Which of the following statements are correct?
(i) Sound is produced by vibrations.
(ii) Sound requires a medium for propagation.
(iii) Light and sound both require a medium for propagation.
(iv) Sound travels slower than light.
Option (iii) is incorrect. As light do not need any medium for propagation. It can also travel in vacuum too. On the other hand, sound needs a medium for propagation. All other options are correct.