Question

The frequency of the sound emitted by an organ pipe will increase if the air in it is replaced by
1) Hot air
2) Moist air
3) Hydrogen

• A. 1 is true
• B. 1,2 are true
• C. 2,3 are true
• D. 1,2,3 are true

Answer 1

The correct option is D 1,2,3 are true

Velocity of sound is directly proportional to the density of the medium in which the wave travels. So, when it comes to moist and dry air, the density of moist air is more than that of dry air.
Therefore, the velocity of sound in moist air will be more than the velocity of sound in dry air.
$v$ $\propto$ $\nu$

$\nu =\text{frequency}$

$v=\text{velocity of sound}$