The S in buna-S refers to;
Answer & explanation
Correct answer: option 3
The S in Buna- S refers to styrene. Buna stands for butadiene and Na for sodium. Buna-S refers to styrene Butadiene Rubber (SBR). It is copolymer of buta-1,3-diene and styrene in the ratio of 3:1 in the presence of sodium.