Section A — Choose the Correct Option

1. Which process of heat transfer takes place mainly in solids?

(a) Convection

(b) Radiation

(c) Conduction

(d) Evaporation

2. Which of the following is a good conductor of heat?

(a) Wood

(b) Glass

(c) Copper

(d) Air

3. Heat transfer by the actual movement of particles is called:

(a) Conduction

(b) Convection

(c) Radiation

(d) Reflection

4. Which process allows heat from the Sun to reach Earth?

(a) Conduction

(b) Convection

(c) Radiation

(d) Insulation

5. Which of the following is a poor conductor of heat?

(a) Copper

(b) Aluminium

(c) Iron

(d) Wood

6. During the day, a sea breeze generally moves:

(a) From land to sea

(b) From sea to land

(c) From land to sky only

(d) From sky to sea

7. At night, a land breeze generally moves:

(a) From sea to land

(b) From land to sea

(c) From sea to sky

(d) From sky to land

8. Water generally seeps fastest through:

(a) Clay

(b) Sand

(c) Gravel

(d) Solid rock

9. The process by which surface water enters the soil is called:

(a) Condensation

(b) Infiltration

(c) Radiation

(d) Convection

10. An underground layer that stores groundwater is called:

(a) Aquifer

(b) Atmosphere

(c) Reservoir

(d) Glacier

Section B — Fill in the Blanks

1. Heat always transfers from a __________ region to a __________ region.

2. Metals are generally __________ conductors of heat.

3. Wood and glass are generally __________ conductors of heat.

4. Heat transfer by the actual movement of particles is called __________.

5. Heat from the Sun reaches Earth by __________.

6. During the day, land gets heated __________ than water.

7. During the day, cool air moves from the sea towards the land. This is called __________.

8. During the night, cool air moves from the land towards the sea. This is called __________.

9. The continuous movement of water through evaporation, condensation and precipitation is called the __________.

10. The process of surface water entering the soil and rocks is called __________.

Section C — True or False

1. Heat can be transferred from a colder object to a hotter object naturally. ________

2. Metals are generally good conductors of heat. ________

3. Air is a good conductor of heat. ________

4. Convection involves the actual movement of particles. ________

5. Radiation requires a material medium for heat transfer. ________

6. Land heats faster than water during the day. ________

7. Sea breeze occurs during the day. ________

8. Land breeze occurs during the night. ________

9. Water generally seeps faster through clay than gravel. ________

10. Rainwater harvesting can help replenish groundwater. ________

Section D — Match the Following

Answers: 1. ______ 2. ______ 3. ______ 4. ______ 5. ______

Section E — Answer in One or Two Sentences

1. What is conduction of heat?

2. What is convection?

3. What is radiation?

4. Why are woollen clothes useful in winter?

5. Why are light-coloured clothes preferred in summer?

6. Why does smoke generally rise upwards?

7. What is a sea breeze?

8. What is a land breeze?

Section F — Short Answer Questions

1. Explain why the pins attached to a metal strip with wax fall one after another when one end of the strip is heated.

2. Why do the pins farther from the heated end fall later?

3. Why does air trapped between two layers of clothing help keep us warm?

4. Explain how convection takes place when water is heated in a vessel.

5. Explain how a sea breeze is formed during the day.

6. Explain how a land breeze is formed at night.

7. Why are hollow bricks useful for constructing the outer walls of houses in hot regions?

8. Why does water generally seep faster through gravel than through clay?

Section G — Think and Answer

1. A metal spoon is placed in a cup of hot tea. After some time, its handle also becomes hot. Which method of heat transfer is mainly responsible? Explain.

2. Why does a room with a large water body nearby generally experience less extreme temperature changes?

3. A student says, “Radiation cannot occur without air.” Is the statement correct? Give a reason.

4. Why is a smoke detector generally installed near the ceiling?

Section H — Water Cycle and Groundwater

1. Arrange the following processes in a suitable sequence:

Condensation, Collection, Evaporation, Precipitation

Answer: __________________________________________________________

2. Define the following:

(a) Infiltration: __________________________________________________

(b) Groundwater: _________________________________________________

(c) Aquifer: ______________________________________________________

3. Complete the flow:

4. Why is groundwater considered an important natural resource?

5. Write two ways by which groundwater can be conserved or replenished.

Section I — Diagram Practice

1. Draw a neat labelled diagram showing conduction through a metal strip.

2. Draw a diagram showing convection currents in water being heated.

3. Draw and label the direction of air movement during a sea breeze.

4. Draw a simple water-cycle diagram and label evaporation, condensation, precipitation and collection.

Section J — Case-Based Questions

Section K — Challenge Questions

1. A student says, “Conduction, convection and radiation are completely unrelated processes.” Do you agree? Explain using an example from everyday life.

2. Why can we feel the heat of a fire even when we are not touching the fire?

3. Why can two thin blankets sometimes keep us warmer than one thick blanket?

4. Explain why land and sea breezes are examples of convection.

Quick Self-Check