Because the double bonds open up to create a dibromoalkane which is colourless. If it's added to an alkane then nothing happens therefore it remains in its original colour which is orange.
Because the double bonds open up to create a dibromoalkane which is colourless. If it's added to an alkane then nothing happens therefore it remains in its original colour which is orange.
It will still change colour... (unless in darkness)
Bromine can add to the double bond to form a brominium ion and then water or a br- ion can attack one of the carbons bonded to the brominium ion in an sn2 fashion