(i) The parts are:
(1) Atmosphere
(2) Crust
(3) Mantle
(4) Core
(5) Ocean
(ii) The states are:
(1) Atmosphere - Gaseous state
(2) Crust - Solid state
(3) Mantle - Semi-molten and solid state
(4) Core - Solid state
(5) Ocean - Liquid state
(iii) Crust is suitable for human habitation due to favourable conditions for survival, i.e. atmosphere for air, lithosphere for settlement due to ideal temperature, hydrosphere for hydrological cycle for providing rainfall and fresh water bodies on the earth and oceans for navigation and trade routes etc.
