Organ Pipes Questions

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

If we study the vibration of a pipe open at both ends, then which of the following statements is not true?

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

An air column, closed at one end and open at the other, resonates with a tuning fork when the smallest length of the column is $50\text{cm}$. The next larger length of the column resonating with the same tuning fork is:

The second overtone of an open organ pipe has the same frequency as the first overtone of a closed pipe $L$ meter long. The length of the open pipe will be: