The refractive index of water is:

The speed of light in substance X is 1.25 x 10⁸ m/s and that in air is 3 x 10⁸ m/s. The refractive index of this substance will be:

The refractive indexes of four substances P, Q, R and S are 1.57, 1.54, 2.52 and 1.33 respectively. When light travelling in air is incident on these substances at equal angles, the angle of refraction will be the maximum in:

The refractive index of water with respect to air is 4/3. The refractive index of air with respect to water will be:

Refractive indices of water, sulphuric acid, glass and carbon disulphide are 1.33, 1.43, 1.53 and 1.63 respectively. The light travels slowest in: