Question

what is the use of group and ungroup command

Answer 1

UNGROUP removes all objects from the current group. Breaks up the group that you select into its component objects. Specify a group by selecting an object that it contains. Enter All to ungroup all groups in the drawing

Answer 2

Disassociates the objects from a group. UNGROUP removes all objects from the current group. The following prompts are displayed. Breaks up the group that you select into its component objects