Answer :
[tex]\begin{gathered} n1sin\theta1=n2sin\theta2 \\ 1sin(90)=1.35sin\theta2 \\ \theta2=47.79\degree \end{gathered}[/tex]
First, you have to use Snell's law to calculate the refractive angle. Remember the light enters at a 90 angle and the refractive index of air is 1.
[tex]\begin{gathered} h\cdot sin\theta2=1m \\ h=\frac{1}{sin(47.79)}=1.35m \end{gathered}[/tex]