Question

How will the fundamental frequency of a closed organ pipe be affected if instead of air, it is filled with a gas heavier than air?

Answer 1

Fundamental frequency of a closed organ pipe is, v = v - 4l, where v is the velocity of sound in air. When air is replaced by gas heavier than air, then velocity of sound in gas will decrease. (Because, v ∝ 1/√ρ, where ρ is the density of the gas)

Hence, the fundamental frequency will also decrease.