Give a reason for each of the following:

(i) Asthenosphere though underneath the crust is in a semi-molten state.
(ii) Exogenic forces are also called destructive forces.
(iii) Residual mountains are also called mountains of denudation.

(i) The internal heat of the earth doesn't travel to the surface because rocks are bad conductors of heat. The internal heat of the earth melts the rocks and keeps the asthenosphere in a semi-molten state.

(ii) Exogenic forces are also called destructive forces because they cause widespread destruction through weathering and erosion of existing landforms.

(iii) Residual mountains are also called mountains of denudation as they are formed due to denudation and erosion by natural agents such as winds, water, snow etc.