Baeyer's reagent is used for the detection of

The major product of the following reaction is:

Assertion : Addition of $HBr$ on $2-$butene gives two isomeric products.
Reason : Addition of $HBr$ on $2-$butene follows Markovnikov rule.

What is the product of the following reaction?

Unsaturation in organic compounds is detected by ...........

Identify the product of ozonolysis of $but-2-ene$ from the following: