Optical phenomena taking place for a mirror and a lens respectively are . . . . . . and . . . . . . .

In refraction,light waves are bent on passing from one medium to a second medium because,in the second medium,

As shown in the figure,after passing through medium $1$,the speed of light $v_{2}$ in medium $2$ will be $..... \times 10^{8} \, ms^{-1}$. (Given $c = 3 \times 10^{8} \, ms^{-1}$)

Light of wavelength $7200 \ \mathring{A}$ in air. It has a wavelength in glass $(\mu = 1.5)$ equal to.......$\mathring{A}$

$A$ ray of light travelling in air has wavelength $\lambda$,frequency $n$,velocity $v$,and intensity $I$. If this ray enters into water,then these parameters are $\lambda'$,$n'$,$v'$,and $I'$ respectively. Which relation is correct from the following?

$A$ glass cube of length $24 \ cm$ has a small air bubble trapped inside. When viewed normally from one face,it is $10 \ cm$ below the surface. When viewed normally from the opposite face,its apparent distance is $6 \ cm$. The refractive index of glass is: