Question

which thread is called synthetic silk

Answer 1

rayon is called synthetic silk as it is a synthetic fiber having all characteristics of silk and is made up of chemical treatment of wood pulp so it's called synthetic silk
hope this helps

Answer 2

Rayon is called As Artificial Silk or Synthetic silk.
It is also called as Semi synthetic silk due to Following Reasons :

---> It is produced from Wood pulp by chemical treatment.
--->Wood pulp is dissolved in alkaline solution like NaOH solution to form a sticky liquid called as Viscose.
---> Viscose is forced to pass through the tiny holes of a metal cylinder called as Spinneret into a solution of sulphuric acid where silk like fibre is obtained.

Hence Rayon is called As Synthetic silk and it is cheaper than natural silk .