1. Why are nights cooler in deserts than in plains?
a) Sand radiates heat faster than soil
b) The sky is often cloudy
c) Sand absorbs heat faster than soil
d) None of the above
Answer: a
2. What does the temperature of a body indicate?
a) Total molecular energy
b) Average molecular energy
c) Total molecular velocity
d) Average kinetic energy of molecules
Answer: d
3. What happens to water when heated from 0°C to 10°C?
a) Volume increases
b) Volume decreases
c) Volume remains constant
d) First decreases, then increases
Answer: d
4. Alcohol is more volatile than water because its ______ is lower than water.
a) Boiling point
b) Density
c) Viscosity
d) Surface tension
Answer: a
5. Why is a gap left between railway tracks?
a) For areal expansion
b) For volume expansion
c) For linear expansion
d) For apparent expansion
Answer: c
6. What does “supercooling” mean?
a) Cooling at freezing point
b) Cooling at melting point
c) Cooling below freezing point
d) Cooling above melting point
Answer: c
7. Why does a pressure cooker cook food faster?
a) Higher pressure increases boiling point
b) It uses low pressure
c) It generates higher temperature
d) It has high thermal conductivity
Answer: a
8. During temperature change, heat energy is stored as:
a) Heat energy
b) Kinetic energy
c) Potential energy
d) Both kinetic and potential energy
Answer: b
9. At which temperature do Celsius and Fahrenheit scales show the same reading?
a) 40
b) -40
c) -340
d) -1440
Answer: b
10. Why are the bottoms of cooking utensils often blackened?
a) Cleaning becomes easier
b) Black surfaces are good heat conductors
c) Black surfaces are poor heat conductors
d) Black surfaces absorb heat effectively
Answer: d
11. A real gas behaves like an ideal gas under:
a) Low pressure and high temperature
b) High pressure and low temperature
c) Low temperature and high pressure
d) High temperature and low pressure
Answer: d
12. Which of the following is a method of heat transfer?
a) Convection
b) Evaporation
c) Revolution
d) Thermal expansion
Answer: a
13. The Earth acts as:
a) A good heat reflector
b) A poor heat absorber
c) A good absorber and radiator
d) A poor absorber and radiator
Answer: c
14. Which metal has the highest thermal conductivity?
a) Iron
b) Aluminium
c) Copper
d) Silver
Answer: d
15. Why is ice packed in sawdust?
a) Sawdust doesn’t stick to ice
b) Sawdust doesn’t melt easily
c) Sawdust conducts heat well
d) Sawdust is a poor conductor of heat
Answer: d
16. In which process is heat transferred by actual motion of molecules?
a) Conduction
b) Convection
c) Radiation
d) Both conduction and convection
Answer: b
17. What happens to the peak wavelength of blackbody radiation with increasing temperature?
a) It increases
b) It decreases
c) It remains constant
d) No fixed pattern
Answer: b
18. 0 Kelvin is equal to:
a) 273°C
b) -273°C
c) 0°C
d) 100°C
Answer: b
19. Why does boiling water in a steam engine reach high temperatures?
a) Due to dissolved substances
b) Due to low pressure
c) Due to high pressure
d) Due to high flame temperature
Answer: c
20. Why do water pipes burst in extremely cold countries?
a) Water expands on freezing
b) Pipes contract in cold
c) High atmospheric pressure
d) All of the above
Answer: a
21. Energy harnessed from beneath Earth’s surface is called:
a) Thermal energy
b) Nuclear energy
c) Tidal energy
d) Geothermal energy
Answer: d
22. Specific gravity is defined as the ratio of substance’s density to water’s density at:
a) 0°C
b) 4°C
c) 100°C
d) Room temperature
Answer: b
23. Cooling system (radiator) in cars works on the principle of:
a) Conduction
b) Convection
c) Radiation
d) Both conduction and radiation
Answer: b
24. If bodies A and B have the same mass and absorb equal heat, but A shows a greater temperature rise, then:
a) A has higher specific heat
b) A has lower specific heat
c) Both have equal specific heat but A has higher conductivity
d) Both have equal specific heat but B has higher conductivity
Answer: b
25. At high altitudes, astronauts feel:
a) Extremely hot
b) Slightly warmer
c) Extremely cold
d) Slightly cooler
Answer: c