AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.
Rock salt is the naturally occurring solid form of sodium chloride (NaCl). It appears as large crystals, often brown due to impurities.
Formation of beds: Beds of rock salt were formed when seas of bygone ages dried up, leaving behind solid deposits of salt. These beds are mined like coal.
Source: Chemicals from Common Salt, Chapter 2
The question has two parts — definition and formation — each worth 1 mark. The key phrases examiners look for are: "solid salt / sodium chloride," "seas of bygone ages dried up," and "mined like coal." Keep the answer concise and use the exact textbook language for full marks.