Q. A particle moves through an angle to 1.5 radians in 3 sec. Calculate its angular velocity.

One complete revolution is equal to $2\pi$ radians.
Given the angle moved $\theta = 1.5\pi$ radians.

The number of complete revolutions is $\boxed{0.75 \text{ revolutions}}$.

Part [ii]: Angular velocity

Angular velocity ($\omega$) is the rate of change of angular displacement.

Given angular displacement $\theta = 1.5\pi$ radians.
Given time taken $t = 3$ seconds.

Using $\pi \approx 3.14159$:

The angular velocity is $\boxed{0.5\pi \text{ rad/s}}$ or approximately $\boxed{1.57 \text{ rad/s}}$.