$A$ pipe $30 \, cm$ long is open at both ends. Which harmonic mode of the pipe resonates with a $1.1 \, kHz$ source? (Speed of sound in air $= 330 \, m/s$)

The fundamental frequency of an open pipe is $n$. If it is closed from one end, then the frequency of the $2^{nd}$ harmonic of the closed pipe is higher by $200 \,Hz$ than $n$. The value of $n$ is: (in $\,Hz$)

$A$ pipe open at both ends has a fundamental frequency $f$ in air. The pipe is dipped vertically in water so that half of its length is in water. The fundamental frequency of the air column is now ..... $f$.

An air column in a pipe which is closed at one end will be in resonance with a vibrating tuning fork of frequency $415$ Hz for various vibrating air columns. Which one of the following lengths is not in resonance (in $cm$)? (Velocity of sound in air = $332$ m/s) (Neglect end correction)

$A$ gas is filled in an organ pipe and it is sounded in its fundamental mode. Choose the correct statement$(s)$ : ($T$ = constant)

$A$ 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 $300 \,m/s$).