Heat and Temperature (Class 7 Science)

Explore the difference between heat and temperature, methods of heat transfer, and effects of heat on matter.

Heat and Temperature (Class 7 Science)

Explore the difference between heat and temperature, methods of heat transfer, and effects of heat on matter.

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TL;DR: Explore the difference between heat and temperature, methods of heat transfer, and effects of heat on matter.

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Explore the difference between heat and temperature, methods of heat transfer, and effects of heat on matter.

Heat and Temperature MCQs with Answers & Explanations

Q1. What is the difference between heat and temperature?

  1. Temperature is energy; heat is measure
  2. Same thing
  3. No difference
  4. Heat is energy; temperature is measure of hotness ✓ (correct)

Explanation: Temperature measures the average kinetic energy of molecules (in Celsius or Kelvin). Heat is the energy transferred from hot to cold objects.

Q2. What is the SI unit of heat?

  1. Joule ✓ (correct)
  2. Calorie
  3. Kelvin
  4. Degree Celsius

Explanation: The SI unit of heat is Joule (J). Calories are used in older measurements. 1 calorie ≈ 4.18 Joules.

Q3. What are the three methods of heat transfer?

  1. Conduction, expansion, radiation
  2. Conduction, convection, radiation ✓ (correct)
  3. Evaporation, condensation, sublimation
  4. Melting, boiling, freezing

Explanation: Heat transfers by: conduction (direct contact), convection (through fluids), and radiation (electromagnetic waves).

Q4. What is conduction of heat?

  1. Transfer through fluids
  2. Heat generation
  3. Transfer through direct contact ✓ (correct)
  4. Transfer by radiation

Explanation: Conduction is heat transfer through direct contact between materials. Example: holding a hot cup and feeling warmth.

Q5. What is convection?

  1. Transfer by contact
  2. Heat storage
  3. Transfer by radiation
  4. Transfer through movement of fluids ✓ (correct)

Explanation: Convection transfers heat through the movement of fluids (liquids and gases). Hot water rises, cold sinks, creating convection currents.

Q6. What is the normal body temperature of humans?

  1. 36.8°C ✓ (correct)
  2. 38.8°C
  3. 35.8°C
  4. 37.8°C

Explanation: Normal human body temperature is approximately 36.8°C or 98.6°F. This varies slightly between individuals and throughout the day.

Q7. What is thermal expansion?

  1. Decrease in temperature
  2. Increase in volume of objects due to heating ✓ (correct)
  3. Change in shape only
  4. Cooling of objects

Explanation: Thermal expansion is the increase in volume of substances when heated. Most substances expand on heating; water has an exception.

Q8. What are good conductors of heat?

  1. Glass, rubber
  2. Plastic, wood
  3. Metals like copper, aluminum ✓ (correct)
  4. Cork, air

Explanation: Metals are good heat conductors because of free electrons that carry thermal energy. Copper and aluminum are excellent conductors.

Q9. What are good insulators of heat?

  1. Copper, iron
  2. All metals
  3. Silver, aluminum
  4. Cork, wool, glass, air ✓ (correct)

Explanation: Insulators have low thermal conductivity. Examples: cork, wool, rubber, glass, and air. They trap heat and prevent transfer.

Q10. What is the absolute zero temperature?

  1. -273.15°C ✓ (correct)
  2. 0°C
  3. 0°F
  4. -40°C

Explanation: Absolute zero is -273.15°C or 0 Kelvin. It is the lowest possible temperature where all molecular motion theoretically stops.

Frequently Asked Questions

Why does ice melt and water boil at specific temperatures?

These are phase change temperatures determined by the energy needed to break molecular bonds. Melting occurs at 0°C; boiling at 100°C (at standard pressure).

How do thermometers work?

Thermometers use the principle that substances expand when heated. Mercury expands uniformly with temperature, indicating the temperature on a scale.

More Class 7 Science MCQs

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