Question

Draw a curve showing density or pressure variations with respect to distance for a disturbance produced by sound. Mark the position of compression and rarefaction on this curve. Also define wavelengths and time period using this curve :

Answer 1

Wavelength is the distance between consecutive corresponding points of the same phase, such as crests, troughs, compressions, rarefactions or zero crossings and is a characteristic of both traveling waves and standing waves. Wavelength is commonly designated by the Greek letter lambda ($\lambda$).
Frequency ( inverse of time period) is the number of complete vibrational cycles of a medium per a given amount of time. The unit for frequency is the Hertz (abbreviated Hz) where 1 Hz is equivalent to 1 cycle/second.
Below is the diagram showing density or pressure variations with respect to distance for a disturbance produced by sound.