Statement 1: When white light ray passes through a prism, it disperses into seven different colours, and this phenomenon is called dispersion.
Statement 2: In a refracting media, lights of different colour travel at different speed.
Statement 1 and 2 are correct and statement 2 is the correct reason for statement 1.
The splitting of white light into its component colours(VIBGYOR) when passing through a refractive medium is Dispersion'. The cause of this phenomenon is the change in the speed of light with wavelength.
That is, in a refracting medium, lights of different colour travel at different speed. The speed of violet colour(least wavelength) is the least and of the red colour(greatest wavelength) is the greatest. For example, when light travels from air into water, it slows down, causing it to continue to travel at a different angle or direction and so they split into the colour spectrum. So, Statement 1 and 2 are correct and statement 2 is the correct reason for statement 1.