Question

what are silicones? Give their application

Answer 1

Synthetic material which are polymer with a chemical structure based on chain of alternate silicon or oxygen, atom with organic grp attached to silicon grps

Answer 2

silicon is prepared of repeativity units of siloxane which is a functional group of 2 silicon atoms and 1 oxygen atom frequently combined with carbon and/or hydrogen.

they are used in many aspects of aircraft and spacecraft assembly and maintenance. 
Adhesives and sealants are used to seal and protect the following from the elements: doors, windows, wings, fuel tanks, hydraulic switches, overhead bins, wing edges, leading gear electrical devices, vent ducts, engine gaskets, electrical wires and black boxes.