Addition of $HCl$ to propene in the presence of peroxides gives:

The stereochemistry of the product formed in the following reaction is:

The number of possible organobromine compounds which can be obtained in the allylic bromination of $but-1-ene$ with $N-bromosuccinimide$ $(NBS)$ is

How many products will be formed in this reaction?

Which of the following is the major product obtained in the reaction of isobutylene with hydrogen bromide?

The number of sigma $(\sigma)$ bonds in but-$1$-ene is.......