Heat — Previous Year Questions (Class 7 Science)
Study temperature, heat transfer, thermal conductors and insulators. Understand the physics and effects of heat.
TL;DR: Study temperature, heat transfer, thermal conductors and insulators. Understand the physics and effects of heat.
Written & reviewed by the Syllab.in Academic Team (CBSE/NCERT subject experts) · Updated
Study temperature, heat transfer, thermal conductors and insulators. Understand the physics and effects of heat.
Heat — Previous Year Questions with Solutions
Q (2023, 3 marks): Differentiate between heat and temperature.
Answer: Heat: Form of energy that flows from hot to cold body. Measured in joules (J) or calories. It causes temperature change.
Temperature: Measure of average kinetic energy of particles. Measured in Celsius (°C) or Kelvin (K). It is a property of a body.
Heat is energy; temperature is a property.
Q (2022, 3 marks): Name three ways heat is transferred and give an example of each.
Answer: 1. Conduction: Heat transfer through direct contact. Example: A metal spoon getting hot when placed in hot water.
2. Convection: Heat transfer through movement of fluids. Example: Boiling water - hot water rises and cold sinks.
3. Radiation: Heat transfer without medium. Example: Heat from the sun reaching Earth.
Q (2023, 3 marks): What is thermal conductivity? Give examples of good conductors and insulators.
Answer: Thermal conductivity: The ability of a material to conduct heat.
Good conductors: Metals (copper, aluminum, iron) - allow heat to pass easily.
Insulators: Wool, cork, plastic, air - do not allow heat to pass easily.
Conductors have high thermal conductivity; insulators have low thermal conductivity.
Q (2022, 2 marks): Why do we use woolen clothes in winter?
Answer: Wool is a thermal insulator. It has air pockets that trap air. This trapped air prevents heat from escaping the body, keeping us warm in winter.
Q (2023, 3 marks): A thermometer shows 25°C. Convert this to Fahrenheit using the formula F = (C × 9/5) + 32
Answer: Given: C = 25°C
Formula: F = (C × 9/5) + 32
F = (25 × 9/5) + 32
F = (225/5) + 32
F = 45 + 32
F = 77°F
Q (2022, 3 marks): Why does a dark colored car become hotter than a light colored car in the sun?
Answer: Dark colors absorb more heat radiation from the sun and reflect less. Light colors reflect more heat radiation and absorb less. Since the dark car absorbs more heat, it becomes hotter.
Frequently Asked Questions
Can cold be transferred?
No, cold cannot be transferred. Only heat is transferred. What we call 'transfer of cold' is actually the removal of heat energy. When we feel cold, it means heat is being removed from our body.
Why is the bottom of a cooking vessel made thick?
A thick bottom distributes heat evenly across the vessel, preventing hot spots. It also conducts heat slowly, allowing better control over cooking and preventing burning.
More Class 7 Science PYQs
- Chemical Reactions and Equations
- Light (Reflection and Refraction)
- Electricity
- Acids, Bases and Salts
- Metals and Non-metals
- Life Processes
🤖 Stuck on any of these? Ask Syllab's free AI Tutor to explain step by step →