When there is no external torque acting on a rotating body, which of the following quantities can change ? (i) Angular acceleration (ii) Angular momentum (iii) Angular speed.

Explanation

To solve the problem, we need to analyze the three quantities mentioned: angular acceleration, angular momentum, and angular speed, in the context of a rotating body with no external torque acting on it.

### Step-by-Step Solution:

1. **Understanding Torque and Angular Momentum:**
- According to the rotational dynamics, the relationship between torque (τ), angular momentum (L), and angular acceleration (α) is given by:
\[
\tau = \frac{dL}{dt} = I \cdot \alpha
...