Question

why red soil is red in colour​

Answer 1

Their colour is mainly due to ferric oxides occurring as thin coatings on the soil particles while the iron oxide occurs as haematite or as hydrous ferric oxide, the color is red and when it occurs in the hydrate form as limonite the soil gets a yellow colour.

Answer 2

Red Soil is red in colour because it contains a great proportion of iron-oxides. At several places, their colour has slightly changed and appears brown or grey.