a.
In order to calculate the angle of refraction, we can use the law of refraction below:
![n_1sin\theta_1=n_2sin\theta_2](https://img.qammunity.org/2023/formulas/physics/college/5kexpplllqp42dmbn6enbpf4872y2wk2xh.png)
Where n1 and n2 are the index of refraction and theta1 and theta2 are the incident and refracted angles.
So, using n1 = 1.33, theta1 = 15° and n2 = 2.42, we have:
![\begin{gathered} 1.33*sin\left(15°\right)=2.42*sin\theta_2 \\ 1.33*0.258819=2.42*sin\theta_2 \\ 0.34422927=2.42*sin\theta_2 \\ sin\theta_2=(0.34422927)/(2.42) \\ sin\theta_2=0.1422435 \\ \theta_2=8.18° \end{gathered}](https://img.qammunity.org/2023/formulas/physics/college/f72satkaui7udv6z6ogxjlmly55xmr88my.png)
b.
To calculate the velocity of light in diamond, we can use the formula below:
![\begin{gathered} n=(c)/(v) \\ 2.42=(3*10^8)/(v) \\ v=(3*10^8)/(2.42) \\ v=1.24*10^8\text{ m/s} \end{gathered}](https://img.qammunity.org/2023/formulas/physics/college/uiirljgshv24ius9kp7bt7s1pzosohbnuz.png)