Answer
a) $\frac{\pi}{180}$ rad.
b) $\frac{\pi}{6}$ rad.
c) $\frac{5\pi}{36}$ rad.
d) $\frac{2\pi}{3}$ rad.
Work Step by Step
a) $(1\times\frac{\pi}{180})rad = \frac{\pi}{180} rad$
b) $(30\times\frac{\pi}{180})rad = \frac{\pi}{6}rad$
c) $(25\times\frac{\pi}{180})rad = \frac{5\pi}{36}rad$
d) $(120\times\frac{\pi}{180})rad = \frac{2\pi}{3}rad$
( Mentioning unit is not compulsory as the angle is in radians)