You are attempting to create a standing wave with n=7 in a pipe

You are attempting to
create a standing wave with n=7 in a pipe 0.50m in length and
filled with air. the top of the pipe is open to the air and the
bottom of the pipe is barely submerged in water and thus
closed.

a) Draw the diagram
for this standing wave with the proper number of nodes and
antinodes for this open-closed pipe.

b) Calculate the
frequency created by this standing wave assuming the air is at room
temperature.