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You are given a mixture of sand, common salt and naphthalene (Fig. 5.25a). The Fig. 5.25b depicts various steps used to separate the components of this mixture. Identify and write down the correct sequence of separation techniques.
View Answer
Step 1 — Sublimation: Heat the mixture so naphthalene sublimes and is collected, leaving sand and salt behind.
Step 2 — Dissolving and filtration: Add water to dissolve the salt, then filter; sand stays on the filter paper while salt solution passes through.
Step 3 — Evaporation (or crystallization): Evaporate the salt solution to recover the common salt.
Sand + Common Salt + Naphthalene
1. Sublimation
heat — only naphthalene sublimes away
↓
2. Dissolve, then filter
salt dissolves in water; sand is the residue
↓
3. Evaporate
the filtrate leaves the common salt
↓
Sublimation → Filtration → Evaporation
