Q4. a. Give reasons:
1. Ammonium chloride on heating directly goes from solid state to vapor state.
2. Burning of candle can be considered as both physical and chemical change.
3. Solids cannot be compressed, but gases are highly compressible.
4. An iron nail kept open in the atmosphere rusts.
5. Particles of matter move rapidly on applying heat.
Answers
Answer:
1) Ammonium chloride sublimes and goes from solid-state to vapour state because of the low inter-particle attraction. The solids which are sublimable have a low force of attraction between their particles.
2)As the candle burn the wax starts melting which is a physical change,also the flame of the candle converts the wax into vapour and carbon dioxide due to burning which is an example of chemical change hence burning of candle is both physical and chemical change.
3)The inter-particles spaces in solids is minimum and they are closely packed and hence, they cannot be compressed because there is no place for particles to move, while the gases are not compactly packed, the particles of gas can move around freely and hence they are highly compressible.
4)When an iron nail is exposed to atmosphere then the iron nail reacts with oxygen , water , moisture ,etc. or we can say iron nail go on Oxidation and it will form Iron oxide .
5)When heat is applied to particles of matter, the kinetic energy possessed by the particles increases and so does the space, therefore they move more rapidly and freely. The inter-particle attraction also decreases hence, they move distantly from each other.