Question

why halogens are coloured?

Answer 1

halogens have unpaired electrons in their outermost shell or orbital.... ant
d these emitted photons lies in the visible range to the human eye and hence they look coloured

Answer 2

Hey !!

All Halogens are coloured. This is due to absorption of radiation in visible region which results in the excitation of outer electrons to higher energy level while the remaining ligh is transmitted. The colour of the halogen is the colour of transmitted light.

Hope it helps you !!