Find the refractive index of glass with respect to water. The refractive indices of glass and air with respect to air are $3/2$ and $4/3$ respectively.

The correct option is B $9/8$
Refractive index of medium $1$ with respect to medium $2$, ${}^1{\mu }_2=\frac{{\mu }_2}{{\mu }_1}$

Refractive index of glass with respect to air, ${}^g{\mu }_a=\frac{3}{2}$

Refractive index of water with respect to air,${}^w{\mu }_a=\frac{4}{3}$

${}^g{\mu }_a=\frac{{\mu }^a}{{\mu }^g}$

${}^w{\mu }_a=\frac{{\mu }^a}{{\mu }^g}$

$\therefore \text{refractive index of glass with respect to water,}{}^g{\mu }_w=\frac{{\mu }_w}{{\mu }_a}\times \frac{{\mu }_a}{{\mu }_g}=\frac{{}^g{\mu }_a}{{}^w{\mu }_a}=\frac{3}{2}\times \frac{3}{4}=\frac{9}{8}$