1. Why do clothes keep us warm in winter?
a) They supply heat
b) They do not radiate heat
c) They block air from contacting the body
d) They trap body heat and prevent it from escaping
Answer: d
2. What is the melting point of ice in Kelvin?
a) 253.16 K
b) 263.16 K
c) 273.16 K
d) 283.16 K
Answer: c
3. The heat stored in water vapour is called:
a) Specific heat
b) Latent heat
c) Absolute heat
d) Relative heat
Answer: b
4. The term “insolation” refers to:
a) Heat-insulating materials
b) Incoming solar radiation
c) Insoluble substances
d) None of the above
Answer: b
5. The rate of cooling of a body depends on:
a) Temperature difference with surroundings
b) Nature of the surface
c) Surface area exposed
d) All of the above
Answer: d
6. In cold regions, lakes freeze on the surface while water beneath remains at:
a) 0°C
b) 0°F
c) 4°C
d) 4°F
Answer: c
7. Water has a density of 1 g/cm³, which is valid at:
a) 0°C
b) 4°C
c) 25°C
d) 100°C
Answer: b
8. A white, smooth surface is:
a) A good absorber and good reflector of heat
b) A poor absorber and good reflector of heat
c) A good absorber and poor reflector of heat
d) A poor absorber and poor reflector of heat
Answer: b
9. Which of the following is a thermal insulator?
a) Copper
b) Wood
c) Mercury
d) Aluminium
Answer: b
10. Burns from steam are more severe than from boiling water because:
a) Steam has a higher temperature
b) Steam carries latent heat of vaporization
c) Steam quickly penetrates skin pores
d) All of the above
Answer: d
11. A body absorbs maximum heat when it is:
a) Black and rough
b) Black and smooth
c) White and rough
d) White and smooth
Answer: a
12. Match the following processes with their changes:
- Evaporation → Liquid to gas
- Sublimation → Solid to gas
- Freezing → Liquid to solid
- Melting → Solid to liquid
Answer: a) 1-2-3-4
13. What causes cooling in a refrigerator?
a) Ice formation on the freezer
b) Sudden expansion of compressed gas
c) Evaporation of a volatile liquid
d) None of the above
Answer: c
14. Minimum temperature is measured by:
a) Alcohol thermometer
b) Mercury thermometer
c) Maximum reading thermometer
d) Minimum reading thermometer
Answer: d
15. What is the triple point of water?
a) 273.16 K
b) 273.15 K
c) 0°C
d) 100°C
Answer: a
16. When water freezes, its density:
a) Decreases
b) Becomes zero
c) Remains constant
d) Increases
Answer: a
17. Woollen clothes keep us warm because:
a) They conduct heat well
b) They are poor conductors of heat
c) They absorb external heat
d) They reflect body heat
Answer: b
18. Cryogenics (low temperature applications) is used in:
a) Space travel, surgery, magnetic levitation
b) Surgery, magnetic levitation, telemetry
c) Space travel, surgery, telemetry
d) Space travel, magnetic levitation, telemetry
Answer: a
19. SI unit of temperature is based on:
a) Melting point of ice
b) Boiling point of water
c) Triple point of water at 0.01°C
d) Absolute zero
Answer: c
20. Why is water’s boiling point higher in steam engines?
a) Due to dissolved salts
b) Due to low pressure
c) Due to high pressure inside the boiler
d) Due to high flame temperature
Answer: c
21. A 10°C rise on the Celsius scale equals how much on the Fahrenheit scale?
a) 18°F
b) 21°F
c) 10°F
d) 15°F
Answer: a
22. What happens when vapour pressure equals atmospheric pressure?
a) The liquid cools
b) The liquid boils
c) No change occurs
d) The liquid evaporates
Answer: b
23. Why are holes poked in sealed food pouches before microwaving?
a) To prevent bursting from steam pressure
b) To allow heat to penetrate
c) To let microwaves reach the food
d) To release aroma
Answer: a
24. Soldering of metals is possible due to:
a) Diffraction
b) Viscosity
c) Surface tension
d) Cohesion
Answer: d
25. To measure very high temperatures, which device is used?
a) Mercury thermometer
b) Platinum resistance thermometer
c) Thermoelectric pyrometer
d) None of the above
Answer: c