Question

if the source of frequency 220 Hz moves towards a stationary observer in space what will be the apparent frequency.

Answer 1

we know Doppler effect in sound
f=f'{(v-v')/(v-v")}
where f is apparent frequency as experience by observer.
f' is actual frequency emitted by source. v is speed of sound in medium
v' is speed of observer w.r.t medium
v" is speed of source w.r.t medium
now
f=220 {v/(v-v")}