$A$ cylindrical tube open at both ends has a fundamental frequency of $390 \,Hz$ in air. If $\frac{1}{4}$th of the tube is immersed vertically in water, what is the fundamental frequency of the air column (in $\,Hz$)?

The number of possible natural oscillations of an air column in a pipe closed at one end of length $85 \, cm$ whose frequencies lie below $1250 \, Hz$ are (Velocity of sound $= 340 \, m s^{-1}$)

$A$ tube closed at one end and containing air is excited. It produces the fundamental note of frequency $512 \ Hz$. If the same tube is open at both ends,the fundamental frequency that can be produced is .... $Hz$.

$A$ closed pipe of length $300 \,cm$ contains some sand. $A$ speaker is connected at one of its ends. The frequency of the speaker at which the sand will arrange itself in $20$ equidistant piles is close to .......... $kHz$ (velocity of sound is $300 \,m/s$).

In a closed organ pipe, the number of nodes formed in the fifth and ninth harmonics are respectively:

An open organ pipe and a closed organ pipe have the frequency of their first overtone identical. The ratio of the length of the open pipe to that of the closed pipe is