$A$ pipe $17 \, cm$ long is closed at one end. Which harmonic mode of the pipe resonates with a $1.5 \, kHz$ source? (Speed of sound in air $= 340 \, m \, s^{-1}$)

$A$ pipe $20$ $cm$ long is closed at one end. Which harmonic mode of the pipe is resonantly excited by a source of $1237.5$ $Hz$? (Speed of sound in air $= 330$ $m/s$).

$A$ closed pipe is suddenly opened and changed to an open pipe of the same length. The fundamental frequency of the resulting open pipe is less than that of the $3^{rd}$ harmonic of the earlier closed pipe by $55 \,Hz$. Then, the value of the fundamental frequency of the closed pipe is: (in $\,Hz$)

If the lengths of the open and closed pipes are in the ratio of $2 : 3$, then the ratio of the frequencies of the third harmonic of the open pipe and the fifth harmonic of the closed pipe is

$A$ cylindrical tube open at both ends has a fundamental frequency $f$ in air. The tube is dipped vertically in water so that $60 \%$ of the tube is in water. Then the fundamental frequency of the air column is

An organ pipe $P_1$ closed at one end is vibrating in its first overtone. Another pipe $P_2$ open at both ends is vibrating in its third overtone. They are in resonance with a given tuning fork. The ratio of the length of $P_1$ to that of $P_2$ is