In Buna-S, the symbol Bu stands for

Step-by-step solution

When a mixture of 1,3 -butadiene and styrene in the ratio of 3: 1 and in presence of sodium undergoes copolymerisation, it gives styrene butadiene copolymer commonly called as styrene butadiene rubber. (SBR) or Buna-S In Buna-S, Bu stands for butadiene, Na for sodium which is the polymerising agent and S stands for styrene.