) Interaction between two objects
   c) Only moving objects
   d) Only heavy objects
   Answer: b) Interaction between two objects
   A force arises from interaction (e.g., hand and table).
4. The SI unit of force is:
   a) Joule (J)
   b) Watt (W)
   c) Newton (N)
   d) Pascal (Pa)
   Answer: c) Newton (N)
   Force is measured in newtons.
5. Friction is a force that:
   a) Aids motion
   b) Always increases speed
   c) Opposes motion between surfaces in contact
   d) Acts only in liquids
   Answer: c) Opposes motion between surfaces in contact
   Friction resists motion; rough surfaces give more friction.
6. Which is a non-contact force?
   a) Muscular force
   b) Friction
   c) Magnetic force
   d) Push with a stick
   Answer: c) Magnetic force
    It acts without physical contact.
7. Gravity is:
   a) Sometimes attractive, sometimes repulsive
   b) Always repulsive
   c) Always attractive
   d) Only acts on Earth
   Answer: c) Always attractive
   Gravitational force only attracts.
8. Weight is measured in:
   a) Kilogram (kg)
   b) Newton (N)
   c) Meter (m)
   d) Joule (J)
   Answer: b) Newton (N)
   Weight is a force; its SI unit is newton.
9. An object floats in a liquid when:
   a) Weight > buoyant force
   b) Weight = buoyant force
   c) Weight < buoyant force
   d) There is no gravity
   Answer: b) Weight = buoyant force
   Floating occurs when upthrust equals weight.

Q2. Fill in the Blanks

Instruction: Fill in the blanks with the correct word based on the chapter.

1. A force is a __________ or a __________.
   Answer: push; pull
   Both pushes and pulls are forces.
2. If an object’s speed or direction changes, a __________ has acted.
   Answer: force
   Explanation: Force causes change in motion or shape.
3. The SI unit of force is the __________ (symbol: N).
   Answer: newton
   Standard unit for force.
4. Friction always acts in a direction __________ to motion.
   Answer: opposite
   It resists motion between surfaces.
5. Forces that act without contact are called __________ forces.
   Answer: non-contact
   Examples: magnetic, electrostatic, gravitational.
6. The force with which Earth pulls objects is called __________.
   Answer: gravity (or gravitational force)
   Gravity attracts objects to Earth.
7. Weight is a __________ and is measured in newtons.
   Answer: force
   Weight = mass × gravitational acceleration.
8. The device used to measure weight (force) in newtons is a __________ balance.
   Answer: spring
   Stretch of the spring indicates force.
9. The upward force exerted by a liquid on an immersed object is called __________ force.
   Answer: buoyant (or upthrust)
   It acts opposite to weight.
10. An object sinks when its __________ is greater than the buoyant force.
    Answer: weight
    If weight > upthrust, the object sinks.

Q3. Short Answer QuestionsInstruction: Answer the following questions in 2–3 lines.

1. How does friction depend on the nature of surfaces?
   Answer: Rough surfaces have more tiny irregularities, leading to higher friction; smooth surfaces have fewer irregularities, so friction is less.
2. Explain why cycling uphill feels harder than cycling downhill.
   Answer: Uphill, you work against gravity and friction, requiring greater muscular force. Downhill, gravity aids motion, so you need little or no pedaling.
3. What does “forces work in pairs” mean?
   Answer: When you push an object, it exerts an equal and opposite force on you. The interaction ends when contact ends.
4. How do we find the least count of a spring balance?
   Answer: Divide the value between two major marks by the number of small divisions between them.
5. Why do streamlined shapes help in air or water?
   Answer: They reduce fluid friction (drag), allowing objects like cars, planes, and boats to move more easily.

Q4. Match the Following

Instruction: Match Column A with the correct option in Column B.

Correct Matches:

1. Muscular force — c) Force due to muscles in humans/animals
   Explanation: Movements like lifting, pushing, and pulling use muscles.
2. Friction — d) Opposes motion between surfaces in contact
   Explanation: It resists sliding/rolling and depends on surface roughness.
3. Magnetic force — e) Acts at a distance between magnets
   Explanation: Magnets attract/repel without contact.
4. Weight — b) Pull of Earth on an object
   Explanation: Weight is gravitational force; measured in newtons.
5. Buoyant force — a) Upward force by a liquid
   Explanation: Liquids push up on immersed objects; this is upthrust.

Q5. Application/Reasoning (Short Problems)

Instruction: Answer the following briefly in 2–3 lines.

1. A wooden block is pushed on a rough table and stops after some distance. Why?
   Answer: Friction between the block and table opposes motion and converts kinetic energy to heat, bringing the block to rest.
2. A 1 kg object has a weight of about 10 N on Earth. What will be its weight on the Moon (g ≈ 1.6 m/s²)?
   Answer: About 1.6 N. Explanation: Weight = mass × g = 1 kg × 1.6 m/s².
3. A spring balance has marks 0 to 5 N with 10 equal divisions between each newton. What is its least count?
   Answer: 0.1 N per division. Explanation: 1 N ÷ 10 divisions = 0.1 N.
4. Two balloons rubbed with wool repel each other. Which force is acting and why?
   Answer: Electrostatic force; both balloons have like static charges, so they repel.
5. A stone sinks in water but a sealed empty plastic bottle floats. Why?
   Answer: The stone’s weight is greater than buoyant force, so it sinks. The bottle’s average density is less and upthrust balances its weight, so it floats.

Q1. Multiple Choice Questions (MCQs)

Instruction: Select the correct option for each question.

1. What did Oersted discover in 1820?
   a) Heating effect of current
   b) Electric charge of Earth
   c) Magnetic effect of electric current
   d) Structure of dry cell
   Answer: c) Magnetic effect of electric current
   Oersted observed that a current-carrying wire deflects a compass needle, proving current creates a magnetic field.
2. Which instrument can detect the magnetic field around a current-carrying wire?
   a) Vernier caliper
   b) Magnetic compass
   c) Thermometer
   d) Barometer
   Answer: b) Magnetic compass
   The compass needle deflects when near a current-carrying conductor.
3. An electromagnet is:
   a) A permanent magnet made of steel
   b) A coil with an iron core that becomes a magnet when current flows
   c) A bar magnet with fixed poles
   d) A coil without any core
   Answer: b) A coil with an iron core that becomes a magnet when current flows
   Electromagnets work only when current is ON.
4. Which change will increase the strength of an electromagnet?
   a) Using fewer turns of wire
   b) Reducing current
   c) Inserting a soft iron core
   d) Removing the battery
   Answer: c) Inserting a soft iron core
   Strength increases with iron core, more turns, and higher current.
   
5. Lifting electromagnets are used mainly to:
   a) Measure current
   b) Lift and move heavy steel in scrap yards
   c) Store electrical energy
   d) Heat metals
   Answer: b) Lift and move heavy steel in scrap yards
   They can be switched ON to lift and OFF to release.
6. When current passes through a nichrome wire, it becomes hot due to:
   a) Absence of resistance
   b) Magnetic shielding
   c) Cooling effect of current
   d) Heating effect of electric current
   Answer: d) Heating effect of electric current
   Electrical energy converts to heat because nichrome has high resistance.
7. Which factor increases heat in a wire for the same time?
   a) Thicker wire and less current
   b) Shorter wire and less current
   c) Longer, thinner wire with more current
   d) No resistance in wire
   Answer: c) Longer, thinner wire with more current
   Heat increases with resistance, current, length, and time.
8. In a simple voltaic (galvanic) cell, electricity is produced by:
   a) Chemical reactions between metals and electrolyte
   b) Friction 
   c) Magnetic induction
   d) Solar energy
   Answer: a) Chemical reactions between metals and electrolyte
   The reaction releases energy as electrical current.
9. In a dry cell, the negative terminal is the:
   a) Zinc container
   b) Carbon rod 
   c) Electrolyte paste
   d) Air gap
   Answer: a) Zinc container
   The zinc can acts as the negative electrode; carbon rod is positive.
10. Lithium-ion batteries are:
    a) Single-use only
    b) Not suitable for recharging
    c) Only for torches and clocks
    d)  Rechargeable and used in phones/laptops
    Answer: d) Rechargeable and used in phones/laptops
     Li-ion batteries are common rechargeable batteries in modern devices.

Q2. Fill in the Blanks

Instruction: Fill in the blanks with the correct word based on the chapter.

1. A current-carrying conductor produces a __________ field around it.
   Answer: magnetic
   Current generates a magnetic field.
2. The deflection of a __________ needle shows the presence of current nearby.
   Answer: compass
   The compass detects magnetic fields.
3. An iron nail wrapped with a current-carrying coil becomes an __________.
   Answer: electromagnet
   It behaves like a magnet only when current flows.
4. Reversing the direction of current reverses the __________ of an electromagnet.
   Answer: polarity (poles)
   North and South poles swap when current direction changes.
5. The heating of a wire due to current is called the __________ effect of electric current.
   Answer: heating
   Electrical energy changes to heat energy.
6. __________ wire is used as a heating element because it has high resistance.
   Answer: Nichrome
   High resistance produces more heat.
7. A device that produces electricity by a chemical reaction is called an electric __________.
   Answer: cell
   Cells convert chemical energy to electrical energy.
8. In a dry cell, the electrolyte is a moist __________.
   Answer: paste
   Hence called a “dry” cell.
9. In the lemon battery, the lemon juice acts as an __________.
   Answer: electrolyte
   The conducting liquid enables the reaction.
10. Multiple cells connected together form a __________.
    Answer: battery
    A battery supplies higher voltage/current than a single cell.

Q3. Very Short Answer Questions (1 line)

Instruction: Answer the following questions in one line.

1. What simple observation shows the magnetic effect of current?
   Answer: A compass needle deflects near a current-carrying wire.
2. Name any one factor that increases the strength of an electromagnet.
   Answer: Increasing the number of turns in the coil.
3. What happens to an electromagnet when the current is switched off?
   Answer: It loses its magnetism.
4. What is resistance?
   Answer: The opposition offered by a material to the flow of electric current.
5. Which terminal is at the center of a dry cell?
   Answer: The carbon rod (positive terminal).

Q4. Short Answer Questions

Instruction: Answer the following questions in 2–3 lines.

1. State Oersted’s finding and its importance.
   Answer: Oersted found that a current-carrying wire deflects a compass needle, proving that electric current creates a magnetic field. This linked electricity and magnetism and led to electromagnetism-based technologies.
2. How can you make a simple electromagnet at home?
   Answer: Wrap insulated wire around a soft iron nail, connect the wire ends to a cell, and switch ON. The nail attracts iron objects while current flows; it stops when switched OFF.
3. Mention two ways to increase the heat produced in a wire.
   Answer: Use a longer/thinner high-resistance wire (like nichrome) and increase the current (more cells). Heat also increases with time of current flow.
4. What is the basic structure of a dry cell?
   Answer: A zinc container (negative) filled with electrolyte paste and a central carbon rod (positive). It is a commonly used single-use cell.
5. How can you light an LED with lemons?
   Answer: Insert a copper strip and an iron nail into each lemon (electrodes). Connect several lemon cells in series to increase voltage; ensure correct LED polarity.

Q5. Match the Following 

Instruction: Match Column A with the correct option in Column B.

Ans: 

1. Oersted — c) Current creates magnetic field
   He discovered the magnetic effect of electric current.
2. Electromagnet — e) Coil with iron core works only when current flows
   It becomes magnetic only when powered.
3. Nichrome — a) Heating element material
   Nichrome’s high resistance makes it ideal for heaters.
4. Lifting crane magnet — d) Switchable industrial magnet
   Used to lift/drop heavy steel by switching current ON/OFF.
5. Zinc can (dry cell) — b) Negative terminal
   In a dry cell, the zinc container acts as the negative electrode.

Q1. Multiple Choice Questions (MCQs)

Instruction: Select the correct option for each question.

1. According to WHO, health means:
   a) Only absence of disease
   b) Physical fitness only
   c) Complete physical, mental, and social well-being
   d) Ability to work hard
   Answer: c) Complete physical, mental, and social well-being
   WHO defines health as overall well-being, not merely absence of illness.
2. Which is a sign, not a symptom?
   a) Pain
   b) Tiredness
   c) Dizziness
   d) Fever
   Answer: d) Fever
   Signs are measurable/observable (e.g., temperature); symptoms are subjective feelings.
3. Which disease is non-communicable?
   a) Typhoid
   b) Dengue
   c) Diabetes
   d) Chickenpox
   Answer: c) Diabetes
   Non-communicable diseases are not caused by pathogens and do not spread person to person.
4. Which habit helps prevent communicable diseases?
   a) Skipping breakfast
   b) Sharing towels
   c) Washing hands with soap
   d) Sleeping very late
   Answer: c) Washing hands with soap
   Good hygiene reduces spread of germs.
5. Which statement about antibiotics is correct?
   a) They kill viruses like flu
   b) They treat protozoan diseases
   c) They kill bacteria
   d) They are safe to take without prescription
   Answer: c) They kill bacteria
   Antibiotics act against bacteria, not viruses or protozoa.
6. Who discovered the first antibiotic, penicillin?
   a) Edward Jenner
   b) Alexander Fleming
   c) Robert Koch
   d) Louis Pasteur
   Answer: b) Alexander Fleming
   In 1928, Fleming observed mould killing bacteria and identified penicillin.
7. Vaccines protect by:
   a) Killing pathogens directly in the body
   b) Teaching the immune system to recognize germs
   c) Giving energy to white blood cells
   d) Replacing antibiotics
   Answer: b) Teaching the immune system to recognize germs
   Vaccines create acquired immunity by training the immune system.
8. Which factor commonly increases risk of NCDs?
   a) Playing outdoors
   b) Balanced diet
   c) Longer lifespans and less physical activity
   d) Handwashing
   Answer: c) Longer lifespans and less physical activity
   Lifestyle and aging contribute to higher NCD burden.
9. Which practice from Ayurveda supports holistic health?
   a) Variolation
   b) Dinacharya and ritucharya
   c) Overuse of antibiotics
   d) Skipping meals
   Answer: b) Dinacharya and ritucharya
   Ayurveda recommends daily and seasonal routines for balance.
10. AQI is used to measure:
    a) Water purity
    b) Body temperature
    c) Air quality
    d) Sleep quality
    Answer: c) Air quality
    Air Quality Index indicates how clean or polluted the air is.

Q2. Fill in the Blanks

Instruction: Fill in the blanks with the correct word based on the chapter.

1. Health includes physical, mental, and ______ well-being.
   Answer: social
   WHO emphasizes social well-being along with body and mind.
2. Headache is a ______ experienced by the patient.
   Answer: symptom
   Symptoms are felt by the person.
3. A measurable change like a rash or swelling is called a ______.
   Answer: sign
   Signs are observed or measured by others.
4. Diseases that spread from person to person are called ______ diseases.
   Answer: communicable
   Communicable diseases are caused by pathogens and can spread.
5. Diseases like cancer and asthma that do not spread are ______ diseases.
   Answer: non-communicable
   NCDs are linked to lifestyle, environment, or body functions.
6. The body’s ability to fight diseases is called ______.
   Answer: immunity
   Immunity is the defense capacity against pathogens.
7. Using weakened or inactive germs to train the body’s defense is called a ______.
   Answer: vaccine
   Vaccines create acquired immunity against specific diseases.
8. Taking antibiotics without need can lead to antibiotic ______.
   Answer: resistance
   Misuse allows bacteria to adapt and survive the drug.
9. Building and using toilets helps prevent diseases spread through contaminated ______.
   Answer: water
   Sanitation prevents water-borne diseases like diarrhoea.
10. Practising ______, like deep breathing, supports mental health in Ayurveda.
    Answer: mindfulness (or yoga/pranayama)
    Mindfulness, yoga, and pranayama promote calm and balance.

Q3. Very Short Answer Questions 

Instruction: Answer the following questions in one line.

1. What does WHO say about health?
   Answer: It is complete physical, mental, and social well-being, not just absence of disease.
2. Name one vector that spreads communicable diseases.
   Answer: Mosquito.
3. What is the term for the body’s natural defense system?
   Answer: Immune system.
4. Which discovery led to modern antibiotics?
   Answer: Penicillin discovered by Alexander Fleming in 1928.
5. What does AQI stand for?
   Answer: Air Quality Index.

Q4. Short Answer Questions 

Instruction: Answer the following questions in 2–3 lines.

1. How did screen time and loneliness affect student’s health?
   Answer: Excessive screen time and loneliness caused headaches, weight loss, and sleep problems—showing links between mental and physical health. Counselling and making friends improved his well-being.
2. How do communicable diseases spread through air?
   Answer: Infected people release droplets with pathogens by coughing/sneezing/talking; others inhale them and get infected (e.g., flu, TB).
3. Why should we finish a full course of antibiotics?
   Answer: Stopping early leaves some bacteria alive, which can become resistant, making future infections harder to treat.
4. How does community sanitation improve health?
   Answer: Building and using toilets, reducing open defecation, and proper waste disposal stop germs from contaminating water and food, lowering diarrhoeal diseases.
5. Why are relationships important for health?
   Answer: Supportive friendships and family time reduce stress, improve mood, and support mental and social well-being.

Q5. Match the Following

Instruction: Match Column A with the correct option in Column B.

Correct Matches:

1. Edward Jenner — b) Smallpox vaccine pioneer
   Jenner introduced the first vaccine using cowpox, leading to smallpox eradication.
2. Antibiotics — d) Kill bacterial pathogens
   Antibiotics act against bacteria, not viruses.
3. Mosquito nets — e) Prevent vector-borne diseases
   Nets prevent mosquitoes from biting humans and thus reduce transmission of malaria/dengue.
4. Dinacharya — a) Daily routine in Ayurveda
   Daily habits for balanced body and mind in Ayurveda.
5. AQI — c) Measures air pollution level
   Air Quality Index shows how clean or polluted the air is.

Multiple Choice Questions (MCQs)

Instruction: Select the correct option for each question.

1. Who first used the term “cell” after observing thin slices of cork?
   a) Antonie van Leeuwenhoek
   b) Robert Hooke
   c) Louis Pasteur
   d) Ananda Mohan Chakrabarty
   Answer: b) Robert Hooke
    In 1665, Robert Hooke observed cork under a microscope and named the tiny compartments “cells.”
2. Which tool allows us to view objects too small to be seen with the naked eye?
   a) Telescope
   b) Periscope
   c) Microscope
   d) Binoculars
   Answer: c) Microscope
   Microscopes magnify tiny objects, revealing details invisible to unaided eyes.
3. A round-bottom flask filled with water can act as:
   a) A lens/magnifier
   b) A telescope
   c) A prism
   d) A mirror
   Answer: a) A lens/magnifier
   The curved water-filled flask bends light like a lens, making objects appear larger.
4. Which cell structure is present in plant cells but absent in animal cells?
   a) Nucleus
   b) Cell membrane
   c) Cell wall
   d) Cytoplasm
   Answer: c) Cell wall
   Plant cells have a rigid cell wall; animal cells do not.
5. Which statement is true about cheek cells?
   a) They are rectangular and have a cell wall.
   b) They have a large central vacuole. 
   c) They contain chloroplasts.
   d) They are polygon-shaped and lack a cell wall.
   Answer: d) They are polygon-shaped and lack a cell wall.
   Cheek cells are animal cells—irregular, flat, with no cell wall.
6. Which part of the cell controls all activities like growth and division?
   a) Cytoplasm
   b) Nucleus
   c) Cell membrane
   d) Vacuole
   Answer: b) Nucleus
   Explanation: The nucleus acts as the control center of the cell.
7. Spirulina is best described as:
   a) A microalga used as a superfood
   b) A nitrogen-fixing bacterium
   c) A fungus used in bread making
   d) A protozoan that causes disease
   Answer: a) A microalga used as a superfood
   Spirulina is rich in protein and vitamin B12 and is farmed as a dietary supplement.
8. Which microorganism helps convert milk into curd?
   a) Yeast
   b) Rhizobium
   c) Lactobacillus
   d) Amoeba
   Answer: c) Lactobacillus
   Lactobacillus converts lactose into lactic acid, forming curd.

Fill in the BlanksInstruction: Fill in the blanks with the correct word based on the chapter.

1. The jelly-like substance inside a cell where life processes occur is the ______.
   Answer: cytoplasm
   Cytoplasm contains nutrients and is the site of many cell activities.
2. The thin, flexible boundary of a cell that controls entry and exit is the ______ ______.
   Answer: cell membrane
   The cell membrane is porous and selectively allows substances in and out.
3. In onion peel cells, staining with ______ helps make the cells visible.
   Answer: safranin
   Red safranin stain highlights cell parts under a microscope.
4. Cheek cells are commonly stained with ______ ______.
   Answer: methylene blue
   Methylene blue makes the nucleus and cell boundaries more visible.
   Cheek Cells
5. The bacteria that fix nitrogen in legume root nodules are called ______.
   Answer: Rhizobium
    Rhizobium converts atmospheric nitrogen into usable forms for plants.
6. The process by which yeast makes dough rise by releasing carbon dioxide is called ______.
   Answer: fermentation
   Yeast ferments sugars to produce CO2, making dough fluffy.
7. Bacterial genetic material without a nuclear membrane is found in a region called the ______.
   Answer: nucleoid
   Bacteria lack a well-defined nucleus; DNA lies in the nucleoid region.

Very Short Answer Questions 

Instruction: Answer the following questions in one line.

1. Who is known as the Father of Microbiology?
   Answer: Antonie van Leeuwenhoek.
2. What do chloroplasts contain that enables photosynthesis?
   Answer: Chlorophyll.
3. Name the large storage cavity commonly found in plant cells.
   Answer: Vacuole.
4. What shape are muscle cells typically described as?
   Answer: Spindle-shaped (tapered at both ends).
5. Which organisms decompose waste to form manure?
   Answer: Bacteria and fungi (microbes).

Short Answer QuestionsInstruction: Answer the following questions in 2–3 lines.

1. Why are some microorganisms invisible to the naked eye?
   Answer: They are extremely small—often single-celled—and fall below the resolution limit of human vision. Microscopes are needed to magnify them for observation.
2. How does high salt or sugar preserve pickles and murabbas?
   Answer: High salt/sugar creates conditions that draw water out of microbial cells (osmotic effect), preventing their growth and spoilage.
3. How do nerve cells (neurons) suit their function?
   Answer: Neurons are long and branched, allowing rapid transmission of messages over distances in the body.
4. Why is warm milk preferred for curd formation?
   Answer: Warm conditions help Lactobacillus multiply and convert lactose into lactic acid faster, thickening the milk.
5. What role do microalgae play in Earth’s oxygen supply?
   Answer: Microalgae perform photosynthesis and release a major share of Earth’s oxygen, supporting life and aquatic food chains.

Match the Following 

Instruction: Match Column A with the correct option in Column B.

Correct Matches:

1. Yeast — b) Fermentation and rising of dough
   Explanation: Yeast ferments sugars, releasing CO2 that makes dough rise.
2. Robert Hooke — e) Coined the term “cell”
   Explanation: He named the cork compartments “cells” after observing them.
3. Rhizobium — c) Nitrogen fixation in legume roots
   Explanation: Rhizobium in root nodules converts atmospheric nitrogen into plant-usable forms.
4. Methane — d) Main component of biogas
   Explanation: Anaerobic microbial action produces methane, a fuel.
5. Chloroplast — a) Photosynthesis in plant cells
   Explanation: Chloroplasts contain chlorophyll and perform photosynthesis.

Multiple Choice Questions (MCQs)

Instruction: Select the correct option for each question.

1. According to this chapter, what starts every good scientific investigation?
   a) Expensive lab equipment
   b) Memorising facts
   c) Asking focused “Why?” and “How?” questions
   d) Copying others’ experiments
   Answer: c) Asking focused “Why?” and “How?” questions
   Curiosity drives science; good questions lead to investigations.
2. What does “controlling variables” mean in an experiment like puffing a puri?
   a) Changing many things at once
   b) Changing nothing at all
   c) Changing only one factor while keeping others the same
   d) Ignoring measurements
   Answer: c) Changing only one factor while keeping others the same
   This helps identify which factor causes the observed effect.
3. In the “roots and kites” symbol, roots mainly remind us to:
   a) Fly kites higher
   b) Rely only on imagination
   c) Stay grounded in careful observations and facts
   d) Ignore data
   Answer: c) Stay grounded in careful observations and facts
   Roots = solid observations; kites = creative ideas.
   Roots and Kites
4. Which topic best illustrates “the invisible world”?
   a) Moon phases
   b) Microbes in a drop of water
   c) Cyclones
   d) Mirrors and lenses
   Answer: b) Microbes in a drop of water
   They are unseen without microscopes.
5. Which is NOT a correct match of topic to key idea?
   a) Health — immunity and vaccines help prevent disease
   b) Electricity — only lighting bulbs, not heating
   c) Forces — change speed/direction of objects
   d) Pressure and winds — air moves from high to low pressure
   Answer: b) Electricity — only lighting bulbs, not heating
   Electricity also has heating and magnetic effects.
6. What is the main reason for doing “one change at a time” in an experiment?
   a) To finish faster
   b) To make it more exciting
   c) To clearly link cause and effect
   d) To avoid writing observations
   Answer: c) To clearly link cause and effect
   This makes conclusions reliable.
7. Which tool of science is most directly used when you record time to puff a puri?
   a) Classifying
   b) Measuring
   c) Predicting without testing
   d) Guessing
   Answer: b) Measuring
   Measurement turns observations into usable data.
8. Why do we learn about Moon phases and eclipses under “keeping time with the skies”?
   a) For decoration
   b) To ignore calendars
   c) Because celestial motions helped humans define days, months, years
   d) To stop using watches
   Answer: c) Because celestial motions helped humans define days, months, years
   Sky observations underpin calendars.

Fill in the Blanks

Instruction: Fill in the blanks with the correct word based on the chapter.

1. Writing down what you see is called __________.
   Answer: recording (or observation)
   Notes make results reliable and comparable.
2. Health is complete physical, mental, and __________ well-being.
   Answer: social
   This is the WHO view of health.
3. Air moves from high pressure to __________ pressure to form winds.
   Answer: low
   Pressure differences drive air flow.
4. All matter is made of tiny __________ that behave differently in solids, liquids, and gases.
   Answer: particles
   Arrangement and motion vary by state.
5. Light can __________ from mirrors and __________ through lenses.
   Answer: reflect; refract
   These behaviors help us see and focus images.
6. Watching the Sun and Moon helped humans create __________ to track days and months.
   Answer: calendars
   Sky motions define time units.
7. Science balances careful observation with __________ thinking.
   Answer: creative
   Both are needed for discovery.

Very Short Answer Questions

Instruction: Answer the following questions in one line.

1. What two words best start a scientific investigation?
   Answer: “Why?” and “How?”
2. In an experiment, what do we call the factor we deliberately change?
   Answer: The variable (independent variable).
3. Name one measurement you could take in the puri experiment.
   Answer: Time taken to puff (in seconds).
4. Give one reason to keep a science notebook.
   Answer: To record observations and compare results later.

Short Answer Questions

Instruction: Answer the following questions in 2–3 lines.

1. Why is changing only one variable at a time important?
   Answer: It isolates cause and effect. If only one factor changes, we can confidently link any outcome difference to that factor.
2. How does this chapter connect small observations to big ideas?
   Answer: It moves from simple experiments (like puris puffing) to major topics (health, forces, climate), showing the same scientific method applies everywhere.
3. What skills are highlighted as core to doing science well?
   Answer: Asking focused questions, controlling variables, careful observation, measurement, recording, and reasoning from evidence.
4. Give two example variables for the puri activity.
   Answer: Oil temperature and dough thickness (keep other factors constant while testing one).

Poori puffing up in Oil

Match the Following

Instruction: Match Column A with the correct option in Column B.

Ans:

1. Curiosity — d) Asking Why/How to start inquiry
   Explanation: Questions trigger investigations.
2. Variable — a) Factor you change in a fair test
   Explanation: Only one variable changes at a time.
3. Observation/Recording — c) Careful noting of what happens
   Explanation: Data makes conclusions reliable.
4. Roots (symbol) — e) Grounded in facts and evidence
   Explanation: Stay connected to observations.
5. Kites (symbol) — b) Creative ideas and imagination
   Explanation: Let thinking soar to new possibilities.