In the following reaction, the major product(thermodynamically stable) is

${\left({\mathrm{CH}}_3\right)}_2\mathrm{C}=\mathrm{CH}-{\mathrm{CH}}_2\mathrm{Br}$ is 1-Bromo-3-methylbutane.

1-Bromo-3-methylbutane is also known as Isoamyl bromide, Isopentyl bromide. It is a colourless liquid. It has a higher density than water and is only slightly soluble in it. Vapors weigh more than air.