List of top Physical Sciences Questions on Waves

Reason for the blue colour of the sky is
The unit for refractive index is
Loudness depends on
A person can hear a sound of frequency
Which of the following statements are correct?
(i) Velocity of sound waves is greater in solids than liquids.
(ii) Velocity of sound waves in vacuum is 330 m/s.
(iii) Sound waves are longitudinal waves.
(iv) Velocity of sound waves in vacuum is zero.