Answer: (b) (ii)
When the prism is reversed, the colours that are noticed after dispersion are: VIBGYOR. As a result, figure (ii) is the correct image to obtain the third colour, which is blue, as the colour of the sky.
- Band of colour show violet at the bottom of the prism is kept with BC in the bottom.
- If the prism is kept with BC at the top, then violet will be at the top followed by indigo and blue.