Which of the following statements are true? Correct the false statements.
Melting ice into water is an example of the transformation of a solid into a liquid.
True. Ice (solid) melts to form water (liquid) when heated.
Melting process involves a decrease in interparticle attractions during the transformation.
True. During melting, energy is supplied which weakens the interparticle forces of attraction.
Solids have a fixed shape and a fixed volume.
True. Solids have definite shape and definite volume due to tightly packed particles and strong interparticle attractions.
The interparticle interactions in solids are very strong, and the interparticle spaces are very small.
True. In solids, particles are tightly packed with minimum interparticle spacing and maximum interparticle attraction.
When we heat camphor in one corner of a room, the fragrance reaches all corners of the room.
True. The particles of camphor fragrance spread throughout the room because gas particles are constantly moving.
On heating, we are adding energy to the camphor, and the energy is released as a smell.
False. On heating, energy is added to camphor which increases the movement of its particles, causing them to escape and spread throughout the room as vapour, not released as smell.
Explanation
(i) The chapter explains that when ice is heated, it changes from solid to liquid state at its melting point of 0°C. (ii) As described in the chapter, when solids are heated, particles vibrate more vigorously and the interparticle forces of attraction get weakened, allowing the solid to convert into liquid state. (iii) The chapter states that solids have a definite shape and volume because particles are tightly packed and interparticle attractions are very strong, holding particles in fixed positions. (iv) The chapter confirms that in solids, the particles are tightly packed, interparticle attractions are very strong, and particles can only vibrate about their fixed positions. (v) The chapter explains through Activity 7.9 that when an incense stick is burnt, the fragrance spreads throughout the room because air particles are constantly moving and help spread the fragrance particles. (vi) The chapter explains that heating adds thermal energy to particles, which increases their movement and helps them overcome interparticle forces. The particles then spread and mix with air particles, allowing us to detect the fragrance.