(i)** **When a ray of light travel from denser to rarer medium, the refracted ray bonds away from the natural

Correct option is** (A)**

(ii)** **Critical angle \(\theta = sin^{-1}\left(\frac{n_{air}}{n_{water}}\right)\)

\(\theta = sin^{-1}\left(\frac1{1.33}\right)\)

\(\theta = 48.75^\circ\)

Correct option is **(c) water**

(iii)** **Critical angle \(\theta = sin^{-1}\left(\frac{n_2}{n_1}\right)\)

\(\theta = sin^{-1}\left(\frac1{2}\right)\)

\(\theta = sin^{-1}\left(sin30^\circ\right)\)

\(\theta = 30^\circ\)

Correct option is **(b) 30°**

(iv)** **\(\theta = sin^{-1}\left(\frac1x\right)\)

\(sin\,\theta = \frac1{x}\)

\(x= \frac1{sin\,30^\circ}\)

x = 2

\(x = \frac c{v_m}\)

\(v = \frac{c}{x}\)

\(v = \frac{3\times10^8}{2}\)

v = 1.5 x 10^{8} m/s

Correct option is **(b) 1.5 x 10**^{8} m/s