Temperature and Its Measurement – Short Answer Type Questions
Class 6 Science — Chapter 7: Temperature and Its Measurement
Content Bank — Topics Covered
- Basics: temperature, heat, particles
- Thermometers & Scales: reading, types, precautions
- Changes of State: melting, freezing, evaporation, boiling, condensation, sublimation
- Heat Transfer: conduction, convection, radiation
- Practical work and experiments: observations and safety
- Applications & daily life examples
Basics — Temperature & Heat
- 1. What is temperature?Temperature is a measure of how hot or cold an object or environment is; it indicates the average kinetic energy of particles.
- 2. What do we mean by heat?Heat is energy that flows from a body at higher temperature to one at lower temperature due to a temperature difference.
- 3. How are temperature and heat related?Temperature determines the direction of heat flow: heat flows from higher temperature to lower; however, temperature is not the same as the amount of heat.
- 4. What happens to particles when temperature increases?When temperature increases, particles move faster and their average kinetic energy increases.
- 5. Define thermal equilibrium.Thermal equilibrium is when two bodies in contact reach the same temperature and no net heat flows between them.
Thermometers & Scales
- 6. What is a thermometer?A thermometer is an instrument used to measure temperature.
- 7. Name two types of liquid-in-glass thermometers.Mercury-in-glass and alcohol (coloured alcohol) thermometers.
- 8. What is a clinical thermometer?A clinical thermometer is designed to measure human body temperature and usually covers a small range around normal body temperature.
- 9. How should you read a thermometer?Hold it vertically at eye level and read the top of the liquid column against the scale to avoid parallax error.
- 10. Why are mercury thermometers used cautiously?Mercury is toxic; broken thermometers can release poisonous mercury droplets and vapour, so care is needed.
- 11. What is a digital or infrared thermometer?A digital thermometer shows readings electronically; an infrared (non-contact) thermometer measures thermal radiation from a distance.
- 12. What are the two common temperature scales?Celsius (°C) and Fahrenheit (°F).
- 13. What are the fixed points of Celsius scale?0°C (freezing point of water) and 100°C (boiling point of water at 1 atm).
- 14. What are the freezing and boiling points of water on the Fahrenheit scale?Freezing point is 32°F and boiling point is 212°F.
- 15. How do you convert Celsius to Fahrenheit?Use the formula T(°F) = T(°C) × 9/5 + 32.
Changes of State
- 16. What is melting?Melting is the change of a solid into a liquid on heating, e.g., ice turning into water.
- 17. What is freezing?Freezing is the change of a liquid into a solid on cooling, e.g., water freezing into ice.
- 18. What is evaporation?Evaporation is the change of a liquid into vapour from the surface at any temperature.
- 19. How is boiling different from evaporation?Boiling occurs throughout the liquid at a specific temperature (boiling point), while evaporation happens at the surface at any temperature.
- 20. What is condensation?Condensation is the change of vapour into liquid when the vapour is cooled.
- 21. Define sublimation with an example.Sublimation is when a solid changes directly into gas without becoming liquid, e.g., dry ice (solid CO₂) turning into gas.
- 22. Are these state changes reversible?Most physical state changes like melting/freezing and evaporation/condensation are reversible under suitable conditions.
- 23. What is latent heat?Latent heat is the heat absorbed or released during a change of state without change in temperature (e.g., during melting or boiling).
- 24. Give an example where temperature causes a change of state in daily life.Water boiling for cooking (liquid to vapour) or water freezing in a freezer (liquid to solid).
- 25. Why does salt lower the freezing point of water?Salt dissolves in water and disrupts ice formation, causing freezing point depression; hence, ice melts at lower temperatures.
Heat Transfer — Modes & Examples
- 26. What is conduction?Conduction is transfer of heat through a material by direct contact of particles, common in solids like metals.
- 27. What is convection?Convection is heat transfer by movement of fluids (liquids or gases), where warmer fluid rises and cooler fluid sinks, forming currents.
- 28. What is radiation?Radiation is heat transfer through electromagnetic waves and does not require a medium (e.g., Sun's heat reaching Earth).
- 29. Give an example of conduction in daily life.A metal spoon getting hot when placed in hot soup is an example of conduction.
- 30. Give an example of convection in daily life.Warm air rising from a heater and cool air moving in to replace it illustrates convection currents.
- 31. Give an example of radiation in daily life.Feeling warmth from the Sun on your skin is due to thermal radiation.
- 32. What are good conductors of heat?Metals such as copper, iron and aluminium are good conductors of heat.
- 33. What are good insulators of heat?Materials like wood, plastic, wool and air are good insulators and slow heat flow.
- 34. Why do warm and cool currents form during heating of water?Heating causes parts of water to become less dense and rise; cooler denser water sinks, creating circulation known as convection currents.
- 35. How does a thermos flask reduce heat transfer?A thermos flask uses vacuum insulation and reflective coatings to reduce conduction, convection and radiation, keeping contents hot or cold longer.
Practical Work & Observations
- 36. How can you measure temperature changes in a simple class experiment?Use a laboratory thermometer to record temperatures of hot, warm and cold water at intervals and note the change over time.
- 37. What precautions should you take while using a mercury thermometer?Handle gently, avoid heating directly over flame, do not shake by mouth, and inform a teacher if it breaks because mercury is hazardous.
- 38. How would you demonstrate evaporation at home?Place equal amounts of water in two shallow dishes — one in sunlight and one in shade — and observe that water in sunlight evaporates faster.
- 39. Describe a simple activity to show conduction.Fix beads on a metal and a wooden rod, apply heat to one end and observe beads falling sooner from the metal rod due to faster heat conduction.
- 40. How can you show that convection takes place in fluids?Heat one side of a tray of water with food colouring and watch coloured currents rise and move, showing convection currents.
- 41. What safety rules should be followed during heat experiments?Wear safety goggles, use tongs to handle hot objects, keep flammable materials away, and follow teacher's instructions carefully.
- 42. How should temperature readings be recorded in a table?Record date, time, object measured, thermometer range, and the temperature reading to maintain consistent observations.
- 43. Why is a control sample useful in experiments involving temperature?A control sample provides a baseline for comparison to see the actual effect of heating or cooling on the test sample.
- 44. How would you test which material is a better conductor of heat?Place identical objects on different materials heated at one end and observe which object warms fastest to identify the better conductor.
- 45. What observations indicate that boiling has started?Formation of bubbles throughout the liquid, vigorous rising of vapour and steady temperature equal to the boiling point indicate boiling.
Applications & Miscellaneous Questions
- 46. Why is it colder at higher altitudes?Air pressure decreases with altitude, causing air to expand and cool; also, thinner atmosphere holds less heat.
- 47. Why does ice float on water?Ice has a crystalline structure that makes it less dense than liquid water, so it floats.
- 48. How do refrigerators use heat transfer to cool food?Refrigerators remove heat from inside using a coolant and expel it outside through the condenser coils, lowering internal temperature.
- 49. Why do we feel colder in windy conditions even at the same temperature?Wind increases heat loss from the body by convection, removing the insulating layer of warm air and making us feel colder (wind chill).
- 50. How does clothing help in temperature regulation?Clothing traps air and provides insulation in cold weather; breathable fabrics allow evaporation of sweat to cool the body in hot weather.
Note: These short answer questions and answers are prepared strictly according to the NCERT syllabus for Chapter 7 and are ideal for CBSE Class 6 revision and practice.