(i) Let initially the edge of the cube be l. Initial surface area = 6l2
If each edge of the cube is doubled, then it becomes 2l.
New surface area = 6(2l)2 = 24l2 = 4 × 6l2
Clearly, the surface area will be increased by 4 times.
(ii) Initial volume of the cube = l3
When each edge of the cube is doubled, it becomes 2l.
New volume = (2l)3 = 8l3 = 8 × l3
Clearly, the volume of the cube will be increased by 8 times.