(i.) The height of the entire object is 10 cm. The radius of the hemisphere is 4 cm, which is also the height of the hemisphere. So, you would subtract 10 by 4 and get 6 cm as the height of the cone.
(ii.) Cone:
v = (1/3)πr^2h
v = (1/3)π(4^2)*6
v = (1/3)π(16*6)
v = (1/3)π*96
v = 32π
v = 100.5 cm^3
Hemisphere:
v = (2/3)πr^3
v = (2/3)π(4^3)
v = (2/3)π*64
v = 42.7π
v = 134.1 cm^3
Added together:
100.5 + 134.1 = 234.6 cm^3