Question

why are some elements and medicines are stored in coloured bottles

Answer 1

this is  Because some chemicals and medicines decompose in the presence of light .So in order to protect it , they are stored in coloured bottles. This is because some chemicals are photosensitive meaning that they break down when exposed to light.

Answer 2

this is because the effect of light on these substances when kept in transparent bottles may disintegrate the substance. thus they are kept in coloured bottles.