An empty vessel is partially filled with water. What happens to the frequency of vibration of the air column in the vessel?

The fundamental frequencies of vibrations of an air column in a pipe open at both ends and in a pipe closed at one end are $n_1$ and $n_2$ respectively. If both pipes have the same length $L$,then:

$A$ pipe closed at one end produces a fundamental note of $412 \, Hz$. It is cut into two pieces of equal length. The fundamental notes produced by the two pieces are:

$A$ student determines the velocity of sound with the help of a closed organ pipe. If the observed length for the fundamental frequency is $24.7 \, cm$,the length for the third harmonic will be .... $cm$.

$A$ man can hear sounds in the frequency range $120 \, Hz$ to $12020 \, Hz$ only. He is vibrating a piano string having a tension of $240 \, N$ and a mass of $3 \, g$. The string has a length of $8 \, m$. How many different frequencies can he hear?

An organ pipe $P_1$, closed at one end and containing a gas of density $\rho_1$ is vibrating in its first harmonic. Another organ pipe $P_2$, open at both ends and containing a gas of density $\rho_2$ is vibrating in its third harmonic. Both the pipes are in resonance with a given tuning fork. If the compressibility of gases is equal in both pipes, the ratio of the lengths of $P_1$ and $P_2$ is (assume the given gases to be monoatomic)