📌 How to Use
First read the questions carefully using the Read section. Use the Details button to understand concepts clearly. After completing reading, click Practice Quiz to test yourself.
📘 Study MCQs
Q1. The transfer of heat by the movement of a fluid is called ______. Heat Transfer
• Conduction
• Convection
• Radiation
• Insulation
Answer: Convection
Convection is the mode of heat transfer in which heat moves from one place to another by the actual movement of the heated particles of a fluid (liquid or gas).
Q2. In which mode of heat transfer does the medium itself move from one place to another? Heat Transfer
• Conduction
• Convection
• Radiation
• Expansion
Answer: Convection
Unlike conduction where particles vibrate in place, convection involves the bulk movement of the fluid particles themselves.
Q3. Convection currents in water can be demonstrated by heating water containing ______. Experiment
• Sand
• Sugar
• A few drops of ink or potassium permanganate crystals
• Salt
Answer: A few drops of ink or potassium permanganate crystals
Colored dyes like ink or potassium permanganate crystals help visualize the path of convection currents as the heated water rises and cools water sinks.
Q4. When water is heated, the warmer part of the water ______. Science
• Sinks down
• Expands and rises
• Contracts
• Remains where it is
Answer: Expands and rises
On heating, water expands, becomes less dense, and rises. The cooler, denser water from the sides moves down to take its place, setting up a convection current.
Q5. The circulating movement of liquid or gas due to uneven heating is called a ______. Heat Transfer
• Wind current
• Convection current
• Electric current
• Ocean current
Answer: Convection current
A convection current is the circular flow of a fluid caused by the rise of warmer, less dense fluid and the fall of cooler, denser fluid.
Q6. A convection tube filled with water demonstrates convection by showing that ______. Experiment
• Water conducts heat well
• Heated water rises and cool water sinks
• Water evaporates quickly
• Water is transparent
Answer: Heated water rises and cool water sinks
When one side of the convection tube is heated, the water on that side rises, and a dye added to the water shows the complete circular path of the convection current .
Q7. The best evidence of convection in air is provided by ______. Daily Life
• A fan
• Sea breezes and land breezes
• A hair dryer
• Smoke from a chimney
Answer: Sea breezes and land breezes
Sea and land breezes are large-scale natural phenomena caused by convection currents in air due to the uneven heating of land and water.
Q8. The process of convection in air is responsible for the formation of ______. Nature
• Rainbows
• Winds and breezes
• Earthquakes
• Tides
Answer: Winds and breezes
Winds are caused by the movement of air from high-pressure areas to low-pressure areas, which are created by convection currents set up by the uneven heating of the Earth’s surface .
Q9. In a convection current, warm air rises because it is ______. Science
• Denser
• Less dense
• Heavier
• Cooler
Answer: Less dense
When air is heated, it expands, becomes less dense, and weighs less for the same volume. This lighter air rises above the cooler, denser air.
Q10. When air is heated, it ______. Science
• Contracts and sinks
• Expands and rises
• Becomes heavier
• Remains unchanged
Answer: Expands and rises
Heating causes air molecules to move faster and spread apart, increasing volume and decreasing density, which makes the warm air rise.
Q11. Sea breeze blows during the ______. Nature
• Daytime
• Night-time
• Early morning
• Midnight
Answer: Daytime
Sea breeze occurs during the day when the land heats up faster than the sea, causing warm air over land to rise and cool air from the sea to rush in .
Q12. Land breeze blows during the ______. Nature
• Daytime
• Night-time
• Afternoon
• Noon
Answer: Night-time
Land breeze occurs at night when the land cools down faster than the sea, causing cool, dense air over land to move towards the warmer sea .
Q13. During the day, the air over the land becomes ______. Nature
• Cooler and denser
• Hotter and lighter
• Heavier
• Moist
Answer: Hotter and lighter
Land heats up more quickly than water during the day. The air above the land gets heated, expands, becomes lighter, and rises.
Q14. During a sea breeze, the wind blows from ______. Nature
• Land to sea
• Sea to land
• Mountains to valleys
• East to west
Answer: Sea to land
The cool, high-pressure air from the sea moves towards the low-pressure area created over the warm land, resulting in a sea breeze .
Q15. During a land breeze, the wind blows from ______. Nature
• Sea to land
• Land to sea
• North to south
• West to east
Answer: Land to sea
At night, the land becomes cooler, creating a high-pressure area. The air moves from the land towards the relatively warmer, low-pressure area over the sea .
Q16. The main reason for the formation of sea and land breezes is ______. Nature
• The rotation of the Earth
• The difference in the heating and cooling rates of land and water
• The gravitational pull of the moon
• The salinity of the sea
Answer: The difference in the heating and cooling rates of land and water
Land has a lower specific heat capacity, so it heats up and cools down much faster than water. This difference creates the pressure variations that drive these breezes .
Q17. Which of the following is a good conductor of heat? Materials
• Wood
• Plastic
• Iron
• Cork
Answer: Iron
Metals like iron are good conductors of heat, meaning they allow heat to pass through them easily.
Q18. Which of the following is a poor conductor of heat (an insulator)? Materials
• Copper
• Aluminium
• Steel
• Plastic
Answer: Plastic
Plastic is a poor conductor of heat, also known as an insulator. It does not allow heat to pass through it easily.
Q19. The materials which allow heat to pass through them easily are called ______. Materials
• Insulators
• Conductors
• Radiation
• Convectors
Answer: Conductors
Conductors are materials that transfer heat energy readily from one particle to another. Most metals are good conductors.
Q20. The materials which do not allow heat to pass through them easily are called ______. Materials
• Conductors
• Insulators
• Transparent
• Radiators
Answer: Insulators
Insulators are materials that do not transfer heat easily. Wood, plastic, and air are common examples of insulators.
Q21. The phenomenon by which heat is transferred from the sun to the earth is called ______. Heat Transfer
• Conduction
• Convection
• Radiation
• Reflection
Answer: Radiation
Radiation is the mode of heat transfer that does not require any medium and can travel through the vacuum of space.
Q22. Dark-coloured surfaces are ______ absorbers of heat. Properties
• Good
• Poor
• Slow
• Moderate
Answer: Good
Dark and dull surfaces absorb almost all the heat radiation that falls on them, making them very good absorbers of heat.
Q23. Light-coloured surfaces are ______ reflectors of heat. Properties
• Poor
• Good
• Average
• No
Answer: Good
Light-coloured and shiny surfaces reflect most of the heat radiation that falls on them, making them poor absorbers but good reflectors.
Q24. Which type of surface is the best emitter of heat radiation? Properties
• Shiny white
• Dull black
• Transparent
• Polished silver
Answer: Dull black
Good absorbers of heat are also good emitters of heat. Therefore, a dull black surface is both a good absorber and a good emitter.
Q25. The degree of hotness or coldness of a body is called its ______. Basic Science
• Heat
• Temperature
• Mass
• Volume
Answer: Temperature
Temperature is a measure that indicates how hot or cold an object is. It determines the direction of heat flow.
Q26. The device used to measure temperature is called a ______. Measurement
• Barometer
• Thermometer
• Hydrometer
• Voltmeter
Answer: Thermometer
A thermometer is a device that measures the temperature of a substance or an object .
Q27. The Celsius scale is also known as the ______ scale. Temperature Scales
• Fahrenheit
• Kelvin
• Centigrade
• Absolute
Answer: Centigrade
The Celsius scale, originally called the centigrade scale, is defined by 100 degrees between the freezing and boiling points of water .
Q28. On the Celsius scale, the lower fixed point (freezing point of water) is ______. Temperature Scales
• 32°C
• 0°C
• 100°C
• -273°C
Answer: 0°C
The freezing point of pure water at standard pressure is defined as 0 degrees on the Celsius scale.
Q29. On the Celsius scale, the upper fixed point (boiling point of water) is ______. Temperature Scales
• 0°C
• 32°C
• 100°C
• 212°C
Answer: 100°C
The boiling point of pure water at standard pressure is defined as 100 degrees on the Celsius scale.
Q30. The temperature of a healthy human body is about ______. Health
• 0°C
• 37°C
• 50°C
• 100°C
Answer: 37°C
The normal average body temperature is 37°C or 98.6°F.
Q31. Which of the following is an example of a good insulator? Materials
• Iron rod
• Copper vessel
• Woollen clothes
• Aluminium sheet
Answer: Woollen clothes
Wool contains air trapped between its fibres. Air is a poor conductor of heat, making woollen clothes a good insulator that keeps us warm.
Q32. The kink in a clinical thermometer prevents the ______ from falling back on its own. Design
• Glass
• Mercury
• Scale
• Bulb
Answer: Mercury
The kink is a constriction that breaks the mercury column, preventing the mercury from flowing back into the bulb until it is shaken down.
Q33. A laboratory thermometer differs from a clinical thermometer because it lacks a ______. Comparison
• Bulb
• Scale
• Kink
• Mercury
Answer: Kink
Laboratory thermometers do not have a kink because they are used to measure the temperature of a substance continuously and need to show the current temperature accurately.
Q34. Which of the following is a liquid crystal thermometer used for? Practical Use
• Measuring high temperatures in a furnace
• Measuring body temperature with a forehead strip
• Measuring room temperature
• Measuring the temperature of boiling water
Answer: Measuring body temperature with a forehead strip
Liquid crystal thermometers, often used as forehead strips, contain heat-sensitive crystals that change colour to indicate temperature.
Q35. The range of a laboratory thermometer is generally ______. Practical Use
• 35°C to 42°C
• -10°C to 110°C
• 0°C to 50°C
• 20°C to 30°C
Answer: -10°C to 110°C
Laboratory thermometers have a wide range to accommodate various experiments, typically from -10°C to 110°C.
Q36. In which of the following is heat transferred by convection? Heat Transfer
• A metal rod getting hot
• Boiling water in a pan
• Sun’s rays reaching Earth
• A spoon in a cup of tea getting hot
Answer: Boiling water in a pan
In boiling water, the hot water at the bottom rises to the top and cool water sinks, creating convection currents.
Q37. The air conditioner in a room is usually fitted near the ceiling because it ______. Daily Life
• Cools the incoming air
• Allows the cool air to descend and set up convection currents
• Looks better
• Saves electricity
Answer: Allows the cool air to descend and set up convection currents
Cool air is denser and sinks. By placing the AC near the ceiling, the cool air can descend, pushing the warm air upwards to be cooled, thus setting up a convection current.
Q38. Room heaters are usually placed on the floor because ______. Daily Life
• They are heavy
• They need to be near a power point
• Hot air rises and sets up convection currents
• They are safer on the floor
Answer: Hot air rises and sets up convection currents
Hot air from the heater rises, and the cool air from the upper parts of the room moves down to take its place. This creates a convection current that warms the entire room.
Q39. During a sea breeze, the air above the sea is ______ than the air above the land. Nature
• Warmer
• Cooler
• Drier
• More humid
Answer: Cooler
During the day, water heats up more slowly than land, so the air above the sea remains cooler and denser than the air above the land .
Q40. The specific heat capacity of land is ______ than that of water. Nature
• Higher
• Lower
• The same
• Double
Answer: Lower
Land has a lower specific heat capacity, which means it requires less heat to raise its temperature and loses heat more quickly than water .
Q41. The process in which heat is transferred without any medium is called ______. Heat Transfer
• Conduction
• Convection
• Radiation
• Conductor
Answer: Radiation
Radiation is the only mode of heat transfer that can occur through a vacuum, as it uses electromagnetic waves.
Q42. In a thermos flask, the vacuum between the two walls prevents heat loss by ______. Design
• Conduction and Convection
• Radiation only
• Conduction only
• Convection only
Answer: Conduction and Convection
A vacuum has no particles, so it prevents heat transfer by both conduction (which needs a material medium) and convection (which needs fluid movement).
Q43. The shiny silvered surfaces in a thermos flask reduce heat loss by ______. Design
• Conduction
• Convection
• Radiation
• Expansion
Answer: Radiation
The silvered surfaces reflect the heat radiation back into the liquid (or outwards, if the liquid is cold), thus minimising heat transfer by radiation.
Q44. Which of the following is the best example of a heat conductor? Materials
• Cork
• Glass
• Aluminium
• Sponge
Answer: Aluminium
Aluminium is a metal and is an excellent conductor of heat, which is why it is used to make cooking utensils.
Q45. Which of the following is the best example of a heat insulator? Materials
• Iron
• Copper
• Steel
• Air
Answer: Air
Air is a very poor conductor of heat and is used as an insulator in many things, like wool, feathers, and double-paned windows.
Q46. The formation of clouds and thunderstorms is associated with strong ______. Nature
• Conduction currents
• Convection currents
• Radiation
• Reflection
Answer: Convection currents
Warm, moist air rises rapidly due to strong convection currents. As it cools, the water vapour condenses to form clouds and can lead to thunderstorms .
Q47. To demonstrate convection in air, you can hold a ______. Experiment
• Thermometer near a candle flame
• Pinwheel above a lighted candle
• Metal rod in a flame
• Glass of water in the sun
Answer: Pinwheel above a lighted candle
The rising hot air from the candle will strike the blades of the pinwheel, causing it to rotate. This shows the movement of air due to convection.
Q48. The earth’s atmosphere is heated by ______. Nature
• Conduction only
• Convection only
• Radiation and Convection
• Conduction and Radiation
Answer: Radiation and Convection
The sun’s heat reaches the earth by radiation. The earth then warms the air in contact with it by conduction. This warm air rises, and the rest of the atmosphere is heated by convection.
Q49. The range of a clinical thermometer is 35°C to 42°C because ______. Health
• It is cheap to make
• Human body temperature never goes beyond this range
• It looks better
• It is easy to read
Answer: Human body temperature never goes beyond this range
This range is sufficient to measure all possible body temperatures, from severe hypothermia to very high fever, making the thermometer precise and easy to handle.
Q50. The correct method to use a clinical thermometer is to ______. Safety
• Wash it with hot water before use
• Hold it by the bulb while reading
• Read the temperature while it is still in the mouth
• Wash it with an antiseptic solution before and after use
Answer: Wash it with an antiseptic solution before and after use
This is a crucial precaution to maintain hygiene and prevent the spread of germs. It should also be washed with cold or lukewarm water, never hot.