Wavelength of a colour of light for air is $6000\;\mathring{A}$ and in water the wavelength is $4500\;\mathring{A}$. What is the speed of light in water.

Question

$(a)\;5.0 \times 10^{14}m/s \\ (b)\;2.25 \times 10^8 m/s \\ (c)\;4.0 \times 10^8 m/s \\ (d)\;1.5 \times 10^{14} $