(a) Why is crystallisation technique better than evaporation ?
(b) Write any two physical properties each of metals and non-metals.
(c ) Name the technique used to separate butter from curd.

Explanation

(a) Both these techniques are used to separate the solid substances from their solutions. But crystallisation is considered better because during evaporation certain solids may decompose or some of them like sugar get charred when the solution is evaporated completely to dryness. As a result of crystallisation, even the shapes of the crystals donot change.
(b) (i) Metals have a shining surface known as lustre.
(ii) Metals are malleable and ductile.
(iii) Non-metals are mostly poor conductors of electricity.
(iv) Non-metals are generally soft.
(c ) Butter can be separated from curd by the process of centrifugation. This is usually done by churning which is very common as well as convenient.