State with reason(s) whether the following statements are True [T] or False [F]. (i) Heat transfer takes place in solids through convection. (ii) Heat transfer through convection takes place by the actual movement of particles. (iii) Areas with clay materials allow more seepage of water than those with sandy materials. (iv) The movement of cooler air from land to sea is called land breeze.
False. In solids, heat transfer takes place mainly through the process of conduction, not convection. In conduction, particles do not move from their positions; they pass heat to neighbouring particles. Convection occurs in liquids and gases where particles actually move.
True. In convection, heat is transferred when particles of liquids or gases actually move from one place to another. When a fluid is heated, the heated particles expand, become lighter, and rise, while cooler, heavier particles move down to take their place.
False. Water seeps fastest through gravel, slower through sand, and slowest through clay. The spaces between clay particles are very small compared to those in sand and gravel, so water cannot seep through clay as easily as through sandy materials.
True. At night, land cools down faster than water. The air above the sea is warmer and rises, causing cooler air from the land to move towards the sea. This movement of cooler air from land to sea is called land breeze.
Explanation
(i) The chapter clearly states that 'In solids, heat transfer takes place mainly through the process of conduction' and that 'In convection, heat transfer takes place by the actual movement of particles' which is possible in fluids (liquids and gases) but not in solids. (ii) The chapter states: 'In convection, heat transfer takes place by the actual movement of particles' and explains this with the example of water heating in a beaker where heated water rises and cooler water comes down. (iii) Activity 7.5 in the chapter demonstrates that 'water seeps fastest through gravel, slower through sand, and slowest through clay' because 'the spaces between gravel particles are wider when compared to those in sand and clay.' (iv) The chapter explains that 'At night, the process reverses. In the absence of sunlight, land cools down faster than the water in the sea. As a result, the air above the sea is warmer and rises up. Cooler air from the land then moves towards the sea, creating a land breeze.'