Glass is a very brittle material and likes to crack and shatter under pressure. It would not be possible to cleanly cut glass using scissors without cracks appearing, and a high risk of the glass shattering.
Glass is an amorphous solid which means unlike most solids, it has no repeating arrangement of molecules within its structure. The glass used to make drinking vessels and windows is composed of around 75% silica mixed with sodium oxide and calcium oxide – known as soda-lime glass.
The best way to cut this type of glass is by scoring the line you want to cut with a glass cutter, then applying some pressure to both sides of this line to make a clean break.
Answered by Rik Sargent