(i) Small pieces of stone can be removed from rice by handpicking

Hand picking is the method of separating easily identifiable material from a mixture. The components of the heterogeneous mixture can be separately identified from each other.

(ii) Grains are obtained from stalks by threshing.

The grains are separated from stalk (on which they grow) by the process of threshing. In this process stalks are beaten to separate grains from bundle of stalks. Being soft stalks can be broken and grains can be released.

(iii) Husk from wheat flour is generally removed by sieving.

Sieving is used to separate those solid mixture which have components of different sizes.

(iv) The process of settling of heavier particles is called sedimentation.

The process of settling or being deposited as a sediment.

(v) Filtration is helpful in separating an insoluble solute (solid) from a solution (liquid).

Filtration is any of various mechanical, physical or biological operations that separate solids from fluids (liquids or gases) by adding a medium through which only the fluid can pass.