Is a viola an example of idiophone?

No, a viola is not an example of an idiophone. Idiophones are musical instruments that produce sound primarily through the vibration of the instrument itself, rather than through stretched membranes, strings, or air. Examples of idiophones include xylophones, marimbas, and triangles. A viola, on the other hand, is a stringed instrument, which means that it produces sound through the vibration of strings.