$A$ beam of white light falling on a glass prism gets split up into seven colours marked $1$ to $7$ as shown in the diagram.
$(a)$ The colours at positions marked $3$ and $5$ are similar to the colour of the sky and the colour of gold metal respectively. Is the above statement made by the student correct or incorrect? Justify.
$(b)$ Which of the above shown positions corresponds approximately to the colour of:
$(i)$ a brinjal
$(ii)$ danger signal
$(iii)$ neel (indigo) which is applied to clothes
$(iv)$ orange

(N/A) As a result of dispersion produced by the prism,the white light is split up into seven colours. These colours are represented by the acronym '$VIBGYOR$' in the order of increasing deviation: $1$ (Red),$2$ (Orange),$3$ (Yellow),$4$ (Green),$5$ (Blue),$6$ (Indigo),$7$ (Violet). Thus,the colour at position $3$ is yellow and at position $5$ is blue. The student's statement is incorrect because the sky is blue and gold is yellow,which corresponds to positions $5$ and $3$ respectively,not $3$ and $5$.
$(b)$ The positions of the colours of the given objects are represented by:
$(i)$ Brinjal (Violet) $- 7$
$(ii)$ Danger signal (Red) $- 1$
$(iii)$ Neel (Indigo) $- 6$
$(iv)$ Orange (Orange) $- 2$