How do you use the phenomenon of beats for determination of unknown frequencies ?

The phenomenon of beat is due to

The phenomenon of beats can take place

name any one use of the phenomenon of beats.

Explain how the phenomenon of beats may be used for finding the unknown frequency of a tuning fork.

Discuss the experimental demonstration of the formation of beats. How can we find the unknown frequency of a fork (i) by loading with wax (ii) by filing fork ?

The number of correct statements are 1) Maximum intensity of sound(waxing) is produced in the beats when constructive interference takes place II) Minimum intensity of sound(waning) is produced in the beats when destructive interference takes place III) Beats phenomenon used to detect the presence of dangerous gases in mines IV) Beats phenomenon used to detect unknown frequency of a tuning fork with the help of a standard tuning fork