The number of possible natural oscillations of air column in a pipe closed at one end of length 85   c m whose frequencies lies below 1250   H z are: (velocity of sound = 340   m s - 1 )

Step-by-step solution

Fundamental frequency of a closed organ pipe is f 1 = V 4 l = 340 4 × 0.85 = 100   H z The natural frequencies of the organ pipe will be f = 100   H z ,   300   H z ,   500   H z ,   700   H z ,   900   H z ,   1100   H z which are below 1250   H z