Question

Ultrasonic waves are used for stirring liquid solutions because they ________.

• A. can produce perfectly homogenous solutions
• B. do not produce chemical reactions in the solution
• C. are easy to produce
• D. do not produce noise during the operation

Answer 1

The correct option is C are easy to produce

Ultrasonic waves can be easily produced using piezoelectric materials.

These waves have frequency above hearing range of human ear, i.e. above $20,000Hz$.

So these won't be heard, and can be easily used to vibrate and stir the chemical solutions.