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Q1. Convection _______.    

• takes place best in gases
• takes place best in liquids
• takes place best in vacuum
• takes place best in solids

Solution

Convection takes place best in gases.

Q2. Copper plated utensils help cooking:

• Faster
• Slower
• Does not effect in cooking
• Moderately slower

Solution

Copper plated utensils help cooking faster since copper is a good conductor of heat.

Q3. A liquid which is a good conductor of heat is:

• water
• milk
• mercury
• alcohol

Solution

Mercury is a good conductor of heat.

Q4. The two temperature scales with the same interval step size are the

• Celsius and Fahrenheit
• Fahrenheit and Kelvin
• Kelvin and Celsius
• None of the above

Solution

The two temperature scales with the same interval step size are the Kelvin and Celsius scales.

Q5. The freezing chest (or cooling unit) in a refrigerator is kept near the top because:

• it is convenient to use
• it reduces cost
• convection currents can be set up this way
• it cools the remaining space by the process of conduction

Solution

The air near the top in contact with the freezing chest gets cooled. It becomes denser  and therefore descends and the hot air from the lower part rises, thus giving rise to convection currents which gradually cool the whole refrigerator space.

Q6. What type of heat transfer takes place in a refrigerator?

• Conduction only
• Convection only
• Conduction and convection only
• Conduction, convection and radiation

Solution

The system by which a refrigerator removes heat from the freezer and refrigeration compartments and disposes it off outside the unit relies on the concept of convection.

Q7. Which of the following is the best reason why car engines are painted black?  

• Black is a good absorber and poor conductor of heat.
• Black is a good radiator and poor absorber of heat.
• Black is a poor radiator and good absorber of heat.
• Black is a good radiator and good absorber of heat.

Solution

Black is a good radiator and good absorber of heat so it absorbs energy and re-radiates it. In the case of engine, it absorbs heat from the engine and radiates it into the environment.

Q8. Heat content of a substance does not depend upon:

• Mass of the substance
• Nature of the substance
• Temperature of the substance
• Volume of the substance

Solution

Heat content of a substance does not depend upon the volume of the substance.

Q9. The degree of hotness or coldness of a body or environment is called :

• Pressure
• Temperature
• Melting point
• Boiling point

Solution

The degree of hotness or coldness of a body or environment is called temperature.

Q10. A process of heat transfer which does not need a medium is called:

• Conduction
• Convection
• Radiation
• Induction

Solution

A process of heat transfer which does not need a medium is called radiation.

Q11. The clinical thermometer can be used to find out temperature of:

• Human body
• Animals
• Birds
• Insects

Solution

The clinical thermometer can be used to find out temperature of human body

Q12. Sea breeze is the movement of air particles from:

• Sea to the land during day
• Land to the sea during day
• Sea to the land at night
• Land to the sea at night

Solution

Sea breeze is the movement of air particles from sea to the land during the day.

Q13.  The heat from the hot water in a metal radiator passes through the metal and then spreads around the room. What are the main processes by which the heat is transferred through the radiator and then spread around the room?

•   Through the metal radiator Around the room Conduction Conduction
•   Through the metal radiator Around the room Conduction Convection
• Through the metal radiator Around the room Radiation Conduction
•   Through the metal radiator Around the room Radiation Convection

Solution

  Through the metal radiator Around the room Conduction Convection

Q14. Which of the following is not based on the 'principle of heat radiation'?

• Greenhouse
• Chimneys in factories
• Vacuum flask
• Radiators of car

Solution

Chimneys in factories are based on the principle of heat convection.

Q15. A hot object cools itself by transferring:

• Heat
• Light
• Sound
• All the above

Solution

A hot object cools itself by transferring the heat by means of radiation.

Q16. Constructing buildings with walls having trapped layers of __________, makes it beneficial in controlling the heat of the surroundings.

• Air
• Water
• Moisture
• Oxygen

Solution

Constructing buildings with walls having trapped layers of air makes it beneficial in controlling the heat of the surroundings.

Q17. Which of the following is not a possible reason for not using water as a thermometric liquid?

• Water has a high specific heat capacity.
• Water is transparent.
• Water sticks to glass.
• Water is non-volatile.

Solution

Non-volatile liquids are preferred as thermometric liquids, so this cannot be a possible reason.

Q18. Given room temperature as 38 deg. celsius, which tin would cool first - Tin 1 at 45 deg. celsius or Tin 2 is at 55 deg. celsius?

• Tin 1
• Tin 2
• Neither
• Both at the same time

Solution

Tin 1 will cool first as its temperature difference with the surroundings is lower than that of tin 2.

Q19. Heat from sun reaches to us due to

• Conduction
• Convection
• Radiation
• None of the above

Solution

Heat from sun reaches to us due to radiation.    

Q20. Thermometer should not be exposed to:

• Sunlight or flame
• Room temperature
• Cool atmosphere
• All the above

Solution

Thermometer should not be exposed to direct sunlight or flame.

Q21. Windows in coastal areas face

• towards the sea
• towards the sky
• away from the sea
• anywhere

Solution

Windows in coastal areas face towards the sea, in order to get the cooler sea breeze.

Q22. Which of the following is the best reason why a metal ruler feels colder than a wooden ruler?

• Metal conducts heat better than wood.
• Metal expands more than wood.
• Metal absorbs less heat than wood.
• Metal can be polished till it is shiny.

Solution

Metal conducts heat better than wood.

Q23. Objects that radiate relatively well

• Absorb radiation relatively well.
• Reflect radiation relatively well.
• Both of these
• Neither of these

Solution

Absorb radiation relatively well.  

Q24. Iron, copper are examples of:

• Good conductors
• Bad conductors
• Insulators
• Alloys

Solution

Iron, copper are examples of good conductors.

Q25. Two cars were painted; one was in black, the other white. The cars were left under the sun to dry. The black paint dried more quickly than the white paint. Which property of black paint makes it dry more quickly?

• It is a better conductor of heat.
• It is a better absorber of heat.
• It is a better insulator of heat.
• It is a better reflector of heat.

Solution

Black is a better absorber of heat so the car painted black dries faster. 

Q26. The range of clinical thermometer is :

• 45^oC to 55^oC
• 35^oC to 42^oC
• 40^oC to 50^oC
• -12^oC to 20^oC

Solution

The range of clinical thermometer is from 35^oC to 42^oC.

Q27. The rate of emission of infra-red radiation does not depend upon:

• Color and texture of surface
• Temperature of surface
• Area of surface
• Position of surface

Solution

The rate of emission of infra-red radiation depends upon the color and texture of surface, surface temperature and surface area only.

Q28. A laboratory thermometer can measure:

• + ve and - ve temperatures
• Only + ve temperatures
• Only - ve temperatures
• Only zero deg.

Solution

A laboratory thermometer can measure both + ve and - ve temperatures.

Q29. Clinical thermometers cannot be used to measure:

• High temperatures
• Body temperature
• Range from 35 deg. to 42 deg.
• All the above

Solution

Clinical thermometers cannot be used to measure high temperatures.

Q30. In supermarkets, it is observed that the freezers where frozen foods are kept do not have a lid and yet, the temperature of the freezer remains below 0^oC. How is this possible?

• The cold air is denser and does not rise out of the freezer.
• Conduction of cold air away from the freezer is slow, as the surrounding temperature is low.
• The air-conditioned environment at the supermarket helps the freezers to remain cold.
• Heat is not radiated to the freezer, as there is a layer of cold air above the freezer.

Solution

The cold air is denser and does not rise out of the freezer and hence the temperature of the freezer remains below 0^oC.   

Q31. Green house effect used in plant houses works on

• Conduction
• Convection
• Radiation
• None of the above

Solution

Green house effect used in plant houses works on radiation.    

Q32. The vacuum present in a vacuum flask reduces heat transfer by _______.

• Convection
• Radiation
• Conduction and convection
• Conduction

Solution

The vacuum present in a vacuum flask reduces heat transfer by conduction and convection.

Q33. While reading a thermometer, we should not hold it by the:

• Bulb
• Glass tube
• Kink
• Thread

Solution

While reading a thermometer, we should not hold it by the bulb.

Q34. Rubber is a good example of:

• Conductor
• Insulator
• Inductor
• Capacitor

Solution

Rubber is a good example of insulator.

Q35. Which of the following methods of heat transfer require a medium? (I) Conduction    (II) Convection     (III) Radiation 

• (I) and (II) only
• (II) and (III) only
• (I) and (III) only
• (I), (II) and (III)

Solution

(I) and (II) i.e. conduction and convection require a medium for heat transfer.

Q36. Black color is a good absorber of:

• Heat
• Air
• Breeze
• Moisture

Solution

Black color is a good absorber of heat.

Q37. In hot countries, it is preferred to wear light colours on a hot day because _______.

• light colours are poor absorbers of heat
• light colours are good radiators of heat
• light colours are good absorbers of heat
• light colours are poor radiators of heat

Solution

In hot countries, it is preferred to wear light colours on a hot day because light colours are poor absorbers of heat

Q38. Pick a good conductor of heat from the following:

• Aluminum
• Plastic
• Wood
• Rubber

Solution

Aluminum is a good conductor of heat.

Q39. The pupil of your eye is a net

• Absorber of radiant energy.
• Emitter of radiant energy.
• Both of these
• Neither of these

Solution

The pupil of your eye is a net absorber of radiant energy.

Q40. Can we use a laboratory thermometer for measuring body temperature?

• No
• Yes
• Sometimes yes
• Sometimes no

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