Answer
a). $25^{\circ}$
b). $1.97\times10^{8}m/s$
c). $362nm$
Work Step by Step
a). By Snell's law,
$n_{a} sin(i) = n_{g} sin (r)$
Thus, $sin(r) = \frac{sin40^{\circ}}{1.52}$
Thus, $r=25^{\circ}$
b). $velocity=\frac{c}{index}=\frac{3\times10^{8}}{1.52}=1.97\times10^{8}m/s$
c). $Wavelength _{glass}= \frac{Wavelength_{air}}{index_{glass}}=\frac{550nm}{1.52}=362nm$